45 ACP chambers

[JGSFAB]

Why does it seem like there are alot of TIGHT 45ACP chambers being produced today? LW Alphawolf G21 barrel- Tight AF, won't take polymer coated bullets.
KAK 45ACP AR15 barrel, every round is a super tight fit.
Remington R1? takes anything.
Is it CIP vs. SAAMI? I'm lazy and have not done any measuring/reverse engineering, full length sizing everything in RCBS carbide dies.
Our standard SAAMI reamer won't even come close to fitting in the LW G21 barrel, I'd rechamber it but its HARD and I didn't have a carbide reamer to mess up.
I'm guessing they're all MIN chambers.

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[RX-79G]

I would imagine that the list of mostly aftermarket barrels all put an accent on accuracy over the factory barrel with its looser chamber.

 

[JGSFAB]

I would imagine that the list of mostly aftermarket barrels all put an accent on accuracy over the factory barrel with its looser chamber.

That would be great if it functioned and actually shot any better lol. I'd say after decades of my family working with most of the OEMs, their standards are actually pretty high. The best chamber is the right sized , not tommy gun loose and not every other case stuck tight.

 

[RX-79G]

That would be great if it functioned and actually shot any better lol. I'd say after decades of my family working with most of the OEMs, their standards are actually pretty high. The best chamber is the right sized , not tommy gun loose and not every other case stuck tight.

Years ago I had a very, very accurate .45 Witness. Wouldn't chamber my lead handloads, but ran perfectly with factory ammo. I wouldn't say it was out of spec. My equally accurate 1911 with a throated barrel chambered them fine. Glock chambers are generally looser.

You could always try a factory crimp die.

 

[Koda]

I would imagine that the list of mostly aftermarket barrels all put an accent on accuracy over the factory barrel with its looser chamber.

Im going to go out on a limb here but in my experience (see my 9mm barrel thread) tight chambers do not mean improved accuracy.

 

[JGSFAB]

Everything ran 200-300 rounds (same dies) just fine. Our reamers are SAAMI Min +0.0005/-0.
Running things to SAAMI min. is asking for problems IMHO.
I really haven't deep dived it so its all guessing (besides trying a JGS standard reamer and even getting close to headspace).

 

[Koda]

Why does it seem like there are alot of TIGHT 45ACP chambers being produced today? LW Alphawolf G21 barrel- Tight AF, won't take polymer coated bullets.

Because tight tolerances are bragging rights in machining communities. And the new comers, while good at machining doesnt mean experienced at shooting reliable gun designs. People just cant get it out of their heads that some play in just the right places doesnt mean poor quality or less accuracy.

 

[JGSFAB]

Because tight tolerances are bragging rights in machining communities. And the new comers, while good at machining doesnt mean experienced at shooting reliable gun designs. People just cant get it out of their heads that some play in just the right places doesnt mean poor quality or less accuracy.

Most days I hear lots about the proper clearances giving more accuracy. "Tight" and "Precision" are not the same thing.

 

[Koda]

Most days I hear lots about the proper clearances giving more accuracy. "Tight" and "Precision" are not the same thing.

what would be the correct term to use for this discussion?

Im not a gunsmith but one of my most "precise" accurate pistols has some slop but eats any ammo Ive fed it so far.

I recently built a 9mm that took me forever to figure out why it was failing to feed, randomly. "tight chamber". I bought a cheap barrel to try and so far its up over 200rds and is one of my most accurate pistols. The barrel maker told me his tolerances were "tighter" but of course everything is gauged with a SAAMI gauge in spec.

 

[TTSX]

Because you're only supposed to shoot SWC bullets so you don't blow your whole wad at once

 

[JGSFAB]

what would be the correct term to use for this discussion?

Im not a gunsmith but one of my most "precise" accurate pistols has some slop but eats any ammo Ive fed it so far.

I recently built a 9mm that took me forever to figure out why it was failing to feed, randomly. "tight chamber". I bought a cheap barrel to try and so far its up over 200rds and is one of my most accurate pistols. The barrel maker told me his tolerances were "tighter" but of course everything is gauged with a SAAMI gauge in spec.

I really don't know. Precision is making the same size everytime down the many decimals.
The thinking of "tighter" chambers being better (IMHO) came from the old loose production grade chambers vs. "match grade".
Every modern chamber is now "match grade" is its a moot point.
Unless you have a full function gauge (fairly rare), a headspace gauge only shows headspace.
Every reamer made "should" be over SAAMI min... but spring back, shady torrences , etc etc.

 

[Koda]

I really don't know. Precision is making the same size everytime down the many decimals.
The thinking of "tighter" chambers being better (IMHO) came from the old loose production grade chambers vs. "match grade".
Every modern chamber is now "match grade" is its a moot point.
Unless you have a full function gauge (fairly rare), a headspace gauge only shows headspace.
Every reamer made "should" be over SAAMI min... but spring back, shady torrences , etc etc.

When I think of "tighter" in regards to machining I think of either less tolerance or "material safe" in regards to being able to remove more material later if needed. I guess that applies here if so.

agree that "match grade" is a moot point now with so many companies cranking out expensive barrels.

Im not a gunsmith, but it seems like a "tight" chamber is not what makes a gun super accurate. My guess is a couple thou is all it takes to make the chamber feed any brand ammo and not affect the guns accuracy. At least thats the case with the super cheap barrel I bought to validate my expensive "match" barrel was the culprit.

 

[RX-79G]

Im going to go out on a limb here but in my experience (see my 9mm barrel thread) tight chambers do not mean improved accuracy.

I wouldn't say so either, especially since 9mm is a tapered chamber and .45 is not, but that is the conventional wisdom.

Of course, tight chambers also come from worn tooling.

 

[oremike]

One thing you might look at is that the chamber is cut for .451 bullets and the cast/coated bullets are .452 and so you'll have to seat them a scouch shorter.

 

[Koda]

I wouldn't say so either, especially since 9mm is a tapered chamber and .45 is not, but that is the conventional wisdom.

Of course, tight chambers also come from worn tooling.

either caliber, id love to hear the reason a tight chamber is better?

My 45s eat any ammo and some are super accurate pistols.

 

[TTSX]

I had a problem where I loaded rounds for my Glock 21. Ran great. Tried the loads in other .45s and not a single one of them would chamber. 1911s, M&P, HK etc. You could see on the bullets where they were jammed into the rifling. So I shot up that batch and readjusted to a shorter length that all my pistols agreed with. Easy peasy.

Though I have found the loading SWC or tapered bullets like the Hornady XTP kind of eliminates that particular issue from the start. YMMV.

 

[RX-79G]

either caliber, id love to hear the reason a tight chamber is better?

My 45s eat any ammo and some are super accurate pistols.

The idea is that the cartridge is held in better alignment with the bore. With too large a chamber the casing can tilt and the bullet enters the lands slightly skewed.

I imagine minimizing how much the casing swells before the bullet leaves it could also be a factor.

Obviously, these are just pistol bullets in a relatively sloppy accuracy system overall, so all this chamber stuff is polishing a turd. Glock says their barrels will print 1/2" groups at 25m from a fixture, so the majority of the 3" group accuracy the assembled guns produce is slide to barrel to frame wiggle. Which even a perfectly fitted barrel isn't going to fix.

 

[Koda]

The idea is that the cartridge is held in better alignment with the bore. With too large a chamber the casing can tilt and the bullet enters the lands slightly skewed.

I imagine minimizing how much the casing swells before the bullet leaves it could also be a factor.

Obviously, these are just pistol bullets in a relatively sloppy accuracy system overall, so all this chamber stuff is polishing a turd. Glock says their barrels will print 1/2" groups at 25m from a fixture, so the majority of the 3" group accuracy the assembled guns produce is slide to barrel to frame wiggle. Which even a perfectly fitted barrel isn't going to fix.

sure, for "true match grade" custom built competition guns maybe I could see the reason for a tighter chamber, but then those would be made specific to a specific ammo to run reliably to compete.

But the vast majority of people buying these high end custom barrels are putting them in home defense gun builds (at least thats my impression).

and that said, if a Glock can print 1/2" groups at 25m then the idea of a tight chamber is moot.

I think these barrel makers need to loosen up a bit...

 

[RX-79G]

Or, it could just be worn chamber reamers.

 

[Koda]

Or, it could just be worn chamber reamers.

thats a sign of an inexperienced machinist.