Upper giving me light primer stikes

[mdewitt71]

Friend bought an Sanders 18 inch Grendel upper and is getting light primer strikes... every time. Swapped his upper to my Grendelhunter lower still the same, put my BCG in his upper still light strikes.
I put a new gas tube and has block on it still giving light primer strikes.
Threw the ammo in my AR with BCG and it fired....

[Klem]

Might be too much headspace (chamber too long).

Has any round fired out of it?

[mdewitt71]

Yes after i put my Grendel hunter bolt in it... i got a few rounds to fire then went to light strikes again i think....

[biodsl]

Didn't I read somewhere that there are firing pins in two different lengths? Something having to do with a .125 and .136 bolt face?

[mdewitt71]

Didn't I read somewhere that there are firing pins in two different lengths? Something having to do with a .125 and .136 bolt face?

Yea... I'm not at home now but will pull his BCG apart and compare it to mine tomorrow.... never had an upper do this before, I have built dozens.

[Klem]

Yes after i put my Grendel hunter bolt in it... i got a few rounds to fire then went to light strikes again i think....

md,

The reason I ask this is because if you don't have Grendel headspace GO-NOGO gauges you can get an idea of the shape of the chamber from those few cases that fired. If the load is normal (not mild) then they should have expanded to the chamber. Compare them against the unfired ammunition, and spent cases from your own rifle.

Is the ammunition hand-loaded?

Do you have the Hornady Comparator headspace gauge?

[VASCAR2]

[Klem]

Vas,

The OP swapped his mates BCG for his and still got light primer strikes. Fair to assume the OP's gun functions OK. His BCG works in his gun, but not his mates. This is why I think it's more to do with either the chamber reamed too long, or the ammo is too short, and the BCG is OK.

[montana]

Head space, function and depth gauges saves a lot of headache..

Be sure to check the case moves freely in and out of the bolt face and the ejector pushes completely flush..

Normally I would say light hammer spring/out of spec bolt-firing pin, out of spec gas tube interface with gas key, etc, but I think the others could be right about a chamber problem..

[VASCAR2]

Vas,

The OP swapped his mates BCG for his and still got light primer strikes. Fair to assume the OP's gun functions OK. His BCG works in his gun, but not his mates. This is why I think it's more to do with either the chamber reamed too long, or the ammo is too short, and the BCG is OK.

Another poster mentioned the difference in some Grendel bolts so I was just trying to provide information I had saved in regards to different products on the market. I think the OP can sort out the issue given enough time. It sounds like a chamber/head space issue but hard to say without having the upper to inspect.

[LRRPF52]

Vas,

The OP swapped his mates BCG for his and still got light primer strikes. Fair to assume the OP's gun functions OK. His BCG works in his gun, but not his mates. This is why I think it's more to do with either the chamber reamed too long, or the ammo is too short, and the BCG is OK.

[mdewitt71]

So, I took the owners BCG apart, it was gummed up pretty bad.... Asked him how he cleaned it and he said he has never taken it apart before.
When I took the firing pin and cam pin out, the bolt would not come out of BCG... Stuck solid...then when I did get it out, the extractor was stuck solid too.
Lots and lots of cleaning and soaking and then a long class given to the owner on how to maintain an AR .....

[VASCAR2]

Thank for the update!

[biodsl]

Lots and lots of cleaning and soaking and then a long class given to the owner on how to maintain an AR .....

Your public service. Uncle Sam taught me this way back in 1981. I had to relearn it when I got back into ARs many years ago. This forum has been instrumental.

[LRRPF52]

So, I took the owners BCG apart, it was gummed up pretty bad.... Asked him how he cleaned it and he said he has never taken it apart before.
When I took the firing pin and cam pin out, the bolt would not come out of BCG... Stuck solid...then when I did get it out, the extractor was stuck solid too.
Lots and lots of cleaning and soaking and then a long class given to the owner on how to maintain an AR .....