Cartridge swipes?

[Robin]

I loaded five rounds below max for the setup I am using and they do have marks from the ejector on the rim. The primer isn't flattened out and pin dent look okay though. Sure doesn't seem to me I'm over doing it, but would appreciate opinions.

Three of the casings have dents from the deflector boss.

I fired about twenty rounds of Armscor 147 gr. factory loads before my test load and they have that same, what appears to be an ejector swipe or indent.
Could this be because the gun is new?
Robin

 

[dsdmmat]

I would suspect timing.

An Official Journal Of The NRA | Case-Head Swipe

Case-head swipe (CHS) with AR rifles is similar to, but not the same as, ejector marks on cartridge-case heads fired in bolt-action rifles.

www.shootingillustrated.com

 

[1075tech]

Could be early unlocking. Did you build this yourself or is it a "factory" build? I recall reading somewhere that a lot of 308 ARs are over-gassed.

I had a DPMS LR-308 that was way over-gassed.

 

[meketrefe]

I loaded five rounds below max for the setup I am using and they do have marks from the ejector on the rim. The primer isn't flattened out and pin dent look okay though. Sure doesn't seem to me I'm over doing it, but would appreciate opinions.
View attachment 69338
Three of the casings have dents from the deflector boss.
View attachment 69339
I fired about twenty rounds of Armscor 147 gr. factory loads before my test load and they have that same, what appears to be an ejector swipe or indent.
Could this be because the gun is new?
Robin

those internet 'expert' writers are all over the place.
Many high pressure rounds are going to show rotation marks.
Those are totally normal marks from the plungers pocket as the pressure spikes and the brass seats and some pressure remains at the rotation of the bolt.
Most times, dangerous pressure signs come in twos and threes. like extrusions. flatten or blown primers and/or split necks.
to prevent the dings stick a bit of velcro tape or something with some cushion to avoid the dinging.
In a AKM type of receiver is a must of the brass gets all banged up. The SIG also chews on the brass pretty badly so
one has to put some measures to preserve it a bit for future loads.

 

[Robin]

Thank you fellows!!!!
Robin

 

[Robin]

Going to try a heavier buffer. If that doesn't get it I'll add a heavier spring. If that doesn't get it I'll add an adjustable gas block. After reading the stuff provided I'm pretty confident the buffer will do the trick! Sticking a tuft of velcro on the deflector boss too.
Thanks again fellows!!!!!
Robin

 

[meketrefe]

Going to try a heavier buffer. If that doesn't get it I'll add a heavier spring. If that doesn't get it I'll add an adjustable gas block. After reading the stuff provided I'm pretty confident the buffer will do the trick! Sticking a tuft of velcro on the deflector boss too.
Thanks again fellows!!!!!
Robin

That is not necessary unless you know the barrel job is out of spec or you are using a carbine type barrel that is a mistake in a AR.

 

[Robin]

It is an eighteen inch barrel. I just like things to run smooth. No hiccups.
Robin

 

[meketrefe]

It is an eighteen inch barrel. I just like things to run smooth. No hiccups.
Robin

I mean carbine porting not length of barrel. Carbine length porting is a mistake in a AR.
Mid lenght is better and rifle porting is best.

 

[Robin]

That I don't know. I didn't drill the hole. It is an AR-10 and the recoil is a bit more than I would have expected so the heavier buffer won't hurt.
Robin

 

[dsdmmat]

That I don't know. I didn't drill the hole. It is an AR-10 and the recoil is a bit more than I would have expected so the heavier buffer won't hurt.
Robin

You would be better off with going for an adjustable gas block First.

 

[1075tech]

You would be better off with going for an adjustable gas block First.

Agreed.

@Robin , measure the length of the gas tube from the gas block to the carrier. ~9" = carbine, ~11" = mid-length, I think. Something like that without looking it up right now.

 

[Robin]

I took a measurement and it is 11".
I did think about swapping out the gas block for an adjustable one and in hind sight I do believe you are right, but the buffer is on order. If it doesn't do the trick I will order the gas block. I want to stay with the load I got, Its fast, accurate and perfect for any NYS big game.
Robin

 

[meketrefe]

That I don't know. I didn't drill the hole. It is an AR-10 and the recoil is a bit more than I would have expected so the heavier buffer won't hurt.
Robin

What type of porting is it, carbine, rifle? ... and what is the diameter of the port?

 

[Robin]

11" is I believe considered 'mid-length'. I have been shopping for an adjustable gas block, surprised at all the vendors that are out of stock. When I find one and get it here, I will remove the one on there and measure the port.
Robin

 

[Robin]

Okay Mek, you piqued my curiosity and I had to check the gas port diameter. My Tri-Cal's have a tough time getting a true and accurate measure, but a 5/64" (.078) drill passes freely, so thats pretty close to my measurement, maybe .080". Let me know what you think.
Robin

 

[JamieZ]

11" is I believe considered 'mid-length'. I have been shopping for an adjustable gas block, surprised at all the vendors that are out of stock. When I find one and get it here, I will remove the one on there and measure the port.
Robin

Whats the gas block size? I just checked Odin Works,,,which in my opinion make some of the best adjustable gas blocks,,,not the tunable one but the adjustable one,,,,they look to have them in stock for .750,,,,.875,,,,and .936 diameters. Have them on 2 of 3 black p-shooters I have.

 

[JamieZ]

To me port size is a non issue being that we already know there is enough gas coming out. Which means adjust it or send the barrel back if the port size is to big.

Just my opinion, I could be wrong

 

[Robin]

Thanks JamieZ. Odin Works for me too so what the heck, I'm getting one.
Robin

 

[JamieZ]

Thanks JamieZ. Odin Works for me too so what the heck, I'm getting one.
Robin

Just a PS Robin,,,Ive never ordered directly from them,,,always Brownells or one of the other dealers that stock them but Im sure you will have no problems ordering direct.