Modern Sporter - Build Discussions

[welkie3]

thank you sirs, dont know much about AR 15 or AR 10 style firearms

[greg olmstead]

You want a 223 wssm if you want that kind of performance in a AR15 length action.

The 223 wssm is way to big around to even try and fit in a small frame like the sporter. The fastest 22 cal round you can cram into the sporter would be the 22 grendel or 22 valkyrie. The 22 grendel is the faster of the 2

[lj007]

Thinking of doing 7.62x39. Is it really finicky? I need to pay for assembly. And I’m not that patient. Anything I should do to avoid having to debug and raise the probability of working first try? TNA or MRA bolt/barrel combo most likely since price is nice there and I can splurge on a trigger then.

[jiffx2781]

...

[ColinD]

there's lots of info about the 7.62x39 not being a very reliable cartage for the AR pattern design.

If you wanted something similar (arguably) I'd look into 300BLK. MRA has barrels on sale, and it uses the same bolt as .223

[rommelrommel]

The 223 wssm is way to big around to even try and fit in a small frame like the sporter. The fastest 22 cal round you can cram into the sporter would be the 22 grendel or 22 valkyrie. The 22 grendel is the faster of the 2

Olympic arms has been putting 223wssm in AR15’s for over a decade. Jard and Dtech also do it. With the 50 Beowulf sized ejection port I think it’s possible in a sporter, although I’m not exactly sure if they use modified uppers.

[greg olmstead]

Olympic arms has been putting 223wssm in AR15’s for over a decade. Jard and Dtech also do it. With the 50 Beowulf sized ejection port I think it’s possible in a sporter, although I’m not exactly sure if they use modified uppers.

Its impossible to use a standard ar15 barrel extension and bolt for the 223 wssm. The bolt would have no material between the bolt face and lug. Dtech is using what seems to be a modified ar10 bolt which requires a custom barrel extension and a proprietary upper receiver. There would be next to nothing for material in the barrel extension if you made it fit a standard ar15 and with the pressures the wssm cases run you would be shearing lugs off left right and center.

Is there an upper out there in 223 wssm that fits a standard ar15 lower? Yes there is. Can the parts be swapped to the modern sporter? No they cant. The fastest 22 caliber cartridge that will fit in the modern sporter is the 22 grendel. Which gives up very little to a 22-250 as is and it burns less powder. The 223 wssm is also a lot longer than the 22 grendel.

From what I've read is that they use an ar10 sized barrel extension and an ar15 upper that is the same size as the ar10 where the barrel goes. So in conclusion no you can not shoot 223 wssm out of a modern sporter. Well you could but just once

[purplezuk]

Thinking of doing 7.62x39. Is it really finicky? I need to pay for assembly. And I’m not that patient. Anything I should do to avoid having to debug and raise the probability of working first try? TNA or MRA bolt/barrel combo most likely since price is nice there and I can splurge on a trigger then.

I would definitely avoid all TNA branded parts. They are the lowest grade Chinesium and cause more issues than they are worth.

[rommelrommel]

Its impossible to use a standard ar15 barrel extension and bolt for the 223 wssm. The bolt would have no material between the bolt face and lug. Dtech is using what seems to be a modified ar10 bolt which requires a custom barrel extension and a proprietary upper receiver. There would be next to nothing for material in the barrel extension if you made it fit a standard ar15 and with the pressures the wssm cases run you would be shearing lugs off left right and center.

Is there an upper out there in 223 wssm that fits a standard ar15 lower? Yes there is. Can the parts be swapped to the modern sporter? No they cant. The fastest 22 caliber cartridge that will fit in the modern sporter is the 22 grendel. Which gives up very little to a 22-250 as is and it burns less powder. The 223 wssm is also a lot longer than the 22 grendel.

From what I've read is that they use an ar10 sized barrel extension and an ar15 upper that is the same size as the ar10 where the barrel goes. So in conclusion no you can not shoot 223 wssm out of a modern sporter. Well you could but just once

Bummer but thanks for the good explanation of what they do to make it work.

I want to do something different with my second upper... 30 ar is impossible to get a barrel and bolt for any more. I don’t really want to make brass.

Maybe 7mm Valkyrie if they get the Starline brass going.

[lj007]

I would definitely avoid all TNA branded parts. They are the lowest grade Chinesium and cause more issues than they are worth.

Is MRA bad?