Need opinions on twist rate for heavy .224 bullets

[Rifleshooter308]

Looking to buy a long range barrel for my next build. I want to shoot the 80g A-Max at 1.06" long seated to 2.40. I am torn between the McGowen 26" 1:8 Wylde chamber or the 1:7 .223 chamber. I know the 1:7 will certainly stabilize the uber long 80 Hornady bullet but I'm not sure if the .223 reamer used will allow the higher pressure loading the 80 to 2800FPS I'm looking for. I know the Wilde chamber will but will 1:8 spin the 80 sufficiently. I emailed MCGowen and they don't know or have any experience with this bullet at all.

[bootsmcguire]

What does Hornady recommend?

I am thinking that 1-8" will work but I can't remember for sure. Call Hornady customer service, when I have called they have been very helpful.

[BoilerUP]

1:7 will provide ample stability margin with the 80 Amax in cold temps/low DAs. 1:8 will work, but gets pretty marginal with that bullet near sea level & freezing temps.

I run a 1:7 22" 223AI with the 80 Amax and loooooove it.

[dcloco]

Boots & BoilerUP have it right.

I run a 222 Magnum AI with a 1:8 twist, but is 28" long. Definitely stablizes the 80 gr AMax rather well.

[MrMajestic]

26" 8tw chambered in .223 Ackley Improved loves the 80 grain A-Max! Woodchucks hate it with my longest at 403 yards for the season. The Criterion tube screwed on a non-designated action stuffed in a HS Precision stock with a 24X Leupold on top seems almost like cheating!

[Texas Solo]

I run a Shilen 28" 1/7 Wylde. It shoots 80gr Bergers sub MOA @ 500yds. 24.5gr of Varget gets me going 3020fps. yeah it's a tad hot, but my barrel loves it.

FWIW...I recently contacted McGowen asking if their 1/8 .223 Wylde bull barrel could be ordered in 1/7. Here's their response:


"This barrel can be purchased as a 7 twist from the Montana Plant.
Give Dan a call and he will be glad to help you."
Thank you,Dennis

Montana’s phone number,

McGowen Precision Barrels, LLC
4051 Hwy 93 South
Kalispell, MT 59901

Phone: 406-755-4907

[darkker]

Run the stability calculation yourself...
http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

[granite1]

I wonder if you are going to have a problem with that OAL. seems a little short for an 80gr bullet.

[Rifleshooter308]

Thanks for the help guys. I think I'm going to roll with the 1:8 Wylde because they have them in stock ready to ship. I don't want to wait for one custom made. I have boat loads of 77g SMK which I know will shoot well out of the 1:8 if for some reason it does not like the 75 or 80 Amax.

Granite I would hope to load them longer depending on the chamber. The reason I stated 2.40 was that the recommended minimum from Hornady is 2.390. I'll measure the chamber then load them to within a smidge of the lands depending on where it likes it.

[granite1]

roger.

[eddiesindian]

I think you,ll be ok. seeing as how texas solo is only 2" longer on the tube and speeds are @ 3K. having alonger tube sure does have its advantages.
whats your elevation?

[Rifleshooter308]

Well it appears my 1:9 twist Savage Varmint barrel stabilizes the 80g A-Max quite well. This barrel started out as a 26" Stock Varmint. I cut 2" off it and recrowned it with an EGW crown tool. The load is 25g of Alliant Power Pro 2000MR under the 80g A-Max seated to 2.45 in Lake City cases and a Wolf Magnum 5.56 primer. Chrono showed 2680 FPS. The first four where beautiful until I pulled the 5th.

[eddiesindian]

Well it appears my 1:9 twist Savage Varmint barrel stabilizes the 80g A-Max quite well. This barrel started out as a 26" Stock Varmint. I cut 2" off it and recrowned it with an EGW crown tool. The load is 25g of Alliant Power Pro 2000MR under the 80g A-Max seated to 2.45 in Lake City cases and a Wolf Magnum 5.56 primer. Chrono showed 2680 FPS. The first four where beautiful until I pulled the 5th.

how cool is that a?
After my ladder test on the 80,s I found 2650 speeds to be more promising.
congrates....great shooting! and thanks for the info

[GaCop]

I'm using a 1 in 8 twist, heavy varmint Sinarms barrel, 28". It handles the 80gr VLD's very well.