Buffer/Spring set-up, Can it Damage a AR?

[PA PATRIOT]

First let me say that I'M Not Trying To Start a Steel Case vs Brass Case debate but more what would be the possible results or damage if one tuned a 14.5 inch carbine length gas system to run lower pressure .223 steel cased ammunition by using a standard carbine buffer and spring but mixed in higher pressure 5.56 with the same system on occasion say 500rds to 1000rds at a pop?

I run steel case exclusively for weekly training as that is all the budget will allow. Now when I can find some 5.56 on sale I like to throw it into the mix running it at paid training events. So by running the higher presser 5.56 ammo on occasion can it beat up my .223 tuned rifle.

What if any damage/enhanced wear could occur when shooting 5.56 pressure ammunition with a lightly sprung/weighted .223 reliability set-up?

If so what parts would take the most wear/damage.

I'M sure there will be some responses that say just to switch out the spring/buffer when using 5.56 ammunition, but my question is more on the mechanical aspect of what could/would occur if I decided to run one set-up only.

[ForTehNguyen]

shouldnt have to change out anything. Just keep a spare bolt and extractor as those are the usual suspects to fail first.

[Belmont31R]

You have more violent unlocking of the bolt as the buffer is there to regulate the speed the carrier moves back (and unlock the bolt from the barrel extension). That can lead to increased fatigue on the bolt including the lugs and cam pin hole area.



You might try experimenting with throwing an H buffer when you know you are going to be using the gun with 5.56 for a class or such.



Basically how the gun works is gas comes back through the gas tube, goes into the BCG, and acts like a piston to push the BCG group reward. At that moment in time the bolt is still locked into the extension. As the BC moves back the bolt rotates and unlocks. The rear of the bolt lugs, until the bolt is rotated and pulled out of the barrel extension, will be put under stress as the BC is trying to pull the bolt out. If you look at a used bolt you will see the lugs have worn on the back as well as the front. If you over gas the system you're putting more pressure on those lugs and over time more fatigue which leads to a higher change of a failure. A heavier buffer will reduce this fatigue by slowing down the speed at which the BCG moves reward.


This is one reason KAC came out with the rounded lugs. More material = stronger lugs. LMT also has under cut lugs. I don't have a picture of that but someone will shortly.


But I would avoid shooting a gun tuned for .223 with 5.56 esp with a standard buffer in a class. You're putting extra wear on the gun and increasing the chance of a failure when you're out there to train not dink around with a broken gun because it was setup incorrectly.

[wahoo95]

Don't overthink it. There are LOTS of people out there running 14.5" Middy with standard springs and buffers and having no issues.