AR-15 Accuracy to 600 yds

[greentips]

Heavy barrel deforms less when pressure propagates down the length. As long as the barrel returns to the same position consistently and fast enough, it is good to go.

Now, heat also changes the dimension of the barrel and other properties of the steel, and that affects the consistency of the deformation of the barrel "whip".

It matters more with a machine gun. For a semi automatic, at one point adding more beef to the barrel probably does not do anything at all because the rate of fire is not high enough and it never gets that hot.

 

[Maple Leaf Pilgrim]

ARs are quite accurate at distance. Using a Mk12 USN SEALs have recorded one shot stops on moving X-rays at 700m+. They were running a Mk262Mod1 (77gr?) round.

I have made good hits on moving X-rays out to 500m+ using L119s with just a red dot.

Throw a 3-10x bit of glass on a good 18"+bbl and you can reach out to 700m or so, I'll bet.

-S.

 

[Stoner99]

I'm pretty sure the SR16 in 14.5 are heavy barrel versions as of late.

 

[Ganderite]

Kac did some extensive testing with regards to optimal barrel length and found 18.5 offered the most consistent whip/barrel harmonics with an almost zero loss of velocity.

Heavy barrels don't improve accuracy as much as many want to believe. Their claim to fame is heat dissipation and added weight for a more stable sight picture. The are more rigid that lesser diameter barrels but its of minimal gain.

Tdc

This is interesting. One maker I am looking at offers a 1:9 20" and a 1:7 18".

I would prefer 20" for the added velocity. And 1:7 so I can stabilize the 80 MK.

I have shot 80s in a 1:9 bolt rifle, but had to use a 28" barrel and 2 scoops of powder to do it. I would expect a short barrel AR in 1:9 to have a problem with the 80s.

If a 18" will work, great! A medium heavy 18" would be an interesting rifle to work with.

I will try RL15 and VV N150 to start with.