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Posted: 11/16/2008 3:13:09 AM EDT
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Sorry if this has been discussed before, but I could not find what I need with the search function.
I am planning on building a 24" varmiter upper and need to decide on the barrel twist rate. I am not familiar with 1-14 rate and need to know what are the advantages and dis-advantages of this vs. 1-7 or 1-8 or 1-9 twist for a varmiter rifle. Thanks for your input. |
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My only experience varmint hunting was with my M700 VS in .223. The barrel twist rate was 1 turn in 12 inches and it was very accurate with 45 grn. bullet reloads.
My buddy had a Rem. M700 in .222 with a twist rate of 1 turn in 14" and he used 50 grn. factory ammo and it was very accurate. I never experimented with bullets heavier that 55 grns. but my rifle was accurate with those. I've read some folks claims that the really fast twist rates (1 in 7, 1 in 8) will result in worse accuracy with the light bullets, but I've not tested that myself. I guess the size of the "varmint" you expect to hunt will determine the bullet weight you expect to use. |
| With a 1-7 or a 1-9, it is incorrect that you will experience worse accuracy with lighter bullet weights. No such thing as overstabilizing. However, some of the lighter varmint rounds....like 30 something grains, can actually spin apart in 1-7 twist barrels. That is due to thin jacketing and cavernous hollowpoints. A lot of folks like using the faster twist barrels because it will stabilize heavier rounds... like 75gr and above. This allows added accuracy and terminal ballistics at longer distances. I personally have two varmint rifles, a 1-9 twist and a 1-7 twist. I like taking long shots for the challenge. I shoot 60-69 grain from the 1-9 and 69 to 77gr in the 1-7. I could shoot lighter, but prefer to "buck" the wind more effectively. The ammo oracle also has some good info |
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I have a RRA 20" Varmint A4 with a 1-8 twist. It shoots 53 & 55 gr bullets VERY well, but it LOVES the 77 gr bullets for the best accuracy. I think it would depend on what you are going to shoot and from how far away. If you want to go 200 yards and out - I would go with the 1-8 for the heavier bullets and superioir accuracy they provide. |
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http://www.superiorbarrels.com/FAQs.htm#With%20all%20other%20things%20equal,%20will%20a%201:7%20twist%20be%20less%20accurate%20than%20a%201:8%20twist.
"Q.) With all other things equal, will a 1:7 twist be less accurate than a 1:8 twist. A.) "The theory is you don't want to spin a bullet any faster than necessary as it obviously spins up the RPMs. Any irregularity like off center core or jackets not being concentric will show up more pronounced as it is spun faster. All 308 bench rest rifles were 14 twist shooting 168s. The 308 BR game is shot with 14, 15 and 16 twist barrels these days. Winchester 70 Palma rifles were 12 twist shooting 190s in 308 to 1000 yards. Faster twist rates also put wear on the lead edge of the rifling which is what it did in APG testing (Aberdeen Proving Ground). It sheared off the lead edge of the rifling." Mark Humpreville, Palma Individual Trophy, 1985 and 1986, Centenary Trophy, 1885, National Championship 4 Man Team Smallbore (Blackhawk Rifle Club)" Very light bullets will come apart in a 1:7. http://www.youtube.com/watch?v=GTJaNHjEa_k |
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