AR upper Pin carbine build 45/450 bushmaster/ 350 Legend

[Joe4d]

Talking bowling pin carbine division here. 5 pins front of table at 30 feet... Straight wall cartridge only.
Been wanting to get into this division, and  with the 45 guys it seems like whoever can get through 4 runs without a malfunction wins. A couple folks shoot 9mm, but they really dont do well. Knock over alot of pins vs clearing them.

Really considering a 350 legend or 450 bushmaster. As I have a standard AR lower in 300AAC, I could pretty much just mailorder a complete upper. 
Anyone worked with these ?  

Coated bullets, how will these work in an AR gas system ?

Could I get the 450 to run with downloaded ammo ? or would gas be insufficient even with lighter spring and buffer?

350 looks good but I think Winchester screwed up on bore and chamber dimensions. may be an issue with bullets.

[pcschwenke]

To be perfectly honest, the .45ACP would be what I’d use.  Factory ball ammo would work, but 255gr SWC loaded around 850fps work best in 1911 pistols.  The trick is to get them to feed.   Maybe 250gr round nose flat points would be better in the carbine.  The 9mm won’t consistently take pins off the table.  The other rounds you mention would recoil too much to be competitive.  

[Joe4d]

the 45's dont run and I would need alot more parts and a trip to an FFL,

350 or 450 would recoil as much or as little as I wanted them too assuming I could get reduced loads to run, was really looking for info on loading these for an AR and if coated bullets would work in an AR or clog it up

[SteelCityShooter]

The 350 is basically a hot 9mm using a similar bullet diameter and weight.  How about a 38 Super Comp or even a 40 S&W or 10mm?

[gerritm]

Have you talked to Tim @ Taccom? He has been running a .45 reliably. Has a super feed ULW barrel. Not sure what all his setup is, but it I know his stuff works.

 

gerritm

[pcschwenke]

Hot .40s running heavy bullets work fine, so do 10mm with heavies.  

[Joe4d]

9 hours ago, SteelCityShooter said:

The 350 is basically a hot 9mm using a similar bullet diameter and weight.  How about a 38 Super Comp or even a 40 S&W or 10mm?

 rifling is set up for much heavier bullets. And not looking for caliber lists. 

Back to the topic, Coated  truncated cone style bullets in a gas AR ? and can I run a light buffer and spring to make up for less gas in reduced rounds. Kinda concerned if I got the ejection right I wouldnt have enough  spring to get the chambering right.

[TRUBL]

my 45 barrels.......just run, run, run. I've only been using Ball ammo......but pretty much  have had zero issues for the past two summers. I've only had two issues......had a blown aluminum case (don't use aluminum anymore) and I've had springs wearing out prematurely. but not since going to the the dreaded ETS mags.....and that is really only half true, I don't really use ETS mags, just the springs in my SRM magazines. I've had zero issues with glock factory mags.

[AHI]

Will the match director allow 350/450 caliber? They are considered rifle calibers.

Coated bullets are working in 300BO with no issues. What weight bullet do you thank

you can use in the 350?

If your 350 barrel has a pistol length gas system . A ultra light bolt carrier. Extremely light

buffer(cut down) spring. In theory it should run.

Have yet to see a 45 acp that did not run 100%. Just saying. 

Edited October 8, 2020 by AHI

[Joe4d]

Well I have yet to see one that has, plus for me 350 or 450  will do other things.

Mainly just wanted to know if the hardcast truncated come style bullets would feed in an ar, I have seen them loaded in 300 AAC, but no idea if they were used in a bolt gun or AR.

350 legend ammo is available in 255 gr,, seems I saw coated cast flat nose 220's.  For these I would probably run them at factory level,, 900-1000 fps.

I think the specs on the 350 are kinda bouncing around at the moment. 

[AHI]

If I may ask were are you going to get coated bullets heaver than 160gr in 35 caliber?

Or are you going to make them your self?

[Joe4d]

good point , I see plenty of 200+ grs for the 300 AAC,  figured 350 would come along as well, looking like 450 BM may be a better project. More I read about the 350 less I am likeing it. Seems winchester really messed up alot of things. Not to mentiom the very states it was meant to be used in it isnt legal for hunting in its current form. Cant come out with the correct ammo, as their are guns out there already said ammo wont work in. DOnt see it sticking around for long.

[TRUBL]

458 SOCOM......nuff said

[Norther]

.45 ACP won’t run in a standard lower, which I think is what the OP is looking for. And .458 isn’t a straight wall cartridge, also required. Although I agree, for other things it is far preferable to the .450. 

[Norther]

A lot of people run coated bullets in subsonic .300 BO, so I doubt they clog the gas system too quickly. And I’ve never had any trouble running some pretty blunt shapes in my .458 Socom.  You’ll just have to give it a try!

[Joe4d]

Thanks thats what I was wondering about , see the 300 bullets but wasnt sure if they were bolt gun only bullets.