Do the newly manufactured pencil barrels get less accurate as they heat up? Back when I was really paying attention to ARs that was the common thought.

quote:

Originally posted by Basenji:
Do the newly manufactured pencil barrels get less accurate as they heat up? Back when I was really paying attention to ARs that was the common thought.

This has been a burning question so long that the waters are well and muddied. Regardless of what I say, no doubt somebody will think it wrong. But here is the simple answer to the question:

Don't worry about it.

A more complete answer:

Somewhat, but not enough to matter if you're using your rifle for the purpose a pencil barrel is suited for.

An even more thorough answer:

Barrel manufacture, metallurgy, and stuff like cryo treating have come a long way, baby. So have bullets. Every barrel will have POI shifts as it heats and cools, and fouls. An important piece of the puzzle is - what are you trying to do with the rifle? If the goal is a "tack driver," then you're going to be building a heavy barreled rifle with certain features. If the goal is one like my rifle in this thread, being a "tack driver" isn't necessary or practical.

If you sit at the range off a bag or bench, and slow fire into a target, any POI change will be almost unnoticeable. If you're shooting a competition, or using automatic fire in combat, a piece of it will definitely be the barrel heating up. The other oft discounted piece is the human or nut behind the butt. Groups shifting or opening can of course be because of the barrel, but don't forget the part you play. Your shooting position and fatigue are a huge piece of the puzzle, but not one you'll hear about when people focus on barrel profile.

If you're aware of what a barrel/rifle is supposed to do and capable of, the heating of a pencil barrel is of no concern. Certainly not in 2023, and this issue goes waaaaaaaaaaaaaay back to the beginnings of these rifles, which is over 50 years unless you're a lefty gun grabber (then these are space guns that are as new and foreign to our world as the babies they want to murder in the womb). The "gun community" seems to hold on to flaws reported back in the day and keep assuming that those things just always apply to anything with the word "pencil." that's what I mean by muddy waters. The discussion has moved glacially while technology and quality have moved very quickly.

This is why I say the important part about AR "builds" is to have a purpose. If you want too many things, you're not going to be happy and find yourself pulling away from a given goal. Your lightweight rifle won't be anymore, your "DMR" isn't quite as accurate as you think you wanted... First folks need to let go of the "do all" idea or understand its compromises. Then, be aware enough to not take that template and unconsciously still apply it.

All I want from a rifle like the one I built here, is "dinner plate" or "minute of man" accuracy. It'll do better than that, most AR's today can without getting fancy at all. If I find myself shooting the rifle enough that I observe degraded accuracy, I'm probably in a gunfight then it doesn't matter because it'll still be accurate enough to put a bullet in a guy.

That was the answer I was hoping for. The rifles I have are not tack drivers and neither am I. I just want light and serviceable.

That's a cool looking build.

The 8" 9mm AR I built was pretty handy and light.
Closest I have now is a 14.7" FN light weight profile barrel at 7.5 lbs with a PA 1-8 scope and EMOD stock.
The new PA prism looks pretty nifty and would knock a pound off easy.
Just messing around with the LPVO at 5 looks like it would work well.

I also put this one together. Nothing lightweight, adjustable or fancy. Selections once again guided by Brownells "in stock. I had the stripped upper for a loooooooong time. The company is out of business, too bad, it's a pretty slick nonreciprocating side-charger. The magpul moe stock is annoying, I'm getting another ctr.

There are a bunch of side charging options out there. None of them that slick. Lets be honest, the dumbest thing about the AR is the charging handle. Why didn't we learn this lesson:



The best FAL.