ActionJackson

Alliant Promo. 2.8 under a 147 coated bullet will make minor all day. No dirtier than TG and $100 / 8 lbs.

I can't speak to BBI, but in pretty extensive Ransom Rest testing the SNS 147 (groove less) made slightly tighter groups than the Bayou 147 (with groove) using a G34.

Promo is available most places that sell Alliant powders. Powder Valley lists it for $103/8lbs. You can use Red Dot load data; the older Alliant and third-party manuals include a lot of data for most handgun cartridges. It's like Clays, but not as spikey and has a lot more top end. 2.8 under a 147 coated LFP will make +900 fps out of a G34 all day. I use it for a variety of cartridges, including for low-recoil .308 and .44 Magnum. 7.5 under a .44 240 SWC gets me nearly 1300 fps out of my Marlin 1894, and it's a hoot. I don't find it any dirtier than Titegroup.

Alliant Promo. $100/8lbs and I run 147 coated over 2.8 out of a G34 (OAL depends on the particular bullet, but I load long). Makes 900 fps.

Have you verified, such as by using a metal pick, that the rifling is not being hidden by lead deposits? I have seen that happen before. Ballistol and a Boresnake may not disturb any lead deposits enough for you to notice.

I'm not aware that KKM publishes the twist rate of its Glock barrels. I emailed KKM a couple of years ago asking about the rate, but didn't get a straight answer. I've seen speculation that they are anywhere from 1:16 to 1:32. Based on my testing, I would guess that it is greater (slower) than 1:16.

After conducting significant ransom rest testing with my G34, I determined that my KKM barrel would not group well with anything over 125/125 grains. I even tried pushing 147's really hard (+1000 fps) with the KKM to no avail. The stock Glock barrel shot all bullet weights well, with 147's being the most accurate in my testing. YYMV.

The SNS 125 coated fails the plunk-and-spin test in my G34 stock barrel unless seated down to at least 1.12. You may want to retest a dummy cartridge and make sure it spins freely. That being said, I got better accuracy using 147's with the stock barrel.

I don't have any experience with Dillon equipment; however, the Hornady Custom and RCBS seating dies include both a cupped and a flat stem. You should be able to look up into your Dillon die and see the cup; the die can also likely be disassembled so you can directly inspect the seating stem.

I would check to make sure that you are using a flat-tipped seating stem; otherwise, the bullets will want to tilt while being seated.

IMHO if your bullet has a flat point, then you need to use a flat-tipped seating stem. If you don't, two things will happen: 1) you will get inconsistent OALs; 2) the bullet will tip, causing it to shave. The Hornady Custom Grade 9mm seating die should include a round stem and a flat stem; mine did, and it works like a champ if, and only if, you use the right stem. Edited to clarify: I do not use the 3-die set; I did but got tired of mashing/gouging my coated/plated bullets during the seating operation. I use the individually sold Custom Grade Seater Die and the individually sold Custom Grade Taper Crimp Die.

I loaded to 1.135 for my G34. Longer and it would fail the plunk-and-spin test.

See The Plunk Test - Setting your OAL

I've found that bullets that have a sharp shoulder (the point between the ogive and the bearing surface), such as TCN-type bullets, are very sensitive accuracy-wise to overall length. Make sure to re-run the plunk-and-spin test for your 125 TCN.

My load for the Bayou 124 TCG in a stock G34 barrel is 1.086 with 3.5 grains of Promo / Red Dot. Comfortably makes minor. 3.4 makes minor, but is cutting it close.