Why are 9mm barrel inner diameters so non-stardard?

[prickett]

I have a number of 9mm pistols that I've slugged. The inner diameters are all over the place. I don't see the same with my .45s. Why is there no standard with 9mm's? Is 9mm an exception or do other calibers have the same variances?

Also, what 9mm's do you have and what are their barrel inner diameters - for curiosity sake?

[JSnover]

How far do they deviate and where were they made?

[jcren]

I suspect it is due to the 9mm being native to so many you tried and each having their own preference. Example, the 9mm makarov measures .365ish by our standards because Russia sized by the lands, not grooves.

[scottfire1957]

How far do they deviate and where were they made?

Because tools wear as they are used is one reason. You should look only for firearms with barrels reamed with first used tools.

Edit: meant to quote OP. Sorry.

[JSnover]

Tool wear is an issue but worn tooling (ideally) would be replaced before it starts cutting out of spec barrels. I'd bet if you measured 'good' barrels from Russia, South America, and the US you might be surprised by the differences.

[Outpost75]

In European practice unless otherwise specified, the normal tolerancing convention is +0.05mm/-0.00mm (about 0.002") on diameters. US WW2 practice was +0.0015"/-0.0000 for the M1911 .45, Browning .30 cal. and cal. .50 BMG. Rifle and carbine tolerance was generally held to +0.001"/-0.0005" although exceptions can be found.

This has also been my observation in hundreds of barrels I have checked over the last 50 years.

Wartime production may exceed that tolerance if parts were needed desperately and accepted on waivers.

You should try measuring 100 .30-40 Krag or Trapdoor Springfield .45-70 barrels sometime if you really want to be shocked! (which I have done).

Modern rotary hammer forged barrels exhibit the least variation, with button-rifled barrels being nearly as uniform, if heat treatment and stress relief is properly executed. In button rifled barrels finished bore diameter depends greatly upon button driving force, which is influenced by blank diameter, bore size and surface finish, whether the button is pulled or pushed, the lubricant used, how much is turned off the OD of the barrel in profiling and when in the manufacturing sequence the blank is stress relieved. Cyro treatment is just another form of stress relief.

Shops which thoroughly understand these factors can control the bore and groove size very closely and, if desired, also produce button-rifled barrels having an internal taper which diminishes slightly from breech to muzzle, which many feel is beneficial.

The most variation is observed in cut rifled barrels produced before introduction of the P&W 1/2B series machines in the late 1920s, as earlier sine-bar riflers lacked an automatic cut-off after a given number of cycles and if the operator was not paying attention it wasn't uncommon for a barrel to receive a few extra draw strokes which increased groove diameter.

Poorly resharpened deep hole drills during wartime were another cause because bores would need to be reamed larger to remove circumferential tool marks.

Prior to the introduction of carbide cutting tools during WW2, early tool steel broaches commonly used for pistol and SMG barrels were initially ground to maximum diameter, and would be periodically touched up by the operator or setup man and used continuously until the minimum tolerance was reached before changing the tool. Properly managed very good surface finishes were obtained.

The S&W Victory Model revolver was the first production military arm produced with broached barrels.

[Char-Gar]

The 9mm is a Euro round and the 45 is an American round. It has been my limited observation that Euro 9mms tend to run larger than American 9mms. I use .357 or .358 cast bullets in them all and get good results in them all.

[victorfox]

just more to the fire.... I've read many Taurus guns these day in 380/9mmP are leaving factory .357/358". Probably yhr wanted to simplify tools and thought .002 wouldnt make a difference, but in the end it does. About the same happens with newer 44-40 bored from 44mag barrels.

[prickett]

Yes, its new guns I'm talking about, not guns affected by machinery wear. I had a Taurus with a .357" barrel. I have a SIG P226 and a CZ-75 - one with a .355" and one with a .356" barrel.

My question is why aren't the barrels sized to a standard spec (e.g. .355")? My .45's all seem to conform to a .451" spec.

[Shiloh]

It is a rare 9mm indeed that measures .355. .356 and up seems to be the norm.

Shiloh

[NuJudge]

The explanation I have read for 9mm barrels having a big groove diameter is that it allows some of the highest pressure gas to blow by the bullet, reducing peak pressures. This causes no harm with a jacketed bullet, but causes huge problems for us with Lead bullets.

I am not sure how much I believe this, as my Beretta 9mm barrels are all a little under .358", but my Beretta .40 barrels are all right at .401".

[Fishman]

I've measured only about a dozen, and the smallest was a Kahr at .355, the largest was a Beretta 92 at .357. More problematic is the variability in the transition from the chamber to the rifling. Throw in several dozen brass manufacturers and you have the making of a pita.

[DerekP Houston]

This is why my 9mm mold is still sitting on the shelf...Mine walther wouldn't chamber anything larger than .356 but the beretta that was terrible. :shrug: 9mm plated are cheap enough for the amount i need. I'd rather shoot my revolvers anyways.

[prickett]

Which guns have tight (i.e. .355") barrels? Glock? Springfield XD?

Given the wide variance, I'm surprised I've not heard tons of complaints of commercial lead boolits not performing in their gun. I originally thought my Taurus PT-99 was terrible because I couldn't hit the broadside of a barn. But once shooting .358", it became my most accurate gun (compared to my CZ-75 and SIG P226).

[bangerjim]

Simply to make the lives of those that insist on casting for 9's totally miserable! That is, until you figure out what you are doing with your specific 9's.

[victorfox]

Prickett... I've noticed the same in 380 (as 9mm is restricted in my country) and handloading requires a lot of time money paper and luck. We're pretty much tied to factory ammo (which is about .355/356). Shot a Bersa thunder, sweet little gun, bang bang close group. Shot a taurus 938, big shotgun pattern... not even close to 10 mark... A lot of j*words I find fired at the range in 380 are almost black with soot. 45 and 40 J* not, all cleanly engraved.

[GhostHawk]

My Hipoint tumbles cast .356 but has a nice tight group on jwords.

So I intend to try feeding it some .358's but simply have not gotten it done yet.
Sitting on 900 rounds of Jwords for it just cuts the "need" to get it sorted.

[mdi]

Manufacturing tolerences. SAAMI 9mm groove diameter is .355" +.004"/-.000". Or that's what the SAAMI drawing says...

That's new production dimensions. I have an older Norinco 9mm (mebbe 60+ yrs old?) of Chinese mfg. that slugs out at .358"...

[Frank46]

Have had my beretta 92fs for about 18 years. Got some horrible leading when I tried .357 dia cast. Slugged the barrel and got .357. Did this three times so when I do shoot it I use 357 dia jacketed HP's works great and no pressure problems. My sig P6 shoots so well with WWB that I don't even reload for it and haven't slugged the barrel. Used to be a brass rat. Picked up anything brass. 9mm I don't even bother. Frank

[lightman]

The 9mm has always been that way. The brass is too. Maybe because they have been made by so many different countries? I remember 30 or 40 years ago you would have to have different shell holders for some 9mm brass. I think RCBS listed different numbers.

[mdi]

The 9mm has always been that way. The brass is too. Maybe because they have been made by so many different countries? I remember 30 or 40 years ago you would have to have different shell holders for some 9mm brass. I think RCBS listed different numbers.
Yep, plus the 9mm has been manufactured in many, many different countries in many, many factories over many, many decades with different standards...

[williamwaco]

Caveat:
I have never fired, let alone slugged any military 9mm handgun.

That said.
Every 9mm I have ever slugged came in between.3570 and .3580

[gwpercle]

Getting one cast boolit load to work , in 9 mm, for all three different guns, Walther P-38 , Taurus PT-92 , Springfield XD ,
has been the only round that I almost gave up on...it made me curse at it. After much adjusting of seating depths , powder charges , boolit sizes , and boolit shapes , I finally got loads that would work in all three. But I came real close to throwing in the towel.
The one that was most problematic about everything was the Springfield XD , that bad boy has little or no throat. The old WWII era army surplus Walther P-38 would shoot anything...go figure. The 9 mm is a stinker in my book. I'll take the 45 acp or 38 special any day !
Gary

[prickett]

The 9mm has always been that way. The brass is too. Maybe because they have been made by so many different countries? I remember 30 or 40 years ago you would have to have different shell holders for some 9mm brass. I think RCBS listed different numbers.

Odd, though that if SAAMI says .355" that the NEWER model guns still don't comply.

[prickett]

Getting one cast boolit load to work , in 9 mm, for all three different guns, Walther P-38 , Taurus PT-92 , Springfield XD ,
has been the only round that I almost gave up on...it made me curse at it. After much adjusting of seating depths , powder charges , boolit sizes , and boolit shapes , I finally got loads that would work in all three. But I came real close to throwing in the towel.
The one that was most problematic about everything was the Springfield XD , that bad boy has little or no throat. The old WWII era army surplus Walther P-38 would shoot anything...go figure. The 9 mm is a stinker in my book. I'll take the 45 acp or 38 special any day !
Gary

I'm very close to punting on 9mm myself. Starting to look at plated or jacketed, just in case my final experiment (.358" with almost no crimp) fails.

I'd much rather be shooting than spending countless frustrating hours trying to sort this stuff out.

[trapper9260]

What I end up doing on my 9's is that after i slug them and then see what ones will work with what cast boolit . That I make the data for . That I make a note on my index card and color code for what gun to use it in and then on the round .I color code the primer and then It is less to mess with in the end.I just look at the color on the primer and know what gun need to use it in. beside i make a note on the box I have the rounds in. with the cart and weight and powder and color for it of the gun. Other wise I got all my data on a index card for my loads.It works for me.

[ioon44]

The 9 mm's I have slug from .355" to .357", I have good results with .3575" Hi-Tek coated 15 BNH bullets great accuracy and no leading problems.
My Walther PPQ's are .355", Glock .356" and SR9 and S&W shield .357". Just make sure your loading dies are not swagging the boolits down in the case.

[dragon813gt]

All of mine are .355-.356. But they are all new(er) production models from European manufacturers.

[Petrol & Powder]

First - there's no doubt that 9mm bores are all over the map.
Second - The post by Outpost75 (#6) was very informative, thank you for that Outpost.
Third- I did give up ! My solution for 9mm was to pick 1 of my 9mm pistols (Beretta) and cast for that one pistol. It was too aggravating to attempt to sort it out for multiple pistols, segregate loaded ammo, segregate sized bullets, re-adjust dies constantly, etc. With the exception of that one Beretta, all of my 9mm pistols get fed jacketed or plated bullets. If I'm shooting with other people, I don't even bring the cast 9mm loads along.

[DerekP Houston]

yeah...I gave up on 9mm, I may give it a try if I feel like bashing my head against the wall. I'm just not a big fan of having different loads for different guns that all look identical on the shelf. I know at one point in time I'll grab the wrong box. Berry's plated chamber in all of them for me and are cheap enough to I don't mind. If anyone is interested in a 2 cavity rcbs 124gr TC hit me up via pm.

On the other spectrum 45acp and 38 spec have given me nothing but flawless results and will never see factory ammo again.