First grendel range report. Rifle not cycling(pics included)

[Squatchy]

I got a chance to hit the range up today and sighted in my recent build. Build has an odin works 20" barrel and matching bolt. I was sighting in with hornady 123gr amax factory ammo. Average velocity came out to be 2488fps

The problem I ran into was the rifle was not chambering a new round after firing. I'm thinking it's the mags or maybe a gas issue? I am using ASC mags that I purchased from 44mag (I tried 2 different ASC mags and both failed). I doubt it would be my accuwedge making contact but I will remove it and retest just to rule it out. I shot a total of 40 rounds and I managed to have a string of 5 shots cycle in a row and the rest did not cycle.

This was the only hangup I had. The rest of the failures were the bolt cycling but no round going in the chamber




After firing the last round

[ah1whiskey]

how many rounds per mag?

[Squatchy]

I have the 10 and 15 round mags. I tried combinations of 5 rounds and 10 rounds in each of them and same result

[RAM2940]

Looking at the bottom picture, looks you are locking on the bolt carrier, should lock back on the bolt. Your bolt is not going back far enough to pick up the next round. Do you have an adjustable gas block. With out knowing anything else about the gun, i would think you are undergassed.

[Drillboss]

+1 on Ram. My last build ran fine with factory ammo, but the bolt carrier was catching the bolt catch rather than the bolt face with some of my hand loads. I had the gas block partially obstructing the gas port. After re-measuring and resetting the block, it ran fine.

[Squatchy]

Looking at the bottom picture, looks you are locking on the bolt carrier, should lock back on the bolt. Your bolt is not going back far enough to pick up the next round. Do you have an adjustable gas block. With out knowing anything else about the gun, i would think you are undergassed.

Below is the setup I have. Gas block isn't adjustable. I am using a standard ar15 gas tube.

http://www.odinworks.com/product_p/b-6.5-20-r.htm

I checked the gas block and it's as straight as it can be

[LRRPF52]

Short stroke malfunction. Not enough gas.

Check gas block alignment to the gas port.

Carrier key attachment (no wiggle, leaks)

What buffer and recoil spring are you using?

[RAM2940]

Shoot one round at a time until you get the bolt to lock on the bolt catch, or you just going to waste ammo.

[Squatchy]

Short stroke malfunction. Not enough gas.

Check gas block alignment to the gas port.

Carrier key attachment (no wiggle, leaks)

What buffer and recoil spring are you using?

Carrier key is rock solid, block alignment looks good, rifle buffer and not sure which recoil spring. I use this same lower for my 5.56 and it has never malfunctioned and I've shot everything from 55gr-80gr light and hot loads


I'll try taking off the gas block and reinstalling it to see if maybe it's slightly off

[Drillboss]

Below is the setup I have. Gas block isn't adjustable. I am using a standard ar15 gas tube.

http://www.odinworks.com/product_p/b-6.5-20-r.htm

I checked the gas block and it's as straight as it can be

My gas block had to be snug against the shoulder. It wasn't a function of being rotated out of alignment.

[LRRPF52]

The gas block needs to be checked for alignment along the bore axis (front to rear), not just is it aligned with Top Dead Center.

[Cornbread]

Is it a set screw block? If so take it off and remove the front set screw. You should be able to look through the hole and see if the hole in the tube is centered in the block. Also, take a drill bit by hand and stick it in the gas port hole in the barrrel see if there is resistance. Sometimes when the holes are drilled a flap of metal gets left in the hole. Make sure the front hole is centered in the dimple. You can also see where the soot ring is on the barrel, if it's centered on the hole. Look for signs of gas leakage(soot) at the tube and the block.

[Squatchy]

I took my rifle out today after realigning the gas block by marking it and still no luck. I'm heading over to a friends house tonight to check with an air compressor if everything is lined up properly.

One thing that's still leading me to think it's the mags is what happened today:
1. Load up magazine(bolt is locked back at this time)
2. Insert mag and give it a good tap to make sure it's in the whole way
3. Hit the mag release
4. No round is chambered

This happened with both of my mags

[ricsmall]

If your friend has a drill index find a bit that fits your gas port. On a 20" it should be a 3/32.
If it's not drill it out with the 3/32. A 1/4" dowel in the barrel will protect the bore

Richard

[NIevo]

Not sure if related but I had almost the same thing happen to an AR-10 .260 build I did. Rounds would either end up like in your pick or the empty round would actually end up halfway out the ejection port. No matter what I tried from different mags, checking gas block, changing bcg etc. I could not figure it out. Ended up swapping gas block to a JP adjustable unit and it functions perfectly.

[Squatchy]

So we checked the gas and everything was working fine. Looks like the problem is my bolt catch. We noticed it doesn't have much spring to it and just from dry cycling the rifle the bolt actually catches prematurely on the catch(shown in the picture) and not on the actual mag. We put the bolt and mags in a different ar upper and it didn't catch. Hopefully it's just an easy spring swap and it will be g2g. I will post updates