.40 In A 10mm Barrel

[John Dunn]

I have a Delta Elite in 10mm that has been gathering dust for many years. As I am now shooting a ton of .40 through my STI, I've toyed with shooting .40 through the 10mm after switching out recoil springs. My question is, do I really need a .40 barrel, or is it kosher to jump the gap and headspace off the extractor?

[BrianH]

No, its not. You're going to destroy your brass.

[joshua]

Hmmm.... The brass length for 40S&W is .836 and .975 for the 10mm - I'm using a caliper and both brass are fired once. I will definitely agree with Brian and will add you may even end up destroying your extractor. Just get another barrel fitted to your Delta Elite. You will need to load long for your Colt Delta Elite. I use to shoot a 40 in single stack using the 9 rnd 10mm mags, and it called for long loading the 40 just to make it reliably feed. If you use the 8 rnd 40 mags you won't have to load long. If you load long closer to 10mm cartridge OAL you may as well use the 10mm loading, the large primer vs small primer on 40 makes up for the unburnt powder in the medium to slow burning powders. If you use the fast burning powders you'll have too much air in the case causing erratic speed deviation. Goodluck with your project. josh

[DougCarden]

Yes you can do it, but.......................minor loads will be fine, major will be rough on the chamber and reduce the life of the bbl. It will be rough on the extractor, try an aftec! I have a buddy that shot thousands of .40s through his 10mm with just changing extractors, and I am currently torture testing 9x19 through my 9x23(AFTECall the way) with STI 9mm spacers as well. I will probably have a 9x19 bbl fitted this winter, but in the short term it will work. Not the best thing though, and hard on parts. my .02$

[Guest bulm5]

Hmmm.... The brass length for 40S&W is .836 and .975 for the 10mm - I'm using a caliper and both brass are fired once. I will definitely agree with Brian and will add you may even end up destroying your extractor. Just get another barrel fitted to your Delta Elite. You will need to load long for your Colt Delta Elite. I use to shoot a 40 in single stack using the 9 rnd 10mm mags, and it called for long loading the 40 just to make it reliably feed. If you use the 8 rnd 40 mags you won't have to load long. If you load long closer to 10mm cartridge OAL you may as well use the 10mm loading, the large primer vs small primer on 40 makes up for the unburnt powder in the medium to slow burning powders. If you use the fast burning powders you'll have too much air in the case causing erratic speed deviation. Goodluck with your project. josh

I am using V V 320 over 200 grs precisions. Pretty consistent velocities 825 FPS to a high of 835 FPs.