This may be a question that Chad from Dallas Reloads can answer easily.....

I bought some of the 208 gr. Amax SBR loads to use in my 300 BO SBR, 8.5" barrel. I was sighting in my gun today and these rounds would not seat during cycling. It was almost like the bolt would get stuck and not lock all the way down when cycling the rounds. Also, the bolt would get stuck and I had a hell of a time pulling it back to get the stuck round out, I even broke the latch off of the charging handle pulling so hard. Should I get the 180 Gr. Sierra SP semi-auto rounds to better cycle my AR or should the 208 Amax's work ok?

I'm wondering if the extended length of the Amax rounds was the problem or if it could possibly be a gun issue?

For comparison the 125 SST's were shooting and cycling just fine. This was a new rifle that was lubed and has not been shot previously. I was shooting suppressed.

Any input would be appreciated.

Thanks!

Can you see any rifling marks on the bullets, If seated too long they could be engaging the lands not allowing the bolt to fully close.

I had a similar issue with some of Chad 's Blackout loads in a couple of my rifles. They were tight but still worked fine in my 700 but would not allow the breech to close on my Contender or go into full battery in my ARs. Good luck, hopefully his customer service has improved.

My crusader barrel was real tight but my cmmg is a little looser. Maybe a tight chamber maybe out of spec rounds.

Hey Doc,

What AR rifle are you using? Mainly, what barrel and what chamber is used in your blk out? What you describe happens sometimes with tight chambered rifles, mainly the Wilson and Noveske chambers. I run 5.56 LC brass cut down to 300 blk out. When you cut down 5.56 brass to blk out, the case wall of the 5.56 brass is now the neck and shoulder of the blk out brass. It makes it much thicker than standard blk out head stamped brass. I account for this by sizing the cases below minimum spec. Most chambers on a 300 blk out are a SAAMI maximum spec. Some rifle manufactures run a minimum spec chamber, which is .006" smaller than max. This smaller minimum chamber in an AR platform can fit tight in the cut down 5.56 LC brass. It should fit without a problem. But if some of them are fitting tight, let me exchange the tight fitting ammo for another lot. I'll re-check the lot to make sure it fits correctly in my minimum spec chamber gauges. Most of the time if it fits tight, it is with the subs. The long bullets of the subs seat deeper, and flare out the case some at the shoulder. The brass will generally grow about .003" to .004" at the shoulder. My brass source sizes the cases .005" below minimum spec to allow for this growth. So a rifle chambers on a minimum spec reamer, my ammo should have about .002" clearance, which is not much. But on the majority of rifles chambered with a SAAMI spec reamer (maximum), there is about .008" additional head space room, which is a lot.

I honestly do not know why there is a minimum spec reamer used on the blk out. Most of the time a minimum spec reamer would be considered a "match" or tight reamer. But we are talking about a blk out, not a 223 or some match round. This round is used for hunting and shooting, not match shooting. And the tight reamer reduces your reliability of feeding and chambering. I've had numerous customers with the min spec reamer not like how their rifle gets dirty and ammo starts to jam up. On a subsonic round, you only get about 80%-85% powder burn. The remaining 15%-20% of unburned powder starts to get into the chamber and clog things up on a tight reamer.

Give me a call on Monday, and we'll figure it out. In the mean time, don't chamber any more of the 208's. If the 125's are working, then they should be ok. Thanks, Doc!!

Chad

No, it's not the bullet length. It will be the shoulder of the case causing the issue.

Good explanation, just thought that would be one place to check, that I have seen with other loads. Can easily see the issues you talked about above with the BO spec as it is off of 223 brass. In the past have loaded for 2 different 30 Herret TC barrels, one you had to turn the necks for the other you didn't.

Chad,

Thanks for the response and explanation. From my somewhat uneducated opinion it seemed to be the junction where the bullet seats into the case causing the jam. On a couple of them I thought I could tell that the head of the case was binding, but honestly I didn't really know what to look for. It just looked like some of the cases were a little thick and were getting "squished" back on the leading edge which would follow your explanation about the tolerance on the chamber.

BTW, it is a Radical Firearms complete upper.

Thanks for the help, I'll give you a call Monday or Tuesday.

I had a similiar problem with my noveske using my own handloads. It turns out it was totally caused by length. I accidentally set had my seating die to .10" too long. Bullet got stuck in the rifling and was extremely hard to extract. In one case I extracted the case but the bullet got stuck in the barrel. They also were binding up in the magazine (hint hint!). After going back to the bench and figuring out the problem with the length it performed flawlessly. This was with cut LC brass. I load mine .02 shy of mag length and everything runs perfect in my sbr.

It could be the lip of the case. The easiest way to find out is to take a black sharpie and color the case up and chamber it a few times. You will begin to see rub marks on the area where it is making contact. That would be your problem area.