20 cal twist rate/bullet?

[Sniper338]

Ive decided to build a 20 cal AR upper...

Not many choices, 20 practical or 20 tactical... i doubt a vartarg would run through an AR magazine Ha! So it will probably be a 20 tactical.

What twist rate? 12?

I want small and fast! 32 gr vmax or 35gr berger?

I want to make small creatures explode... like dynomite in a crows a**....

 

[Wirelessguy2005]

I would go with an 11 twist, just in case you ever decide to run heavier bullets

 

[Sniper338]

I would go with an 11 twist, just in case you ever decide to run heavier bullets

Na... i wont run heavier bullets... ill build a bolt gun later this year in 20 vartarg and 300 blk switch barrel.. ill build the vartarg for 39 to 45 gr bullets...

I want this AR to scream fps accuratly...

 

[Wirelessguy2005]

You won't see any velocity difference between a 12 and an 11 twist.

 

[Sniper338]

You won't see any velocity difference between a 12 and an 11 twist.

Not velocity, but will an 11 twist stablize a 32gr vmax is the question...

 

[SS427]

For a 20 VarTarg using the same two bullets I went with 12 twist and have no regrets. I would do it again. But if you ever plan to run 39 or 40 grain bullets, for sure go to 11 or even 10 twist. Lots of people say the 39 grain Sierra's will shoot just fine in a 12, but I wouldn't chance it if that was my primary bullet I wanted to shoot.

You are going to love the 20 caliber. I'm not a big AR fan, but am thinking about one, and if I do it will be a 20 Practical, not .223.

 

[Sniper338]

Everything on the 6br site says 12 twist...

 

[Wirelessguy2005]

An 11 will work with 32's just fine, I run my 20SCC with 32 grain bullets going 4,100 fps plus thru an 11 twist.

Not velocity, but will an 11 twist stablize a 32gr vmax is the question...

 

[Phil]

No problems going with the 11..........

 

[GrocMax]

Go with an 11tw, don't discount using the 39-40's, 20P you'll hit 3700 easy with a 20" barrel, faster if you try. For a cheap plinking bullet use the 34g HPFB VNE/Dogtown, 4100+, and blow up small critters good. The 32g tipped bullets cost twice as much or more than the 34g VNE/Dogtown, and don't work any better at short range.

 

[SS427]

The logic for using a 12 is the potential accuracy edge. Same reason everyone uses a 13.5 or 14 twist with the PPC. Right on the edge of stability is suppose to yield best accuracy with 65 to 68 grain bullets used in competition. I really doubt you will see an accuracy difference with an AR between the 11 and 12 twist though.

On the other hand a faster twist should yield more of an explosion, which you are after.

Get some 32 Grain Z-max bullets. Cheap at less than $60 per 500, and very accurate. I'm hoping if more people keep buying these bullets, Hornaday will keep making them.

 

[L.Sherm]

Go 11 you won't regret it!

 

[1raggedhole]

I have WOA upper in 204 Ruger with a 10 twist (which I believe is a pac nor blank). Shoots 32 gr vmax or 32 Blitkings into tiny groups with H322.

 

[JLT]

Sniper, if you're going to feed it a steady diet of 32s and 35s, the twist rate question is not critical. Either twist rate will give you good results with bullets in this range. I have an 11 twist barrel that shoots the 32 grain V/ZMax bullets as well as the 39 gr Blitzkings.

You're going to love that .20 upper. The .20 Practical or the .20 Tactical are stomp-down brilliant varminters in the AR platform.

 

[sundance]

I called Krieger to order a new HV 20 caliber barrel yesterday. I spoke to Shay ? there and asked him what twist I need to run 32 gr vmax and 35 gr Bergers in a tac 20 barrel. He recommended a 12 twist for those 2 bullet weights. He did recommend an 11 twist if I wanted to run 40 grainers but I like the splat factor of those 32 grainers in my 204 12 twist. I ordered the 12 twist barrel - 4 month wait. He did say he had complete MTU contours available now in 12 twist.
Call whoever is going to build your barrel and ask them for advice. Let us know what you decide on and why they recommend that twist. I have been stuck on Kriegers since around 2000 and always got a shooter.

 

[TAJ45]

The diff twixt an 11 and 12 tw re accuracy will be in the .050" range at 100 imo. You want SPLAT, KABLOOIE and lotsa MIST? Well the Eleven is mo betta. Yes, with 32's and 35s, no stability issues but never say never to OPTIONS in life. You won't lose meaningful velocity as according to Brian Litz.

 

[wholman]

11T

 

[TAJ45]

The logic for using a 12 is the potential accuracy edge. Same reason everyone uses a 13.5 or 14 twist with the PPC. Right on the edge of stability is suppose to yield best accuracy with 65 to 68 grain bullets used in competition. I really doubt you will see an accuracy difference with an AR between the 11 and 12 twist though.

On the other hand a faster twist should yield more of an explosion, which you are after.

Intelligent answer, that.

OP wants the accuracy edge so is looking at .050" or so to gain on tw rate. However, how much is being given away with an AR trigger, probably in double figure ounces - at best. Round forearm? Weight? The baby is being tossed out with the bath on this.
Kinda like cc'ing the heads when the carb is 100 cfm less than needed. As stated above, the RPMs gained will yield more red mist, in line with your blow'em half again in two desires.

 

[Hotshot]

I have had dozens of 20's since 2004. Go 11 twist for all the reasons Wirelessguy gave you. Never say never about 40 grain bullets and think of possible resale. I would not buy an expensive barrel that was 12

 

[Ledd Slinger]

Only varmint rifles ive ever owned have ALL been various 20 cals. First one was when the 204 Ruger hit the market. So I've had plenty of 12" twist barrels in 20 VT, 204R, 20 K-Hornet, 20 TAC.

Now that barrel makers have caught up to the 20 cal craze, I've moved on to 11" twist barrels. Trust me when I say there is NO sacrifice in accuracy using the lighter bullets in a slightly faster twist. No sense in having a 12 twist, they'll barely stabilize a 40gr bullet. 11 twist opens the doors to a wider range of bullets and keeps top notch accuracy across the board.

I built an AR upper in 20 tactical with a 20" bull barrel, .936" gas block, 3 groove 1 in 11" twist.
Pushes my 34gr HP bullets very fast and accurately. Easily puts 5 rounds in a row under 1/2" at 100 yards.