LR-308 .243 spring weight?

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mljdeckard

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In a part of Utah that resembles Tattooine.
So, (going back and forth between Utah and Texas) I finally managed to shoot my .243 AR, and the headspacing was good. Next problem,

It's short stroking. Ejects about half the time, never cycles a new round. So I take it back to the gunsmith in this one gunsmith town who helped me assemble it, and my guy (who assured me when we built it that gas isn't an issue,) says my buffer spring is WAY stiff. I guess it is, it's a pain to charge it, I just figured that AR-10 buffer springs are heavier, and I would just have to man up and deal with it. HE SAYS, it's really stiff even for a .308. I assembled the lower years ago, I don't even remember what process I used to order the spring I did. I am running a 1/8 barrel with 100 gr bullets.

Does a .243 need a significantly lighter spring than a .308?
 
There are 2 different platforms for the AR-10 & LR-10. The 2 systems use different gas systems, and bolts/barrel extensions. I ran into this when I built my LR-6.5CM. I did all the machining on the profiling the barrel and drilled the gas port. I had an adj gas block wide open and it was doing the same thing, ended up opening up the gas port. There are also 2 different strength buffer springs. If you went with the std 308 spring, try the lighter duty one.

What length barrel and gas system are you running?
The specs I found are for the DPMS LR-10: Carbine (0.0635-0.076"), mid (0.078"-0.081") or rifle (0.0935-0.096")
 
I just got it back from the smith, and they said the spring I had in it was WAY heavy. They got a lighter one, and now they say it cycles just fine, but it still doesn't lock open. (He said he cut a couple of coils off of it when he got it back to the shop, hasn't fired it since. I will shoot it this weekend and see what it does.) The bolt locking open is a minor issue to me, I'm not using it for combat or competition. I used off the shelf 100 Core-Lokts, because it was the only heavy bullet .243 I could find here. I will order some other options, and load more when I get home, maybe it will work itself out.

I can't even remember where I got the heavy spring, I assembled the lower years ago. I told them to keep it for when they have a guy who wants to build a .338 Federal. :)
 
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