In the airgun world can we have too fast of a twist rate for slugs? I have a TJ .25 auto barrel on order which is 1:14 twist rate. For some reason I originally thought it was 1:16. My current barrel is a TJ 1:22 twist and I am shooting slugs too fast out of it and am not fully stabilizing the slugs per the calculators. However when I put 1:14 into the same calculators I will over stabilizing the slugs. Anyone have results from over stabilizing their slugs?
Twist rate too fast
- Thread starter revenger
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Believe the target, final print on paper trumps all, seeing is truth, but knowing without seeing is faith which must be strong
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From what I’m familiar, higher/ shorter twist rate 1/14 would lend itself to shooting longer and heavier slugs. Lesser twist rate 1/22 would likely favor shorter lighter slugs. In the end , let the target paper do the talking.
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Overstabilizing on subsonic velocities aint really a thing. Never seen any proof of it. Only bad thing is little higher barrel friction. Pellets are different story tho.
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I hope you can find the slug to match your barrel. Will you be casting and sizing to .251-.251?
The 14 twist will allow you to shoot the heavier commercial 25 cal slugs like the Altaros ATP King 66gr. Might have to single load em though and these might not have a large enough diameter to work well.
From now on I'm looking to go around 900 fps for whatever slug I shoot because you don't gain any wind drift advantage by going faster than that, and save on some air, and maybe less barrel leading too.
The 900 fps thing will also help when using the 14 twist with medium heavy slugs because the chance of over spinning is lessened somewhat vs sending out at 1000+ fps which would increase spin rate.
Success is highly dependent on the tolerance of slugs to barrel. Many suggest .001" smaller bore groove than projectile for a sealed fit.
Please make a thread about your experiences later on so we can what happens.
The 14 twist will allow you to shoot the heavier commercial 25 cal slugs like the Altaros ATP King 66gr. Might have to single load em though and these might not have a large enough diameter to work well.
From now on I'm looking to go around 900 fps for whatever slug I shoot because you don't gain any wind drift advantage by going faster than that, and save on some air, and maybe less barrel leading too.
The 900 fps thing will also help when using the 14 twist with medium heavy slugs because the chance of over spinning is lessened somewhat vs sending out at 1000+ fps which would increase spin rate.
Success is highly dependent on the tolerance of slugs to barrel. Many suggest .001" smaller bore groove than projectile for a sealed fit.
Please make a thread about your experiences later on so we can what happens.
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How has your experience been with that TJ 1:22 barrel? Having one made and am getting anxious to see how it does!! Feel free to PM me so the thread doesn't get hijacked
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The barrel is good. I have it in my avenger so a different platform may perform better or worse. It seems 36-40 grain slugs it what it prefers best for accuracy. My gun can send the 40 grain slugs around 1070 so it is potentially a bit too fast. With the 46+ grain slugs I just need more twist rate it seems. But I will say that this twist rate will shoot pellets pretty dang good too if you pick the right speed. With the hammer spring and hammer weight I have in the gun now I am sending 34 grain jsb's at almost 1200 fps so that is not too friendly. Would have to change the power to shoot them. It is a great barrel though for a wide range of projectiles and I think it's good for slugs up to maybe 44 grain.
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I don't do any casting but I have a broad selection of slugs at the moment. The gun likes most anything .250 to .253.
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This is what I was wondering. Since it is subsonic.. well most slugs, then I shouldn't have too much of an issue. Plus I mainly shoot 50 yards and under in my yard so hopefully the fast twist rate will be beneficial. My goal would be to be able to shoot from 34 grain slugs up to 55 grain slugs. We shall see.
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You dont really need 1:14 for that light slugs tho. I had sumatra with 1:18 and it was shooting 50grainers well but some 50+gr BT bullets didnt have stability. 1:16 would probably be ideal for 55grainers if BT bullets will also be used. But as I said you dont really lose much by taking 1:14.
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I'm kind of just going off my recent experiences. The larger and longer slugs arent grouping quite as well. 46 grain slugs for example I can shoot about 1030. The gun will key hole boat tail slugs so I know they aren't getting stabilized. My guess is 1:18 or 1:16 would be ideal but don't think I can get that twist rate from them.
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These are my observations and your mileage may vary. Over stabilization (of slugs) will cause shots at longer ranges to strike tip up. At very long ranges the holes in the paper will likely show be oval top to bottom. Under stabilization, as you have observed results in wobble and in the end tumbling. On pellets over stabilization will result in corkscrewing. Under stabilization will show up as reduced accuracy.
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Yes, you can over stabilize a subsonic bullet. When the speed of the bullet is too slow for the spin, they spiral.
Good luck trying to make that happen. Iv seen 30grain bullet shot out from 1:7 22cal barrel at 1100fps without any problems. It just isnt factor in airguns and our speed when shooting solids.
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To my understanding yes a twist to fast could destabilize your slug..if not just as a example why the 1-14 works best for the 257 ..and the 1-10 do not .. bullets at 70gr do awesome.. but not to good with cast 85gr and up for 100y+ because the twist rate calculator tells you that the 1-10 is to fast .. so if is simply not accurate .is indeed destabilizing the bullet...so if thee bullets or slugs are going hole in hole with a twist and .all around the paper with the other..what more prove is necessary..some times a slower twist would work because you could bump the speed enough to make it work. But if the twist is to fast it will simply not work..unless you have the bullet heavy and long enough, and the power to push it.
what happens is that some people think that because they have machined one or to things, they are the law and experts in ballistics N PCPS.. and trying to learn something from their comments simply sucks..
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As a slug loses speed, the rate of twist increase because the slug remains at the same RPM, but the forward motion decreases.
Laws of physics.
Laws of physics.
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The 25 cal TJ barrel with a 1:22 twist was made to shoot the 32.80gr Wicked Monster slugs
from Rat Sniper back in the day a very long time ago it did not like to go over 1010 fps but a
speed of 1004-1007 was best and shot very well for me out to 250 yards.
from Rat Sniper back in the day a very long time ago it did not like to go over 1010 fps but a
speed of 1004-1007 was best and shot very well for me out to 250 yards.
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I agree with @SlugmasterABC , Subsonic interpretation is not available, 1:22 is a slow twist and 1:14 is a fast twist. for 25 cal slug it should ideally be 1:16 or 1:18 no more no less. The 1:18 is forgiving for it balances the friction and twist rate well.
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