JRoss

Yes it has the 308 bolt stop

Do you know the measurement from the center of hole to end of bolt stop by chance?

Yes ejecting and extracting ok

Yes it does lock back when puling the charging handle and an empty mag installed. The bolt stop I will have to check on but it is what they sent me along with the upper. I checked the gas tube and it is not clogged and the stock screw has a hole and it clear also.

Still not holding bolt open with gas block fully open one round in mag and firing. Maybe the spring has too much pressure or too long. More research on springs and length and pressures. I will just order 1 of each spring made hahahaha

The one in the 20" is pretty much what mine looks like. I have been taking close measurements on buffer to end of buffer tube and it might be good to go without shortening the buffer. I received the adjustable gas block today so next is changing the old out for new.

Maybe you can swap your older build parts into the new 18'' and see if that works better. I was at a gun shop today and they had some AR15 buffer kits on display and like you said they don't look right for an AR308. Buffer is shorter and spring looks different.

The coil count on the spring I have now is 39 and the length is 12 and 3/4 inches and the wire diameter measures .076" the buffer weighs 4.8 ounces. The AR10 spring on Slash's chart is 34 coils and the length is 13 and 3/4" and the wire diameter measures .074" the buffer is 5.4 ounces. Looking at the numbers the spring rate might be close but there are special tools to measure spring rates that are very accurate and would tell the real tale of the difference in the 2.

Yes buffer tubes are the same for rifles but the springs and buffers are different from what I have researched. Slash's data says for a DPMS 308 use an AR10 Buffer and AR10 spring. I did get my buffer weighed and it came in at 4.8 ounces. Next will be to get the adjustable gas block installed and go from there. At least now I know what I have as a starting reference with the buffer system.

Its an A2 style stock 10 and a half inches long non collapsible.

Ok still waiting to get a weight of the buffer but in the mean time with the buffer assembly apart I removed the spring and installed just the buffer in the tube and screwed it into the lower. Reinstalled the upper to the lower with a mag installed. Pulled the charging handle back and the bolt locked back in open position. Looking into the threaded hole on the butt end of the tube I see the plastic of the end of the buffer and it looks very close to end of the tube, so I grab a toothpick and push on the plastic.......... the buffer does not move! So what this means is that its time to shorten the length of the buffer. I am going to knock the roll pin out, pull the plastic out and cut a half inch or so off the end and then reinstall the plastic and drill it for the roll pin. The dumb asses at the blackthorne factory don't know jack about anything. The buffer spring did not coil bind with the factory length buffer compressed fully to the end of the tube but I will still check for coil bind after the buffer has been shortened........... And what was the reason the gas block blew apart?....... blackthorne is full of guano!

Fired 2 rounds today with mag installed and 1 round in mag, bolt did not stay open after fired.Took the buffer apart and found a 12.75" length non compressed spring with 39 coils that fits into a 9.5" length tube. The buffer measures 5.188" long. My powder scale is too small to measure the weight of the buffer so will check that later but it has weights inside and they rattle around if I shake it. I did order an adjustable gas block from SLR.

I want to thank everyone for the help here and will continue to work on the rifle until it is right. No plans to send it back to factory for sure.

Maybe I should email them a POS letter just because they deserve some sort of recognition for their ass wipe merchandise. Any suggestions on material .......oh wait might get banned for my real opinion ;)

Yes I am too now but taking it apart and getting help from the people here was a good reason. after 10 rounds it blew the gas block free of the barrel. POS rifle from the factory

Ok so I have had enough of this company. I have given them enough time to respond to my last email and they have not responded. So I was building the marquis to put there name in lights and it could be a good show or a bad show. It is a bad show!!! I do not recommend this company to anyone except an enemy. If you have followed this thread you know what has been going on with the denial process and the blaming issues. These people are idiots, morons or both and also just plain stupid. They have no business being in business. If there are any blacklists I can add these POS numb nuts SOBs to please let me know or help yourself in adding them along with myself. Below is a link to there POS website. Oh and guess what? they don't give out their telephone number either! Gee I wonder why? the POS SOBs! http://www.blackthorneproducts.com/

I am taking your advice and will be looking into the ejector and extractor. I have not seen any shavings and the headstamps all look normal. The gas block screws are staying tight so far. I have some torque seal which you may have seen before. It is a special paint used on bolt or screw heads. Once applied to the head it dries and if the bolt or screw is tampered with or becomes loose the paint will show a crack. Once I get the rifle figured out I will put some on the screw heads just for a reference.

Yes 4th round bolt stayed back

Shot 4 more rounds and still not right. All fired from 1 round in mag only. 3 did not eject from bolt, they were grabbed and pulled out of chamber completely but did not exit the bolt. The 4th round ejected but at about 4 o'clock. 20 rounds total fired in rifle. Patience is a virtue with this rifle!

Assembled bolt with original parts but with some lapping and minor polishing. Lubed generously during assembly. Fired 3 more rounds with 1 round in mag. Bolt stayed open on all 3 rounds fired and were ejected at 3 o'clock. Checked gas block screws and they were both tight. Went back inside as the wind was blowing crazy with rain blowing sideways, maybe tomorrow it will calm down and I can load a mag and try again.........or maybe right now..... but its dark and still blowing rain around, better wait. Thanks survivalshop for the research on the DPMS 308AR Extractor! I might have to remove the oring then if things go bad.

Here is the email I sent to Polymer 80 who manufactured the lower: Not sure if my email made it to you but I bought a new complete assembled upper and I bought one of your 308 80 percent lowers. I machined it out and installed the trigger parts kit and it works great. The problem I am having is the rifle does not want to cycle out of the magazine into the chamber more then just one round.Have you had problems with your lowers having the mag well “off”. And what magazines should be used? I have been using the Magpul mags . Sounds like they are blaming the lower and the mags being used on their upper. Is this a common issue ? Thanks Polymer 80 response: Well that’s an unusual response.Here is the reality, there have been thousands of WarrHoggs sold and of those at least in the hundreds have been built into shooting rifles. The problem with the below response is that is just doesn’t work when you have WarrHoggs and FAR more prevalently MagPul Pmags working flawlessly in the market place in large numbers.I cannot speak to their product, but as for mine, no, we do not have these issues at all. I do not know the company who made this upper but that response sounds very deflective and defensive and not very helpful. Our lower is made to spec and works great on many uppers and almost always has a PMAG with it.What is the brand of the upper? Can you shoot over a pic of the lower and upper mated so I can check to see if I can spot something? Thanks! So I sent a copy of this email to the company I bought the upper from and waiting for their response. In the mean time I have disassembled the bolt group for a cleaning polish and lapping where necessary. I took the extractor apart and see it has 2 springs and an O-ring. A smaller spring slips inside the larger spring and the O-ring around the larger spring. Did not know it used 2 springs...............

So they responded to my email when I asked what magazine and how to check the magazine well and what lower receiver I have: Use a FACTORY mag. DO NOT use a plastic magazine… nothing but trouble. We’ve never heard of an “80 Warr Hogg” receiver…. Was this an “80%” receiver you finished? If so, almost all of our experience with people emailing us with functional issues are due to people using an “80%” receiver. Almost zero issues when assembled on to a factory receiver. You should stick to factory receivers, they are all dimensionally correct. If you do not have a CMM (coordinate measuring machine… and most people don’t) you can use a digital caliper and compare the essential dimensions in YOUR lower to a factory lower to see if any of them are “off”. It was an 80 percent but no mag well machining was required, just the trigger pocket was machined and that works fine. So I guess emailing the company who made the 80 percent lower is in order to see what they have to say.

It looks like they seem to feel the gas block is working as it should which as of so far it is operating the bolt and ejecting 1 round and staying open with a spent magazine. Now its a feeding issue. Time for a new thread I guess.

Got a reply from the Co. : Without inspection it is possible for us to say with any certainty… However, from what you describe it sounds like it may be a magazine issue. What type of mag are you using? New factory or some type of aftermarket mag? Also, what type of lower (if the mag well is off this could also cause this) Magpul Pmag 10 LR/SR magazine and a polymer 80 WarrHogg Lower Will be inspecting the mag well for alignment and the magazine . Anyone know a good way to check mag well alignment?

Interesting gas block system they have come up with. I would not mind having one right about now. I guess with an adjustable block a restrictor bushing is not needed in the barrel transfer port. A warranty is a good feature also. So I emailed the company I bought my upper from explaining the symptoms. Hope I will get a reply soon and will go from there.