204 ruger ideal length and twist for ar barrel?

[Niro]

hi all! ive been reading posts on and off for a few days trying to find an answer but nothing difinitive yet. sorry in advance if this does end up being a "clone post"

to start, i do not reload and would prefer to shoot 40 grain poly tip bullets. i do not have a need to shoot beyond 600 yards and will use this on coyotes and smaller game at comfortable ranges, mostly on fox. i intend to do a side charging upper but have been eyeing up WOA 20" with 1:10 twist. with that in mind i am wondering how much insight everyone has into barrel length and twist for an AR upper. i want to keep between 16" and 20". the shorter the better but do not want to throw lead downrange without burning all the powder before the muzzle. losing velocity with a shorter barrel doesnt bother me since the 204 is so fast anyways, but not getting the most out of the powder behind the bullet does.

i have read that at 18 and shorter muzzle blast gets pretty fierce, is this unburnt powder?

is it true the shorter you go, the faster the twist should be for heavier bullets?

how short can i effectively go before it start negatively affecting performance?

what barrel twist would be best/very well suited for the 40 grain bullets in a 16-20"? apparently there is bad luck with 1:12 twist and hornady v-max

thanks everyone in advance

[Rick in Oregon]

If it were me, I'd build it with a barrel 22" or 24" (my personal favorite), and 11-twist.

That combination will give you decent velocities without too much muzzle blast, and the ability to shoot virtually any 40gr bullet, including the 40gr V-Max.

[Bill K]

I am with Rick on that as to barrel length and twist, for what you seem too want. But remember the 39 tipped bullets, like Sierra BK's usually stabilize and are very accurate in comparison with many of the 40 grain ones. It would work for you just fine, wanting the 4- grain bullets, one grain will not be that much.
But saying that you might check out the Swap/classified section on this site. One fellow has a complete upper in 204 R with goodies for a decent price and it has a 18 inch barrel. Look it over and go from there.
And yes, the shorter the barrel, with a 204R, and many others, blast is louder and FPS drops off, on a average of 50FPS for each inch under 26 inch. Bill K

[Niro]

thanks rick and bill much appreciated

any thoughts on the 20" 1:10 being able to stabilize 39/40 grainers?

what manufacturer makes the 39's in a box of ammo? I havnt been able to find any, just the bullets themselves.

[Rick in Oregon]

Niro: The barrel length really won't have any effect on bullet stabilization, so whatever length you decide will not be a factor. I would not go any shorter than 22" for a 204R, but that's just me. The 11-twist will properly stabilize the 40's, so not sure why you'd want a ten twist.

As for loaded ammo with the 39gr SBK, I believe that HSM loads it in 204R, and maybe also Federal, but not sure as I handload for every rifle I own. A quick search should tell you what you're looking for though.

[Niro]

Rick-

I would like to go 20" just to stay a little more compact, this will be mostly for fox at 300 and closer, as I live in a heavily wooded area and often call in the timber. but I will be sure to wear my muffs at the range!

I was asking about a 1:10 simply because WOA makes a complete upper in that twist and length. can you forsee any issues with going 1:10?

ill do some more looking for the ammo, seemed the 39's are sold out everywhere I have looked ><

again, much appreciated

[Rick in Oregon]

Rick-I was asking about a 1:10 simply because WOA makes a complete upper in that twist and length. can you forsee any issues with going 1:10?

Niro, you should do just fine with that 20" AR with a ten twist. No real drawback to a faster twist, in fact the "splat factor" will increase due to the increased RPM's of the bullet. That's not a bad thing either. I'd say order that WOA upper with the ten twist and not look back.

[Niro]

alright you twisted my arm im convince thanks rick you been a huge help! cant wait to get this thing put together!