Working up an accuracy load. What next?

[Ericpwp]

I had a reloading session to start working up a load for my 20" SS15G2 Premium 5.56mm 1:7 Rifle Length A2 Profile upper (sku 35693) $435 otd.

Loading 75gn Hornady Match over IMR4064 w/ cci#41 srp, 5 rounds at 7 different charges would be the dataset. I tried to be meticulous as I could with the variables. The cases federals brass trimmed within +/-.003 in. The OAL was as close to the lands as I could get it with only a dummy round and calipers. Using a Lee scale, I started at 22.3gr, and then worked my way up through 22.7, 23.1, 23.5, 23.9, 24.3, and the max load at 24.7, 5 rounds apiece.

At the range I did a quick boresight, and zeroed my BSA 6-24x scope with some 55gn at 50yds. I then moved to the 100yrd lane and got shooting. I was shooting off a cheap plastic Caldwell rest. Not wanting barrel heat to skew the results too much, I would shoot 1 shot from each load group. I shot all of the first 4 loads, and then finished with the last 3.


I’ll start backwards, here are the results:

These 15 shots were after the first 20, so would barrel heating be an issue at 35 total shots? The max load was not good. The first shot, the case ejected without a primer. The psi listed was well under the max for the 5.56 chamber, so I proceeded. I did not see any more pressure signs.


24.7gr: 2.349-.224= 2.125

24.3gr: 1.364-.224= 1.14

23.9gr: 1.455-.224= 1.231

Not bad, other than the 24.7 load. I may have been scared of the gun blowing up, so I’ll blame that.


And the first 20 shots:

23.5gr: 1.162-.224= .938

23.1gr: 1.363-.224= 1.139

22.7gr: 1.485-.224= 1.261

and...
22.5gr: .989-.224= .765

This was my best shooting ever, and it feels good that it was with ammo that I made. Enough already E...


So, it seems my gun likes close to the min load. Where to go from here? Should I attempt to go under the min? What should my next load workup look like? Closer increments? What should I do differently?

 

[IndyGunworks]

start a bit under the lower load, load up in .1 grain increments to .5 grains over and repeat the test.

choose the best out of that, and start playing with seating depth.

 

[jblomenberg16]

Good shooting! Lots of fun dialing in a load that works great with your particular gun, isn't it?!?

 

[Ericpwp]

start a bit under the lower load, load up in .1 grain increments to .5 grains over and repeat the test.

choose the best out of that, and start playing with seating depth.

Sounds like a plan! The tips of these rounds were very inconsistent for measuring OAL, so I took apart a 5.7 seating die and used the seater rod(?) to measure from the base to the ogive with calipers.

Good shooting! Lots of fun dialing in a load that works great with your particular gun, isn't it?!?

Sure is! Now if I could just get to the range more often...

 

[IndyGunworks]

i would definitely play with seating depth based off the ogive and not OAL

 

[Ericpwp]

Agreed

 

[Dave A]

I had terrible groups using CCI #41 primers with some of the faster ball powders like H335 and TAC. I changed to Remington 71/2 and the groups dropped to 1 MOA.
This is with a 20” - 1/7 barrel on an AR.

 

[DocIndy]

I like CCI primers and use the BR primers for my bolt gun load in my .308. Now that I found a load, it's boring to shoot. It keeps putting those 168 AMAX in neat touching groups. I need to find someplace I can stretch it out and see how the groups look.