new 260 AIAX where to start?

[idaho1]

New AX in .260 should be be here this week. I only have ten days to develop a load and get my dope dialed in for a competition that is coming up quick with shots out to 1400 yards. With all the crazy lack of supplies, it's a little tough to have a lot of options for load development. I have amassed a few options. Any help with good starting points could help improve my success.
Here's what I have to work with:

AIAX 260 24 inch barrel, 1:8 twist with AX mags

Lapua brass 100 pieces
Nosler brass 200 pieces

Berger 140 vld hunting 300
SMK 142 300

Federal 210 plenty
CCI 215 LR plenty

H4350
RL17
I have had good velocity numbers with the R17 in a hunting 260 but I here it is not preferred over H4350

I cant get any Amax 140's or Scenars or Berger hybrids Lapua brass on account of enemies of the Second Amendment!

Thanks for any help/input!!!!!

 

[turbo54]

If it were me, I'd load four 5-round groups, all loaded at 2.820" COAL with 142smk and H4350:

5 @ 42gr
5 @ 42.5gr
5 @ 43gr
5 @ 43.5gr

If one shot better than the rest, I'd choose it. It is likely it will shoot them all well, in which case I'd go for the 43.5gr load, because most 260s shoot 140s and 142s well with 43.5gr H4350.

 

[bm11]

My .260 AX is an absolute hammer. My loads are with 140 Hybrids, so not really applicable.

FWIW Rl-17 gets me about 100fps over 4350 with less pressure and still shoots lights out. In fact, I bought a slew of different bullets to try but the hybrids were almost immediately shooting amazing so I didn't need to go further. I have shot multiple 5 shot groups in the .1's, you will not be disappointed.

 

[K_4c]

Word is the 142 SMK's and 139 gr scenars almost mirror each other....

I'd do exactly what turbo54 stated.

The 142 SMK's won't let you down.

 

[shoot4fun]

I use H4350 for 260 and RL17 for 6.5CM and haven't really seen any temp issue with RL17, even in my hot climate.
If you can get another 100 FPS and maintain accuracy this would be the way to go.
I also agree with Turbo that you'll be better off with the 142 SMK. My AW 260 barrel shoots its best with H4350 and 142SMK seated 16 thou off the lands.

 

[idaho1]

My .260 AX is an absolute hammer. My loads are with 140 Hybrids, so not really applicable.

FWIW Rl-17 gets me about 100fps over 4350 with less pressure and still shoots lights out. In fact, I bought a slew of different bullets to try but the hybrids were almost immediately shooting amazing so I didn't need to go further. I have shot multiple 5 shot groups in the .1's, you will not be disappointed.

What charge of R17 did you find best?
What COL?

 

[phxfa]

Mine likes 42.5 gr of H4350. 210M primer, 140 JLK .010 off the lands gives me 2800fps,,,,140 Bergers were at 42.9

 

[bm11]

What charge of R17 did you find best?
What COL?

43.5 grains. And long. .010" off, I don't have the measurement handy but somewhere in the 2.90" range.

 

[idaho1]

Thanks for the info!