.224 Valkyrie cycling issues anyone?

Lenny62 · Mar 24, 2021

I just put a .224 V AR together, - A heavy, virgin 22" Wilson barrel, 6.5" twist, rifle-length gas system and standard AP gas block, Ultradyne Apollo S brake, and standard rifle-length extension and spring, and 5.5oz buffer.
(Nothing trick at all. Haven't even put an optic on yet, using and Ultradyne sight set up.)

Started out with some off-the-shelf Federal 75 grain ammo. Squeeze a round off, and...

Fired casing would eject, but the next round would stick cocked up about 1/2 way, with the bolt jamming it in place. Mmmm

Pull the charging handle and clear things up, fire, and the same thing. Almost like the bolt would try to close up before the round had time to make it's up and in, or the fresh round was just taking it's sweet ass time moving up....

Firing 1 round at a time, bolt would lock back like it should.

Switched uppers to my .223 Wylde, and everything runs just fine.

My guess is the buffer is the wrong weight? But do I want to go heavier or lighter? (I'm figuring lighter...)

The buffer in there now is 5.5 oz. I have a 3 ounce carbine buffer I could try as well.

I want to stay with the rifle-length stock. I took a Magpul rifle stock and loaded the storage compartment with lead shot bags, to balance out the heavy 22" and 24" barrels. It doesn't budge. I like that.

I can't be the 1st guy to experience this, cycling thing, soooooo What does the gang say?

Orcon · Mar 24, 2021

I had a similar experience with my first Valk build. Total milspec rifle platform save for the bolt and cartridge, swapped the new bcg for a well worn one and swapped out the gas block for an adjustable unit.

Never had problems with factory ammo though, what mags are you using?

Varminterror · Mar 24, 2021

If you are using a rifle receiver extension, you cannot use a carbine buffer.

Lenny62 · Mar 24, 2021

Orcon said:
I had a similar experience with my first Valk build. Total milspec rifle platform save for the bolt and cartridge, swapped the new bcg for a well worn one and swapped out the gas block for an adjustable unit. Never had problems with factory ammo though, what mags are you using?

Well, the BCG is a little used, the bolt itself is new from Daniel Defense. I've got a 10-round Stoner mag for the Valk. Did you need to throttle the gas way back?

Lenny62 · Mar 24, 2021

Varminterror said:
If you are using a rifle receiver extension, you cannot use a carbine buffer.

Yeah, I figured that much comparing the two, doesn't look like a good swap to me, but I had to ask just in case there's a hot-rod trick out there somewhere...

Orcon · Mar 25, 2021

I had problems with Stoner mags in mine but I have some additional questions. Is your upper and barrel extension cut for M4 feed ramps?

Lenny62 · Mar 25, 2021

Orcon said:
I had problems with Stoner mags in mine but I have some additional questions. Is your upper and barrel extension cut for M4 feed ramps?

This is first Stoner mag I've used, the rest I have are Gen 2 and Gen 3 Pmags for 5.56 - But I digress...
Yes, everything is M4 cut.

I'll be making a trip to the range either Friday or Saturday, and will bring a carbine lower with me, just to see if the action will cycle with the shorter spring and lighter buffer.... ya never know....!

Orcon · Mar 25, 2021

Well, I'm not there to see it happen but make sure the bcg is good and lubed and the ammo is loaded right. Best of luck, friend. Let us know how it goes.

Varminterror · Mar 25, 2021

If the bolt is riding over the tail of the cartridge and the round is being partially fed, it’s one of two things:

1) short stroke, such the bolt isn’t clearing the tail of the cartridge

or

2) Low or slow mag, such the round isn’t rising high enough to be in front of the bolt face to be stripped properly from the mag

The first is easy to test: first, make sure the carrier can travel far enough. Do this pulling the charging handle fully to the rear and observe through the port the gap between the bolt face and the bolt catch - if the bolt face clears the rear of the bolt stop by .075”, the width of the rim of a Nickel, then you know the travel is sufficient.

Next, do a lock back test. First, do a manual test, with an empty mag, pull the charger and confirm if it locks back. If not, then the follower is likely hanging and not engaging your bolt catch. For live fire - Load one round into your mag, charge, and fire, if the bolt locks open on the empty mag, you know you have sufficient bolt stroke. Do this with multiple mags, multiple times. If it doesn’t lock back, then you know something is causing the carrier to fail to travel its full path when firing, or confirming your mag is slow. If it locks with some mags but not others, ditch the slow mags.

If it passes the above tests but still misfeeds with a missed pick-up, failure to feed, then you know something is happening in the mag which is hanging up when multiple rounds are present, so bail on that mag.

Lenny62 · Mar 30, 2021

Varminterror said:
If the bolt is riding over the tail of the cartridge and the round is being partially fed, it’s one of two things:

1) short stroke, such the bolt isn’t clearing the tail of the cartridge

or

2) Low or slow mag, such the round isn’t rising high enough to be in front of the bolt face to be stripped properly from the mag

The first is easy to test: first, make sure the carrier can travel far enough. Do this pulling the charging handle fully to the rear and observe through the port the gap between the bolt face and the bolt catch - if the bolt face clears the rear of the bolt stop by .075”, the width of the rim of a Nickel, then you know the travel is sufficient.

Next, do a lock back test. First, do a manual test, with an empty mag, pull the charger and confirm if it locks back. If not, then the follower is likely hanging and not engaging your bolt catch. For live fire - Load one round into your mag, charge, and fire, if the bolt locks open on the empty mag, you know you have sufficient bolt stroke. Do this with multiple mags, multiple times. If it doesn’t lock back, then you know something is causing the carrier to fail to travel its full path when firing, or confirming your mag is slow. If it locks with some mags but not others, ditch the slow mags.

If it passes the above tests but still misfeeds with a missed pick-up, failure to feed, then you know something is happening in the mag which is hanging up when multiple rounds are present, so bail on that mag.

The bolt locks back fine when I'm single feeding cartridges. I can do that all day.

Brand-new Stoner mag, (I just have the one for the time being - ) At any rate I need another, for the obvious reasons. - My lower for this build is on a standard rifle lower.

Another suggestion/idea was the buffer spring, (Got a new one just the other day) - It's easy enough to swap the barrel over on one my carbine lowers.
Also made sure the BCG and bolt are nice and clean and slippery. Tomorrow may be a range day (Wasn't able to get to the range last weekend as I hoped...)
I'll report back with hopefully good news - I'll have news at any rate!

.224 Valkyrie cycling issues anyone?

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