224 Valkyrie Cycling Issues

[fisherman1122]

Hi Guys, I am new here. I recently completed my 5th AR build. I choose the 224 Valkyrie as the round. I took it to the range and am having some cycling issues. I did a bunch of reading online and this forum seemed to have a bunch of good info so I decided to join and see if you guys have any ideas. The gun will not eject the shell, this leads me to believe the system is under gassed. My build components are a Wilson combat 20" barrel 1-6.5 twist with a rifle length gas system, an odin works adjustable gas block, areo precision nitrided BCG, a rifle length buffer tube with a standard weight buffer (5.4 oz) and a standard spring. I have gone through ever setting on the gas block trying to get the bolt to lock back on an empty mag and have had zero luck. I have been shooting the 75 gr federal tmj rounds. I measured the gas port on the barrel at 0.082". Based on some other threads this sounds like it might be the issue but I wanted to see if I was on the right track before opening up that port.

Thanks for the help!

 

[hlee]

Start by making sure the gas block is aligned with the gas port. Then make sure the system is properly lubed. Doesn't need to be sloppy wet, but the bolt and carrier should be wet with some firearm lubrication- I use Mobile 1 full synthetic, but pretty much any gun oil is sufficient.

 

[fisherman1122]

Gas block is aligned, the set screw is/was centered in the dimple and the you can see that the hole in the gas block was centered over the gas port in the barrel. BCG is/was lubricated with a lightweight gun oil. The gun cycles smoothly by hand.

 

[TonyTheTiger]

Gas key tight and unobstructed? Gas rings making a good seal?
Just saw a guy with the same symptoms, turns out he installed the gas tube upside down.

 

[hlee]

I had a similar issue with a s224 predator build. Turns out the buffer was too heavy- but I was using a JP SCS with 2 tungsten weights. Switching them for steel weights solved the problem.

 

[Snuby642]

I bet the guy had to work hard at getting it in there upside down.

Dos mas tequila.

Accidentally aligning the gas rings could have enough gas blow past I suppose but I would suspect the agb to be partially clogged.

I had a partial clog in one caused by a metal shaving missed in the mfg cleanup before assembly.

It happens on any brand, rare but understandable.

You could try removing adjustment and set screw and blow shop air through a half blocked barrel before removing for further checks.

 

[Longshot231]

I got a Rock River upper in 224 Valkyrie. I started off with an SCS but with the heavy buffer. It had problems ejecting so I changed out one weight to a stainless steel standard weight.

The problem was solved. BTW, I'm shooting Federal GMM with 80.5 grain Berger bullets.

 

[Snuby642]

The gun will not eject the shell, this leads me to believe the system is under gassed. ------- I have gone through ever setting on the gas block trying to get the bolt to lock back on an empty mag and have had zero luck. "

Looking back on op, you list not ejecting and then not locking back.

Could you clarify that please, is it both?

 

[fisherman1122]

Okay I went through and checked the gas key, gas ring, gas tube orientation, and the blew out the gas block. I am still having the same results. The gun does not eject the shell or lock back on an empty mag.

 

[TonyTheTiger]

How do the case rims look? I've seen guns overgassed so hard the extractor slips off the rim and cycle so violently they won't lock back.

 

[fisherman1122]

Case rims look normal. Would you recommend upgrading to the JP SCS to help with this issue?

 

[hlee]

The SCS builder kit will give you options, but I'd hold off throwing parts at the gun until you know the cause of the issue. Then again, if you were already looking to upgrade, get the builder kit as it comes with extra springs that are both heavier and lighter than standard.

 

[hlee]

How many rounds down the barrel so far? Ive had a few barrels that wouldn't extract (or extract well) for the first mag or so- until some chamber imperfections smoothed out a bit is my supposition. Maybe consider lightly polishing your chamber?

 

[TonyTheTiger]

Case rims look normal. Would you recommend upgrading to the JP SCS to help with this issue?

No, I wouldn't buy anything just yet. Dump the weights out of your buffer and see if it runs.

 

[fisherman1122]

Ive had 60 rounds down the gun all trying to get the gun to cycle. I'll try removing the weights from the current buffer next time i shoot.

 

[Snuby642]

I've allways been over gassed so added tungsten and heavy springs.

Your situation is completely opposite. I don't know if all three weights removed at the same time could hurt anything but that energy is going some place.

I would place something in the buffer to replace the distance of weights removed if you only take out one or two.

First time removing the buffers (plastic / nylon?) end cap can be a bitch.

Somewhere I saw aluminum replacement weights.

@TonyTheTiger has a good idea.

 

[fisherman1122]

I made replacement weights out of aluminum. With all 5 aluminum weights in the buffer it weighs 2.9 oz. I am going to the range this weekend and will update with my findings.

 

[Snuby642]

? Five weights.
My carbine length buffers have only ever had 3.
How many did you remove?

I did see on the op where you said rifle lenght system. Is it possible for a carbine length tube to have been swapped ?
Or spring?

 

[fisherman1122]

The rifle length buffer had 5 steel weights. I am using a rifle length buffer, buffer tube, and buffer spring. I measured the dimension of the stock steel weights and remade them using a lathe. My plan is to take both the steel and aluminum weights to the range, so if the all aluminum setup results in the buffer being to light, I can swap out the weights and get the buffer weight right.

 

[Snuby642]

Not even sure if those could be mismatched but decided to ask.

I run carbine h2 buffer and tube on rifle lenght gass system so I can swap uppers with preset agb's.

Maybe not the best but works on the carbine upper and the rifle upper.

I have not yet ran a rifle lenght buffer tube but figured it may be smoother cycling?

 

[Neurotic]

I have two Valkyrie setups that will cycle the 75gr & 90gr Federal, but not the 88gr Hornady. Neither setup's gas system can be restricted and still reliably cycle.

One is a 22" Criterion barrel with a rifle length gas system, a 0.078" gas port and a rifle buffer setup. I think Criterion's gas port spec is supposed to be 0.080 or slightly larger.

So, I'm a bit surprised yours won't cycle the 75gr. I would keep looking for gas system restrictions or leaks (gas block to barrel?), the quality of the chamber, extension and bolt; things that could slow/inhibit cycling. The lighter mass should help, but I can't help feeling your setup should cycle.

 

[fisherman1122]

So went through the gas system again and swapped the buffer out with another standard weight rifle length buffer. Gun cycles perfectly. Must have been something in the gas system. Thanks again for all your help!