Converting 9mm to 38 super

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Converting 9mm to 38 super

Post by desben on 6/7/2017, 4:32 pm

In some posts, on this forum and others, people have stated that a 9mm 1911 can be converted to 38 super by simply swapping barrel and mags. (e.g. http://www.bullseyeforum.net/t7033-38-super-barrel). However, in Gun Digest Shooter's Guide to the 1911, Robert K. Campbell writes:

Robert K. Campbell wrote:Converting from 9mm to .38 Super is more difficult. The 9mm has a .384" breechface and the .38 Super measures .405". The 9mm breechface must be opened in order to allow the slightly wider .38 Super casehead to function properly.

I was thinking about buying a 9mm Springfield Range Officer and get get a gunsmith to fit a 38 super barrel in it, thinking that it's easier to load down 38 super to bullseye speeds (~700fps) and get good accuracy. The gun would be used for 1800 matches and International Centerfire (max 38 cal); we rarely get a full 2700 around here. But Robert's comments have me worried that it may not be as straightforward as I thought.

Thoughts?
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Re: Converting 9mm to 38 super

Post by Jon Eulette on 6/7/2017, 4:49 pm

I just did a RO conversion. I had to modify breechface slightly for larger rim.
Jon
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Re: Converting 9mm to 38 super

Post by mpolans on 6/7/2017, 7:20 pm

Or you could shoot .38 supercomp (basically rimless .38 super).

But why bother?  Why not just work up an accurate 9x19 load?  If folks are able to get their 9x19 Bianchi Cup guns to shoot 1.0 - 1.5" at 50 yards, I would think the caliber wouldn't be holding you back.

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Re: Converting 9mm to 38 super

Post by Jon Eulette on 6/7/2017, 7:27 pm

mpolans wrote:Or you could shoot .38 supercomp (basically rimless .38 super).

But why bother?  Why not just work up an accurate 9x19 load?  If folks are able to get their 9x19 Bianchi Cup guns to shoot 1.0 - 1.5" at 50 yards, I would think the caliber wouldn't be holding you back.
You need velocity to get 9mm to group st 50yds. 1050-1100 fps. Very snappy.
Jon
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Re: Converting 9mm to 38 super

Post by desben on 6/7/2017, 7:35 pm

That's what I read; 9mm needs to go fast. So what is it about 38 super that makes it easier to get accurate loads at lower velocity? They are using more or less the same bullets. Twist probably is a factor in some cases, but 1-10 barrels are available for 9mm too.
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Re: Converting 9mm to 38 super

Post by LenV on 6/7/2017, 8:08 pm

Probably around 800 rds thru my RO 9mm to 38 Super conversion. Never had to do anything to the breech face. I use nothing but the Starline competition brass which is actually consistently larger then the regular brass. I guess not all 9s were created equal.

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Re: Converting 9mm to 38 super

Post by Dr.Don on 6/7/2017, 9:28 pm

I get 2 1/4 inch groups at 50 yds with my 9mm 10 twist using 147gr bullets at 700-730 fps.  Nice and soft.  But the 147's take the fast twist.

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Re: Converting 9mm to 38 super

Post by mpolans on 6/7/2017, 10:14 pm

Jon Eulette wrote:
mpolans wrote:Or you could shoot .38 supercomp (basically rimless .38 super).

But why bother?  Why not just work up an accurate 9x19 load?  If folks are able to get their 9x19 Bianchi Cup guns to shoot 1.0 - 1.5" at 50 yards, I would think the caliber wouldn't be holding you back.
You need velocity to get 9mm to group st 50yds. 1050-1100 fps. Very snappy.
Jon
IIRC, don't most aftermarket 9x19 and .38 super barrels have the same twist rate?  If so, it would seem the same velocities would be required of .38 super.

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Re: Converting 9mm to 38 super

Post by Rob Kovach on 6/13/2017, 5:34 pm

I'm interested in understanding how .38 super can deliver good 50 yard accuracy at 700fps but 9mm cannot.

Jon?
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Re: Converting 9mm to 38 super

Post by jglenn21 on 6/13/2017, 5:58 pm

Our supers run a  1 - 16 twist and shoot outstanding groups with 126 Dardus SWCs.  Around 720 fps with 3.6 of BE. Easily  under 2" at 50 yds 

very soft recoil with a slide mounted dot.
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Re: Converting 9mm to 38 super

Post by messenger on 6/13/2017, 7:03 pm

jglenn21 wrote:Our supers run a  1 - 16 twist and shoot outstanding groups with 126 Dardus SWCs.  Around 720 fps with 3.6 of BE. Easily  under 2" at 50 yds 

very soft recoil with a slide mounted dot.
What crimp and COL are you running. I'm having a 38 super built and would like to get a little ahead of the curve.

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Re: Converting 9mm to 38 super

Post by jglenn21 on 6/13/2017, 7:08 pm

will check and let you know
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Re: Converting 9mm to 38 super

Post by jglenn21 on 6/13/2017, 7:20 pm

On mine and my nephew's Supers we are running 1.269 OAL with a .379 Crimp ( Remington brass)

one is a Kart and one a KKM barrel.

our recoil springs are 8 lb ISMI with 4 coils cut off.

you can run 3.6-3.8 gr of BE to find what your gun likes. We all pretty much use.356 sized bullets. I have tried some .357 and didn't see anything there in my Kart
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Re: Converting 9mm to 38 super

Post by messenger on 6/14/2017, 5:20 am

jglenn21 wrote:On mine and my nephew's Supers we are running 1.269 OAL with a .379 Crimp ( Remington brass)

one is a Kart and one a KKM barrel.

our recoil springs are 8 lb ISMI with 4 coils cut off.

you can run 3.6-3.8 gr of BE to find what your gun likes. We all pretty much use.356 sized bullets. I have tried some .357 and didn't see anything there in my Kart
Thank you for the information. This will make dialing in my new gun a lot easier. Can't wait to receive it.

Bill
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Re: Converting 9mm to 38 super

Post by desben on 6/14/2017, 9:50 am

Rob Kovach wrote:I'm interested in understanding how .38 super can deliver good 50 yard accuracy at 700fps but 9mm cannot.

I'm wondering the same thing. Especially when they are both using the same bullets, with the same barrel (twist rates). But over and over, you hear the people who know saying that 9mm needs to be run fast.

Dr. Don on this site had a thread about successfully running 9mm at 700fps using 147gr bullets. He used fast twist (1/10 or 1/12). He's the exception it seems.
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Re: Converting 9mm to 38 super

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