Loading to 10mm level in .40 STI Edge?

[ericm]

Has anyone done this? 180 gr @ 1200 fps +/- ?

STI Edge 5" bull bbl, have shot the hottest factory .40 out there, no issues.

Would use 18# spring, new .40 brass, SR primers, Hornady XTP, load to 1.2"+ OAL, proper powder for 10mm, etc.

Anything else?

Please let me know if you've done this....

....no lectures please, experienced reloader since way before the interweb...

ericm

[wgj3]

Maybe a heavier recoil spring? 20#? 22#?

[noylj]

I can't help it, experienced reloader:

After 40 years plus of reloading, I have had one case failure--.40 S&W.

If you have a 10mm Auto case, section it and a .40 and compare the web thickness and ask yourself if you trust the .40 to produce 10mm velocity (pressure would almost certainly be over SAAMI limit for .40 S&W).

The best that I have are max loads of Longshot, N350, and 3N37 and they only got up to 1187fps maximum (range of max loads was from 1078 to 1187fps.

The XTP load in the manual was 8.0 gn Longshot, 180gn XTP, 1.125" COL and 1159 fps.

I wouldn't even think of trying it myself, but if I did, I would be sure that a COL of 1.235" worked in my gun first.

[kneelingatlas]

If I can push a 115gr to 181 PF in a 9mm, I'm sure you can make 216 with a 40, same approach: a whole case full of slow powder.

I imagine Longshot will work, but the slower you go the safer it will be, I would use 3N38, N105, AA9, True Blue or something in that range.

There's plenty of 10mm book loads which get you where you want to be, just pick one and back off the charge as you shorten the case.

Like Noy said 40 brass is a little thinner but as long as you're using a supported chamber and new brass it shouldn't be an issue. I'll bet Longshot at 216PF produces less chamber pressure than Titegroup at 180

[sbo76]

That does not sound bright at all but it's your hands. Why not just have a 10mm barrel fit and run 10mm?

Edited February 19, 2016 by sbo76

[Con]

Why not just have the chamber cut deeper?

[Alaskapopo]

That does not sound bright at all but it's your hands. Why not just have a 10mm barrel fit and run 10mm?

reaming the chamber to accept 40 loads as long as the 10mm essentially makes it a 10 mm with 40 brass whcih is actually a little stronger due to the small primer. You have the same powder space and same pressures. The only issue is you need to use heavy bullets so you can load to that over all length. You won't be able to do it with lighter bullets. The advantages are cheaper brass by far and more reliable extraction due to the shorter case.