Do 9mms have sloppy chambers?

[GLOOB]

I've always felt I could rely on my 45 Glock to shoot a hair more consistently than any of my other semiautos. Over the course of reloading many thousands of rounds, I have made a simple observation regarding chamber tolerance.

With my 45 ammo, I can make ammo with minimal or no flare, using plated and jacketed bullets. Even when there's no visible flare left after seating, I usually still need a bit of taper crimp to ensure rounds will chamber and drop out, freely. I haven't tried cast bullets in 45ACP, but I assume they would likely need a bit of crimp, too.

With my 9mm luger ammo, I don't need to crimp any of my plated or jacketed ammo. And even when I go hog wild on the flaring die for cast bullets, I still don't need a crimp on most rounds. I learned I can seat and crimp cast luger in one step without shaving the bullets, because I can set the crimp so far out, it doesn't even touch 99% of the cases. Maybe 1 in a 100 (mixed brass, not trimmed) gets the tiniest bit of crimp.

My 45 is a Glock.
I have 3 9mm, including Glock OEM, Glock LW barrel, and a DP-51.

Anyone else notice this? Or are my particular guns unusual? If so, does my Glock 45 have a tight chamber, or are all 3 of my 9mm chambers sloppy? Would a looser chamber at the mouth be detrimental to accuracy to the point where it would be noticeable in a service pistol?

I have thought on it, and I don't think it's my die sets. I think the bullet is what determines the final diameter of the mouth, as long as I'm not over-flaring.

 

[LightningMan]

The 9mm uses a tappered case, it is not the same diameter front to back, and I believe the .45 acp is a straight wall case. That might be the difference. LM

 

[Walkalong]

Most of my 9MM chambers are "generous" to say the least.

 

[Siggie]

I consider my Glock 17 chamber a bit as "garbage-bin" as well. It accepts almost anything you throw in.

 

[243winxb]

Chambers have a working range, look it up here. http://www.saami.org/specifications_and_information/index.cfm?page=CC

 

[capreppy]

I had this same question a few days ago. I'm looking to get a Beretta 92A1. I was told by a few commercial lead bullet casters that the 92A1 barrels can vary from .356 to .358. Unless I slugged the barrel to determine exactly what is the barrel diameter, using lead was definitely not a good idea as I will likely experience leading. Most lead bullets are .356 and FMJ/TMJ/JHP rounds are .355.

 

[rodregier]

Glock has also varied the "as manufactured" specs of their 9mmx19 chambers over the years, so not all Glock 9mm chambers are created equal.

You'll find that so-call "match grade" barrels will have tighter chambers as part of the choices to get the barrels to shoot tighter. This can be to the detrement to functional reliability, either due to debris tolerance or ammunition tolerance.

(If you feed clean well-made ammunition to such chambers, they'll normally work fine).

 

[RidgwayCO]

Reading the above, I believe LightningMan has brought up an interesting idea. Maybe the reason some reloaders can get 9mm Luger to chamber in their "sloppy chambers" without any crimp is because of the tapered case. Perhaps your barrel is actually "taking the flare out" of the case upon the round being full chambered. This won't hurt the cartridge (as it duplicates the work of a light crimp), but I'm not sure if this action is any good for the barrel/chamber...

 

[1SOW]

9mm CZs and XDs have less 'head space' than many/most other 9mm's. Out to .378-ish mouth width will feed reliably.
Bullets with nose shapes like the XTPs, flat points & other hollow points have to be loaded 'shorter' than most reloading data gives and what other guns like Glock can chamber with no problem.

Glocks in particular have generous 9mm chambers/headspace.

 

[GLOOB]

^
It's not the throat/leade that I'm talking about, specifically. My DP-51 has a short throat, too. I have to seat most bullets well below the minimum OAL I find in any of the loading manuals.

Example:
MBC small ball has to be loaded 1.08" or shorter.
XTP has to be loaded 1.06" (actual manufacturer recommended OAL, in this case)
Berry's FP or MG JHP 1.05"

Out to .378-ish mouth width will feed reliably.

This is what I'm more curious about. Is it a coincidence that CZ's have a reputation for being accurate, and they also have a tight chamber, here?

Perhaps your barrel is actually "taking the flare out" of the case upon the round being full chambered.

I made sure the cartridges would drop in/out under gravity. So I don't think this is the case. It's not barrel, either. It's barrels, as in three different luger barrels.

My sample size is very small, of course. It's curious to hear some others have made similar observations, too! I'm just curious how I can get away with not crimping, even when using mixed, untrimmed brass and cast bullets on all 3 of my 9mm's, and what that might indicate for potential accuracy.

I've also read that most 9mm cases are well short of SAAMI specs. This could be another factor in the equation.

 

[Clark]

If you want to measure your chambers, look at the SAAMI specs, compare to what you can measure with a set of pin gauges.

http://www.saami.org/specifications_and_information/index.cfm?page=ANSI

http://www.saami.org/specifications_and_information/index.cfm

If you want to measure feed ramp intrusion, take the barrel out of the pistol, scribe a line on a piece of brass with a needle, tracing the outline of the feed ramp. Measure the distance from that line to the base of the case. Compare that distance with the thickness of the web. To measure the thickness of the web, cross section a piece of brass.

Almost all 9mm pistol with have a chamber that the diameter is close to the minimum per the tolerance in the SAAMI specs. The feed ramp intrusion will probably be .19" and the case web WILL be .16".

If you want sloppy, measure the diameter of an old Glock 40 sw chamber or the feed ramp intrusion of an old Glock 10mm.

 

[LiveLife]

You'll find that so-call "match grade" barrels will have tighter chambers as part of the choices to get the barrels to shoot tighter.

Not entirely.

Glock chambers are "generous" primarily near the case base/ramp area to facilitate more reliable feeding/chambering even with fouling buildup inside the chamber. With near max loads, case bulges around this bottom 1/3 of the case. My Lone Wolf barrels have "tight" chambers at the case base/ramp area to fully support the case base and minimize bulging of the case. But both factory Glock and LW chambers have similar dimensions at the end of case neck area to seal the case against the chamber when fired (you can wiggle the chambered case base but not at the case neck).

For me, use of the term "match grade" has more to do with the barrel dimensions/tolerance/fit, barrel bore diameter and design/construction of the rifling than looseness of the chamber as looseness of chamber don't necessarily determine accuracy (many match shooters will take tight "match grade" barrels and widen the chamber/ramp feed area without affecting accuracy of the barrel).

Many factory barrels have larger bore diameters with deep land/groove rifling that are roughly finished. This allows for more hot gas to leak around the bullet and result in less consistent chamber pressure/shot groups. Higher end pistol barrels/match grade barrels have tighter spec'd barrel dimensions/bore diameters with shallow land/groove rifling that have polished finish for less hot gas leakage around the bullet resulting in more consistent chamber pressure/shot groups. Glock's hexagonal rifling with rounded hills/valleys (instead of lands/grooves) and polished surface hardening allows for very tight bullet-to-barrel fit and minimize hot gas leakage which increases the chamber pressure for more consistent powder ignition/accurate shot groups (but if you are loading at the max load data that used conventional land/groove rifled test barrel, this results in higher chamber pressure than published).

BTW, my factory Glock barrels actually shoot more accurate than the Lone Wolf barrels with the same load.

Really, looseness of Glock chambers is for reliable feeding/chambering and won't affect accuracy.

 

[918v]

Glock 9mm barrels have tighter chambers than Sig, Beretta, S&W, or Ruger. Brass fired in Glock 9mm barrels expands to .388/.389" while brass fired in the rest expands to .391". Glock 9mm chambers are not sloppy and do not need to be because the 9mm case is tapered and feeds just fine as is.

 

[SHR970]

Depends. With all of the millions of 9mm's out there made over the last 109 years, you will find a little variation in chambers. If you looks at 45's and try to comare a stock RIA mil. spec. barrel vs. a Wilson Combat match barrel, you will think the RIA is sloppy too.

 

[highlander 5]

When I bought my 92fs and started to reload for it I was concerned over the chamber and bore diameter. When I measured the bore it was nearly .357. I called Beretta and was told it was normal along with the case head being unsupported. I bought a Bar-Sto barrel and the bore is .3555 and the chamber is so tight that fired case will slide in with no problem. IIRC a fellow that went to my range had a P 38 that used .358 diameter bullets
and it still didn't shoot all that well.

 

[tkcomer]

Had a High Power when I first started loading the 9. The OAL was way to long on my first attempt to adjust the seating die, but I wanted to see how far up it stuck out of the barrel. Imagine my surprise when it dropped right in.

 

[rodregier]

Lot of variance in chamber throats as mfgr too, in my modest experience. Cast bullets handle a large jump in the throat poorly, jacketed will tolerate it more.

On chambers -

I had a new Bar Sto brl years ago for a S&W autopistol that had a short chamber after fitting. Little too tight a dimension, Bar Sto tries to keep tolerances to a minimum. Sent back to have it cut a bit deeper, no extra charge. Too bad US ITAR export controls would make such projects a nightmare of paperwork today for Canadian residents. (I believe Bar Sto doesn't even bother exporting any more - sigh).

 

[1SOW]

I've also read that most 9mm cases are well short of SAAMI specs. This could be another factor in the equation.

Most of the SAAMI specs are the "maximum" allowable--not the optimum sizes.

My 9mm loads (THESE ARE ALL JACKETED/PLATED BULLETS) are taper crimped to .377-ish. I have fired many K's of these reloads through my and many friends competition guns, and "all" fed without problems. CAN you NOT crimp and reliably feed? Maybe.
What is the benefit of not removing the bell? In the 9mm tapered case, the case gets bigger as the bullet seats deeper. Neck tension from resizing would be optimum at one narrow band on the case. It might be easier to have a "non-concentric" bullet seat without removing the flare and "straightening" the case to the rim. The classic 9mm Coke-bottle shape.

I do not have experience with lead bullets.

Another thought is that are a number of posts from bullseye shooters and others that cite "tighter crimps" as being "more accurate". I can't vouch for this.