Pursuit of an inexpensive accurate super bullet - 125 tnt speer

[gomeybear]

Good evening folks!

Been loading up Speer TNT 125 grain with the following: 17.4 grains of W296 / CCI 400s / 2.06 COAL / 1.35”Trimmed LC Brass

2 moa @ 100 yrds is about as good as Im pulling off with that load. Looking for some pointers on how to optimize this bullet out of my 8.3” Hanson Barreled AR. Should I work through an OCW to dial it in or is this sort of accuracy just expected with this bullet. I dont see that Speer lists it as a 300 blackout round on their load data either.

[Ben B.]

What loads does that rifle shoot better, and how good were they?

[gomeybear]

Just swapped out the barrel to a 8.3” BA Hanson; so, working with limited data too. Curious if most folks find accuracy loading these bullets a bit hotter.

[Netpackrat]

I fired 3, five shot groups ranging from around 1 to 1.5 moa using this bullet out of my 10" Aero SBR, over 18.5gr W296 and a CCI450. Reformed Lake City brass, same OAL as you are using. Same load, out of my 16" Model 7 bolt action, fist sized groups at 100. It just didn't like them for some reason. FWIW I tested these up to 19.0 grains charge weight but I saw some flattened primers in the M7 at that level (not the SBR though), so I backed off to 18.5 for my final load.

If you can get some of the CCI450 magnum primers, maybe try those and work up to a higher charge weight.

[20X11]

I've done a lot of work with that bullet...most accurate COL is 2.075...2.06 won't give you good accuracy. H110/W296 load that works best is 18.1 at 2.075 COL.

BTW...this is my favorite 300BLK projectile.

Also..1.35 trim is pretty short...I only trim mine to 1.358

[Netpackrat]

Yeah, being not specifically designed for blackout, it's a pretty short bullet, and you can't really seat it out as far as you would want to because you are limited on neck engagement. I had initially wanted to use a longer OAL but quickly found that was not practical and 2.06" was as long as I was willing to go. I was satisfied with the accuracy from my SBR at that length, but your mileage may vary as mine did when I tried the same load in my bolt gun. The shorter trim length definitely won't help matters, but it's only an .008" difference. IIRC, I am using 1.358" as well

[20X11]

Yeah, being not specifically designed for blackout, it's a pretty short bullet, and you can't really seat it out as far as you would want to because you are limited on neck engagement. I had initially wanted to use a longer OAL but quickly found that was not practical and 2.06" was as long as I was willing to go. I was satisfied with the accuracy from my SBR at that length, but your mileage may vary as mine did when I tried the same load in my bolt gun. The shorter trim length definitely won't help matters, but it's only an .008" difference. IIRC, I am using 1.358" as well

FWIW...I have loaded and successfully fired well over 2 k rounds at the 2.075 COL with a multitude of powders. That length was arrived at by loading many ladders at different lengths and loads and measuring accuracy and velocities across those many powders.
I do put a light crimp on with a Lee FC die, but I have never had an issue with that COL.

[dellet]

For what is worth, this was a different bullet, 150 Gold dot, but here is the difference .005" seated depth can make.

Two 6 shot strings, note the first 6 looked more like two groups of 3 and then that the second 6 fit inside the group of the first 6.

[dellet]

Add this to the above post. Seating depth test at 200 yards. The 1.65... numbers are base to ogive measurements. The other is group size.

Pretty graphic what happens within .010” of adjustment and how easy it would be to skip over a sweet spot.

It’s hard to burn the components in times like these, but nothing replaces small changes for being thorough

[20X11]

What loads does that rifle shoot better, and how good were they?

I shoot 3 different 300BLK rifles and 1 pistol. The H110/W296 load I listed shoots 1 jagged hole (.75 inch) groups at 50 yds from all of them. Using 17.7 grs of 300-MP powder tightens the groups up on all 4 guns and becomes repeatable at 100 yds. (shooting from a rest to eliminate shooter error as much as possible).