BrianK

You don't think the carbon fiber will handle any heat?

Long story on this. I never intended to build it. I ordered a Desert Tech MDR in 300BLK, except when I ordered it years ago the only way to get it was to order it in either .308 or .223. So I bit the bullet and ordered it in .223. Years later it arrived and I waited patiently for the 300BLK conversion, and waited and waited and waited some more. I had everything fully paid up years before. Then I found out that they were allowing other retail outlets to the head of the line. That kinda pissed me off, so I canceled my order and only have the MDR in .223. That's not exactly what I wanted. But I still didn't have my .300BLK so I decided to build my own. This was during the lefts burning of Portland, Seattle, and such. But I found the parts I wanted and got it assembled. There is no comparison to the MDR. The MDR is an anchor and my build isn't. It's also shorter than the MDR bullpup. It was conceived and designed from day one with the idea of always having a can in place. If it's fired without something to get th eblast outside the handguard it'll self destruct, so it always wears an Amtac 7.62 CQB-M or a linear comp'. It has a 10.3" Ballistic Advantage barrel, and the can is something like 10" long, but since the can covers something like 6" of barrel the "barrel" is only made longer by 4" resulting in a relatively short handgun. Here it's seen with the linear comp in place. Here it's seen with a different (heavier) sight and the can in place. If you look closely through the slots in the handguard you can see where it ends.

By James Tarr. It's in the latest issue and is only part 1. It's worth checking out if someone is on the fence or wondering what it's all about. Frankly, just looking at the numbers would have most folks scratching their head and muttering as they walk away. That is, until understanding dawns.

All that was left to do was to test the can (Amtac 7.62 CQB-M) with my chosen load for HD in the closed up shop. Despite the name I always test to make sure. The can is unlike any other I own. I forget the exact specs, but I think it's a 10" can that only makes the "barrel" 4" longer, and it has no baffles. If it didn't blow out my eardrums in the shop then it's house safe. The result? It's house safe. My build will do what I want it to do as designed. It'll take the place of a 12ga and slugs which will over penetrate. I hope I never need them or the replacement bt I think we're going to be Venezuela north. It'll also be far more effective than 9mm. Not as effective as a 5.56, but far easier to maneuver in CQB. Today I loaded the heads I had and that should be more than enough. As I wrote, I hope I don't need any of them. Now I move on to other bullets. Ultimately I'm hoping that I can find a sight-in where all of the chosen loads for serious social use all will have a reasonable point blank range. All of these test loads shot to the same POA, but quite different from the S&B supersonic loads. Fingers crossed.

Aren't we all?

I did more in depth testing today. I'll just give a synopsis of all loads tested then the data for the winning load. The short story is that the bullets are keepers. The data shows just how fast they slow down, but I expected that. I started testing them at 19.0gr ww296 and worked up to 19.8gr. The winning load was 19.6gr. Accuracy for all loads was better than my very low standard with no load having a group larger than 1 1/8". But the sight is a red dot, so some of that could have been my eyes and the sight. There was no POI shift with the can. The bullet has a crimping groove and that governed the COAL. I don't have the actual measurement at hand. I used a heavy crimp. Stats - Average 2308.7 fps Stats - Highest 2321.7 fps Stats - Lowest 2294.02 fps Stats - Ext. Spread 27.68 fps Stats - Std. Dev 13.92 fps Shot ID V0 V4 V15 V25 V50 V100 Ke0 Ke4 Ke15 Ke25 Ke50 Ke100 PF4 Proj. Weight Date Time 1 2322 2304 2255 2210 2088 0 1017 1001 959 921 823 0 195.84 85 05-16-2021 12:58:50 2 2294 2277 2230 2187 0 0 993 978 938 902 0 0 193.54 85 05-16-2021 12:59:36 3 2310 2294 2247 2204 0 0 1007 992 952 916 0 0 194.99 85 05-16-2021 13:00:23

I wonder how this turned out? I may have missed it, but do we know that the load he was using was actually capable of cycling the gun with a rifle length gas port?

Yeah, I looked it up. Like I wrote I kept my .50 simple.

Interesting. I kept it simple with .50 Beowulf and in an AR15.

I appreciate that. Yes, I'll use those powders with 125gr supers and with heavier bullets for subsonic loads. Looking at load data my gut tells me that the slower poders won't be suitable for an 85 grain bullet and a 10" barrel. Except for the H-110 which is WW296. I have 1680, Lil'Gun, VV n120, of course WW296, and maybe one or two others that escape me at the moment. All I need is time to get the testing phase over with. I've considered going to fast pistol powder for the 85s but I have no data and don't want to blow the gun up. But with a short barrel and a can I think the fast pistol powder might be an attractive way to go.

Yes, they will go through a can and yes they are supersonic. I have no use for subsonic 85s if it could even be done and get semi-auto action (I don't think so). I don't know if it makes a difference and I've never stressed the can at all... yet... it's a "flow through" can (my term). There's no back pressure involved with it. Maybe it'll work differently? IDK. I'm playing with it but I appreciate the heads up. Something for me to look out for. I'll find out if my handguard does what I want it to if the can does get real hot. The can is an Amtac 7.62 CQB-M and not very attractive to the civilian market near as I can figure. But it has attributes that I liked. With a 10" barrel and a 10" can the overall "barrel" length is near 14". That's not exact, but close. Here's the handgun with it in place (below). also a can that gets screwed onto the end in place for comparison below that. OK, that didn't work. I'll try again. That worked. The pix are old and it's changed a bit but the barrel length hasn't, same 10.3" barrel, same foreend.

Yeah, I see that... tit for tat.

I did some fast and dirty load development this past w/e with Maker 85 Trex and WW296. I saw a plateau around 19.6gr 296 where adding more powder didn't give more velocity (2400ish fps). But my data was quick and dirty. I hope to get to the range this w/e to generate real data and shoot for accuracy. I might also try Lil'Gun since it's a bit faster than 296. It might work better in my 10.3" barrel. We'll see if I pursue that. I'll come back to this after I have more data to add.

Thanks for the welcome folks. I see the same "verbal grab ass" is in effect here as at Full30. I'll take part here same as I do at Full30, that is to to say I won't. As I previously wrote, lot's of "faces" that I already know.

Lots of "faces" that I already know. Thanks gents.

makes sense. It also works the way I added to the post. Just not as pretty as I would have liked. It would have been worse if there were posts between and I probably wouldn't have bothered.

Thanks. So far I like it a lot, for all the reasons everyone here owning one can also give. I just started handloading for it. My first bullet is the Maker 85 and I'll shoot a bunch of loads this weekend to get some data. I'm looking for 2400ish fps. I'm looking at it for a relatively short range round so I'm not going to go crazy trying for MOA accuracy (that bullet only). (editing) Well that sux. That's the reason we have gun control. I never thought I'd see that reasoning used on a gun forum. (One can't handle it so the rest of you can't either.) Whatever.

Hi Ladies and Gents, as the subject suggests I'm new to this forum. Not at all new to firearms and shooting. Why am I here? I have a 300BLK handgun and I'll be able to give and take. I've been handloading for the past 50+ years for both production and wildcat cartridges. I enjoy spending time shooting competition (USPSA PCC and Steel Challenge RFRO). Is it possible to spend too much time shooting? If so, maybe that would be me. Shooting is what I do.

Hmm, couldn't edit it again to add this much older photo of the above. Here it is more "normal looking with a Dead Air Ghost on the end of the barrel. It can only be used for subsonic rounds. It's also wearing a much heavier arm brace. Weight is why the Blade brace is on it today.

An up to date photo. The pic on Full30 was an older one, the sight has changed. The 10.3" barrel terminates inside the CF handguard so it must always wear a can or blast forwarder. Here it is with a blast forwarder in place because I was shooting some experimental rounds and until I know that they are stable they won't go through my can. The can is and Amtac 7.62 CQB-M, Since it's an over the barrel can it's mostly hidden by the handguard, just a hair more shows than the blast forwarder seen here. Here it is with the can in place (old photo)