Some "Advanced" Questions About Hand Loads

[freonr22]

http://www.ar15barrels.com/data/223weights.xls

Read some if it helps?

My pic may not have great resolution. But Randall has some great "tech information"

[CSACANNONEER]

That was someone else, not me. Both rifles (.223 and .243) have less than 500 rounds apiece through them so they're barely broken in. It's possible I could shoot out the .223 barrel in this lifetime if I can find enough "pest control" opportunities.

Sorry, I misread the bold but, in my defense, you did mention those things.

I've developed hand loads for my .223 and .243 (both Tikka T3 Lites with 20" barrels) that work and produce groups on the order of 1-1 1/4" at 100 yards with acceptable velocity. They're good enough for hunting but I would like to see what I might be able to do in the course of the reloading process with a reasonable amount of effort to close the groups a bit and get more consistent muzzle velocities. Ideas like swapping barrels and stocks, turning cases and weight sorting cases and bullets are off the table for now.

The two things I've noticed are:

A) Relatively small vertical spreads with somewhat larger horizontal spreads. I do my testing with little or no wind and what I remember reading is that barrel whip affects horizontal spreads rather than vertical spreads so I'm puzzled by this source of variation. The rifle is supported in front with a sandbag and in back by a bean back I hold and squeeze with my left (non-shooting hand) to keep the reticle on the bullseye. Triggers are adjusted to be as light as possible and I squeeze very (perhaps too) slowly but I can't rule out bench technique either.

B) Occasional large variations in muzzle velocity. This was particularly apparent with a .223 load using 35 grain Hornady NTX bullets with IMR4198, where the groups were surprisingly consistent size wise but standard deviations were on the order of 2% and extreme spreads on the order of 4%. I measure each charge using a digital scale from Cabelas. It drifts but I check the charges pretty carefully. All cases are Lake City once-fired brass with CCI small rifle primers.

Like I said, I'm willing to tinker with the reloading process but I can still hit what I'm aiming at.