SmallCaliberCentral

Did about an hour of searching on the forum. Hate repeat questions. Couldn't find info I want so help out please. Been doing a lot of reading. Got a RCBS Supreme. Need a few more new items I'm borrowing from another loader. Just needing a starting place with the .204 bullet.

Rifle
Bushmaster AR-.204
18" Barrel
1:12 Twist

Read enough to see that 40+ gr bullets are problematic for many with 1:12 twist. I'd really like to use 45 gr SP but not sure if they are worth trying with an 18" barrel. Where should I start with an 18" barrel? Everything I read was with 20"+ barrels. Many, from what I've read, are having success with 35-39 gr bullets. But with shorter barrel should I start with lighter bullet.

If anyone is loading for an AR with my rifle specs I'd be curious in your recipe.

My primary purpose is to shoot crows at max distance, yotes out to 500 hundred, deer under 125 yards max. I know most rifles will outperform my abilities I just want the best set up bullet to match.

Thanks for helping this newbie.

I was surprised to find that the 45gr Hornady SP shot so well in my 1:12 twist Ruger #1.Must be the longer bearing surface.

Zen, dont' get all wacked-out over barrel length. You're gonna have to dial in a recepie anyway. Just pick something and enjoy the experimentation process. Here's where I've landed with my rig:

RRA AR15, 24" bull 1:12 (.204, of course...)

40 gn Berger
Nosler brass (fired 1x)
Trim 1.845 +/- .002"
COAL (appx) 2.250"
25.4 gn Benchmark
CCI small magnum primer
flash holes preppec (didn't need it)
weight sorted +/- < 1 gn (didn't need it)
VLD chamfered (didn't need it)
Primer pockets uniformed (didn't need it)
Regular 5 shot group: 2" @ 300y, (excluding one shot: 1.0" @ 300y)

Hornady 32 gr VMax
Nosler brass
CCI small rifle mag primers
COAL 2.245" (to fit the mag)
Untrimmed (tad shorter than spec "trim-to")
26.8 gr Benchmark
Wilson seated
I can count on 5 shots grouping 2" @ 300y, and most are 1.5" if I exclude 1 shot.

Also
Hornady 40 gr VMax
25.0 gr Benchmark
Groups the same, maybe a tad better (still tweaking).

Sierra 32 gn Blitzking
Nosler brass (fired 4x)
Trim 1.845 +/- .002"
COAL (appx) 2.250"
26.5 gn Benchmark
CCI small magnum primer
flash holes preppec (didn't need it)
weight sorted +/- < 1 gn (didn't need it)
VLD chamfered (didn't need it)
Primer pockets uniformed (didn't need it)
Regular 5 shot group: 2" @ 300y, (excluding one shot: 1.3" @ 300y)