Gas Checked 30 cal issue

[Avit187]

I have been playing around with a new upper for my AR chambered in 300 whisper from model 1. I loaded some j-words up and sighted in. Everything worked great.


So i moved onto the boolits i cast.
This is my first attempt at casting boolits for a rifle.

I used this mold

http://www.midwayusa.com/viewProduct/?productNumber=112896

Lubed sized and gas checked.

I loaded some up using 14.5 gr of H110.

They shot great. Grouping were decent at a hundred yards. Now here is the issue:

After shooting 20 rounds, i inspected the barrel for leading. There was none. What i did find was very fine copper shavings all over the bolt carrier/ bolt.

It seems as though the Gas check is burning up and sending these shavings down the gas tube and onto the bolt. I took the Bolt carrier apart and the amount of shavings were so great that the bolt was starting to bind/ not move as freely as it should inside the carrier.

Any ideas of how to fix this?

I should also say i loaded some of the same boolits up using AA#9 and a lighter load (just barley enough to cycle the action, some rounds even short stoked around 12.5 grs) With the same results.

Besides being a good reason to convert this upper to a piston system, any thoughts on what i am doing wrong?

Thanks for all your input guys!
__________________________________________________ _______________
UPDATE

Thank you for the help everyone. Went to the range on Sat and shot 30 boolits.

Groups were very good at 100yards. No leading, no copper shavings.

Everything ran perfect.

Sunday went out with just "J" words and shoot 40 rounds. Groups were excellent at 100 yards. No copper shavings found when i cleaned the rifle.

SO it seems as though the copper is coming from the "J" words, but only gets sent down the gas tube an onto the bolt when I shoot Boolits directly after "J" words without cleaning.

Firing either round independently followed by a cleaning and there is no problem.

Thanks again for the suggestions, it made figuring this one out very easy.

Now onto playing around with different powders to find the one this boolit/my rifle like the best.

[Calamity Jake]

Did you clean between "J" and cast shooting? If so did you get copper shavings there?

If you didn't clean then the GC could be scraping copper from the barrel that was left after the
"J" shooting putting in the gas system an on the bolt.

GC"s will not burn up going down the barrel but will scrape stuff off ahead of them.

[stephen perry]

Avit
Have you ever taken the time to inspect your AR for jacketed bullet leftovers. Or now that you are shooting lead gas checked bullets you are more conscious of pollution in your gun. Gas checks don't burn up they are made of similar material as the bullet jackets you shoot on your jacketed bullets.

Stephen Perry
Angeles BR

[thehouseproduct]

I'm working on the exact same project. I would ask if you need gas checks at all. How fast are you pushing these?

[Avit187]

I am shooting all loads super-sonic....have not put them through a Chrono yet, but based on the load data i am using i would guess i am pushing these at around 1500fps.

I did not clean between the two rounds (J's and Boolits)

I did shoot just "j" rounds the first time out (no cast ones that day) and did not notice any issues.

I clean my rifles after every range session no matter how little they were used. All my equipment gets put away cleaned and lubed.

I shoot many different rifles and calibers and have never experienced fouling of this type. Shot thousands of J rounds through my AR and have never seen copper residue on the bolt carrier group.

All that said...every gun is unique and it is certainly possible that this is from j rounds. If that is the case, how do i go about fixing it?

[243winxb]

My guess is the hole drilled into the barrel for the gas port, has a burr, shaving the gas check.

[Calamity Jake]

My guess is the hole drilled into the barrel for the gas port, has a burr, shaving the gas check.

If that were the case then there would be lead too.
And copper from the first "J" bullets

[PatMarlin]

There's a member here I think has been having the same problem but with a different caliber, and wants a gas check that is taller? Something about the short check and the AR. Memory slips by me at the moment and I've got get to work.

[Doby45]

I bet when shooting the j-word bullets it would not remove the copper fouling from the previous shot because the front of the j-word boolit is not scraping the rifling, but I bet there WAS fouling in the bore. Now you shoot a boolit with a GC on it and the front edge of that GC COULD be scrapping the fouling from the bore. I would do a very good cleaning of the bore and then shoot JUST GCed boolits and see if it does it.

[243winxb]

The front edge of the gas check could be catching on a burr left from drilling the hole. When drilling into the bore, a product like cerrosafe is used to keep from forming that burr. Firing more Jacketed bullets may smooth it out, or a compound could be used to polish the bore, or maybe fire lapping. http://www.davidtubb.com/finalfinish.html

[243winxb]

faulty recoil spring,???? http://webcache.googleusercontent.com/search?q=cache:DIsyJkwQcYUJ:www.sigarms556.com/viewtopic.php%3Ft%3D5345%26sid%3D29ed5451e5f18e266 43a510238cabd5d+copper+shavings+all+over+the+bolt+ carrier/+bolt.&cd=2&hl=en&ct=clnk&gl=us&client=firefox-a

[243winxb]

How about this one > the carrier tilts backward so the back / bottom of it hits the bottom of the buffer tube causing wear and metal shavings there.

[243winxb]

How about this guess > The extractor is shaving brass off the rim of the cartridge on loading. Check the rims.

[Avit187]

thanks for all the reply's.

I am shooting tomorrow, and will only shoot Cast boolits. Will see what happens.

Plan on shooting Sunday too so, I will try a few things and report my results.

Thanks again for all the suggestions.

[qajaq59]

Those shaving could be from the rim of the case mouth. Your cast bullet is likely a little larger then the Js are and something may be scratching the case. It might even be doing it as they come up from the mag before they are fired. Just a guess though.