Chamber/throat junction shearing lead.

[Trapperscott]

Hello all. I'm sure I'm not the first to experience this and yes, I have searched for a while and haven't found much on how to correct this.

The problem is, where the chamber ends, and the throat/rifling start, there is an abrupt sharp edge that shears a tiny sliver of lead on every shot. My 21, 45 acp is not to bad but it is there and does shear a little lead. My 22 is about the same.

The real kicker is my 19, 9mm. I just got a Lee, 358-125 rf this week after reading about it here. My 19 slugs at .356. I am powder coating with HF flat black, and then sizing to .357 with a Lee push through sizer. After 5-7 rounds it has sheared enough lead to jam the gun and not let it go into battery all the way. When I work the slide, the little ring of lead that is sheared off usually comes out on the loaded boolit. I have shot 5 and broke the pistol down and with a dental pick am able to pick out a perfect circle of lead right at this junction.

I'm sure there is a fix for this, just not sure how.

Any suggestions, hints, remedies for this would be greatly appreciated.

Scott

[runfiverun]

you'll have to put a throat in there.

I have been looking for a new 9m pistol for a while now but keep putting it off because I don't wanna have to buy the thing then get it fixed before I even shoot it.
the new chamber square barrel rifling is the new way to save money.
I guess I might as well get used to it.

[JonB_in_Glencoe]

I assume your are talking about Glocks ?

I have recently been looking for a 1911, and especially the Ruger SR1911,
but I have read the same thing you are talking about, with a 'sharp' start to the rifling and the 'shearing' of Lead from boolits...I still haven't bought one yet.

I think your solution is to chamfer the throat.
==========================


R5R,
I have tested about 5 Hi-Point C9 pistols in the last year...no issues with those throats...if you don't mind shootin' an ugly gun :bigsmyl2:

[singleshot]

I agree with JonB on Hi-Points. No problems with 9mm or 45acp. Ugly never bothered me.

[runfiverun]

I have one of their little carbines it needs a 50 round drum, that dinky 10 round magazine is ridiculous.
it has never had a hiccup or a mis-feed and is actually pretty accurate.
it will digest ammo that will make other guns choke just thinking about shooting it.


I seriously have been looking for a 9mm, something with good sights that I can shoot groups with.
I know they have to exist, the Europeans shoot the 9 like we shoot the 38.
I'll even take the time to trim cases, and sort head stamps if I have to.

[Hannibal]

High-Point. A black brick with sights and a trigger. But it shoots cast? Go figure.

[geargnasher]

Hi-points are awesome, really, you have to shoot one of the clanky, hideous, awkward things to believe it. They have long, gently-tapered, generous throats to reduce engraving pressure with jacketed bullets, it's the same with the pistol topper carbine conversions, has to do with making the blowback mechanism time properly and has the side-effect of making them just perfect for cast bullets. They're incredibly accurate and reliable, too.

Runfiverun's first post is spot-on, gotta ream some sort of decent, tapered throat into these new plastic automatics if you want to shoot cast in them. Brownell's sells a throating reamer for the .45 ACP that's been discussed here a lot and used to good effect by many, not sure about the other calibers but it's worth a look.

Gear

[DougGuy]

If the ojive of the boolit don't at least fit into the throat, it will continue to shear rings .356" of lead will only go into a .356" hole. The rest gets sheared off if you have a .355" throat.

I throat barrels all the time for this reason. I do not do 9mm but if there is enough call for it I will buy the reamer. This is what a throated .45 ACP barrel looks like, and the throat is .4525" for shooting .452" boolits. A .4525" pin gage will go in the throat all the way up to the rifling. THIS is what your 9mm needs. If I had a .356" throating reamer it would be a $20 fee + shipping but I have not been approached by shooters wanting this work done on a 9.

SA chamber on left before throating, on right, after throating:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Both1_zps194dd462.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Both1_zps194dd462.jpg.html)

KKM barrel for a Glock, owner wanted to seat .452" out long, and run .45 Super in it:

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/8b5f5e57-990e-4a7d-9b80-9911ab6438f1_zps53fb17d2.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/8b5f5e57-990e-4a7d-9b80-9911ab6438f1_zps53fb17d2.jpg.html)

[Trapperscott]

Guys, I appreciate the replies, and advice. I hope I have found the answer to my problems.

DougGuy, I sent you a pm.

[tomme boy]

Doug, them don't lead? That ridge all the way around is not good. The reamer is larger than the groove. That will make it lead also. That reamer needs to be re ground smaller. IMO

[MBTcustom]

Doug, them don't lead? That ridge all the way around is not good. The reamer is larger than the groove. That will make it lead also. That reamer needs to be re ground smaller. IMO

I don't see it that way at all. 45 ACP headspaces on the rim. If you want to throw a .453 diameter boolit down a barrel like that, you're going to have to have something larger than groove as a starting hole which Doug obviously accomplished.
Now personally, I wouldn't have cut so much freebore in there, but Doug says it works so who am I to question?
One thing's for sure, if you were to match that freebore diameter with your boolit, you would not have any leading. Should engrave like a champ.
Like I said, I would have gone to a much shallower angle on the throating reamer, opened it up to .453 at the casemouth/lead junction, and shoot the thing, but that's just how I would do it.

[DougGuy]

There's more than one way to do it, the bottom line is the old story about stuffing 10# of s**t in a 5 # sack still holds here too. The boolit must fit into the throat or the gun won't go into battery. Some ppl seat the boolit deeper and get away with it but you have to compensate load data or you risk dangerous pressures.

The barrels I have done this way haven't come back with anything except how well they shoot and no leading. That ridge you see there is not sharp, it's on the same angle as the leading edges of the rifling and I also polish as best as I can in there with fine abrasive before the barrels are sent out. Unless you do it with EDM you will see some tool marks, this is normal and it doesn't have to be polished mirror smooth it just needs to be smooth.

Again, if you have a .451" barrel, and you need a .4525" throat or your .452" loads will not chamber, you have .0015" to distribute somewhere in there, so seeing a transition from .4525" to .451" you would see a step of some kind. I personally would like to see the boolit have some freejump before it hits the rifling, it reduces pressures and I *think* it can raise velocity a small amount to have the freebore, and it doesn't seem to hurt accuracy at all.

Some of the stainless that these barrels are made of is some really tough stuff, it pulls and tears at the grain no matter what cutting oil you use (I use Tap Magic) it's just the nature of the metal the barrel is made of. Some cut like butter, some look like you used a piece of 80 grit sandpaper on it until you polish it out. I really have no control over the surface finish, that's totally up to the properties of the alloy the barrel is made of. Some cut and polish really easily, some I have to use a custom made aluminum lap and some automotive finish polishing compounds and they are aggravating as h3ll to try and smooth them out. You never know until you cut one, how it will act.

[tomme boy]

OK, the ones I have seen like this the ridge is sharp. And they leaded like crazy.