300 Blackout in a WK 180. Assistance needed getting it to run.

Levon12345

Levon12345

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Hey there gun nutz. There was a thread on this a long time ago but the original poster redacted his comments so his info isn't available anymore.

I've put together an upper with a 18.5 MRA barrel and am having issues getting it running. It short strokes with my hand loads with a 147 gr campros with loads of Lol Gun amd H110. The brass clears the chamber but doesn't get out of the barrel extension so it's got a way to go before it's cycling with enough chutzpah to run and lock back on empty. It's really accurate, just a straight pull rifle at this point. I've built a thingy that covers the ports on the gas block to try and get more gas onto the piston (I'll add a picture later). I'm wondering how best to go about balancing a the system. Where I should put my next effort into getting it running? Different weight of projectile? Which powder will give me the pressure curve I need? Trimming piston or recoil springs?

Looking forward to hearing your suggestions.
 
Try some 178 or 220 grain projectiles for the heck of it otherwise you may have to find another way to increase your dwell time. How much powder are you using on your reloads?
 
There is an adjustable gas block coming that will likely fix the issue, after you drill the port out that is.
 
It is carbine length. These are supersonic loads. I will up the gas port diameter first. I want to say it's already .125" but can't say for certain. And 1680 seems to stand out as the powder for auto loader reliability in any reading I've done. I was at 17 grains of lil gun and 16 H110 so middling loads.

I'm hoping to stick with the 147 grain bullets for plinking but I think I've got some 180s around to try out to up that dwell time.

If it comes to it, which spring should I chop first? The piston or the recoil springs?

Thanks for all the tips.
 
If it chokes on Supersonic my inexperienced self would say you have other issues. Does it reliably extract/eject spent shells manually??? I'm wondering if the spent cases are falling off the bolt face before it clears the barrel extension. This is the curse of such a short case that is the 300.
 
Levon12345 said:
It is carbine length. These are supersonic loads. I will up the gas port diameter first. I want to say it's already .125" but can't say for certain. And 1680 seems to stand out as the powder for auto loader reliability in any reading I've done. I was at 17 grains of lil gun and 16 H110 so middling loads.

I'm hoping to stick with the 147 grain bullets for plinking but I think I've got some 180s around to try out to up that dwell time.

If it comes to it, which spring should I chop first? The piston or the recoil springs?

Thanks for all the tips.
Click to expand...

Another powder to try is cfe blk. From my experience in running AA1680 and CFE BLK in 7.62x39, CFE BLK definitely has a noticible edge over 1680 both in speed and accuracy.

Someone metioned case falling off the bolt. The easy way to prove if your gas system works is to load a single round and see if the bolt locks back. If it does then your gas system is fine and should look into extractor.

I would chop the recoil spring and leave piston spring alone. Also I noticed the gas port on my carbine length 18.6 MRA barrel is smaller than the original. Runs fine in my 223 setup though.
 
Update:

Fed it some factory Hornady supersonic and it still had the same problem. The action would cycle enough to eject brass about half the time but it didn't have enough travel to pick up the next round or lock back on the magazine. It resets the trigger. So now I'm into trimming springs. Which one should I trim first, piston or recoil? I'm feeling I want more jam entering the system but leave the recoil springs the way they are to reliably strip rounds from the magazine. That and I dont have to keep track of different recoil springs between uppers (I have one in 5.56 as well). I have no experience balancing a piston gun so there could be a very good reason I'm not aware of for not doing that.
 
With those springs readily available now you can easily experiment around.

Have you tried removing the piston spring all together and see if that reliably locks the bolt back? If the bolt does not lock back with no piston spring then you know you'll have to work with the recoil springs either way.

It's my opinion that the sole purpose of the piston spring is to return the piston to position. By the time the piston spring is compressed enough to matter, the piston/op rod would have already done its job of transfering the majority of the impulse to the bolt carrier.
 
Levon12345 said:
Update:

Fed it some factory Hornady supersonic and it still had the same problem. The action would cycle enough to eject brass about half the time but it didn't have enough travel to pick up the next round or lock back on the magazine. It resets the trigger. So now I'm into trimming springs. Which one should I trim first, piston or recoil? I'm feeling I want more jam entering the system but leave the recoil springs the way they are to reliably strip rounds from the magazine. That and I dont have to keep track of different recoil springs between uppers (I have one in 5.56 as well). I have no experience balancing a piston gun so there could be a very good reason I'm not aware of for not doing that.
Click to expand...

I wouldn't trim either spring... but especially not the piston spring. You're talking about a gas volume issue. 'Carbine' length (crap term for the distance of the gas port relative to the barrel shoulder) for a gas port on any .300 blackout is likely going to lead to some issues with transferring enough gas at a high enough pressure to reliably cycle an AR15 type gun, let alone dealing with the volumes of piston in a WK180. Remember, 300 Blackout was developed to burn the large majority of it's powder within 9"-12". I would suspect that the gun isn't maintaining a high enough peak pressure within the gas manifold/piston to reliably drive the bolt and carrier assembly rearward enough for proper function.
 
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