Ar 10 in 260 or 6.5cm?

[TEAMSENDIT]

Well i am building a ar10 with pof upper/lower/forend and benchmark is building me a 6.5mm barrel for it so i was wondering what recommendations you guys have from using the two different cartridges in semi auto. i have played with both in bolt guns but have no experience with either in the ar version. it will be a 24" 8 twist either way.

thanks for your time and knowledge?

 

[hognuts]

Re: Ar 10 in 260 or 6.5cm?

I have a DPMS chambered in 6.5 creedmoor, it has a Timney trigger that has been massaged by a local gunsmith and the JP recoil eliminator brake. It shoots well. For some reason I cannot find my mv in my data book although I know that I recorded it when doing my data collection (guess I will have to re-confirm and get back to you) It does very well I have used it some local matches and one over in Arizona. Here are my drops in MOA out to 1050 yards shooting 140 AMAX with the factory recipe of 41.5 grains of 4350. Nightforce 5.5x22x56 NPR1 reticle, with Barrett medium rings.


200 yards - 1.75 MOA
300 yards - 3.00 MOA
400 yards - 6.00 MOA
450 yards - 8.00 MOA
500 yards - 9.25 MOA
550 yards - 11.50 MOA
600 yards - 12.50 MOA
650 yards - 14.00 MOA
700 yards - 16.25 MOA
750 yards - 18.50 MOA
800 yards - 20.00 MOA
850 yards - 22.00 MOA
900 yards - 25.00 MOA
950 yards - 27.50 MOA
1000 yards - 30.00 MOA
1050 yards - 33.00 MOA

 

[hognuts]

Re: Ar 10 in 260 or 6.5cm?

Here are some pics of the DPMS 6.5

 

[ranger1183]

Re: Ar 10 in 260 or 6.5cm?

TSI,
I have lots of experience with a DPMS 260. If I were to do it again, I'd go with the 6.5 Creedmoore. From what I've "heard", the Creedmoore is much more AR friendly. Working with HOT loaded .260 caused a real nightmare of gunsmithing on my end. Best of luck either way.
Good shooting!

 

[overkill]

Re: Ar 10 in 260 or 6.5cm?

ballisticly, the two are almost identical.
I think that the shoulder on the .260 lends itself better to reliable feeding in a semi. but with a quality gun neither rounds should jam.
I have custom DPMS REPR in .260 rem and have been over joyed with it. it has a 24" Kreiger sst bbl on it, and it will do better then 1/4moa with handloads.
140gr Berger VLD's over 42.8gr IMR 4350 @ 2715fps

in the end, they are both great rounds. I went with .260 because of the shoulder angle and fact that i can make brass out of the while .308 family.

 

[m1ajunkie]

Re: Ar 10 in 260 or 6.5cm?

I am really interested in this topic as well. I am thinking of picking up a barrel for my mws in either caliber this summer.

My question is, what is the heaviest amax and smk round you can run and still load to mag length for both cartridges?

 

[Goin'Hot]

Re: Ar 10 in 260 or 6.5cm?

140 / 142

 

[cuffm4615]

Re: Ar 10 in 260 or 6.5cm?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: overkill</div><div class="ubbcode-body">ballisticly, the two are almost identical.
I think that the shoulder on the .260 lends itself better to reliable feeding in a semi. but with a quality gun neither rounds should jam.
I have custom DPMS REPR in .260 rem and have been over joyed with it. it has a 24" Kreiger sst bbl on it, and it will do better then 1/4moa with handloads.
140gr Berger VLD's over 42.8gr IMR 4350 @ 2715fps

in the end, they are both great rounds. I went with .260 because of the shoulder angle and fact that i can make brass out of the while .308 family.</div></div>
Just ordered a 260rem barrel from kriger 2 weeks ago inorder to convert my LR308. My question to you Overkill is have you compared the 140 berger vkd's to 139gr lapua scenars (which seem very popular) or 142gr SMK ? Any info on comparisons to these loads or any other you tried would be GREATLY APPRECIATED. Also I have read some comments on the importance of finding the correct seating deph on Berger VLD's and was wondering how you worked that out on a semi. Thanks in advance.

 

[pawprint]

Re: Ar 10 in 260 or 6.5cm?

The only weak spot that the 260 HAD was brass quality-now that Lapua is making 260 brass, the 260 is the way to go.

 

[k2peaker]

Re: Ar 10 in 260 or 6.5cm?

I've jumped on the bandwagon recently as well.
I went with a JP LRP chambered in .260 (22" 1x8"tw) a few months back. Since I already shoot in .260 for my principal LR competition rig (AIAW in 26" Krieger/GAP) I wanted a gas gun that had some things in common. .260 vs. 6.5CM question: I had made that choice when I bought my bolt gun. It was a virtual toss up for me at that time; I was comfortable with the brass availability and/or steps required to form good .260 brass.

A few findings & opinions:
Load: I was interested in standardizing reloading components as much as possible. I'm settling on a similar load to what Hognuts is using, i.e., 41.5gr-41.6gr of H4350 using the 139gr Scenars. I shoot at altitude but am getting in the 2650-2700 fps range, OAL to mag length (Magpuls). I mainly shoot the 142gr SMKs (bolt) but started with the Scenars as they are comparable and slightly shorter bullets.
Optics: I swapped in a PR 3-15 mounted using the Spuhr cantilevered mount. The Spuhr fits this application well, is really nicely designed/made, but is pricey with the current exchange rate. Buy once, cry once on this one as I try not to think about it as a % of my total optics spend.
Stock: Magpul PRS (with Accushot bipod)
Brass: Mostly using Win .243 necked up (and neck turned). Some donated 1xFired PMC and other .308 necked down/turned.
My estimate of where to start with load development based on the Hodgdon data and my bolt gun experience was too high. Good thing my initial range/chrono sessions were in January at altitude in Colorado! I've backed off as I've seen pressure signs until arriving at the 41.5-41.6gr range. Still, this gun is hard on the brass. I'm expecting about 4 reloads from my brass. At the prices that Lapua seems to want for their new .260 brass ($90+Per100), I'm probably going to stay the Win .243 route for this gun.
Function: the left-side charging handle of the JP LRP design rocks -- very happy with that decision. With 350 rounds through it, no failures to chamber. I have been able to tweak the factory gas setting back slightly and maintain good function. Weight: with the PRS, Heavy contour barrel, AccuShot, Atlas, PR, Spuhr, etc. this is no lightweight. I haven't weighed it but it's probably in the 14.5 lbs range.

 

[overkill]

Re: Ar 10 in 260 or 6.5cm?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cuffm4615</div><div class="ubbcode-body">Just ordered a 260rem barrel from kriger 2 weeks ago inorder to convert my LR308. My question to you Overkill is have you compared the 140 berger vkd's to 139gr lapua scenars (which seem very popular) or 142gr SMK ? Any info on comparisons to these loads or any other you tried would be GREATLY APPRECIATED. Also I have read some comments on the importance of finding the correct seating deph on Berger VLD's and was wondering how you worked that out on a semi. Thanks in advance. </div></div>
I have not used those two bullets. first bullets i bought for it were Hornaday 140gr SST's and the Berger 140gr Match VLD. The bergers shot so well that i didnt feel a need to try another match brand. I had bought the Hornadays for deer hunting,still quite accurate(around .5moa @43gr IMR4350) but was unimpressed with thier performance on game at long range (400yd+)so i bought the Berger 140gr <span style="font-weight: bold">hunting </span>VLD to try. same POI as the Match VLD. and suprizingly work much better then the tipped round at long range.
for the seating depth, it was the first time i had used the VLDs and was unaware of the seating depth causeing a problem. I had just loaded them about as far out as i could and still reliably function in the magpuls. mine are loaded to 2.810COAL. so appearantly i'm just lucky on that point.
when i ordered the bbl from Kreiger i told them i was planing on useing the heavy bullets and VLD's. i seem to remember that they said they were going to cut the throat a bit diff so it would be geared more twards those rounds.

 

[rpk762]

Re: Ar 10 in 260 or 6.5cm?

I would like to do one in 260. I know the cm has a good folowing on the XC shooters. Nice paint job on that DPMS.