Chamber comparison: G 37 vs Colt Mark IV Series 1

[Haycreek]

We all read that the Glock chambers are "looser" than a Colt 1911--- Don't believe it ! The chamber in my G 37 measures the same as my Colt Mark IV Series 70. Empty G 37 cases show no expansion while the Colt 45 ACP expands .008. Both were loaded to the same velocities. IMHO the 45 GAP can be reloaded more times, with a bonus of being a SAFER round for reloading because of the beefed up case! Glocks are not more dependable because of loose chambers, the "simply design" is just more dependable.

 

[Old Fuff]

You are right so far as you go. Both the Glock and Series 70 Colt's have "service" chambers. However most of the guns coming from other makers have tighter "National Match" chambers.

A .45 that is used, or intended to be used as a weapon should have a "service" chamber. Glock knows this, and for that matter Colt does too. But many less-then-knowledgeable buyers want, or expect (should I say, "demand?") a match barrel in whatever they buy, and the gun companies are in business to sell guns, not educate the public.

 

[Jim Watson]

"Match chamber" is an advertising gimmick, nothing more.

The old NRA Handloading manual has SAAMI drawings for most commercial rounds of the time. Although it shows separate drawings for .45 ACP standard and Match, the chamber dimensions are EXACTLY THE SAME. Not just the basic dimensions but the +/- tolerances are the same throughout.

What a lot of the aftermarket barrel makers are selling is UNDERSIZE chambers, so they can claim a smidgen better accuracy with match ammo from a rest. But they are giving up reliability with common ammunition in a fouled gun.

Many production line guns will be found with undersize chambers, too. Probably from trying to get just one more shift of use out of a worn reamer.

My FLG (and a lot of other serious gunsmiths) routinely runs a sharp standard reamer into the chamber of the guns he works on. Strangely, he doesn't get many shavings out of his preferred Kart Match barrels, but some others take a surprisingly large cut. I have a Wilson barrel that he said put out the most cuttings of any he had seen, but another was almost right to start with. A Springfield factory barrel showed cut marks only where the heavy caliber stamp over the chamber had dented the steel.

By the way, Hay, .008" is a lot of case expansion in a pistol, or anything. Either you have a sloppy Colt or are loading ACPs hot to keep up with the high pressure GAPs.

 

[Old Fuff]

The so-called "National Match" chamber was originally developed at Springfield Arsenal back in the early 1960's. I know because I was at Camp Perry when the USGI National Match pistols were first issued to competitors with the new barrels. These did have tighter chamber specifications, and were intended to ONLY be used in bullseye target guns.

Some reamer manufacturers offer a smaller "match" reamer. With barrel makers you never know what they might be using, but yes - they all stamp N.M., "National Match," or "Match" on their products.

For the record, I do the same thing Jim's gunsmith does - he is obviously wise and experienced. And yes, "National Match" like "Tactical" is mostly advertising B.S.

 

[stans]

Ultra tight chambers keep gunsmiths in business. I have a 1911 with a BarSto barrel that I used in IPSC competition. It ran well until it got a little dirty, then it jammed. I had the barrel chamber reamed to standard dimensions, all jams gone and the accuracy did not seem to be affected.

As for Glock vs Colt chambers, the Glock that gets the attention are those chambered in 40 S&W. In order to get the 9mm size Glocks to feed 40, Glock had to remove more of the chambe at the feed ramp and this left a fair amount of case wall unsupported. It seems to be far less of a problem in the large frame Glocks.

 

[Jim Watson]

Well, the Army can do as it likes, including long link lockup - and we know what is thought about THAT these days - but commercial manufacturers ought to stick to industry spec.

 

[Haycreek]

Old Fuff and Jim Watson- I appreciate you comments from your experience. I have over 50 years experience with the 1911, but still trying to learn from others. Now I'll go measure my Kimber Classic Gold Match barrel, and see it it is really a NM barrel as advertised !

 

[Andrew Wyatt]

with a bonus of being a SAFER round for reloading because of the beefed up case!

I'd say this is counteracted by the significantly higher chamber pressure and smaller case capacity of the GAP.

 

[Haycreek]

Chamber comparison: g37 vs Colt Mark IV Series 1

Andrew Wyatt- I believe that you will find that "factory" 45 GAP ammo pressure is between 19800 - 20500 psi, which is about the same as factory 45 ACP, with hardly noticable any lower velocity, and that difference may be gained by different rifling in the two barrels. The 45 GAP is reported to have been tested up to 35000psi without failure, I would not try it myself and certainly not with a 45 acp case. As you may already know, the GAP case is thicker at the shoulder near the rim. I have loaded some fairly hot loads with NO case expansion. I sold my Glock 22 and 23 after experimenting with the 45 GAP. There are lots of choices, I still like the 45 ACP very much, but Speer sure did a good job helping develope the 45 GAP. The 45 GAP is now my first choice for pistols, the 44 mag and 357 mag is my favorite revolvers. Second choices are the 9mm and 45 ACP.

 

[Haycreek]

Chamber comparison: G 37 vs Colt Series 70 Mark IV Series 1

My Kimber Classic Gold Match barrel measured the same as the G 37 and Colt Series 70 . I was surprised to find the Kimber Classic Gold Match has the same deminsions. I have no complaint with the Kimber, extremely smooth, well fitted and dependable. The more I shoot and explore the G37, the more I like it

 

[Old Fuff]

Jim:

The name of the engineer that headed the National Match Weapons Program at Springfield Arsenal in those days was a gentleman named Gene Taylor. When he started he didn't get a very big appropriation, and was still expected to produce match grade pistols while using regular USGI pistols. He was well aware that long links were not the best answer, but given the circumstances it was the best he could do. As soon as the funding situation improved he was able to buy barrels made to the Arsenal’s specifications. One of the things on those barrels was an oversized bottom lug with enough material so that it could be fitted to cam on the slide lock pin. Another feature was an oversized hood that could be fitted to the slide. Up to this point custom pistolsmiths had to weld up barrels at these fitting points. As for his chambers – yes they were tight, and Gene proved with machine rest testing that they grouped better than similar barrels with standard chambers.

However it was never his intention that these MATCH barrels would ever be used in SERVICE pistols. And no, since his only interest was in producing a superior bullseye target pistol he didn’t worry about SAMMI specifications.

 

[Jim Watson]

The article I vaguely recall in an old American Rifleman said that they built military match pistols with link and lug locking in parallel for convenience, oversize barrel availability, and side by side comparison. (A gun marked "L" was a lug fit not a long link; now isn't that clear and obvious.)

This piece said the accuracy was comparable although the long links had to be replaced every once in a while. I was roundly hoorawed for saying as much the last time the subject came up. But I have seen guns set up that way shot, and they would SHOOT, theory and fine gunfitting standards notwithstanding.

I bet ol Gene didn't have to worry about his guns with undersize chambers being shot with ammo reloaded by guys trying to learn how one question at a time over the internet, sweatshop gunshow ammo, WW I leftovers, or Slobbovian surplus, either.

 

[Old Fuff]

Jim:

>> The article I vaguely recall in an old American Rifleman said that they built military match pistols with link and lug locking in parallel for convenience, oversize barrel availability, and side by side comparison. (A gun marked "L" was a lug fit not a long link; now isn't that clear and obvious.) <<

During one year, before they got the new barrels, a few gun were made using USGI barrels that had enough material on the bottom lug so they could be fitted up to cam into battery. I once owned one, and it did have the "L" stamp. The following year all of the guns were built with new barrels, and long links passed into history.

Also - it was the standard practice to rebuild the guns made in the past year. The only ones that survived in their original form were a handful that were sold to civilians.

>> This piece said the accuracy was comparable although the long links had to be replaced every once in a while. I was roundly hoorawed for saying as much the last time the subject came up. But I have seen guns set up that way shot, and they would SHOOT, theory and fine gunfitting standards notwithstanding. <<

Yes, they often did. All of them had to at least shoot into 3 inches off a Ransom rest at 50 yards, using USGI match grade hardball. If they didn't they never left the Arsenal. I don't believe any commercial maker - then or now - ran their products through a 100% machine rest accuracy test. Only a few custom builders did (or do) this.

>> I bet ol Gene didn't have to worry about his guns with undersize chambers being shot with ammo reloaded by guys trying to learn how one question at a time over the internet, sweatshop gunshow ammo, WW I leftovers, or Slobbovian surplus, either. <<

No he didn't. The guns made at Springfield Arsenal (Later Rock Island Arsenal) were issued to military shooting teams and to competitors at the U.S. National Matches. They also issued the match grade hardball ammunition that was expected to be used in them. Sub-standard ammunition was a moot point.

I have no argument with you concerning the need for standard chambers in guns that may fire less then optimal ammunition or be used under less then perfect conditions. Anyone who uses a barrel with a tight chamber in those situations is a total fool. I have said in several threads that WEAPONS SHOULD HAVE STANDARD, NOT MATCH CHAMBERS. All I was trying to do was explain how and why the national match barrel came to be.

So there, now we should be in total agreement.

 

[Jim Watson]

I'll go with you as to Army National Match barrels and chambers, and I am sure Springfield had prints and specifications for the purpose.

BUT, in the book on my shelf, although there are separate drawings for SAAMI .45 ACP standard and Match chambers, the dimensions and tolerances are the SAME in both. There is NO SUCH THING as an identifiable "match chamber' in a gun or barrel made under those specifications. Either SAAMI has changed specifications, or many gun and barrelmakers are winging it for the sake of advertising and to the detriment of many of their customers.

No doubt, as William Davis said, manufacturers hold their own tolerances closer than the standard, and that is good, but it does not give them a license to mess with the basic dimensions.

 

[Old Fuff]

>> Either SAAMI has changed specifications <<

Unlikely.

>> Or many gun and barrelmakers are winging it for the sake of advertising and to the detriment of many of their customers. <<

Very likely, but the customers are getting what they think they want.

>> Manufacturers hold their own tolerances closer than the standard. <<

Some do, many don't.

>> But it does not give them a license to mess with the basic dimensions. <<

Given what we see these days, I question if they have a full set of blueprints. They get away with what they do because no one ever challanges them. If the cartridge will go in that's good enough.

 

[Jim Watson]

*They get away with what they do because no one ever challanges them. If the cartridge will go in that's good enough.*

Well, that's the problem, the cartridges don't always go in.
The companies do get challenged, you can read the stories on the www. A gunmaker gets credit for "great customer service" when they sell somebody a gun that doesn't work but are polite about tinkering with it and sometimes even fixing it. I am sure they have a sharp pencil statistical process control guru who carefully balances warranty department costs vs the expense of better materials and closer QC testing/inspection. So I guess they do get away with it, in the sense of the bottom line.

 

[Old Fuff]

Jim:


Regarding current or recently manufactured 1911 style pistols …

This and other forums are filled with threads or posts from owners complaining about problems that ultimately come down to sub-standard parts, materials or workmanship. Usually these seek help from members such as 1911 Tuner on how to fix (whatever). While Tuner’s help and expertise is greatly appreciated and most welcome, it should always be remembered that when he and/or the pistol’s owner solve a problem the manufacturer who caused it gets off the hook so to speak.

It should be noted that these threads or posts seldom involve older 1911 pattern pistols, particularly those made by Colt or USGI contractors. That is because at the time those companies had effective quality control procedures in place, and as a rule used appropriate materials and workmanship in the manufacturing process.

In the present instance, discussion has centered on out-of-specification chambers, particularly those that are too tight. It has been observed by both of us that tight chambers can, and probably will impact on reliability, and that manufacturers should not use barrels with tight chambers except on pistols specifically intended to be used in formal bullseye target shooting. Unfortunately this is sometimes not the case.

So who is at fault? I submit that on one hand it is the manufacturer who obviously doesn’t check his product with a simple go/no go plug gage, which would only take several seconds per barrel, and customers who want and demand a service pistol (read that “weaponâ€) that will group like a match pistol. Somewhere a compromise between reliability and accuracy has to be made, and having a correct chamber for the job is a good place to start.

Your point about manufacturers keeping a close eye on warrantee repair costs is correct, but every time someone else fixes a manufacturer’s mistakes it helps their bottom line.

As CR Sam has said, in so many words, “manufacturers should be held accountable.†Each time they aren’t we do ourselves a disservice. Nothing will clean up the companies’ act faster then a demanding customer base. The bottom line is simple…

It’s the $$$$ that count.