450Bushmaster.net

I've really been enjoying my 450 , and I've been considering a 2nd upper for the off season. I thought a 223 would be great b/c it would offer an affordable plinking round, as well as good varmint/long range potential. It would seem a .223 should fit the bill. Then I uncover that if I buy a 5.56(higher pressure), it will shoot .223 as well as 5.56, but not the other way around. through more hours wasted I determine certain manufacturers chamber in 5.56 only, and others in .223 only. Then you look at ammo, and most of it is labeled as .223/5.56? Anybody have any suggested links on where to find facts on this, or suggestions based on real experience?

You are correct 5.56 can shoot .223 but not the other way around..

I believe most major mfg's (bushmaster, rra, colt, dpms) only chamber for 5.56.. There are a few companies that chamber in other calibers though..

You may even want to consider a 7.62x39 (russian 308 - same as AK) - ammo is very cheap compared to 5.56 and it can be used for varminting I believe..

Even cheaper than 5.56/223/7.72x39 to shoot would be a .22 dedicated upper (since a conversion wont shoot very well out of a .45 barrel LOL)..

good luck

brian

Also dont forget if you want to shoot the 77-grain Black Hills Mk 262 Mod 1 Open Tip Match ammunition you should have a
1-7 twist to stabalize those bad boys properly. I have been using a 1-9 twist with 55 and 62 grainers.

I've had real good success with both the Nosler 77 grainers and the SMK 77's out of my 1-8 twist as well.
BD

So how does the 1-8 do for the lower grainers?

The lightest bullets I use are the Hornady 55 grain Vmax. They do just fine.
BD

I love to usse the Varmint grenades so I am keeping the 1-9 but intend to put an 14.5" 1-7 barrel on my extra stripped upper when I build it. I have heard a few people say they were throwing the 77 grainers through their 1-9 with only occasional tumble but that is forum conversations so take it as a grain of salt.

I just built a .223 with a 20" SS DPMS in 1-8" twist, pre-ban. I also installed the standard A-2 forearm on it so it looks more like a mil-spec rifle. What a shooter!!! The cheapest UMC ammo gave me 2" group with 15 out of 20 shots (5 were flyers) at 100 yards using open sites. WOW. I could not believe my eyes.
I bought a bunch of 55 gr. bullets, but I am planning also to use the heavier stuff to see how it shoots.