Throat tighter than rest of barrel on Walther PPQ

[Inferno451]

I've been casting for a while now, but just starting to cast for my new PPQ, which I absolutely LOVE. I'm getting HORRENDOUS leading after only 15-20 rounds. Picture the surface of the moon, it's that bad. The leading only starts about 3/4 of an inch past the chamber, squeaky clean before that. Current load is 3.4 grains of IMR PB under a lee TL356-124-TC with a fairly heavy coat of recluse lube. I get the same amount of leading regardless of powder charge. I'm getting some very interesting results slugging the bore that don't seem quite right to me. Long story short, if I slug the bore from the chamber end, there is resistance on the slug until it gets past through the throat area and no resistance whatsoever after that. It will literally fall to the end of the barrel under it's own weight once pushed through the throat. The final diameter of the slug doing it this way is around .3525, which seems awfully small to me. However, if I slug from the muzzle end and only go halfway through the barrel then push the slug back out, resistance is even all the way through and the diameter ends up being around .355. Seems like the throat is considerably tighter than the rest of the barrel. This can't possibly be normal can it? Pics below-

First slug from chamber end w/ final diameter

http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_181754482_zpsk7pikxot.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_181754482_zpsk7pikxot.jpg.html)

One of my bullets from chamber end w/ measurements before and after
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_175003195_zpsycmtw9pe.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_175003195_zpsycmtw9pe.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_175802839_zpsbvg6wnin.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_175802839_zpsbvg6wnin.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_175117265_zpsywwutam3.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_175117265_zpsywwutam3.jpg.html)

Slug from muzzle end only halfway through barrel w/ final diameter
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_181706201_HDR_zpsqd5fri0e.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_181706201_HDR_zpsqd5fri0e.jpg.html)

One of my bullets from muzzle end only halfway w/ measurements before and after
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_180229177_zpsf3jjpxlb.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_180229177_zpsf3jjpxlb.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_180255426_zpslrqlhrjs.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_180255426_zpslrqlhrjs.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_180556735_zpsjjtj7iop.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_180556735_zpsjjtj7iop.jpg.html)

Here's the point in the barrel where resistance ends (when slugging from the chamber end)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150326_180700486_zpsoxzzebna.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150326_180700486_zpsoxzzebna.jpg.html)

[Wayne Smith]

I assume you mean PPK? I'd send this to Walther. They ought to send you a new barrel, but we'll see how they respond. Is this one made in Maine or Germany?

[Inferno451]

No, this is a PPQ, Walther's midsize, double stack, striker fired pistol. SoI'm not crazy and this is a definite barrel problem? This is what a PPQ looks like:
http://i775.photobucket.com/albums/yy32/inferno451/walther-ppq-m1-right-side_zpsmodlqqt2.jpg (http://s775.photobucket.com/user/inferno451/media/walther-ppq-m1-right-side_zpsmodlqqt2.jpg.html)

[Echo]

Definitely a bbl problem. Advice given was good - I would do it...

[Errokk]

You need to contact Smith & Wesson. They handle warranty issues here in the states for Walther. That is definitely a barrel issue.
I have a PPX and you now have me worried! lol

[MT Gianni]

BBL problem but that tl lube bullet will not help things.

[DougGuy]

I have 9mm reamer and mandrel for crown cutter arriving tomorrow. I could definitely throat out the tight part of that and you can size to .357" afterwards. If you don't send it back in, shoot me a PM and we can get it started.

I see you are new here and this is a bit of an odd problem but I do a lot of cylinder throats and barrel throats for people here, and I'd be at least willing to look at it and see if a throating reamer and some polishing could fix it. I guarantee results will be better than what you have now.

[Inferno451]

I just got off the phone with Walther. The service rep I talked to said that only test with factory jacketed ammo and if it functions ok with that then they'll just send it back. They don't care how it shoots with hard cast bullets. He said I'd have to send it in on my own dime overnight (about $70) and then $30 return shipping if they don't see a problem with it. I have to say, I really like the gun, but I'm not real impressed with how they're handling a manufacturing error on a 3 week old gun. If I send it in does anybody have any recommendations on what I could put in a short letter explaining the problem that would make them actually consider doing something about it?

[DougGuy]

This is what a properly throated barrel looks like.

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/1911%20Crowning/DSC03634crop_zpsldtviwoo.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/1911%20Crowning/DSC03634crop_zpsldtviwoo.jpg.html)

The rifling, starts farther up the bore and it allows chambering of cast boolits which when that rifling is right down to the mouth of the chamber, boolits don't even want to load unless you seat them farther down in the case. I do this service as a convenience to members here, I have done a lot of them and have a solid reputation on the forum for quality work, fast turnaround time, and very affordable prices.

In your case, it sounds like a bit of a constriction more so than the rifling too close to the chamber mouth. It may need a longer section of "freebore" which is the smooth, parallel, unrifled portion of bore before the leade in begins. This actually makes a great cast boolit barrel in that it lowers pressure, increases velocity, greatly decreases leading, and shrinks group sizes noticeably. I would be glad to look at your barrel.

[Inferno451]

Here are the best pictures I could get of the throat. There's very little freebore before the rifling starts tapering in, maybe 1mm at most. Nowhere near as much as in Dougguy's barrel. It's really a shame about the throat, the bore is really beautiful, absolute mirror shine all the way through.

http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150327_133127345_HDR_zpsxgq8yynm.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150327_133127345_HDR_zpsxgq8yynm.jpg.html)

http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150327_133244731_HDR_zpsucie2ajm.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150327_133244731_HDR_zpsucie2ajm.jpg.html)

[dilly]

Your emphasis with the customer service representative shouldn't be how it shoots with cast bullets, but whether or not it is in specification. You should still hypothetically experience greatly reduced accuracy with jacketed bullets being sized down to .352, so the point is moot.

Remember, most manufacturers don't acknowledge reloading as a legitimate source of ammunition.

P.S. Reaming may wind up being cheaper than shipping anyway. Consider Doug's offer as a possible fix.

[shooter93]

The infamous..." oh it's in spec" Save time money and grief and send it to Doug or look for a local smith who does that kind of work.

[35remington]

Well.....let me point out that you don't HAVE to have the length of throat shown in DG's barrel. In fact, my preference is to have less throat than he's showing, but you still need clearance for the bullet to fit seated at your chosen OAL. You don't need that much of a throat to chamber most correct OAL cast bullet ammo.....but you do have to have some throat with many cast bullet loads.

That last sentence wasn't opinion, but rather fact.

But....in your instance, the throat YOU need is the amount that removes the restriction, assuming it is near the chamber only and you don't have to rebore half the barrel to get rid of it.

So what you need may be different than my preferences, but I'll reiterate in most instances very little throat lengthening is needed for most barrels to get them to work. Yours may be an exception and need a bit longer throat to get rid of the restriction.

I'm guessing your issue is like most though....a sharp leade and no throat. In that case a small amount of throating is all that is needed.

[Inferno451]

These truncated cone bullets are pretty short, there is no issue with feeding and chambering at my OAL. I'll give Walther a call again on monday and see if we can work something out. I'll keep this thread updated and report back.

[Errokk]

That's a good idea to call them again because your barrel is not in spec, at least to my standard. I'd reiterate to them the lack of accuracy with factory ammo. Might be a good idea to take it out and shoot some factory ammo and see if your getting copper/brass build up in the barrel, depending on jacket metal.

[Handloader109]

Well I have a strong feeling that all of these barrels are the same. And not a manufacturing defect. My ppq needs 356 sizing I didn't measure mine that well due to the **** calipers I HaD, but was about 355 or 354 if I remember. Shoots fmj fine with better than I can shoot accuracy, BTW, op didn't say factory didn't shoot well...... But I have only decent accuracy with cast. But it is a handgun and not a rifle. Walther and other manufacturers don't really care if you are shooting cast. Good luck, but I think you and the rest of us shooting cast are on our own

[Inferno451]

Handloader109, it wouldn't matter what sized bullet i used. Any size bullet is going to be sized down to .352 in the throat and then be 3 thousands too small for the last 3.5 inches of the barrel. I think that's what's causing the leading. I can compensate for for any groove diameter as long as it's consistent through the whole barrel.

[RadarsRUs]

Anyone want to comment on doing an LBT LAPPING-Bullet treatment? Just performed this procedure on a lever gun and results were Fantastic. Not many rounds required and all "tight" areas of bore now uniform effort to push slug though...

[gloob]

Hmmm. What's so special about LBT lapping compound? I would probably just melt some chromium oxide buffing bar into my tumble lube. :)

[dilly]

I would think that by the time you fire lapped (if that's what you mean, because throat reaming could be followed up by a manual lapping to smooth things out) the throat to that degree, the rifling would be overly deteriorated. I think it might be too much material removal for fire lapping.

[243winxb]

Defect, return or repair, Walther PPQ

[Inferno451]

See post #8, I don't think Walther will fix it if I send it in, and Shipping there and back would be on my own dime. I submitted another repair request through their email system yesterday and i'm waiting to hear back. I called a local gunsmith and he told me there's nothing that can be done without removing too much rifling.

[gloob]

Maybe you could start with hand lapping, using a slug.

Logically, if the slug is falling through the bore, both the lands and the grooves are too small in the constriction. Drill and tap your slug and lap that area. Check your progress every now and then by visual inspection and re-slugging the bore, and use that slug as your next lap.

I would apply the lapping compound to the stricture, and insert the slug from the muzzle end, wiping out the bore between each new slug-lap.

I'm thinking this is an excuse to buy a padded vice to hold the barrel and to make/buy a slide hammer to move the slug back and forth.

When you reslug from the chamber end, and the slug no longer falls through on its own, stop and carefully measure. Compare a slug to one from just partway down the muzzle end. At this point, you will see what kind of duck you have, and whether it can be fixed, easily. If you're lucky, you will have made some progress at this point. At any rate, as long as the slug is still falling through, you have done no damage, yet, as far as I can see. So if you stop at this point and check your work, I think you should be safe.

I'm REALLY curious whether other PPQ barrels have the same geometry. It seems odd to me that this should occur in a single pistol barrel.

[dubber123]

The constriction could be confined to just a few thousandths right in front of the chamber. If you don't have faith in Walther fixing it for you, I'd send it to Doug for throating. You stand a very good chance of this fixing the issue, and if it doesn't, in my opinion, it will set you up better for firelapping. Firelapping by the way, is not hard, and has worked every time for me. Good luck.

[RadarsRUs]

Similar to the way many revolvers are choked just ahead of the forcing cone because that is where the barrel threads into the frame (and constricts bore ID)...just in an automatic. Prob caused by some forging or shaping in the barrel hood area (or something).

There are enough solid accounts of guys using LBT LAPPING compound rolled into the driving bands of fairly soft lead bullets and then fired to turn so-so revolvers into Superstar revolvers that it would be purely a closed-mind to not investigate it.

Veral (LBT) makes his own proprietary goo (as well as very premium molds) which is the carrier to roll the bullets in. This guy has forgotten more than most folks will ever know about barrels, chambers, free-bore, rifling, bullet fit, in-the-bore accuracy, etc.

For goodness sake, just research it and talk to / e.mail him... He is a strait shooter and will not ******** you. Proved it to me In SPADES and now I am a big Fan!

[dubber123]

I respect Veral and his accomplishments. I've been quite satisfied using 320 grit valve grinding compound from the auto parts store. Before your scream "TOO COARSE", you should see what a bore looks like after using it. It's not voodoo guys..

[DougGuy]

This is part of the solution we are talking about. Not Taylor throating, but throating a section of bore .3585" until there is no more constriction in the barrel. You can feel this choke with a cleaning rod and a tight patched jag, get it real tight and force it down the bore. When it gets to the tight spot, it will get even harder to push. Well, this is exactly what the bore subjects the boolit to coming the other way.

I'd like to use today's work as an example to explain what (IMHO) will cure this barrel of it's problem.

These are a pair of Lone Wolf barrels I throated today for a Glock. The owner of the Glock has a 10mm barrel, and this .40 caliber barrel he uses interchangeably in the same pistol. He asked me if I could throat the barrel so that it would chamber and fire the .40 S&W loaded out to the same COA as the 10mm. His throat now has .230" worth of .4025" freebore in front of the chamber mouth, before the leade in to the rifling. It chambers the extra long seated rounds easily, and I am sure it will work out for his purposes. Here are the photos:

After throating and polishing, the 10mm barrel on the left (which required throating to .4025" since the factory throat was only .4015" and would not allow him to chamber a .402" boolit) and the long-throated .40 S&W barrel on the right:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Glock%20Throating/DSC03908crop768_zps1r2bypzc.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Glock%20Throating/DSC03908crop768_zps1r2bypzc.jpg.html)

.40 S&W loads seated to 10mm COA:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Glock%20Throating/DSC03877crop768_zpsl5liu2nm.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Glock%20Throating/DSC03877crop768_zpsl5liu2nm.jpg.html)

Lone Wolf .40 S&W barrel after throating, but before lapping and polishing:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Glock%20Throating/DSC03883crop768_zpsqjkxtsob.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Glock%20Throating/DSC03883crop768_zpsqjkxtsob.jpg.html)

My suggestion for this Walther barrel is to throat it until there is no constriction remaining and polish it out. Freebore does some neat things. You can look for lower pressures, a gain in velocity, a LOT less leading, and groups often shrink noticeably. Read up on some of Ross Seyfried's writings about his findings with a Taylor Throated barrel. This is much the same principle, but a smaller freebore only .0005" over boolit diameter.

[Inferno451]

That certainly makes sense. I'm waiting to hear back from Walther customer service, but if they won't fix it I'll probably send it to Dougguy to work his magic.

[prs]

This bit about abrupt and sharp leades and with some revolver cylinders having cylinder throat smaller than barrel groove diameter seems to be too common these days. Back when I had Ruger Vaqueros with tight throats in the cylinders, I was told Ruger did it because they shoot copper clads better that way! I did not and do not buy into that as being so, but maybe Ruger did buy into it. I know for sure they shot better after having the cyinders opened to where the sized lead boolits would push through with a pencil. My SR 1911s also shoot MUCH better and with NO leading after creating some freebore and leade. Before, they leaded so badly and quickly that judging groups was near impossible as they went to H377 in a hand basket before a five shot group would be complete.

prs

[Char-Gar]

Just a couple of thoughts;

1. Calipers, especially digital ones are not the proper tool to take those measurements. The numbers derived are suspect. If your concern come from that source, then shoot the gun before coming to closure about thing.

2. About the only way the throat can be tighter than the rest of the barrel is if you have a two piece barrel. i.e. the barrel was press fit into the chamber and lug portion. This may be the source of your problem. The press fitting might have caused a choke in the breech end of the barrel.

3. If you are not happy after shooting cast bullets in your pistol, then have DougGuy or somebody like that throat your barrel.

[Ballistics in Scotland]

I just got off the phone with Walther. The service rep I talked to said that only test with factory jacketed ammo and if it functions ok with that then they'll just send it back. They don't care how it shoots with hard cast bullets. He said I'd have to send it in on my own dime overnight (about $70) and then $30 return shipping if they don't see a problem with it. I have to say, I really like the gun, but I'm not real impressed with how they're handling a manufacturing error on a 3 week old gun. If I send it in does anybody have any recommendations on what I could put in a short letter explaining the problem that would make them actually consider doing something about it?

It sounds like they have botched up customer service the way they have botched up barrelmaking. Have they really told you that they would deny you your rights if you use a non-overnight service?

I can't make out whether the portion containing the locking lugs, camming surfaces etc. is integral with the round part of the barrel. If not I would guess at over-tight threads or shrink-fitting, as sometimes happens with revolver barrel threads. If it is all one piece it would most likely be the thinner part expanding by button rifling, or springing back more after hammer-rifling.

Before letting Walther out of their obligations by working on the throat, you would have to make really sure it was going to work, and the bottoms of the grooves are just as important as the lands. I would make a cast of a considerable length of the bore, with cerrosafe rather than lead, and cut off as much as seemed constricted. Then by sliding the cast into the muzzle until it comes to a stop, you could measure exactly where the constriction begins.

I think poor accuracy would probably show up in Walther's testing with jacketed bullets, but I'm not completely sure. Besides, what is inaccuracy? It isn't a target pistol, and they may be staving off complaints from hundreds of owners by now. Leading of the bore is mostly caused by gas escaping through the bottom of the grooves, and blasting atomized lead ahead of the bullet. That is something unlikely to happen with jacketed bullets.

[Char-Gar]

Before folks get to hard on Walther, remember they design and produce a product to be used a certain way. They design their small pistols for use with jacketed bullet ammo. Folks who shoot handloaded cast bullets in these firearms are not their intended customers or bullets within their design parameters.

If somebody designs, makes and sells a coffee grinder and folks try and grind unshelled peanuts in it, the maker won't be to sympathetic to their complaints. The product just wasn't designed to do that.

I am quite certain Walther could design and produce a cast bullet friendly autopistol, but that is such a small market they chose not to. If we want to shoot cast bullet in these pistols, then we are the ones to force the pistols to comply with our non-design usage. That is on us, and we probably void the guarantee when we undertake to do that. That is just the way of these things.

[Ballistics in Scotland]

That is the sort of thing I had in mind when I wondered whether Walther might try to scrape through on saying it is up to their standards with jacketed bullets. But it is very hard to believe a pistol which loosens up after a brief constriction is giving the sort of performance with jacketed bullets which customer has a right to expect. They might even be less inclined than cast to expand and seal the bore.

The OP bought a bullet-shooting machine, and the coffee-grinder customer wouldn't have bought a small food item grinding machine.

[Char-Gar]

These are short range defensive pistols and not intended to target work where such niceties as bullet sealing might be important. Walther engineers set up accuracy standards for the intended use of their pistols, and design to those specs. They are what they are, which is not necessarily what a few customers want them to be.

The folks who handload in general and cast bullet in particular are not their intended customers. Most handgun makers, which I suppose included Walthers state that their handguns are not warranted for the use of handloads. You start running handloads through them you are on your own.

Being a cast bullet shooter and handloader, I am sympathetic to the OP plight. However, I am able to pull back from my sympathies far enough to realize Walther has a different point of view. When we buy any product and use it outside it's intended design use, the manufactures has no liability. The manufacturer has no responsibility to modify their products to non-design use.

And yes, I do teach Contract law which includes Product Liability law, so I am not guessing on these things. However, I thought this stuff was just plain common sense, but maybe it is not.

[GP100man]

DougGuy has fixed 5 revolvers for me & while I have`nt had time to group em all properly ,The shooting I have done I can tell they`re GOODER .

I`d spend my coin with DougGuy with confidence.

GP

[Ballistics in Scotland]

I believe I was the first to say this wasn't a target pistol, and we haven't heard from the OP whether accuracy with jacketed bullets is suffering. But I think he would most likely find that it is, relative to firearms of similar type and purpose.

If that is the case, it would seem to be arising from a physically demonstrable manufacturing defect. I expect common sense would say about the lifetime guarantee, for the first owner, expressed on Walther's American website:

WALTHER PPQ pistols are warranted to be free from defects in material and workmanship.
Any such defects of which WALTHER receives written notice by the original owner will be
remedied by WALTHER without charge within a reasonable time after such notification and
delivery of the PPQ pistol as provided below.

[Char-Gar]

I believe I was the first to say this wasn't a target pistol, and we haven't heard from the OP whether accuracy with jacketed bullets is suffering. But I think he would most likely find that it is, relative to firearms of similar type and purpose.

If that is the case, it would seem to be arising from a physically demonstrable manufacturing defect. I expect common sense would say about the lifetime guarantee, for the first owner, expressed on Walther's American website:

WALTHER PPQ pistols are warranted to be free from defects in material and workmanship.
Any such defects of which WALTHER receives written notice by the original owner will be
remedied by WALTHER without charge within a reasonable time after such notification and
delivery of the PPQ pistol as provided below.


Whether or not the pistol is defective, is a matter of opinion and the only opinion that matters is that of Walther.

If the original owner disagree with that, his recourse is legal action which has zero chance of success.

[blackthorn]

Quote "Whether or not the pistol is defective, is a matter of opinion and the only opinion that matters is that of Walther.

If the original owner disagree with that, his recourse is legal action which has zero chance of success."

No help to the OP on this problem--- BUT --- for all of us reading this, the lesson here is --- if you want a gun for cast --- Don't buy a Walther!!
As far as I am concerned, if that is the kind of policy a (any) company has, it is highly unlikely I will buy anything from them!

[Ballistics in Scotland]

And for most other purposes too. Still, I don't believe it has been definitely shown yet whether Walther will take that line.

[Char-Gar]

Quote "Whether or not the pistol is defective, is a matter of opinion and the only opinion that matters is that of Walther.

If the original owner disagree with that, his recourse is legal action which has zero chance of success."

No help to the OP on this problem--- BUT --- for all of us reading this, the lesson here is --- if you want a gun for cast --- Don't buy a Walther!!
As far as I am concerned, if that is the kind of policy a (any) company has, it is highly unlikely I will buy anything from them!

Yes, I think that is the lesson. Do your thinking and checking before you do your buying. This particular model by Walther has less than a sterling record anyway. I have owned PPKs (380) since 1965 and would not be without one. However, they are what they are. I have never fired a handload of any kind, jacketed or cast through one. I don't see them as a recreational firearm, but a social firearm.

It isn't just Walther either. There are number of firearms that are not cast bullet friendly because they were designed around jacketed bullet ammo. Most can be made to be cast bullet friendly, but that will be the owners job.

We need to buy our firearms to suit our purposes. Not all firearms suit all purposes. When they don't suit our purpose, whose fault is that, the designer, the maker or the purchaser?

[Char-Gar]

And for most other purposes too. Still, I don't believe it has been definitely shown yet whether Walther will take that line.

Yes, that is correct, but the OP did call Walther Customer Service and they told him they would test the firearm with jacketed ammo and if it fell within their standards, they would sent it back to him. I think there is a very good chance that is what they will do.

It would cost far less to pull the barrel and send it to DougGuy, which his probably what he will end up doing anyway.

[Inferno451]

A quick update for those following this thread-

A little more background on the situation: Purchase date on this pistol was 2/25/2015 from Budsgunshop, I took delivery of it on 3/6/2015. I am the original owner and warranty paperwork was submitted to Walther.

I've been talking with Buds and although they offer warranties on guns they sell, since Walther handles their own warranty, i have to deal with them. Buds has been great to work with and has graciously offered to pay for shipping to Walther CS. I will be calling Walther shortly to get some more information on turnaround time, ect. My wife and I are moving in a month and i'm not sure if Walther will ship to a different address than it came from. In response to some of the posts on this thread in regards to these pistols being designed around jacketed rounds, i completely agree. However, I can see no reason for a throat to be several thousandths smaller than the rifling, and though these are not target pistols, there must be some mechanical accuracy missing. How much I really couldn't say as i'm no marksman. I consider myself a decent shot and have been shooting for a long time, but without a ransom rest and some statement as to what accuracy standard these are held to I wouldn't feel comfortable saying the gun has a considerable lack of accuracy. I have slugged the barrel several more times to be sure of the restriction and i'm positive the throat is noticeably tighter than the rest of the barrel. It's true that digital calipers are not an ideal tool for this, but even just pushing the slug through the barrel from the muzzle end the restriction is noticeable. Takes a couple taps with a mallet to get the slug started, then very light tapping until it gets to the throat. At that point i have to pound on it a bit before it will pop out. From the chamber end i have to pound on the slug until it gets past the throat then it falls to the end of the barrel under it's own weight. That alone, regardless of measurement says pretty clearly that the barrel is very inconsistent in diameter.

[Errokk]

My opinion, if you like the gun, have the barrel fixed. If you dont, get rid of it.

[DougGuy]

The barrel is defective. Without a doubt. It is also dangerous in that it could cause an overly high pressure event which could possibly cause death or injury if it exploded. For them to balk at fixing it under THESE circumstances is reprehensible. Buds, who sold the gun, would ALSO be liable since they were the seller of the defective product. This is pure B.S. that Walther is not actively trying to get the gun in house so they can fix it, and absolve themselves of any liability the existing barrel might expose them to. And trust me, the risk is VERY REAL.

The effort described by the original purchaser that is required to push a lead ball through the throat is considerable. Put 36,500psi of pressure behind that constriction and you don't have to be a gunsmith OR a rocket scientist to see the potential danger this defective barrel poses to anyone who shoots it.

THIS ^^^^^^^^ IS WHAT you need to impress upon Walther! THEY need to email you a prepaid shipping label for this gun and send UPS or Fedex a call tag to come to your residence and GET IT. Maybe they got lawyers who work for nothing, cheaper than sending a shipping label.

I have no problems throating the barrel and removing the constriction. To me, my efforts are secondary to the real root cause of the problem, and those responsible for this root cause should ALSO be responsible for remedying the situation.

[gloob]

A constriction of 2 1/2 mils is hardly a bomb waiting to happen. With factory jacketed ammo, anyway. The real problem, for Walther, is if a large number of their barrels have been sent / are being sent out like this. They might not want to open the floodgate of repair work if one person gets their barrel fixed/replaced under warranty. You know there could be a lot of folks demanding new barrels, and most of them would be guys that don't shoot cast bullets nor bullseye competitions with their guns.

If they don't fix it on their dime, I am betting it's because they have a lot of guns out there with the same problem/non-problem. If this were an isolated event, I think they would bend over backwards to fix the problem. So what they do next is going to be telling.

Either way, sounds like OP has plenty of reasonable backup options.

[Handloader109]

The barrel is defective. Without a doubt. It is also dangerous in that it could cause an overly high pressure event which could possibly cause death or injury if it exploded. For them to balk at fixing it under THESE circumstances is reprehensible. Buds, who sold the gun, would ALSO be liable since they were the seller of the defective product. This is pure B.S. that Walther is not actively trying to get the gun in house so they can fix it, and absolve themselves of any liability the existing barrel might expose them to. And trust me, the risk is VERY REAL.

The effort described by the original purchaser that is required to push a lead ball through the throat is considerable. Put 36,500psi of pressure behind that constriction and you don't have to be a gunsmith OR a rocket scientist to see the potential danger this defective barrel poses to anyone who shoots it.

THIS ^^^^^^^^ IS WHAT you need to impress upon Walther! THEY need to email you a prepaid shipping label for this gun and send UPS or Fedex a call tag to come to your residence and GET IT. Maybe they got lawyers who work for nothing, cheaper than sending a shipping label.

I have no problems throating the barrel and removing the constriction. To me, my efforts are secondary to the real root cause of the problem, and those responsible for this root cause should ALSO be responsible for remedying the situation.

Kind of an unproven accusation that the barrel is defective. As op stated, calipers are not the method of choice to measure a slug. My measurements vary at least a thou if not two. Owner needs to do a case of the barrel to truly determine the shape and be able to measure the barrel accurately. My PPQ is way more accurate with any out of the box factory loads. And I've tried 4 different cast bullets alox and pcd,and none are as good as cheap white box target ammo. But they ALL hit close enough to hurt.. The PPQ isn't a target gun.. Not a Walther apologist, just fact. I'd send back to Walther if you are convinced of a defect, but I'll bet you a dollar they send it back untouched. Sell it or use factory loads or have someone alter.

[gloob]

^So does your PPQ foul up right after the chamber, too?

[gpidaho]

Guys: I'm just not coming up with the same #s here on a PPQ. SIL bought the Walther 9mm PPQ and we were very impressed with it on our first outing. Shooting Lee TL358-124s powder coated and sized .358 we had no problems and were very impressed with the trigger. When cleaning after 200rnds. fired there was a small amount of lead flakes in the bore but nothing out of hand, they patched right out. After reading these posts I became concerned and slugged the throat and breech. What I came up with using a Starrett mic. was a .3575 throat and a .356 bore. I rechecked using a dial caliper as a comparative measurement and figures were confirmed, the throat was a little over .001 larger than the bore. I don't know if this is something Walther became aware of and fixed, or we're just lucky, you think they would all be the same measurement from the factory. Anyway we're very happy with the PPQ and it's working with powder coated boolits just fine for us. GP

[Inferno451]

Want to trade barrels? :bigsmyl2:

[Inferno451]

Update- I've now called Walther customer service several times over the past week and left messages and used the customer service form on their website. I can't get ahold of anyone and nobody is returning my messages.

[kenn]

Inferno,

That's really disappointing. Just out of curiosity, what does a new barrel cost? If you are looking at $100 to fix it, maybe buds will work something out and split the cost with you if they're going to each overnight shipping. I have a PPQ and thought the tolerances are REALLY tight, it is fantastically accurate and the trigger is among the best I've used (stock) in a production 9MM. Try to get it right before you give up on it. Great gun.

[Inferno451]

It's a fantastic pistol, and I absolutely love it apart from the bad barrel. The concern with a replacement barrel is that the barrel is stamped with the serial number, and i'd like to keep it that way.

[Inferno451]

Update- Finally heard back from customer service from my email. Here it is:

Hi Inferno451,

May I ask why you think that is defective? The throat is manufactured to be tighter than the rifling.


Safe Shooting,

Mary Bryant
Consumer Services Tech
Umarex USA, Inc. / Walther Arms Inc.


Whaaaaaaa? :confused:

[Char-Gar]

Update- Finally heard back from customer service from my email. Here it is:

Hi Inferno451,

May I ask why you think that is defective? The throat is manufactured to be tighter than the rifling.


Safe Shooting,

Mary Bryant
Consumer Services Tech
Umarex USA, Inc. / Walther Arms Inc.


Whaaaaaaa? :confused:

As I said before, they make them the way they make them for jacketed bullets. When the barrel is pressed into the chamber block that cause a constriction in the throat. They consider that a part of the manufacturing process and not a defect. This constriction will have zero negative effect on jacketed bullet ammo.

So;

1. Ream the throat to suit you
2. Shoot it as is
3. Sell the pistol

[Inferno451]

The PPQ is a one peice barrel, machined from a single blank. No separate chamber as on the PPX.
My barrel:

http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150408_101235975_HDR_zpsowipf9rf.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150408_101235975_HDR_zpsowipf9rf.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150408_101243520_zpsd5rudazd.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150408_101243520_zpsd5rudazd.jpg.html)
http://i775.photobucket.com/albums/yy32/inferno451/IMG_20150408_101550708_HDR_zpsylsiyjwp.jpg (http://s775.photobucket.com/user/inferno451/media/IMG_20150408_101550708_HDR_zpsylsiyjwp.jpg.html)

PPX barrel:
http://i775.photobucket.com/albums/yy32/inferno451/PPX-11_zpsigugfdrm.jpg (http://s775.photobucket.com/user/inferno451/media/PPX-11_zpsigugfdrm.jpg.html)

[gpidaho]

inferno451: I'm with Char-Gar, This is just some thing you're going to have to fix, save yourself a stroke and have it throated, if won't cost much as it's simple to do. I think the PPQ is a great little pistol. the trigger is as good out of the box as most are after being worked over. Sadly more and more guns these days come in kit form as they are made by machines not people. You know what's wrong here and puts you ahead of the game. Think. we could have bought one of those 51 Remingtons lol GP

[Inferno451]

Think. we could have bought one of those 51 Remingtons lol GP

Now THERE'S a scary though :|. Update- After discussing further with Walther CS, they have sent me out a shipping label to send just the barrel in. I'll be very descriptive in the problem, as I doubt they will go so far as to actually slug the barrel. If they don't fix or replace the barrel it will be sent to dougguy to be throated.

[DougGuy]

Well, thank you for your consideration of my skills, but may I ask who the hell drew up their barrel when SAAMI specs clearly DO NOT show a throat smaller than the rest of the barrel! This is just getting stupider and stupider on their part. Manufactured to be smaller than the rest of the rifling MY A$$.

SAAMI sets specs as a governing body that most of the sporting arms manufacturers agree upon and accept. There HAS to be a standard, and that's what SAAMI is for.

For a U.S. gun maker to manufacture a firearm or a part of a firearm like a barrel that does not meet SAAMI specs opens them to a lot of liability for accidents, injuries, and lawsuits. For an importer the risks are pretty much the same if they make stuff that there are no specs for or do not adhere to the same specs that are pretty much accepted industry wide as the law.

They got a bad run of barrels and since they cannot dazzle you with their brilliance, they are hoping to baffle you with B. S. so your problem will simply go away. They are NOT fooling this old man, been around this business for many years and never seen a smokescreen I couldn't see through if I just looked hard enough.

Here's the chamber drawing that everybody else goes by:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/9mmChamber768_zpsdzhq6yci.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/9mmChamber768_zpsdzhq6yci.jpg.html)

Ok, let's look at the flip side. If I am wrong, and I don't think I am, but if I am wrong, I will be the FIRST to admit my mistake(s) but they will have to show me the logic in how they get away with a tighter throat than the rifling, they will have to explain to me WHY they did this, and to what end they feel there engineering is superior to SAAMI specs, they will need to prove to me beyond some B.S. excuse as to what they hoped to accomplish with making a barrel like this. I don't think this is going to happen. I think they just don't want it getting out and circulating that they might have had some bad barrels and didn't want to admit it or foot the bill to make them right.

I applaud Inferno451's tenacity and efforts to get to some resolution of this.

[Inferno451]

Help me understand that drawing. I'm a senior M.E. student, but maybe i'm reading this wrong. What's up with that ".354 [8.99] B" Dimension doing in there before the .355 specified for the groove diameter? Is SAAMI spec actually a slightly tighter throat or is that dimension related to the lands in the rifling starting to taper in?

[Inferno451]

Update- I went ahead and slugged the barrel again so I could be extra descriptive with the problem and it turns out the problem is even worse than I thought. Turns out it's not the throat that's too small, it's the whole first half inch or so of the rifling. I can put a bullet that's already been pushed through the bore back through from the muzzle side (matching up the rifling marks) and it will fall down to the last half inch of rifling and then I'll have to push on it pretty hard to get it to come out. Barrel is getting boxed up and shipped to Walther shortly.

[DougGuy]

Help me understand that drawing. I'm a senior M.E. student, but maybe i'm reading this wrong. What's up with that ".354 [8.99] B" Dimension doing in there before the .355 specified for the groove diameter? Is SAAMI spec actually a slightly tighter throat or is that dimension related to the lands in the rifling starting to taper in?

That has to be the leade in to the rifling where it begins the ramp up to the full height of the lands since SAAMI calls for a .355" boolit, however this measurement is given to be .8113" from the breech face, or .0573" from the case mouth, which would be roughly the beginning of the leade in, which is a 2° included angle that reaches full height of the rifling .9258" from the breech face or .204" from the case mouth. If you look at the drawing for the boolit, the ojive of the boolit shows that the diameter .0573" in front of the case mouth would indeed be small enough to fit in the .354" dimension of the throat although they do not specify what that measurement is.

[Bumslie]

Interesting. My ppq shoots cast and powder coated bullets pretty well. I'll have to keep am eye out on this thread

[Inferno451]

Barrel is on it's way to Fort Smith. I included a very descriptive note on the problem along with a dowel and several .356" slugs to (hopefully) encourage them to actually slug the bore and do something about it rather than just visually inspecting it and sending it back. I'll update when I hear from Walther.

[Inferno451]

Just got a call back from Walther CS. The lady I talked to was very nice. She told me the gunsmith made a casting of the chamber and it measured .355". I tried to explain the problem was with the first inch of rifling and she kept insisting it was normal to have resistance there due to the rifling tapering in. I tried to convince her and/or the gunsmith to use the slugs and dowel I included when i sent in the barrel to see what I meant, but they would not. Just kept insisting that it was the resistance due to the rifling tapering in. Apparently that made sense to them even slugging from the muzzle end? Sigh... Not sure what to do now.

[Char-Gar]

I don't want to go back and read all the pages of posts, but have you ever shot that thing with cast bullets? As I recall you have not, all of this angst is over some numbers. If you have not, that is what you should do now. Sometimes all the numbers don't mean squat and a firearm will do things all the experts say it will not do.

[rsrocket1]

I don't want to go back and read all the pages of posts, but have you ever shot that thing with cast bullets? As I recall you have not, all of this angst is over some numbers. If you have not, that is what you should do now. Sometimes all the numbers don't mean squat and a firearm will do things all the experts say it will not do.

First line of OP

I've been casting for a while now, but just starting to cast for my new PPQ, which I absolutely LOVE. I'm getting HORRENDOUS leading after only 15-20 rounds.

There, fixed it for you (I think) :)
So the answer is YES

[Inferno451]

The whole problem is precisely that. Cast bullets lead horribly due to the constriction in the rifling swaging it down to .353.

[Cherokee]

All this bantering back and fro, and still no resolution. Since you can't get a new barrel, use DougGuy's service or stick with jacketed. I would get to know Doug.

[Inferno451]

I no longer think this is something Dougguy can fix. After slugging the bore again before I sent it to Walther I realized that the constriction is actually the first inch or so of rifling. No way i'm having that much reamed out of the barrel. The ability to shoot lead bullets was the entire reason I sold my G19 and bought the PPQ in the first place. Guess i'm going to have to sell the PPQ and try something else. It's a shame really, i absolutely love this thing.

[dondiego]

The G19 shoots lead just fine!

[DougGuy]

I wouldn't normally take that much rifling out of one.

However, for the sake of discussion, Taylor Throating puts freebore in a revolver barrel that is 1.5 to 2x the caliber in length, before the leade in to the rifling begins, and it works. Less pressure, a very easily detected gain in velocity, and groups shrink appreciably.

In a 9mm, this would be a throat of (up to) .700" in length, and another .200" or so of 3° taper before it got to the full height of the rifling, so it is not out of the question whether it can or cannot be done, mathmatically it is possible.

If you google Ross Seyfried and read what he has to say about his well documented tests with a Taylor Throated big bore sixgun, having that long of a throat in a 9mm does not seem so far fetched.

If you would like to send the barrel and let me at least take a look at it and slug it/pin gage it myself, I would be glad to do so free of charge, and even ship it back on my dime.

[Inferno451]

Doug, that's very generous of you! I'd be happy to pay for shipping there and back, and i'd love to get a second unbiased opinion on this. Maybe it's possible I've been wrong this whole time and I'd like to know for sure. I'll let you know when I get my barrel back. Thanks!

[rsrocket1]

How much of a constriction is there? Would you be able to hand lap the first inch of the barrel? Yes you would wear down the rifling a bit, but you would more importantly open up the groove diameter and end the boolits getting squeezed down then gas cut when the bore opens up. Just thinking.

[Inferno451]

I'm not too familiar with hand lapping having never done it before. I'll have to research that.

[blackthorn]

It seems to me that you have reached a point where you can try anything you like to fix that gun. If you really like a gun from a company with that poor customer service and are determined to keep it, at this point the only logical option (as I see it) is to pick a possible "fix it" path and move ahead. You do not seem to have much to lose!

[DougGuy]

Revisiting this thread again. Today I got the PPQ barrel in this discussion from the OP. I could see a fairly nice throat with a long leade in to the rifling, meant to shoot well with j-words which it likely does. I could see a tiny bit of distortion in the light reflected in the bore when looking through it. Upon slugging the barrel I slugged the muzzle and that slug read .3557" on my Mitutoyo mic. After pushing it through the throat, the slug measured .3554" for a difference of .0003" not much, but enough to cause problems.

It is my opinion that this barrel is constricted in the thick chamber part from contraction due to heat treating. All steel expands upon heating, and contracts upon cooling, and this contraction upon cooling from the heat treatment process is why the variance in internal diameter with the rest of the bore. The thicker breech walls simply contracted farther than the thinner barrel walls.

This photo shows the chamber, and the .500" of .0003" constriction coincides perfectly with the thickness of the breech area of the barrel ahead of the chamber.

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/PPQpasted640_zpsi1jekesn.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/PPQpasted640_zpsi1jekesn.jpg.html)

With only .0003" of constriction, a soft enough alloy and soft lube would obturate and seal in the bore, but to shoot a soft enough load to do this, likely it won't be a max velocity load. Maybe 1200fps or even slower.

The barrel is hardened, heat treated with the same Tenifer process that Glock uses for their barrels, and a Manson reamer won't throat these barrels as it is not carbide. It is possible to firelap or cold lap this barrel but my instincts would be to contact Jarvis and see about getting an aftermarket barrel and ask them if they can throat it for cast before they ship it. This would be an expensive fix but likely a really accurate fix. You could set the stock barrel aside and if you decided to sell the gun, put it back in.

If you decide to sell the gun and buy a Glock or another 9mm, keep in mind that to throat them for cast, you need an aftermarket barrel due to their heat treating of factory barrels I won't even accept one for throating.

[Handloader109]

So, it appears from what you are saying that there is nothing wrong with the barrel. I'd hazard to guess my PPQ is very similar as I have to size down to .356 to make things work in cast. And it isn't as accurate in cast as with jwords. A lot of assumptions in this thread based on faulty data:x

[DougGuy]

I got a call back from Jarvis this am. They explained that they had to open up their barrels to greater than SAAMI specs to accommodate a lot of what shooters want to put through them. Their throat is slightly larger in diameter, it is also longer, with an even more gradual leade in to the rifling than the 3° called for in SAAMI specs.

Their groove diameter is .355" which is .001" over SAAMI, I didn't ask him the particulars of their throat dimensions, but I suspect it would shoot cast much better than the factory barrel simply because it's throated more towards cast.

[Char-Gar]

So, it appears from what you are saying that there is nothing wrong with the barrel. I'd hazard to guess my PPQ is very similar as I have to size down to .356 to make things work in cast. And it isn't as accurate in cast as with jwords. A lot of assumptions in this thread based on faulty data:x

It is not so much faulty data as it is faulty expectations. These pistols were designed to shoot jacketed ammo and they do that rather well. They were not designed for the occasional cast bullet shooter, who gets all anal about specs that don't meet his expectations. Some things just are what they are and can't be made to be something they are not.

[Inferno451]

Glad I got a second opinion on this. I'm very surprised the constriction was so small, but apparently it's enough. Looks like I may have to stick with "J-word" bullets. Really a shame as being able to shoot cast was the whole reason I sold my G19 and bought my PPQ.

[DougGuy]

I wouldn't give up on it just yet. You were shooting water dropped coww, probably got a BHN of no less than 18, likely closer to 22. What you would need to overcome this choke, is an alloy that is malleable and soft enough to obturate to the bore after it clears the choke. I would try air cooled coww, and if it leads then mix some soww or pure lead with it, and use some soft lube too.

My SBH took an immediate liking to 50/50+2% coww/pure lead/2% tin with Felix lube and it performs well with other soft lubes. I can scratch the boolits with a thumbnail, and I run them right at 1180 ~ 1200 fps with ZERO leading and great groups. They ARE the gas checked Lee RF boolits, and I admit I am shooting in a revolver with reamed and honed throats, into a nicely cut forcing cone, but the results are very gratifying.


With only .0003" of constriction, a soft enough alloy and soft lube would obturate and seal in the bore, but to shoot a soft enough load to do this, likely it won't be a max velocity load. Maybe 1200fps or even slower.


The rifling in your bore is very proud, it reminds me of looking down a SBH bore. I think there is good reason to try with softer alloy and soft lube and see if you can't hit on a combo that the barrel likes. Might not hit it dead on first time out, it may take 2 or 3 tries but you will get to the point that you look in the barrel and notice something got better. Something's different. It's not leading like it usually does, and from there you should make small changes, one at a time, and see if you can't dial in a combo that works.

[Handloader109]

I'll chime in here one more time, and to agree with DougGuy. I'm shooting a powdercoated bullet try my PPQ. In fact, Several, 95 gr NOE ranchdog, Lee 124 and 125gr. If I shot plain lubed with Alox, it would lead, PC didn't. Now I sized mine down to .356. Accurate is not as good as jbullets, I'm expecting they should maybe be .357, but haven't spent the few $ on sizing die to test. My lead is soft, has been wheelweights and range scrap. Doesn't seem to matter once powder coated. And I'm just plinking. If it were me and I wanted to keep gun, I'd try powder coating and size down......

[GaryN]

I would also keep trying. As above use a softer alloy. Keep in mind that the 9mm can be difficult to load for with cast because it is so easy to decrease the size of the boolit when loading with soft cast boolits. There is a good sticky about loading cast in a 9mm. It addresses a lot of the problems inherent in making a pistol shoot cast. It was posted by Mtgun44. Here it is:
http://castboolits.gunloads.com/showthread.php?121737-Setting-up-for-boolits-in-a-new-9mm

[gloob]

I am not sure if lapping the bore is a good idea on a tennifer treated barrel, but that wouldn't stop me from finding out for myself. I'd size 11 BHN bullets to w/e is smaller than the freebore and larger than the constriction and mix some 400 grit abrasive into my tumble lube, then fire them over a sub-minimum starting charge for the bullet weight, aiming for 600 fps.

I'd bring a jag with a tight patch to clean out the bore every 4 shots and to feel for the constriction. When I can't feel it, I'd shoot a couple more, then slug the gun when I got home. Final polish with a jag and patch and some fine polish, and then see what happens.

[Geezer in NH]

I'd like to know how a button rifled barrel gets a tapered rifling like that? Just on the chamber end, sounds more like Crappy CS to me.

I have been a gunsmith, dealer manufacturer, sold over 100,000 barrels and cannot figure out how?

Pulling a button through a short piece of stock will not do it. Pulling a button through a longer piece and then cutting barrel lengths from it won't either.

[gpidaho]

Not to beat it to death, but try running some powder coated boolits through it. The PPQ I shoot just loves the Lee 356-124 powder coated and sized .358. NO leading after 300+ rounds down range. Good luck GP

[DougGuy]

I'd like to know how a button rifled barrel gets a tapered rifling like that? Just on the chamber end, sounds more like Crappy CS to me.

I have been a gunsmith, dealer manufacturer, sold over 100,000 barrels and cannot figure out how?

Pulling a button through a short piece of stock will not do it. Pulling a button through a longer piece and then cutting barrel lengths from it won't either.

This is a Tenifer treated barrel. It gets HOT when they heat treat it. Over 1,100°F in the salt bath. The breech is 3-4x thicker than the rest of the barrel. When metal cools it contracts. The thicker area ahead of the chamber contracted enough to squeeze the finished bore down .0003" as it cooled from heat treating.


http://castboolits.gunloads.com/showthread.php?273575-Throat-tighter-than-rest-of-barrel-on-Walther-PPQ&p=3262023&viewfull=1#post3262023

[Char-Gar]

Not wanting to ruin your tooling cutting super hard stuff reminds me of the time I tried to get Herretts make me a pair of handgun stocks from Micarta. They said they would do if for an extra $200.00 to pay for the cutter bits that would be destroyed in the process. I decided that wood was plenty good. -:)

[gloob]

This is a Tenifer treated barrel. It gets HOT when they heat treat it. Over 1,100°F in the salt bath. The breech is 3-4x thicker than the rest of the barrel. When metal cools it contracts. The thicker area ahead of the chamber contracted enough to squeeze the finished bore down .0003" as it cooled from heat treating. I understand conventional kinds of heat treating can do this, too, to some degree. I've heard that touted as one of the benefits of a bull barrel, anyway. No taper, no inadvertent "reverse choke."

With mandrel forging it should be possible to shape the mandrel to account for this specific problem. I wonder if Glock and HK adjust for this shrinkage.