300 whisper AR 8"

[cqb]

Hi Forum,

I just got a AR15 in 300 whisper with a 8" barrel.
I can't get it to function
I have 300 whisperbrass made from 221 and some from 223.
For loads I used 150 gn bullet over 18 gn H110 and 220 gn bullet over 9 gn H110.
The bolt won't even open

Anybody have any sugestions ?

Regards,

Geert

[Wrangler]

Head Space?

[cqb]

Are you suggesting I should move the schoulder on the cases further back ?

[RWBlue]

Are you saying that is doesn’t go boom, or are you saying that the next round doesn’t feed?

Although I don’t have a 300-221, if you are saying it doesn’t go boom, I would think that the cartridge is either too long and the bolt isn’t going completely home, or way to short and the firing pin is not hitting the primer.

If you are saying it doesn't feed the next round, you are beyond my skill sets.

[cqb]

It fires, but there's no extraction of the spent case.

[Wrangler]

It might help. I pounded open a remington 700 one time with that problem. Also a poorly spaced Mauser. I do not recommend it as a normal practice.

[Spook]

I had a DPMS do that from brand new.... The chamber was so rough and badly ringed that it wouldnt allow the cases to retract after firing. DPMS's remedy was to remove the barrel and polish the chamber.... It still leaves rings on the spent cases but functions well. Best compromise They could come up with due to me using "handloads". Cheap bastards havent had a good word from me since, Over the cost of a barrel? Good Luck, hope you can fix it.

[Wrangler]

Frustrating as hell isn't it? Makes you want to take up another hobby at times. Problem is some of them are too expensive and want to bring their mother along.

[cqb]

I've tried that other hobby Wrangler.
Why'd you think I took up shooting

[rednek58]

I found that when working up loads for my AR 300 that with the 150 gr bullets loaded with 18 gr of H110 was way too hot. They would not extract. Had to knock it out with a cleaning rod. This load really did a job on the primers. Had to go down to 16.8 gr with 150's. These produced 2016 fps (avg) with very good accuracy. All my loads are using .223 Rem brass, Rem primers and trimmed to 1.350.

On the subsonic side, I have good luck using 10.8 gr of AA1680 with the 220 gr Sierra MK's. This load yielded an avg. of 1055 fps with outstanding accuracy and functioning with and without suppressor. I have 100% functioning with both of these loads in semi and FA.

Although a brand new AR rifle/pistol will improve with some breaking in, I don't think this is your problem at this point. Another thing to check is to be sure the gas port in the barrel is at least .125. There is no need for it to be any larger since most gas tubes are no larger than .125 I.D. One other point regarding gas flow, be sure that the gas block and the gas port are perfectly aligned with each other, as is obvious, misalignment will restrict gas flow that can cause weak pressure for the operating system to work properly. But with the load you stated, overpressure in the chamber could likely be your problem.