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

[dug]

hi , just entered the ar 10 world and looking to run 123 amaxes .
I bought a dpms lr260 lite hunter. hoping I can get sub moa out of it . or I'll up grade the bbl and try again.
my concerns or questions .... with this 1 in 8.5 turn a 140 amax or ber vld ?
will they fit in the mags ?
those are the reasons that have me looking at the 123 amaxes , a bit shorter to cut down on the bullet [140] taking the case cap. in the 260?
I have some 130 vld's on my shelf to try also .
any insight would be great .
thanks for your time
dug

 

[long450]

I shoot 130 Nolser AB in my 260 and my 6.5 Creedmor. Deer are normally DRT. Any of these bullets work, you just need to find the one that is most accurate in your rifle. My rifles are the heavy barrels.

 

[Nickweis]

Berger now makes a shorter "tactical" 130 grain that is made to fit the AR mags

 

[dug]

i have tried many bullets in my lr 260 after this summer .
berger 130 tactical bullets will run but not a hunting bullet , they don't expand at 2300 fps which doesn't give you much range .
i like the 123 amax but only get 2660 fps out a 22 in bbl with ar comp powder
i like the 108 lapua scenar for targets same bc as amax and 2900 fps
they don't expand either but great for targets .
i have seirra 107's to try next as they are a bit cheaper than scenars
have not tried noslers only because of lower bc . i'm sure they would run well .
i shoot many noslers in factory gun twist bbl with good accuracy and expansion.
seirra 85 gr hp run awesome also but not for long range . i would think a great coyote bullet.
i did kill 2 coyotes with the 123 amax this season neither argued about falling right down dead .
was hoping to kill deer with them , but this yrs high temps really hurt our hunting here .
it was a tough yr .
i'm now running a jp bbl at 5/8 - 3/4 moa average with amaxs 1/2 moa with scenars.
the best with dpms bbl was 1 1/4 moa with 85 gr seirra's all other bullets were 1 1/2 or bigger grps.

 

[Kansaswoodguy]

With the 123's you might try varget. A lot of guys have issues running the heavy 140gr bullets in 6.5 creedmoor AR's but this is due to beating up there brass not mag length issues in the 260 the mag length may very well be more previlent issue . I have a creedmoor and can't really say. I have found that the 139gr Scenar don't seem to be as sensitive to seating depth which helps when dealing with mag length issues.

 

[Feugo Jeuvo]

I shoot the 123 A maxs. Be careful with advice from folks not shooting gas guns. Dug, I get the same velocity as you in a 20" Lilja barrel. Heavy bullets and lock time is an issue. JP rifles has a great write up on this exact subject ( he mentions all the pitfalls). Think about an adjustable gas block. I have harvested a coues deer and quite a few coyotes with this round. PM me for load details. These guns like H4350 and Varget for sure. Bottom line is this is an awesome round in a great platform.

 

[Skytow]

Dug,

As already mentioned, H4350 is a great choice for the 123 AMAX and your 260. I'll be doing a ladder test on just this combo in Lapua brass with CCI BR primer later this week.

I have a 24" Bartlein on a DPMS pattern custom upper and a modified DPMS lower.

I've been running mostly 142 Sierra HPBT and made some great groups. One was 5 shots which were .33 MOA shot @ 200M. I have been using H4831 for the 140's but needed to go to H4350 for the 123's. (you run out of case capacity)

Your 1 in 8.5 should stabilize 140's no problem. I have the same twist rate and it runs fine. As to length, see what your mags will hold. I can get to 2.810" and that's it. Guys with bolt guns are running much longer to help with the limited case capacity but not an option for shooting from the mags for SR25 / DPMS style gas guns.

My next ladder test will be IMR 7828SC for 142 / 140 g bullets. I do have an adjustable gas block which let's me keep the bolt speed to a minimum while trying all these combinations. I will get odd feeding issues if over gassed. Turn the block down and it runs like a charm.

Great round in a very interesting platform!

JD

 

[dug]

what velocity are you getting with the 140 grainer ?
try some ar comp i think you ll like the fps and accuracy.

 

[Skytow]

what velocity are you getting with the 140 grainer ?
try some ar comp i think you ll like the fps and accuracy.

I'm getting ~2700 with the 142's and 4831SC but am out of case capacity with Lapua brass. I could get a little more in my necked down WIN 308 brass but I have an accuracy node where I am.

IMHO AR COMP seems really fast for this round. When I saw it mentioned I ran it through quickload and it did indeed seem fast for heavy bullets. 35.3 gr nets about 2650 FPS @ 60,000 PSI. (maxed out) I bet it would rock with some <123 grainers though....

Everything I've read, and so far had success with, seems to point to slower powders. Really interested now in some 142's with 7828SC. I got over 2800 FPS with H1000 and really good SD/ES but haven't had time to mess around with it more.

Since the 123 AMAX's are reasonably priced I'll be shooting them with H4350 if it stops raining!!


JD

 

[Txhillbilly]

I mainly shoot the Sierra 140 gr Gameking out of mine behind 42.0 gr of H4350,it's going 2848 fps out of my 20" barrel,and groups in the 1/2-3/4 moa range.

 

[FNA3G]

I mainly shoot the Sierra 140 gr Gameking out of mine behind 42.0 gr of H4350,it's going 2848 fps out of my 20" barrel,and groups in the 1/2-3/4 moa range.

That seems very fast. H4350 is great in the bolt gun but H4831 is a little better for the DPMS gas gun in 260 rem. With that being said i run the 123 amax exclusively in my DPMS with H4350 but i do see "pressure signs" not due to pressure but due to the action cycling while pressure is still high even with my adjustable gas block well before reaching 'max" charges. I am currently at 43.6gr H4350 @2920fps with a 24" barrel,t hats why 2848 with 140's and a 20" barrel seems fast to me??

 

[Skytow]

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!

 

[Skytow]

FNA3G,

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

JD

 

[Txhillbilly]

That seems very fast. H4350 is great in the bolt gun but H4831 is a little better for the DPMS gas gun in 260 rem. With that being said i run the 123 amax exclusively in my DPMS with H4350 but i do see "pressure signs" not due to pressure but due to the action cycling while pressure is still high even with my adjustable gas block well before reaching 'max" charges. I am currently at 43.6gr H4350 @2920fps with a 24" barrel,t hats why 2848 with 140's and a 20" barrel seems fast to me??

Yep,I hit the wrong key I guess,it should be 2648 fps not 2848. I've never had any problems with H4350 out of mine. My rifle hasn't liked to shoot the Sierra 140 gr Gamekings very well with H4831.