6x45 upper

[Moleman-]

For some reason since 6x45 is a wildcat the PSI limit is similar to the 55K limit of the 223 Rem SAAMI. If you're compairing 223 62K psi limit loads to 55K psi limit loads for the 6x45 then yes some of the 223 loads can beat it. Apples to apples, the 6x45 will beat the 223. At 58K psi a Hornady 70gr SP will go 3,116 fps and have 1509 ftlbs out of a 20" barrel. If you really wanted something neat look at a dasher or 6mm brx. Only reason I don't have one of those last two is I can't deer hunt with them locally.

[Lloyd Smale]

that's about like saying if the 3030 is enough why isn't the 30 carbine. You have to draw the line somewhere. 200 fps difference between a 300 H&H and a 300 wby mag isn't game changing because both are pretty much overpowered for taking game in the US. When you talk the same 20O fps between a 762x39 and a 30 blackout it means a lot more. then factor in that I'm looking at doing it in a 10.5 inch barrel that's going to loose another 200 fps or more because of length then no it is not close enough. I think it fools some because its a bottle neck rifle round. Put 125s in it and push them to max velocitys out of a 10 inch barrel and your probably looking at 1900 fps or less. Like ive said not quite the same level as a 30 carbine. Or a 357 lever gun shooting 125s and even that has the advantage of a bigger bullet. Hardly a powerhouse deer rifle and adding 200 fps to it puts it in a different league in my opinion. I guess my question is why did they go with the shorter case. Other then less powder space to make sub sonic loads work better a full length 223 necked to 30 cal would be a much better round and a lot less work to deal with and would be able to run right on the heals of a 762x39. I guess that's the deal with the blackout. Like the 30 carbine it was never intended as a hunting round. It was more of a military application for a quiet suppressed AR and not much does that any better.

If the 7.62x39 was near ideal, isn’t the .300 BO close enough?

[dverna]

Lloyd I did not realize there was a 200 fps difference between the .300 BO and 7.62x39 out of a 10" barrel. The data I have shows them near equal but that is based on rifle barrels.

[adcoch1]

The 30-223 is a full 45 mm long case with a 30 cal bullet, and can easily run with factory 7.62x39, but it won't fit in an ar 15 mag with a long bullet. The 300 blk is specifically designed to run in the ar15 mag. It is a fun cartridge, but it doesnt really compare to 7.62x39, they are in different classes. The comment about pressure comparison between 223 loads and 6x45 is dead on. Running the pressure at similar levels, you really see a performance jump on deer with the 6mm bullet. At least the two deer I've seen shot with them. DRT on both. Pretty nice. I want one myself.

[Lloyd Smale]

just wish adcoch1 that someone made an inexpensive complete pistol upper in 6x45. Only inexpensive ready to go ones are 5.56, 300bo and 762x39. 6x45 and 6.8s just aren't there. The 762x39 comes closest but after the nightmare I had with my bushmaster 762x39 rifle I'm a bit leery of AR's chambered in it. An AR and a chambering can be made to make a lot of sense on paper but NO AR is staying in my house that doesn't run reliably.