Been doing some testing with Glock G40 MOS 6" barrel.
Swapped for a KKM 6" barrel. Put in Jentra guide rod that runs Wolff springs and running a 24 lb spring--strongest Wolff makes and brass is still getting flung 5 yds.
Working with Sig brass at the moment but have some nickel plated DT brass on the way. Bullets: working with 200g XTP at the moment and Beartooth Bullets 200g 10mm hardcast as well (while waiting for 200g DT). Using Hodgdon Longshot as I've got quite a bit of it as it's a good 10mm powder, as well as for .40SW and 9mm, I've found. CCI 350 large pistol primers.
Pretty impressive performance so far, I have to say, I've worked up in mid-60s temps such that both the 200g XTP and 200g Beartooth hardcast are in the upper 1375 fps range or just a bit more, depending on the round. If you do this, it's on you to work up slowly and know what you are doing--I'm using KKM barrel, not Glock, and heavy recoil spring, mind you. Sixteen rounds in your pistol pushing 860-890 ft. lbs. a round is not too shabby and this thing is accurate--helps to have that long slide.
Just by way of comparison, several years ago I worked up a load with a 6" barreled SW .357. I was using well known data from the owner of Beartooth Bullets who had worked up a load with his 185g hardcast bullet over 16g of H110 for a MV of right around 1360 fps. This load is said to have ventilated many an elk all the way through over the years by a number of folks. It was right about that velocity that I felt was max as well in that revolver. That is a stiff load and just about the stiffest .357 load I've seen. I think I've seen one load that claimed more energy. 185g at 1360 fps is still 100 ft. lbs. (760) less than these 10mm loads I was working with today, if that says anything, with a bullet of slightly larger diameter. If you can shoot accurately and quickly, it's gonna be hard to beat that 6" barreled 10mm with a good match barrel. Like I think I said earlier in this thread, some acquaintences did some testing and realized that 3" barreled .44s were producing less energy than their hot 10mm loads. I'll keep working/testing this and the new DT bullets/brass when they get in and report back. Plan is to stagger 200g XTPs and 200g DT hardcast gaschecks in the mag for woods carry.
Have a 'lighter' load of 180g Montana Gold target bullets over 8.5g Longshot at 1.25" OAL that runs about 1300 fps that I plan on using in a comp or two to try to get better used to this pistol under a little bit of pressure. Should be fun!