Have Y’all Seen This W/ Gas Guns

[sanpedroranch]

I was looking at my reloading logs last night and noticed with all my AR-10’s that the accuracy nodes are on the starting charge side of things. Doesn’t bother me but 308, 6CM, and 6.5CM all shoot best near starting charge and accurate degrades as I go up. Anyone seen this in their AR-10’s?

 

[Darqusoull13]

I found a couple good nodes with 140's but to be perfectly honest I was intentionally looking for the lower node. More forgiving and way easier on brass. The higher nodes were good too, just not worth the trouble.

 

[eastexsteve]

I was looking at my reloading logs last night and noticed with all my AR-10’s that the accuracy nodes are on the starting charge side of things.

I don't reload anymore, but from past experience, this can be the same for bolt guns too. But yes, I have an AR10 that seems to like the "slower" factory loads comparatively speaking.

 

[Carlos Danger]

I've been working on my Grendel and I seem to have a very low node and another not really close to top end. I'm going to work those two and see which I choose.

 

[mtrmn]

I've historically found 2 nodes, one low and the other right at max. Haven't done much load development in recent years. I intend to try a little harder during this virus vacation.

 

[Yondering]

I was looking at my reloading logs last night and noticed with all my AR-10’s that the accuracy nodes are on the starting charge side of things. Doesn’t bother me but 308, 6CM, and 6.5CM all shoot best near starting charge and accurate degrades as I go up. Anyone seen this in their AR-10’s?

Personally, no, I have not found that to be generally true in either the small frame or large frame ARs. It is sometimes true with certain powders and loads, and can definitely be true if your rifle is overgassed (it'll be gassed more correctly with a mild load). With a properly tuned gas system though and powders that take advantage of the cartridge's potential, I've usually found a good accuracy node near max. But it helps to find the optimum seating depth before going off the rails looking for the perfect powder and charge weight; you'll find more good loads that way IME.

 

[eastexsteve]

I should mention something else that will have a more pronounced effect on the slimmer profile AR10 barrels is barrel harmonics. Load can affect this, and generally speaking, I found that the hotter the load in a slim profile barrel, the more pronounced the harmonic is. But, this is not a bad thing as long as the bullet is consistently hitting the same spot.

For example, to try and compare apples to apples, I have a Savage 110 Tactical rifle 24" heavy profile barrel that shoots FGMM 168s like a laser beam. I'm talking damn near the same hole. But, go to the FGMM 175s, and on a good day it can barely hold 2 moa with them. But, keep going to FGMM 185 Bergers, and it settles back down to 1 moa.

By comparison, I have a 2A Armament XLR .308 AR10 slim profile 18" barrel that does the opposite. It's kinda sloppy with 168s. But, go the 175s and it tightens up to 1 moa. With both rounds it's gassed right, and you can assume they are both factory full power loads. The only difference is bullet weight.

In both guns, I think I'm seeing the effects of barrel harmonics. And, you can tune this by playing with powder charge, powders, or bullet weight.

 

[lennyo3034]

My AR-10 in 6.5 likes it hot. Like 130 Berger hybrids at 2910 hot. I try to keep charges around 2800 to not beat up the gun so much but not as accurate.

 

[hlee]

My lr308 prefers a higher node. My 224predator likes a low node. Kind of sucks as I bought it for speed. Still beats my 6.5 Grendel, but it's not smoking it...

 

[Yondering]

My lr308 prefers a higher node. My 224predator likes a low node. Kind of sucks as I bought it for speed. Still beats my 6.5 Grendel, but it's not smoking it...

Turn the gas down, find the best OAL, and then change powders if necessary. No reason to put up with a slow load; there will be an accurate fast load it likes too.

 

[D1gger]

Turn the gas down, find the best OAL, and then change powders if necessary. No reason to put up with a slow load; there will be an accurate fast load it likes too.

That's a great idea-never thought of that! My AR10 is the first gas gun that I've tried to load for accuracy. I had a higher node, but I used the lower because I felt it was rough on the brass. I'll give that a try-Thanks

 

[Carlos Danger]

Think I'm going to stick around this node and play up or down in tenths.