Ar-15 Problems Sig Sauer M400

[randy7390]

So this is my problem. I have sold the Gun off to a Buyer. He has Bought it. Rifle Does not Fire at all. Here is a Brief History. I purchased the Fire Arm from a Dealer. the AR-15 is a Sig Sauer M400 Brand New, used it for 1 yr on and off decided to Switch Some Parts, Like the Nickle Boron BCG, Charging Handle. Buffer spring and the Rear Stock. Gun was Firing Flawlessly for over a Year Span. I locked it up in the safe after Having Kids, decied to sell it needed the Money. Had no time for that Hobby. It was perfect before i had to sell the Rifle. I don't know what went wrong.

Here is the problem: The Rifle is not Firing the Projectile, it is putting an Indentation on the Primer of the Bullet and the Round is not Going Off the Bolt Carrier Group Pushes Forward but does not Close all the Way.

Any Advice will Help. I took it to 1 Gun Smith SO Far and he said he has not time to work and it and he does not want to help. So please any suggestions would help.

[Diesel12]

Did you take the rifle to the range after the parts were replaced? Sounds like you have a light primer strike. Could be a headspace problem with the new BCG. If you have the original parts for the rifle, I would suggest putting the old parts back on and try it out.

[randy7390]

Yes I did operation was great fired no problem. I don't have the original bcg. I will have to buy the new bcg. What would cause the headspace Issue?

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[buellster]

If the bolt doesn't close all the way, of course it won't fire. Why won't it close? Dirty chamber? Binding? This is the symptom you need to be focused on.

[Devilmonkey89]

Was he using steel cased ammo or quality brass ammo?

[randy7390]

It's a 5.56 only NATO rounds shot through the air. It seems to be some kind of binding not letting the bolt close all the way.

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[etwinam]

I would clean it, Then make sure the BCG cycles correctly. Could be a problem with the spring also, A loose or old spring will not cycle properly and the BCG won't have enough enertia coming back to strike the primer. Did you Purchase a full size BCG? those lightweight low mass BCG require an adjustable Gas block. lastly did you check the gas block. Is the gas tube all the way in?

[randy7390]

I purchased a Fail Zero Nickel Boron BCG. Maybe Spring I will try that.the gas tube is in all the way correct position ing Same as the factory.

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[randy7390]

How do I test and make Sure the bcg works without going to the Range every time? Do I buy one of these red caps?

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[etwinam]

Fail Zero is good stuff, You should be golden there. I run one in one of my builds and it cycles perfectly.

[jericho89]

Dirty chamber or out of spec ammo

[etwinam]

Dirty chamber or out of spec ammo

I would start with a deep cleaning of the chamber

[shafferds]

Could be bad coating job due to excessive headspace on the bolt causing issues.

[tdp113530]

Is the Firing Pin retaining pin in correctly?

[randy7390]

To how do I determine that if the retaining pin is holding the firing pin correct

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