Running 140s out of 6.5 CM AR

[lennyo3034]

I remember a few years ago, most people running 6.5CM/.260 out of large frame ARs were using 120 grain class of bullets. Apparently the 140 class and associated powders had too much pressure at the gas port for the rifles to run reliably.

Now that it's a few years later, we have high pressure bolts and rifle+2 gas systems. Are people able to reliably run the 140 class of bullets? If so, at what velocity?

Im looking to have a barrel made by PVA and am wondering if I should get it chambered for the 140 eld or something like a 130 Berger.

 

[elfster1234]

I run 142 smk's out of my mega 22" Krieger with an extra 2" gas.

 

[VegasHKShooter]

I have some of my very best Accuracy out of my GAP-10 using Hornady 140 ELD-M. I have also shot the 147's quite well. I have not experienced any popped primers, cratering, or other issues. I adjusted my gas block to where it will just reliably lock back the bolt. Very, very good shooting round.

 

[Roslyn]

Both 140 ELD-M and Eagle Eye 130 gr rounds shoot sub MOA in my JP LRP-07 if I do my part. Tunable gas block seems pretty essential to getting the rifle to cycle correctly, but no issues with the ammunition once that gets sorted. The rifle wasn't chambered for a particular round so far as I know.

 

[MT Casual]

I remember a few years ago, most people running 6.5CM/.260 out of large frame ARs were using 120 grain class of bullets. Apparently the 140 class and associated powders had too much pressure at the gas port for the rifles to run reliably.

Now that it's a few years later, we have high pressure bolts and rifle+2 gas systems. Are people able to reliably run the 140 class of bullets? If so, at what velocity?

Im looking to have a barrel made by PVA and am wondering if I should get it chambered for the 140 eld or something like a 130 Berger.

143 ELD-X at 2675 fps with Hunter and IMR 4451, no problems.

 

[stevieb92]

No issues here. I'm running a 22 inch BA 6.5 CM barrel, rifle length gas with a SLR Sentry 9 adj gas block. Also have a JP HP 308 Enhanced bolt with their FMOS QPQ bolt carrier. I've tried 123 AMAX, 130 ELD-M, and 140 ELD-M, with various powders. Settled on 140 ELD-M, with 41.6 grains of IMR 4451 in Hornady brass with CCI 200 LRP. That recipe runs out of my Mega MATEN approx 2630 fps. Brass looks fine, and ejection is 4 o-clock. Locks bolt back and feeds 100% reliably. I agree with other comments above; adjustable gas block and small firing pin with small hole (HP bolt) are essential to getting these large frame ARs to run.

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500 meter target from a varmint shoot last weekend. Shot off a bipod and rear bag.

 

[padom]

Im running H4350/140 ELD-M's out of my 22" Bartlein +2 gas 6.5cm semi. Zero pressure issues

 

[Jeffd]

Running Hornady 140 ELDM'S out of my gassers.

 

[VKC]

Having over-pressure with the 140-142grs bullets has to do with headspacing and running too high of powder charges rather than the actual bullet. In other words, you try to get a heavier bullet going fast enough to match the performance of a lighter bullet (123gr-130gr) going faster. An extended gas tube and HP bolt face allows you at push the pressures up to maximize muzzle velocity but that comes with the trade off of decreased barrel life and throat erosion. The more important issue is that running max pressures results in temperature sensitivity which can be dangerous. Many factory 6.5cm loads are loaded hot and with longer COAL for bolt-guns in order to make it look favorable when compared to a 260rem for non-reloaders, that is why they don't run well in gas guns. The 140s really only overtake the 123gr & 130grs at longer distances if loaded at the same pressure, since the lighter bullets can be pushed faster. Once you get pass 1000-1300yards, muzzle velocity SD and ES matter much more for shot dispersion and no matter what bullet you use, a gas gun will have more variation than a bolt-gun. Run your numbers,
At least for me, running the 123gr-130gr at lower pressures and less steep curves still make more sense, and even more so with shorter barrel lengths.

 

[FALex]

I run a 22" rifle-length with the JP LMOS and am able to shoot 139 Scenars. They are not super fast at 2720, but they damn sure are accurate.

 

[lennyo3034]

I appreciate all the help. My MATEN is in 6mm Creedmoor and I'm not convinced the AR is the best platform for that caliber since I can't run the best .243 bullets.

Accuracy has been decent but 2900 on a 107 SMK isn't really worth it IMO.

 

[VegasHKShooter]

I agree with you there. If you're shooting a .243 with 107, I'd expect you would be looking for 3050 or so? I'm not a .243 expert by any stretch, but 2900 seems a tad slow.
What velocity are you getting out of a bolt gun?

 

[lennyo3034]

I agree with you there. If you're shooting a .243 with 107, I'd expect you would be looking for 3050 or so? I'm not a .243 expert by any stretch, but 2900 seems a tad slow.
What velocity are you getting out of a bolt gun?

I don't have a bolt gun in 6mm CM, but from what I've read people are pushing 3100.

 

[Garrettvw]

Have Noticed Eagle Eye Ammo in Thread anyone have more info on them? Websits has no address and no phone number. Don't want another Southwest Ammo!