Spin rate ??

squid20

squid20

Member
What do most of you look at for best terminal expansion on a given bullet. I know all bullets will do the job, but has anyone seen a given bullet work better at a given spin rate or do poorly with to much spin ?
 
I don't know if it was due to spin rate or velocity and/or the RPMs due to that velocity but I've see a lightly constructed SX (Super Explosive) 50 gr bullet out of a 22-250 disintegrate in mid air. I could see grey streaking while spotting for a friend shooting at a coyote and missing several times. The bullets were coming apart and veering off target. I'd call that poor performance
 
squid20 said:
What do most of you look at for best terminal expansion on a given bullet. I know all bullets will do the job, but has anyone seen a given bullet work better at a given spin rate or do poorly with to much spin ?
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I don't even run the ragged edge for RPM's on my BT's/Varm. jacketed bullets, and the highest Vel. I run on one rifle is 3150 Vel, @ around 21-k RPM spin on some vmax's .
Me.. I concentrate more, look to see the ' minimum ' Vel. for expansion ' that the Manufacturer recommends for the bullet I using . Then double-check my ballistics/Velocity that the bullets is 'loosing' moving down-range with my holdovers . So I dont get even close to the Minimum factory recommended Velocity for good expansion for wound channel.

what ( txccoondog ) say's.. I use that 'simple mans ' RPM formula a lot when working up a new bullet load. I don't ever want to go close to or above 300-k rpm, especially when using muzzle suppressor, using jacketed bullets .
.
 
IndexFinger said:
I don't even run the ragged edge for RPM's on my BT's/Varm. jacketed bullets, and the highest Vel. I run on one rifle is 3150 Vel, @ around 21-k RPM spin on some vmax's .
Me.. I concentrate more, look to see the ' minimum ' Vel. for expansion ' that the Manufacturer recommends for the bullet I using . Then double-check my ballistics/Velocity that the bullets is 'loosing' moving down-range with my holdovers . So I dont get even close to the Minimum factory recommended Velocity for good expansion for wound channel.

what ( txccoondog ) say's.. I use that 'simple mans ' RPM formula a lot when working up a new bullet load. I don't ever want to go close to or above 300-k rpm, especially when using muzzle suppressor, using jacketed bullets .
.
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Have you seen any difference in under 300k vs over 300k in performance.
 
This never used to be something that most people even thought about, but as the science has progressed in recent years I'm seeing more and more mention of this. Some of the monolithic bullets rely on faster twist rates to help reliable opening, meanwhile some of the old varmint bullets that were used with 14 twists will not hold up to fast speeds + fast twists and can lead to disintegration and splashes.

I'm not really up on it 100%, but I believe that is why the 8.6 blackout uses a 1-3 twist, to ensure reliable expansion at subsonic speeds.

If you give a specific example of what your looking at, someone will probably have some experience with it.
 
so im shooting 243 with 65gr vmax @ 3500 fps with a 9T is @ 280k spin. Just built a bolt rig with 87gr vmax @ 3300 with 7.5T @ 316K spin. Iv been hunting wiht the 65gr setup for last 2yrs, no complaints with it other than shoulder shots just blow up and usually have to have another shot. Still waiting on my other can for the bolt rig before i put it to use hunting. Just never read actual spin numbers from anyone or manufacturer.
 
Usually spin numbers are addressed by barrel twist rate MINIMUMS by bullet manufacturers. Long/heavy for caliber bullets require FASTER spin(twist rates). As monolithic and high BC bullets and their use becomes popular, matching barrel twist rates to bullet stability(spin rate) requirements is critical. Under spin a bullet results in poor accuracy and keyholing, over spin and in extreme cases(conditions) bullet jacket damage is possible.
 
Hellgate said:
I don't know if it was due to spin rate or velocity and/or the RPMs due to that velocity but I've see a lightly constructed SX (Super Explosive) 50 gr bullet out of a 22-250 disintegrate in mid air. I could see grey streaking while spotting for a friend shooting at a coyote and missing several times. The bullets were coming apart and veering off target. I'd call that poor performance
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Hornady SX bullets used to come with a disclaimer in the box that stated they were designed to work with .222 velocities. Them coming apart with higher velocities than they were designed for isn’t poor performance.
 
I have run the Hornady 50 gr SX at 255,000 rpm(1 in 9 twist) and 288,000 (1 in 8 twist) AR barrels. The bullets shoot very accurately and perform well on coyote and smaller critters. No exits even on raccoon, until shots get past 200 yards. The 18-20" barrels are 3150-3200 fps at the muzzle. Definitely much higher spin rates than a 222 Rem which have much slower twist barrels(1 in 14+).
 
Running at the upper edge of RPM can turn to disaster when the barrel gets long in the tooth with their accompanying rough bore.
 
I have seen a difference with 50 gr vmax in a 7 twist and say a 12 or 14 twist when shooting ghogs. This is with a 223 and velocity around 3200-3400. I feel that the spin rate is why some guys have good or bad luck with a bullet and others have the opposite.
 
why said:
I have seen a difference with 50 gr vmax in a 7 twist and say a 12 or 14 twist when shooting ghogs. This is with a 223 and velocity around 3200-3400. I feel that the spin rate is why some guys have good or bad luck with a bullet and others have the opposite.
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That’s my thoughts, has anyone or manufacturer figured out on optimal spin rate or window even that they are most effective on expansion but not blowing apart hitting a small obstruction
 
What I do know is when talking to people at a couple of manufacturers I was told that they don't recommend target bullets for hunting simply because they don't test them for hunting, although they may work very well. If you want to use them you must do your own testing.
 
All varmint bullets will fragment that's what they are designed to do, could be hair/skin/flesh or sticks,grass, ice,snow. At a wide range of velocities. Spinning them very fast will enhance the deconstruction of the bullet.
 
spotstalkshoot said:
All varmint bullets will fragment that's what they are designed to do, could be hair/skin/flesh or sticks,grass, ice,snow. At a wide range of velocities. Spinning them very fast will enhance the deconstruction of the bullet.
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But at what point to they come apart un naturally or splash in mid air. I’m sure every bullet has different limits, just tryin to see if someone knows what to much is by just spin rate
 
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