Light Primer Strike

[returntrue]

Ammo, BCG, LPK, or…?

I have stock BM 16" carbine with a brand new BCM BCG. I test fired with 130 rounds of PMC 55gr .223 and got a single light primer strike resulting in a failure to fire. It was in the last magazine of the session, approximately half-way down, so at/about round 115.

Assuming that this is an issue, what should I be focusing on to diagnose and correct it?

[Col_Crocs]

It may just be a bad round. Did you compare the primer stikes on the fired shell casings with the one that didnt fire?
Also, Just to clarify...
New weapon or new upper with new bcg or just new bcg? If it's not a new weapon, how many rounds have you had through this upper and/or your FCG?

[Eric]

Bad primers happen, but more details would be helpful. Not to insult your intelligence, but if this was a lower that you assembled are you sure the hammer spring was installed correctly? It should be oriented as depicted below. Note how the bottom legs of the hammer spring come from underneath and ride on top of the trigger pin. If the spring is reversed it provides inadequate tension on the hammer.

http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg

[Makintrax73]

I had a bunch of light primer strikes on a 7.62x39 upper. One of the fixes was to adjust the firing pin protrusion. It couldn't hurt to measure the pin protrusion with the back of dial caliper and shoot an e-mail off to BCM to make sure what you have is in spec. I would imagine that if it wasn't in spec BCM would make it right, and if it is in spec that is one thing you can check off your list.

[Russ D]

Most likely it's a bad primer if it's just a one time thing.

[returntrue]

It may just be a bad round. Did you compare the primer stikes on the fired shell casings with the one that didnt fire?
Also, Just to clarify...
New weapon or new upper with new bcg or just new bcg? If it's not a new weapon, how many rounds have you had through this upper and/or your FCG?

Hi Col Crocs, thanks for the response.

I did compare the the primer strikes. There was a visible difference, with the fired cases having a deep strike mark and the 'light strike' round having a comparatively shallow indentation.

The firearm is an otherwise stock Bushmaster. It had maybe 500 rounds through it in its original configuration.

Maybe I'll cool my jets and wait until I can get a few more rounds through it to see if there is a trend?

Thanks.

[returntrue]

Bad primers happen, but more details would be helpful. Not to insult your intelligence, but if this was a lower that you assembled are you sure the hammer spring was installed correctly? It should be oriented as depicted below. Note how the bottom legs of the hammer spring come from underneath and ride on top of the trigger pin. If the spring is reversed it provides inadequate tension on the hammer.

http://img.photobucket.com/albums/v503/AR15forme/IMG_5660.jpg

Hey Eric -

No worries. The lower is factory assembled by BM. I did see that as a possible explanation when I did my initial searching, so I double checked, but it looks just like the pic you posted.

I've got another couple of hundred rounds of this ammo, so maybe I'll run the rest through and see how it shakes out.

Thanks.

[returntrue]

I had a bunch of light primer strikes on a 7.62x39 upper. One of the fixes was to adjust the firing pin protrusion. It couldn't hurt to measure the pin protrusion with the back of dial caliper and shoot an e-mail off to BCM to make sure what you have is in spec. I would imagine that if it wasn't in spec BCM would make it right, and if it is in spec that is one thing you can check off your list.

No caliper handy. I'll see if I can get my hands on one.

Thanks.

[returntrue]

Most likely it's a bad primer if it's just a one time thing.

Fingers crossed...

[Russ D]

I've had issues when using the JP light power springs but never had an issue with factory springs.

[Col_Crocs]

Hi Col Crocs, thanks for the response.

I did compare the the primer strikes. There was a visible difference, with the fired cases having a deep strike mark and the 'light strike' round having a comparatively shallow indentation.

The firearm is an otherwise stock Bushmaster. It had maybe 500 rounds through it in its original configuration.

Maybe I'll cool my jets and wait until I can get a few more rounds through it to see if there is a trend?

Thanks.

Yup, I think youre ok. Keep us posted though, and if it happens again, keep notes of the entire session.

[R3V3LATIONS]

agreed. Most the problems with light strikes that Iv noticed are ammo related. Hopefully it was just one band round. happy blastin'!

[Ilove2shoot]

did you reset you hammer and try firing the round again? my guess is ammo.....I would not go tinkering with anything over a single light primer strike. could be the primer was seated a hair deeper......