AR problem

[300sx]

I just built this AR and when i shoot the remington.223 55gr white/green box ammo the gun shoots fine..But when i change to 5.56 XM193 or some reloaded ammo i bought from 1500 show it will shott maybe every other rd. or non at all.. when looking at the ammo it doesn't fire..the firing pin hits it, but just not enough..

Anyone else run into this problem? does the some in the BCG need adjusted?

the gun specs are a spikes lower, yhm upper and barrel, BCM BCG

please help

 

[Marc]

sounds like a light primer strike to me.

 

[shooter521]

Sounds like hard or high primers. With XM193 and reloads of unknown pedigree, I am not surprised. Try some other reputable brands of ammo (Win/Rem/Fed, PPU, Black Hills, etc) and report back.

 

[300sx]

i know reloads aren't the best thing to judge the problem by but the thing that has me is the xm193 will shoot every other cartrige every time..

 

[kwelz]

When you say build did you put the upper onto the lower or did you buy a stripped lower and install your own LPK?

It could be a weak hammer spring. I have seen it happen on a couple DPMS parts kits I used in the past. It could also be a problem with the firing Pin although that is much less likely.

 

[300sx]

yes I built it..Its a spikes lower. with their lpk..unknown manufacturer of lpk.

 

[Marc]

i think hammer spring be your problem

 

[pftraining_in]

Did you install your hammer spring correctly? Even installed wrong, the hammer will work, however you will receive weak hits on the primers.

If the XM193 was loaded even close to spec, it will be loaded with a harder primer than Remington green box or other commercial loads. Harder primers requires a constant and repeatable impact from the hammer.

Are the fail to fires after the bolt is sent into battery or is it after a shot is fired?

If it occurs after the shot, the spring is installed incorrectly. If it occurs after the bolt is sent into battery or randomly, you may have a weak or out of spec spring.

Spring installation:

 

[Smitty506th]

First off... Is your chamber .223 or 5.56. It does matter. Second have you had anyone else fire the ammo to see if the problem is with your weapon?

 

[kwelz]

While I agree that the chamber matters I am not sure if that would have any impact on light primer strikes. I could be wrong however and often am.

 

[CountryBoy19]

Did you install your hammer spring correctly? Even installed wrong, the hammer will work, however you will receive weak hits on the primers.

This ^^^
Are you sure the spring is in correctly? That is the most likely culprit.

First off... Is your chamber .223 or 5.56. It does matter. Second have you had anyone else fire the ammo to see if the problem is with your weapon?

That shouldn't have any bearing on light primer strikes or FTF.