9mm bore diameter size regarding S&W M&P guns and Sig Sauer guns

[Wayne Dobbs]

Wolfie,

You say it groups "fine" (a dangerous word in my experience) but haven't defined what "fine" is. Tell us what it does for 10 shots off the bench or other solid support at 25 yards. That gives us a usable metric. As JHC stated, 10 yards doesn't tell us anything from a full sized standard caliber service pistol. Not trying to step on your puppy, but if you will go and read some of Molon's posts on this forum, you'll get an idea of what careful testing looks like and it's not done at 10 yards.

[WOLFIE]

Wolfie,

You say it groups "fine" (a dangerous word in my experience) but haven't defined what "fine" is. Tell us what it does for 10 shots off the bench or other solid support at 25 yards. That gives us a usable metric. As JHC stated, 10 yards doesn't tell us anything from a full sized standard caliber service pistol. Not trying to step on your puppy, but if you will go and read some of Molon's posts on this forum, you'll get an idea of what careful testing looks like and it's not done at 10 yards.

10 yards will work for sighting in a pistol. It may not show the complete inherent accuracy potential of the gun. You set a target 10 yards away and the rounds go into one ragged hole (not so ragged if shooting a flat nose bullet such as the 40 S&W) one inch to the left. You may now adjust the sights and bring the group one inch to the right. If the rounds and we can use a 10 shot group go into one hole again in the center ring, you have adjusted the sights. If the sights are off, you will be able to determine that is so at 10 yards.

I was trying to determine if the ammunition caused the problem or if it was the gun. The good ammunition - one inch group. Bad ammunition - 3.5 inch group. This test was measurable. For what I was trying to accomplish, the 10 yard test worked. In theory:
If a target was placed perfectly behind the 10 yard target but at 25 yards, bad ammo - greater than 3.5 inch group. Good ammo - greater than 1.0 inch group.

[Bruce Gray]

For my part, I'm impressed with the results you obtained with MagTech!

FWIW, we test and zero a couple thousand pistols a year here, most of them SIG Sauers. In recent memory, the only SIG I recall that did not group at least acceptably (and most are flat stellar) at 13 yards was an SP2022 with a badly mis-machined slide. Out of one 64-unit batch, a few got out with this unseen flaw. They were replaced.

-Bruce

[Alpha Sierra]

Another suggestion is the bore diameter is larger than needed for 9mm bullets so that 357 sig or 38 special bullets can be used.

Just for your FYI

1) 357 Sig uses the same exact bore diameter and bullets as 9 mm Luger. Both CIP and SAAMI say so.
2) Nobody reputable deliberately oversizes their 9 mm barrels to work with Ø0.357" bullets

[WOLFIE]

Just for your FYI

1) 357 Sig uses the same exact bore diameter and bullets as 9 mm Luger. Both CIP and SAAMI say so.
2) Nobody reputable deliberately oversizes their 9 mm barrels to work with Ø0.357" bullets

I have wondered this. I did hear that Smith and Wesson makes oversize 9mm barrels to accommodate the 357 Sig bullets to make manufacturing simpler or cheaper. You mentioned SAAMI though.

[JV_]

Another suggestion is the bore diameter is larger than needed for 9mm bullets so that 357 sig or 38 special bullets can be used.

Are you confusing 357SIG and MAG? .357 Magnum and .38 Special have the same bore diameters. 357SIG uses a 9mm bullet.

9mm / 357SIG = .355"
.38 Special /.357 Mag = .357"

[Tamara]

I did hear that Smith and Wesson makes oversize 9mm barrels to accommodate the 357 Sig bullets to make manufacturing simpler or cheaper.

Whoever told you that was wrong.

[WOLFIE]

Are you confusing 357SIG and MAG? .357 Magnum and .38 Special have the same bore diameters. 357SIG uses a 9mm bullet.

9mm / 357SIG = .355"
.38 Special /.357 Mag = .357"

I am not confusing 357 Sig with 357 magnum or 38 special. I could be wrong but isn't 357 Sig .356 in diameter ?

[WOLFIE]

Whoever told you that was wrong.

It is nice to hear that is wrong.

[Maple Syrup Actual]

I am not confusing 357 Sig with 357 magnum or 38 special. I could be wrong but isn't 357 Sig .356 in diameter ?

That depends...what's 9 millimetres in thousandths of an inch?