hows running 123 amaxes in a dpms 260 rem set up ?

[FNA3G]

Ran my ladder with H4350 and 123g AMAX's and got the following:

42.6g = 2725 FPS
42.9g = 2743
43.1g = 2766
43.4g = 2812
43.7g = 2830
44.0g = 2849
44.3g = 2886
44.5g = 2892

This was out of a 24" Bartlein on a DPMS format gas gun. Gas block was turned down but I can go one click lower and suppose I'll get a few more FPS then. My Chronograph was 20 feet from the muzzle. There was a node from 43.7- 44.3. I ran a second test of the same loads and got very similar data with the most repeatable from 44.0 to 44.5.

FNA3 my barrel seems slow! Maybe it will get better with some more rounds down the pipe but I think it should be broken in by now with about 500 rounds so far...

These were safe in my gun but I don't know about yours so start low and work up!

44.3 @2886 is real close to what i am getting. That little difference could come from many things. I might be closer to that than the 2920 that i have setup to make my ballistics work out.

FNA3G,

When you mentioned "pressure signs" in your .260 loads due to action cycling are you talking cratered primers??

JD

No cratered primers more case head swipe. H4350 is a little faster burning than the H4831 so the "general consensus" is the 4831 is a little easier to use especially if you dont have an adjustable gas block but mine liked 4350 better so i ran with it.

 

[Skytow]

44.3 @2886 is real close to what i am getting. That little difference could come from many things. I might be closer to that than the 2920 that i have setup to make my ballistics work out.

No cratered primers more case head swipe. H4350 is a little faster burning than the H4831 so the "general consensus" is the 4831 is a little easier to use especially if you dont have an adjustable gas block but mine liked 4350 better so i ran with it.

I'm dealing with cratered primers, even with moderate loads. This is since the gun was new. Firing pin, bolt and carrier were all brand new. Oddly, I do NOT have flattened primers, in fact very little flattening at all.

I'm getting great groups if I do my part and almost no brass stretching. I have done 3 reloads with my latest Lapua brass and not had to trim at all. Go figure...

JD

 

[tbrice23]

This thread is a few months old but...

I tried posting in 'rifles ,barrels, and ballistics section with no response.
So, my Shilen 24" SS 1:8t heavy varmint DPMS barrel is on the way. I have never loaded for a 260 or owned a Shilen bbl.

I have 123 amax, 143 eldx, 140hvld, 140 amax, h4831sc, h4350, imr4350, arcomp, varget, imr4064, rl17 to try but it sounds like h4350 is a winner in this cartridge.
( I do have an adjustable gas block. )

Anyone have any comments or experience with Shilen AR barrels ?

Any updates from anyone on load development in 260 AR ?

I know from experience that ARs beat up brass pretty bad but I bought Lapua 260 brass anyway, I'm wondering if that is going to be a mistake? Maybe turn the gas block down.

Any information is appreciated, thanks.

 

[dug]

hi guys an out date for my lr 260
runnin amaxes and 4064 now
it gives me good accuracy and high fps at 2920.
i m very happy with this load

 

[tbrice23]

Update if anyone is interested.
I think I've found my choice of powder, Reloder 19. Nothing yet as shot this consistent. My chrono has been acting up recently , that's why the velocities have question marks by them. I actually believe the load might be a little faster than listed.
These were shot at 200 yards from front and rear bag.
I'm happy with this from a gas gun.