300PRC load development at 300-400yds

[Emerson0311]

I do ammo testing for my 22LR at 100. 1.8 mils up from a zero at 50. The 300PRC is up 2 mils or a bit less at 400 from a zero at 100. Wind does have an effect of course, but other than walking way out and back, is there a big downside to testing this far out, especially for tracking vertical? What group size would you stop at “good enough” for 5 rnds? It’s a Howa with a 26” IBI 8T mounted in an Oryx chassis with a 3-18 Razor. Lapua brass, burning through a bunch of N170 and 220 ELD-X because component supply is what it is.

 

[hafejd30]

I always like to test my long range guns at 300. For vertical as you mentioned. You find many times a target gives different results vs a chrono. I look for 1/2 moa (1.5” ish) for accuracy goals.

 

[Emerson0311]

I always like to test my long range guns at 300. For vertical as you mentioned. You find many times a target gives different results vs a chrono. I look for 1/2 moa (1.5” ish) for accuracy goals.

I moved up a 1/2 grain and got a solid 5 shot group at 365M today.

 

[Emerson0311]

I’ll see if this is repeatable. It was the 4th loading of Lapua brass neck sized with a Redding die. I’ll start another batch until I have 100 4Xfired to anneal and then look for someone who has one.

 

[spife7980]

I see no problem, I set paper out at 500 for some final confirmations and such and am thinking about going further with a paper board.

 

[Pinkes]

What velocities are you getting with the 220gr and N170

 

[Emerson0311]

What velocities are you getting with the 220gr and N170

26” barrel looks to be around 2830 or so. 77.5 N170 Rem 9 1/2 primers, Lapua brass, no pressure signs. It’s chilly out though. I need to rezero to make sure what the drop is 90M to 365M. The load is accurate so I’m doing positional practice now at 365M. With time and better weather I’ll chrono it too, but I don’t really care as long as it shoots well.