I've often heard about twist rate being too slow for heavy projectiles, but what about too fast for light projectiles? I'm thinking .308 16.5 inch barrel with 1:8 twist and 125gr projectiles? Cheers.
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I've often heard about twist rate being too slow for heavy projectiles, but what about too fast for light projectiles? I'm thinking .308 16.5 inch barrel with 1:8 twist and 125gr projectiles? Cheers.
Go to the extreme and bullets can blow up mid flight if they are massively over-spun.
Faster than necessary can be a bit detrimental to accuracy, on average. Bullets behave a little like car wheels - unless they're perfectly balanced around their axis, they wobble. The faster they spin, the more they wobble.
Depends on how fast you you are trying to send them, if you have gone light to achieve speed (16 inch barrel) then that could be counter intuitive. Can try but probably find best accuracy at slower speeds. But I’m bent towards the other way, heavy pill better BC slower but still perform at distant.
Iv heard from mitch maxbury that there were bullets that blew up mid flight in 308 target shooting if certian bullets were spun too fast
Its going to be interesting as 8.6blackout becomes more availble if the 1-3 twist is going to cause it with supersonic bullets
In practical terms the answer is no. I doubt if you can spin the 125 grain pills fast enough to fall to bits in your 16.5 inch barrel. There is a persistant myth that projectiles become less accurate if they are spun too fast which may have been true years ago with the poor quality projectiles available at that time but not today. Still myths die hard in the US and have been responsible for the slow twists used there right up until recently. No doubt there are limits but you are nowhere near them. Your limit on accuracy may be affected more by how far from the rifling you need to seat the projectles. Recent .308 rifles seem to have shorter throats than previously. My .308 has a long throat and shoots flat base projectiles better than boat tails due to the long throat. Forget about your barrel twist, it is a non issue.
Regards Grandpamac.
I've seen that people are suggesting sticking to bonded or monolithic bullets with that one to avoid them coming apart. Even more interesting is the insane amount of spin drift such a high twist creates. X-Ring on YT was needing to hold 2 whole mils at 700 yards with subs.Quote:
Originally Posted by Bill999
Yep, what he just said! I have seen phenomenal accuracy out of quick twist barrels using light for caliber bullets.
Main thing is bullet quality, if the bullet is made with "lesser " quality jackets (meaning bullet metals used & variation in jacket walls thickness) it creates effectively an out of balance wheel effect.
Faster it is spun the worse the wobble from the balance, just like an out of balance car wheel. Faster you drive the worse it gets.
Top quality bullets counter this problem.
Good quality bullets are fine in quick twist barrels in other words.
I agree with @TARGEX assertion fully. On Sunday 3 of his 70 grain 6mm bullets shot through a 1/8 twist formed a cluster that was barely more than a bullet diameter wide...Quote:
Originally Posted by TARGEX
The annoying thing about that is that it wasn't me driving my rifle!
slow it down and you should be ok.........
Iv got some varmit tnt bullets that specify no faster than 1-12 twist
They are super frangible so I don’t doubt they could cause problems
They went fine in my1-10 but I’m not game to try them in my 1-8
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years back I had hornady spsx 50 grn pills for my .223 they were for velocity less than 3100fps......man they were the berries on wallabies,big mess....sort of like the vmax/zmax do now.... from memory there was no twist rate mentioned back then....it just wasnt a "thing"....if you think about it,the speedsters like 22-250 had a slower twist assumably to be less hard on projectiles...so flip that on head and slowing them down in fast twist should make sence...
Just started running the 50g TNT in my 1:9 22-250. Early stages of development but min book charge and they're holding together so far, won't be looking to go full speed just incase. About 3500fps currently. Should blow some critters up
No, it's simply that at that point in history, the ballistic advantage of more slippery projectiles wasn't fully appreciated. That's why the 1-in-12tw Rem .244 was toast after the .243W with its much faster twist came out. The 6mm Rem sorted that but the damage was done. Shame as the 6Rem is a far better cartridge.Quote:
Originally Posted by Micky Duck
I remember reading about long range 2506 rifles. They were specially made with extra long throats, 1 in12 or 1 in 13 twist and 26 - 28 inch barrels. Faster speeds could be gained with a slower twist than a standard or fast twist.
Don't you just hate it when that happens?Quote:
Originally Posted by Steelisreal
GPM.
This kinda pre-dates dially scopes when if you wanted to hold fur to 400 or whatever, you needed a faster flatter shooting cartridge. Hence 270 was standardised around 130gr (which only needed a 1:10 twist) and 22-250 got a 1:12 or 1:14. 25-06 will no doubt be similar. Yeah this definitely had an added benefit of providing some insurance against bullets blowing up... but I don't think it was the primary reason.
Nowadays, to get a 270 to perform well beyond 400 out to long range like something such as a 6.5 PRC, it'd need a similar 1:8 twist and a ~165gr bullet.
The difference in pressures and speeds with something like a 55gr bullet in a 223 are pretty negligible between 1:12 and 1:7. Most bullets can hold up to some pretty extreme amounts of spin too - I've got a fast twist 22-250ai and so far no blow ups with the lightweight bullets at 4k+ and 400,000rpm either... though I'm sure it's just a matter of time as the barrel rapidly wears out :)
The standard 1:12" twist will handle bullets from 110 grain to 180 grain no real point going to a faster twist some use 1:11" barrels for 175 to 190 grain match bullets,Quote:
Originally Posted by MB
The Full bore shooters use 1:13" and 1:14" barrel goethe 155 grain match bullets they have to use,
I have a .300 BLK and three .308"s with 1:13" barrels main diet is cast bullets but they will handle 168 SMKs have some 175 SMK's to try,
You only need a 1:8 to shoot super heavy bullets subsonic.