OnePivot

I used a clymer finish reamer, it cuts to about 1.14" on a regular fmj. I believe Manson finish reamers go closer to 1.17. Just have to be careful to not cut the chamber any deeper. A regular throat reamer will do any depth you want though. I did want to clean up the chamber while I was in there.

There's powder combos that work, but you're closer to pressure spikes, running less gas to the comp, and just increasing recoil for no reason. A moderate +p 147gr load is easy with most powders. Going beyond that is sketchy without a benefit.

I reamed all my guns and load to about 1.12 with a RN. But now 1.12 works with every bullet brand or profile I can find. Before I was loading some to 1.140 and some to 1.090, depending on profile. Now, 1.120" works no matter what. It just makes life easy. I mostly load minor, but not always. Working up an occasional +p load with certain bullets and powders can be sketchy when your OAL is far under any load data. Theres safe workarounds, but reaming takes out guesswork. I bought my own finish reamer, and another thing I'm finding is that a lot of barrels are finished like crap, with out of spec burrs and edges, or poor taper angles into the rifling. Can turn an occasionally wonky gun into one that just works like it should.

The profile is different between brands. Missouri and bayou are fat and need to be loaded shorter than other brands. Blues are probably the slimmest. Summits are on the slim side. Brass monkey might ship you .365" bullets. I shoot 95% coated bullets now. They go faster with less powder, they're cheap, and they're plenty accurate. Not the most accurate, but easily better than nearly any off the shelf ammo.

$240/k is a good price, especially for local ammo with no shipping.

I've shot thousands of summits now. I've shot most coated bullets. Summits are good, the bullets you order will be the same every time. Same size, same finish, same about a grain weight variance. 124s actually weigh 124gr (not 128 like brass monkey). They're on the big side, maybe .3562, but it's not a problem. If for some reason you absolutely need <.3555 bullets or something, summits aren't it. Also the profile is the modern slim profile. Blues might be less fat, but the summit profile is appropriate for short throat guns.

Any of the popular 9major powders will do it. I'm guessing that was 1.080" oal. You're incredibly short for your velocity goal. Dangerously so. Your Glock mags are going to max out around 1.150, and it would be good to use the whole 1.150. Barrel reaming is probably necessary as well. My g3 17 will do xtp's out to maybe 1.130.

Supervel select 124gr is 1050fps/130pf. A 34 might be 135 pf. Its reliable and cheap.

I lightly scuff my lee pins and crank them down. I don't want them slipping, ever. Squirrel daddy pins will punch out norma brass too. Sometimes lee dies need a little polish, but they work incredibly well.

That's a very stubby hp! Xtp's are 0.654, or 0.054" difference. Autocomp load data lists 147gr xtp's at 1.100, so at the same insertion depth, your loaded ammo will be 1.046". I think you need to redo your oal using the plunk method. Fired cases have basically no tension and the bullet gets hammered into the case further than the real max oal. Definitely measure with the barrel out, and using a sized case, gradually pressing in deeper until it plunks. Either way, your 1.04 loads do basically match book loads exactly, so you're not wildly in the weeds or anything. Autocomp is pretty slow too, but if it's what you got there is data. Faster powder would work out better. There's also nothing wrong with a compressed load.

I definitely had less than a 1/4 inch. I ended up short stroking it and don't have lock back anymore, but I don't think I like it. I have a 3d printer and just made a spacer.

I can give that a try, it's easy enough to swap around. Is the difference significant? I figured weight from either would be the same.

That did it. Removed 2 tungsten weights and replaced with steel. 22.3oz now, and runs great. Blowback9 has been spot on besides this. You definitely can go too heavy on bcg/buffer mass.

What's unique about the bcg? Does the article mean it's just a regular ar9 unit, unique from the normal 223 carrier? All the DD stuff I've seen or built has been very well made and finished, but in ways that are inconsequential to actually shooting the gun... It sounds like a regular old ar9 with a kynshot.

Thanks! I think that'll be my next step, to pull some weights out.