I just built a AR platform 6mm rat and it is not picking up the rounds out of the clip I have used several different clips with the same results. last night I pulled the gas tube off and checked for blockage and all is fine and it is lined up right also. I'm at a loss and need some help.
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AR 15 6mm rat new build not picking up bullits
- Thread starter mlc0341
- Start date
I've tried several diff. ones with no luck and my friend can use mine and they work fine. could it possibly have to strong of a buffer tube spring not letting the bolt go all the way back. I can do it manually and it chambers fine.
What load are you running? (bullet weight - powder - grains)
What buffer/spring combo? (rifle - carbine)
Next time at the range, load one round in the chamber, put empty mag in rifle.....hold the rifle solid, shoot the round...if the bolt doesn't lock back on an empty mag the likelihood of getting the rifle to cycle in its current state is slim...
I built a couple 6mm wildcat uppers recently similar to the rat....heavier weight bullets and higher pressure loads are going to be easier to get to run than lighter bullets and anemic loads if ported on the small size...
If using C products Grendel mags, there are a couple dimples/ribs on the inside of the feedlips that can rob cycle inertia...I usually smooth mine out...
Of course you want to check the usual suspects...gas rings, carrier key/gas tube make-up, etc...
Knowing what load you're shooting will help...
What buffer/spring combo? (rifle - carbine)
Next time at the range, load one round in the chamber, put empty mag in rifle.....hold the rifle solid, shoot the round...if the bolt doesn't lock back on an empty mag the likelihood of getting the rifle to cycle in its current state is slim...
I built a couple 6mm wildcat uppers recently similar to the rat....heavier weight bullets and higher pressure loads are going to be easier to get to run than lighter bullets and anemic loads if ported on the small size...
If using C products Grendel mags, there are a couple dimples/ribs on the inside of the feedlips that can rob cycle inertia...I usually smooth mine out...
Of course you want to check the usual suspects...gas rings, carrier key/gas tube make-up, etc...
Knowing what load you're shooting will help...
Lee Wells is building me an upper right now for 6mm Fat Rat. Won't have it until July. But I've build a ton of .223 uppers so we'll see what I can suggest to add to the last post.
Are these your fire forming loads? Are you following the instructions to NOT fully size them? The die needs to be spaced out some to make sure you don't size the neck too deep into the shoulder. I think if you do, the cases don't head space right. Lee offers a spacer to adjust die depth. Not sure if that would cause the cases to stick in the chamber or not.
The load sounds plenty hot enough to cycle the gun considering his "max" load is 30gr so I would look at the gas system as the other poster commented. Specifically with the gas block alignment to make sure it's on canted or spaced wrong off the shoulder. Not sure if Lee makes them to seat to the shoulder or space off like a mil-spec barrel is. Are you using an adjustable gas block? Will the bolt lock back on a single load? What's the setup in the lower? What buffer? Spring? Doe it cycle by hand without any dragging? Does this lower work okay with a .223 upper without any issues? Is the bolt and bolt carrier new or used? Any chance the rings are shot as stated above? Gas key is tight? Does the bolt carrier drag on an empty mag with the follower/spring removed? Are the mags all from the same lot? Could they all be out of spec? Is the bolt head lower lug dragging on the next round to be chambered? When fired does the bolt close on an empty chamber or does it stop and jamb in any way?
That's all the questions I have for this session...
Are these your fire forming loads? Are you following the instructions to NOT fully size them? The die needs to be spaced out some to make sure you don't size the neck too deep into the shoulder. I think if you do, the cases don't head space right. Lee offers a spacer to adjust die depth. Not sure if that would cause the cases to stick in the chamber or not.
The load sounds plenty hot enough to cycle the gun considering his "max" load is 30gr so I would look at the gas system as the other poster commented. Specifically with the gas block alignment to make sure it's on canted or spaced wrong off the shoulder. Not sure if Lee makes them to seat to the shoulder or space off like a mil-spec barrel is. Are you using an adjustable gas block? Will the bolt lock back on a single load? What's the setup in the lower? What buffer? Spring? Doe it cycle by hand without any dragging? Does this lower work okay with a .223 upper without any issues? Is the bolt and bolt carrier new or used? Any chance the rings are shot as stated above? Gas key is tight? Does the bolt carrier drag on an empty mag with the follower/spring removed? Are the mags all from the same lot? Could they all be out of spec? Is the bolt head lower lug dragging on the next round to be chambered? When fired does the bolt close on an empty chamber or does it stop and jamb in any way?
That's all the questions I have for this session...
As FCB covered, the load you're shooting should have plenty impulse to run the action...
If you try the empty mag test, and it locks back on an empty mag, but it continues to not strip rounds out of a loaded mag....that's usually a symptom of the bolt group 'out-running' the mag stack for some reason...or the casehead of the cartridge sitting too low during the cycle to get picked up by the bolt face.....
Out-running the mag stack can usually be solved by running a little heavier buffer, or one with fewer/heavier slugs in it to add a little slap/delay at the rear of the cycle....or an adjustable gas block to powder-puff the impulse a little....
The 6mm pills are about 20% lighter than what the mag spring was designed to feed, so too soft of a spring shouldn't be a problem....
If the caseheads are sitting low in the mag, that can usually be fixed by disassembling the mag and tweaking the top two coils to put more pressure at the rear of the stack....
If you try the empty mag test, and it locks back on an empty mag, but it continues to not strip rounds out of a loaded mag....that's usually a symptom of the bolt group 'out-running' the mag stack for some reason...or the casehead of the cartridge sitting too low during the cycle to get picked up by the bolt face.....
Out-running the mag stack can usually be solved by running a little heavier buffer, or one with fewer/heavier slugs in it to add a little slap/delay at the rear of the cycle....or an adjustable gas block to powder-puff the impulse a little....
The 6mm pills are about 20% lighter than what the mag spring was designed to feed, so too soft of a spring shouldn't be a problem....
If the caseheads are sitting low in the mag, that can usually be fixed by disassembling the mag and tweaking the top two coils to put more pressure at the rear of the stack....
I have 2000 rounds through a rat. What is your load?
Is the gas port moved ahead?
Best powders I found were 8208 and H4895 but VV 140 works
Varget would also be a great choice
I went and shot today and pulled the magazine and stretched the spring a little it helped but did not solve the problem I think the springs are week in my mags I'm going to order new ones. I have checked everything that yall have told and everything seems to be fine. I'm hoping just bad mags.
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