headspacing a barrel on a sig 229

cer

according to sig, and pretty much everyone else a person can change 40 S&W and 357 sig barrels in a p229. My question is: do you have to headspace the barrels if changed out, and if so how is it done?


I fixed it for you...NN[:D]

headspassingbarrel on a sig 229

Ricci Wright

No

rufe-snow

They are, what is know as controlled feed. As the slide goes forward into battery. It's lower surface, pushes the cartridge out of the magazine. As the cartridge goes forward, it is caught between the front face of the slide and the rear surface of the extractor. The rear surface of the extractor, controls headspace on controlled feed guns.

MIKE WISKEY

" The rear surface of the extractor, controls headspace on controlled feed guns."..............SORRY RUFE, NOT EVEN CLOSE. HEADSPACE IS BETWEEN THE BREECH FACE AND THE FRONT OF THE CARTRIDGE CASE (40 S&W) OR THE 'SHOULDER' OF THE CARTRIDGE (.357 SIG). THE EXTRACTOR MAY HOLD THE CARTRIDGE IN THE PROPER POSITION BUT THIS IS SECONDARY. AS TO THE QUESTION, NO YOU DON'T HAVE TO DO ANYTHING WHEN SWAPING BARRELS, ONLY IF YOU ARE BUILDING A BARREL FROM SCRATCH.

rufe-snow

quote:Originally posted by MIKE WISKEY
" The rear surface of the extractor, controls headspace on controlled feed guns."..............SORRY RUFE, NOT EVEN CLOSE. HEADSPACE IS BETWEEN THE BREECH FACE AND THE FRONT OF THE CARTRIDGE CASE (40 S&W) OR THE 'SHOULDER' OF THE CARTRIDGE (.357 SIG). THE EXTRACTOR MAY HOLD THE CARTRIDGE IN THE PROPER POSITION BUT THIS IS SECONDARY. AS TO THE QUESTION, NO YOU DON'T HAVE TO DO ANYTHING WHEN SWAPING BARRELS, ONLY IF YOU ARE BUILDING A BARREL FROM SCRATCH.



Your welcome to your opinion, even though it's wrong.

62fuelie

By the SAAMI specs, for some reason Sig specified that the .357 headspaces on the case mouth, as does the .40. On my .357 barrel from BarSto it is headspaced on the soulder datum line as it should have been in the first place. That said, the barrels interchange without adjustment as long as the chamber is properly cut to allow the case mouth to set up on the head space ridge. This means that the chamber should be kept clean and not left to build up material on that ridge. This works for me on my 226, 229, and 239.

tsr1965

I happen to agree with MIKE, and we have been thru this before. Headspace is determined in ANY firearm by the breech face, and a feature on the cartridge case, be it a rim/belt, shoulder, or case mouth. If it was the extractor which headspaced the cartridge, extractor wear would hinder the headspace.

Yes, you can shoot a 40 S&W in a 10mm auto pistol, as long as the extractor holds the rim secure enough for firing. Just like moon clips in a revolver chambered for 10mm, or 45 ACP, or 9mm. In an auto pistol the defining feature on the firearm is the breech face...PERIOD.

To the OP, the 40 S&W headspaces on the case mouth, while the 357 SIG headspaces on the shoulder. As long as the slide comes into full battery, the headspace should be good, but I would want to make sure it is checked with head space gauges.

EDIT 1
quote:quote:Originally posted by forgemonkey


http://www.gundigest.com/headspace-101-what-happens-inside-your-rifles-chamber

C&P from above,,,,,,,

Headspace is measured from the bolt-face to the mouth of a straight rimless hull like the .45 ACP, whose mouth stops against a small, abrupt shoulder at the front of the chamber. In a belted magnum, the stop is the leading edge of the belt, in the back of the chamber. On a .30-30 case it's the front of the rim. The datum line for rimless or rebated bottleneck rounds like the .270 and .284 lies on the shoulder. Semi-rimmed cartridges theoretically headspace on the rim, but sometimes (as with the .38 Super Automatic) the rim protrusion is insufficient for sure function. The case mouth then serves as a secondary stop. The semi-rimmed .220 Swift has a more substantial lip; but most handloaders prefer to neck-size the Swift, so after a first firing, the case actually headspaces on its shoulder.

From Kuhnhausen Manual II. ,,,,,,,,











Once again...it is not something that was designed to be that way, but rather a phenomena that happens. Much like the "moon clips", in a revolver with a rimless round. It can, and does work, but was not intentional to the way a cartridge headspaces. The way a cartridge headspaces is determined by the design features of the cartridge, as stated earlier.

Hawk Carse

Whatever your definition, the answer to the OQ is that there is no provision for headspace adjustment on a service pistol barrel. Sig's parts interchangeability is good enough for normal use.

You will see 1911 barrels advertised as "short chambered" so that they can be reamed to suit the gunsmith's preferences for best accuracy.

MIKE WISKEY

"Your welcome to your opinion, even though it's wrong.".............Well, I could agree with you........but then we'd both be wrong[;)]

Hawk Carse

62fulie is correct, the SAAMI spec for .357 Sig has headspace dimension defined as the .865" from breechface to chamber mouth, just as though it did not have a shoulder.

Yes, it is possible for a short round to hold position off the extractor, the gun and ammo specs are sloppier than you might like.

And a lot of reloaders set up .357 Sig off the shoulder, but they are not SAAMI members.