Need help tuning AR15 gas system for 358 Wildcat please :)

[lar45]

Rapier- Is that the 358MGP that you are running?
Is that the Lee 358-200 powder coated in the picture?
How fast can you run the PC Lee bullet and still get good accuracy?
I gave it a quick try, but couldn't barely keep them on the backer at 25 yds. I think I was pushing it too fast.
Thanks.

[lar45]

It locks back now!
I switched magazines and it locked back. So I took the first mag apart and stretched the spring and it locks back on that magazine also.
Once ir was running reliably, I dialed the gas block down one step and it still locked back. I turned it down 2 steps and it didn't so I'm down 1 step from wide open.

[lar45]

It shoots reasonably well, but I think it wants to do better, lol.
I picked up some shim stock and I'm considering swimming the barrel extension or bedding it with loctite 620...

[cwtebay]

It shoots reasonably well, but I think it wants to do better, lol.
I picked up some shim stock and I'm considering swimming the barrel extension or bedding it with loctite 620...

Nice! Great outcome!!
I never fail to learn something from this sort of discussion. I was honed in on buffer weight - as always a little education makes me realize that I need to stop being so miopic!

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[popper]

shimming the barrel extension -- never made any sense to me (assume proper barrel nut - old style timing gas tube). Nor the locketite or 'squaring' the upper.

[Texas by God]

I’m glad that you got it running right.
Load up some cheap plated bullets to break it in and have fun.


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[BK7saum]

I am glad you have it working. Makes me want to start load development on my 358 Winchester WC-10. It is a little over 6 lb (rifle only) with lightweight billet upper/lower, carbon fiber butt/tube and carbon fiber handguard, with 16" Wilson threaded barrel.

Been dragging my feet because I don't have a 35 cal suppressor. Need to remedy that as well.

[lar45]

I used a Tromix Linear Comp. It directs the muzzle gasses forwards. I've got them on my 7.62x39, 450bushmaster and now the 358 Razorback.

6# is great for an AR10 sized platform.
I didn't know that you could build them that light.

[BK7saum]

I used a Tromix Linear Comp. It directs the muzzle gasses forwards. I've got them on my 7.62x39, 450bushmaster and now the 358 Razorback.

6# is great for an AR10 sized platform.
I didn't know that you could build them that light.

I need to doublecheck that weight, it might be closer to 7 lbs, Getting it confused with my 6x45 AR15 with similar furniture, but it is really light for a 10.

Nope. Weighs 6 lbs 8 oz with standard BCG. With my low mass BCG, it should weigh about 6lb 5 oz.

Any other smaller parts like titanium takedown pins were not used due to minimal weight savings for the increased cost.

[Rapier]

Sorry, did not get back until now. It is the 358 MGP that mike came up with. I have two, a 12 twist and a 20 twist with 16" McGowan barrels. That is the RCBS 200 grain plain base, double powder coated, no GC at 2,500 fps that shoots .43" at 100. I make a very hard alloy 70-20-10 (WW, Lino, mag shot) water dropped. Dried, PCed , baked, PCed and baked again at 400 for 20 minutes then sized to groove diameter with case lube on a pad using an RCBS Luber Sizer. I use Federal 6.8 brass from Nellis, die formed, trimmed, then fire formed. A very hot load, with a near closed gas block.
Makes a great hog gun. Whatever you shoot with the 200s stays shot.
Here is a picture with 180 power pistol bullets and the rimless 30 Herrett or TAC 30.