.224 Valkyrie

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Joined: Wed Aug 20, 2008 6:01 pm

Re: .224 Valkyrie

Post by Precision » Mon Feb 19, 2018 8:13 pm

HTRN wrote:The 30 ar, which is based on the 450bushmaster, holds 44 grains of water.

The problem is rim diameter if its too large, it can weaken the bolt, reducing max pressure limits.

Something based on the 50 beowulf would probably be the way to go..
I explored this idea in a 458 socom case. Problem is the 458 max pressure is around 33k psi. To properly utilize the space and launch a much lighter pill the psi will HAVE to be in the 50k+ range - maybe more like 60k.
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Rich Jordan
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Joined: Tue Aug 19, 2008 5:04 am

Re: .224 Valkyrie

Post by Rich Jordan » Fri Apr 20, 2018 5:33 pm

The kit finally arrived today; shiny LaRue barrels and bolts for .224 Valkyrie. Now I have to decide... should they stay or should they go.

I kinda bought a couple boxes of ammo that were inexplicably 'on clearance' at Cabelas a month ago, and a friend who got out of 6.8spc gave me a magazine he forgot to put in the box with the rifle when he sold it. He might be interested in the barrel. Then move my best scope (Vortex Viper PST Gen 2) and a LaRue scope mount to that rifle. I _could_ build one up with parts on hand... but do I really want to get into a new caliber, especially one that will be expensive to shoot and require new reloading dies too. That is the question.

Rich Jordan
Posts: 1764
Joined: Tue Aug 19, 2008 5:04 am

Re: .224 Valkyrie

Post by Rich Jordan » Mon Sep 24, 2018 2:12 am

I built a .224V with one of the barrel kits. That build was troublesome. Aero Precision upper, Anderson lower, PRI magazine (and one AR Stoner from Midway) with Brownell's 'mil spec' lower parts kit (and LaRue trigger) with the standard carbine weight buffer, ALG Defense hand guard, etc, with the Vortex PST G2 mounted on a LaRue mount. The BCG was a Toolcraft Nitrided bought from JoeBob Outfitters with the LaRue 6.8 bolt installed. All the ammo I used was Federal, either the practice 75gr TMJs or the 90gr GMM.

No complaints on accuracy especially with the GMM, at the 50 and 100 yard ranges I shot at. But it wouldn't feed; I rarely got two shots in a row, the bolt overriding the top cartridge in the magazine and carving a deep gouge (not just a scratch) in that cartridge, stopping half closed. The end of the gouge had the ball of displaced brass stuck in it and the one I tried to gently manually chamber would not go into battery so the lump was big enough to cause that problem. If any were fired after being gouged but still feeding (if that is possible, assuming the bolt itself was doing the gouging), its hard to tell our to fireforming. The gouges were bad enough that I pulled the bullets and trashed those cases.

Tried a heavier buffer, and a lighter one based on one of the range officer's thoughts, no change.
Tried putting the .224V upper on the lower for my heavy barrel 5.56, and the feed problems went away. The brass was still getting scratched on loading but not gouged. The bolt carrier has brass streaks on the bottom bearing surface; I've seen that on other rifles and there's no sharp edges or corners. The bold did not have any noticeable brass on the lugs but the chamber you can see more sparkly bits than I'm used to seeing.

I swapped the .224V barrel and bolt over to a LaRue upper and BCG from the heavy barrel rifle and used it on both a LaRue and the heavy barrel's lower and it runs fine, but every case that gets chambered has scratches running up the link of the body. Not gouges though. None of the other ARs do anything like that. I didn't have time to check the original Anderson lower with another upper (or with the new rebuilt .224V upper) to see if the problems recur. I am going to try chambering empty new cases (maybe make a couple dummy rounds)

Both the PRI and the AR Stoner magazine seem to have very sharp corners compares to the Magpul (not surprising) or GI 5.56 mags. Just loading the cartridge generates a small scratch, and pushing it out from the rear makes it very noticeable. The Stoner also has the front edge of the magazine top about 1mm higher than the PRI, and there's brass on that edge so I'm going to test relieving that with a Dremel.

I'm wondering now if its a combination of the magazine's sharp edges and that original Anderson lower or the mag catch doing something that makes the bolt gouge the cases so badly. In the meantime I'm going to take a file and break some of the sharp metal edges on the Stoner magazine lips, and probably dremel out the front panel a bit so it matches the PRI...

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