...

Drilling the barrel can only net you what volume of gas the cartridge has to offer. With .300 Blkout, it's going to be in the 15-20 ish grains?

I think the reciprocating mass of the WK-180c is considerably less than a typical AR - hence the short gas system.
But most .223/5.56 use slower burning powders comparable to .300 Blkout and more volume of it to drive the operating system.
There is a decent amount of gas blowing out the four relief vents with the .223.

Have you considered tapping the relief vents and adding set screws to one or two to limit the amount of gas it vents at the extent of the piston travel?
Have you looked at various weighted return springs?
 
I really like the brain storming going on here.

I dont see cutting some coils off the return springs as the end of the world. Like you said you can get some from kodiak.

What about lightening the bolt carrier ? Seems like its a hefty chunk of steel.

Obviously right now i dont know how you would get a spare bolt carrier group from kodiak anytime soon.

Maybe plugging one gas bleeder, cutting a couple coils off and lightening up the bolt will get this thing running.

One thing at a time, enjoy tinkering...
 
I would not cut the original springs, as they give you a baseline of what you have.
I'd look at recoil springs for pistols and get a set that matched the diameter and see if you can get a bunch of tuneable ones. 1911 springs are about double the diameter of what you need. Maybe talk to Wolfe springs to see if they have anything that is similar.
 
jiffx2781 said:
I kinda figured that the pressure spike on the 300blk was starting to decrease by the time the gas reached the carbine length gas port due to less and/or faster burning powder. A lot of 300blk barrels have pistol length ports for this very reason
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Keep in mind too that the AR bleeds off extra gas at the bolt carrier ports. When it's bleeding off on an AR it is at the end of the road, whereas the WK-180C bleeds it off nearer the start of it's travel.
If you tapped one hole for a set screw, you can always drill a smaller hole in the set screw so as to not completely eliminate flow.
 
cr5 said:
I seem to remember you also saying you don't shoot much other than hunting, not as good of a round for someone that also wants to burn off a couple hundred rounds in an afternoon like I've done with other 300BLK rifles I've owned.
And I think it was you who also found that running heavier cartridges in a lighter action like 450BM in an ACR leads to equipment failures. I think that was you anyway.
Click to expand...
supplier has many hundred rounds in Stock every time I buy ammo. FMJ is reasonably priced at $1 a round to.

No failures to report yet
 
Brian46 said:
Which is strange as I run the same piston rod on 450 and the much higher pressure 30 AR with no issue in my ACR
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It is strange, I would like to see the old piston rod. I bent one when I first built my 300BLK conversion but I wrote that off to re-profiling the piston rod to fit through the rod guide after I shortened it. The replacement was simply shortened and I don't use the rod guide any more.

Brian46 said:
supplier has many hundred rounds in Stock every time I buy ammo. FMJ is reasonably priced at $1 a round to.

No failures to report yet
Click to expand...

For $1 a round I'd rather just go with a 308win and not have any issues and be able to push velocities even higher.
Funny how much money we'll spend just to carry something a pound or two lighter or have something no one else has.
 
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cr5 said:
It is strange, I would like to see the old piston rod. I bent one when I first built my 300BLK conversion but I wrote that off to re-profiling the piston rod to fit through the rod guide after I shortened it. The replacement was simply shortened and I don't use the rod guide any more.



For $1 a round I'd rather just go with a 308win and not have any issues and be able to push velocities even higher.
Funny how much money we'll spend just to carry something a pound or two lighter or have something no one else has.
Click to expand...

I would to, too bad the POF Revolution is restricted
 
jiffx2781 said:
*** another update ***

Since I'm at the limit of what a gas flow increase will achieve this leads me to looking into other possible reasons within the rifles operating system.

Even though this rifle takes standard AR15 barrels I believe the operating system and action takes more effort to cycle than an AR15. I can almost confirm this theory just by the size of the gas port in the factory 223 barrel. It's larger than what the gas port size would typically be on a carbine length 223 barrel.

It's so close to working that it can't take much else to get it going. I'm having fun with this and I'm determined so back to the drawing board I go.
Click to expand...

Have you considered lightening the bolt carrier? My theory is that it may be too heavy and thus the gas pressure you have so far simply doesn't provide enough energy to get it to cycle back far enough to pick up a new round from the magazine and less weight in the carrier would allow the gas to push it back further. Lightening the recoil springs may accomplish the same thing.
 
jiffx2781 said:
So after taking some of the suggestions I've received from some very helpful CGN members into account and doing a little more research on the differences in gas volume created by both 223 and 300blk I've came to a conclusion:

The 300blk creates enough pressure that it should be enough to do the job however the gas volume is less than the 223 and, due to the faster powder burn rate, the pressure spike doesn't last long enough to fully cycle this action the way it is.

My only two options left are to find a way of keeping more of the gas in the system for a longer period of time or to reduce the resistance created by the action's recoil/return springs.

But since I'm stubborn and determined I've decided to start with the hardest issue first. Gas. I'll start chopping the springs later if necessary. As beltfed said this will keep my testing consistent.

I didn't want to start tapping the gas venting ports for plugs since I have no guarantee that reducing the gas bleed off is the solution. Once I alter something I can't unalter it. Plus I don't want the possibility of pressure blowing the plugs out.

What I came up with was I made a collar that slides over the tube that has the bleed off ports. I put a locking screw in the collar so I can adjust how far the collar slides over the bleed off ports. This way I can block them off as little or as much as I need depending on if it makes a difference in function.

Now obviously the collar isn't going to be a permanent part because the handguard won't fit over it. It's purpose is to let me test if restricting the gas bleed off makes any improvement to function before I decide if there is a need to permanently alter the firearm component.

I really think these ports are wasting enough gas that restricting them will be the solution.

If all else fails I'll start chopping springs and look into alternative springs.

It's really bugging me because it's so close to working. The final fix can't be overly complicated.

Can't get out shooting today. Testing to resume this week...
Click to expand...

The collar sounds rather FAL-ish.

With reference to experimenting with gas port diameters...
When I made my first AR (.223) barrel from a blank, I researched gas port diameters. Various sizes depending on location and barrel wall thickness. So I carefully drilled a properly indexed but undersized gas port, and went to the range with a set of numbered drills and a battery operated drill. Just kept opening the port one step at a time until function was perfect. Of course a piston gun is different than a ducted gas gun, but determining an optimum size for a gas port can be done by trial and error.
 
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