38 Super chamber vs 9mm

[Broncman]

Can someone with a 38 Super open pistol measure the diameter of their chamber mouth opening( base area) for me? Curious as to what the average of most guns will be.

Thanks

 

[hjweiss]

Just look up the SAAMI specs for both cartridges.  Here's the link:

 

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

[Broncman]

I already have that. But not actual reamer specs.

 

Problem is, the Barrel is supposed to be short chambered and able to be finished in either according to Brazos.

 

It measures to big for "Sami" spec for 38 Super. My wife has a 1911 in 38 Super and it measures larger than Sami spec .

 

Are the "newer" 38 super being finished larger or still straight walled like the original 38 Super.

 

You here of people shooting 9mm in their 38 Super barrels and if finished per Sami spec, that should not be doable as the 9mm is wider at the bottom.

 

Make sense??

[Honkeymcgee]

I did a lot of looking around about this before I punched my 9mm open gun out to 38 super. 

 

The difference in the 2 is .006-7 if I remember correctly and reamers have a tolerance of .004 if I remember that right also.

 

I also want to say I read that only 2 barrel manufacturers(one of them being Schumen) actually short chamber barrels. All the rest are just 9mm barrels punched out to 38 super. I haven't had an issue with mine yet since I punched it out.

 

Not sure if that helps with what you're looking for but those were my observations when looking at the subject. 

 

 

[Broncman]

Thanks!

9mm punched out to 38Super is exactly what I suspected!

 

My short chambered STI Trubore/Brazos Thundercomp definitely measures to 9mm specs at chamber mouth.

 

All 38 Super brass I have found at matches measure to 9mm specs and shows they were fired in a 9mm/38 Super chamber vs a true 38 Super.

 

So....looks like I have been stressing over a non issue.

[Honkeymcgee]

6 hours ago, Broncman said:

Thanks!

9mm punched out to 38Super is exactly what I suspected!

 

My short chambered STI Trubore/Brazos Thundercomp definitely measures to 9mm specs at chamber mouth.

 

All 38 Super brass I have found at matches measure to 9mm specs and shows they were fired in a 9mm/38 Super chamber vs a true 38 Super.

 

So....looks like I have been stressing over a non issue.

Yea I feel ya bud. Sometimes the interwebs will get you worked up over things. I just did a lot of looking around and figured the variance was small enough I would be fine.

In the grand scheme of things the way I look at it is maybe I'll get a couple less firings out of a piece of brass because of the brass being worked a little more. Big whoop

[tomjerry1]

I'm pretty new to open, got a used gun with a 9x21 barrel that shoots 38 super. I myself was wondering about the extra room in the chamber, but the gun shoots great. I was actually thinking of barreling my gun, but the more I talked, and read, I am sticking with what I have. Will see how many reloads I get out of new brass?

[Tom S.]

On 9/13/2017 at 8:11 AM, Honkeymcgee said:

I did a lot of looking around about this before I punched my 9mm open gun out to 38 super. 

 

The difference in the 2 is .006-7 if I remember correctly and reamers have a tolerance of .004 if I remember that right also.

 

I also want to say I read that only 2 barrel manufacturers(one of them being Schumen) actually short chamber barrels. All the rest are just 9mm barrels punched out to 38 super. I haven't had an issue with mine yet since I punched it out.

 

Not sure if that helps with what you're looking for but those were my observations when looking at the subject. 

 

 

As a retired tool and die maker, I hope that reamer tolerance is .0004 not .004. Hell drills are closer than that!