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_rab_
08-12-11, 17:30
I was cleaning my rifle the other day, and noticed a light 'primer dimple' firing pin strike on my 5.56 Tap T2. I am familiar with the situation Doc describes in his 5.56 Duty Loads thread, that this issue can cause failure of the primer to ignite.


When the same cartridge is repeatedly chambered in the AR15, the floating firing pin lightly taps the primer; with repeated taps, the primer compound gets crushed, resulting in inadequate ignition characteristics--despite what appears to be a normal firing pin impression. Once a round has been chambered, DO NOT RE-CHAMBER IT for duty use. Do NOT re-chamber it again, except for training. This is CRITICAL!!! - Doc
Obviously that would be unacceptable.

Currently, I leave my AR loaded, chambered, saftey on. However, this is causing 'primer dimples'. What is the proper solution? Mag inserted, bolt locked back? Or is the best solution to have the mag inserted, but bolt forward?

A contributing factor in this decision process is the lack of factually based knowledge regarding the degradation of springs. I've read some about it, but am feeling like it is all theoretical. If I leave my bolt locked back, will that wear my buffer spring?

Rab

aveisone
08-12-11, 17:46
i derped

aveisone
08-12-11, 17:50
I have had no issues with the dependability of a round with a firing pin mark on it. This mark is made on every primer before it is fired. If it was casing damage then a no rounds would be reliable... right?

That said I leave my go to rifle chamber open safety off.

KhanRad
08-12-11, 18:26
I have had no issues with the dependability of a round with a firing pin mark on it. This mark is made on every primer before it is fired. If it was casing damage then a no rounds would be reliable... right?

That said I leave my go to rifle chamber open safety off.

Having a primer dented a couple of times usually won't hurt anything. However, rechambering the round over and over again WILL eventually result in a dead primer. The compounds inside will become dislodged and will not ignite on impact. I've had officers either have dud rounds at the range or when trying to dispatch an animal when they chamber that first round. Almost all the time, they had chambered the same round over and over again in their ARs.

Dr. Roberts goes into this here:
https://www.m4carbine.net/showthread.php?t=19881

DocGKR
08-12-11, 20:29
We have always trained to have long guns loaded/mag in place, no round in chamber, safety on. When needed, simply chamber a round, acquire target in sights if deadly force is warranted, swipe off safety, press trigger...repeat as necessary.

I am not quite sure how to fully emphasize this point: If at all possible, DO NOT RE-CHAMBER DUTY/CCW/SD ROUNDS...EVER! After chambering once, put the round into the training bin.

Lincoln7
08-12-11, 21:13
If I leave my bolt locked back, will that wear my buffer spring?

Rab

Please note that springs do NOT wear out from being compressed, they wear from cycling them. This applies to magazine springs and all others as well.

I think you could give a brief inspection to that 1st round before reloading it in the magazine or dropping it in the chamber. I will admit to never considering this issue for I keep an empty chamber on my HD AR. So thanks for sharing what I consider a very good question.

bananaman
08-12-11, 22:08
This was pretty extensively discussed recently here (https://www.m4carbine.net/showthread.php?t=49205).

DocGKR's response and advice was just as appreciated then.