Looking to find a few bullet choices that will provide optimum stability. Rifle is 22-250 w 1:12. When I use the Berger twist calculator most of the bullets I punch in have come up with a stability factor of .9-1.2, only 1 was closed to the 1.5 target. So the question is, will quickload give me a list of bullets based with a good stability factor if I were to punch in caliber, twist, temp?
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Quickload question.
- Thread starter 1stmar
- Start date
The best groups I ever had were with 6mmBR 14" twist and 75 gr Vmax.
That is a stability of ~ 0.75 and got a 0.2 moa group.
Some groups got keyholes. It is right on the edge.
I am not saying that under stabilized bullets are good for bucking wind, but for 100 yard groups, they have the lowest run out induced error.
That is a stability of ~ 0.75 and got a 0.2 moa group.
Some groups got keyholes. It is right on the edge.
I am not saying that under stabilized bullets are good for bucking wind, but for 100 yard groups, they have the lowest run out induced error.
Thanks Clark, that was a question I had in the back of my mind... How much credence do I give. Tried a bunch of different bullets, all quality stuff from 52-60grand just not getting the results. All the bullets tried had low stability factor so thought that may be contributing.
The stability estimator at JBM and Berger both use Don Miller's method, I believe. It's a modified version of the Greenhill formula with a number of additional arguments worked in. It usually does pretty well, but for .22 caliber, for some reason, I've seen a number of folks suggest it must be underestimating, based on their experience. As an alternative, take a look at Geoffry Kolbe's calculator taken from Robert L. McCoy's McGyro program. One word of caution, though. The default densities listed often don't work out quite. You can use his drag calculator and in the right column enter densities until the weight window at the top comes up correct for your bullet, then use the density that got that number in the barrel twist calculator. The one in QuickLOAD's companion program, QuickTARGET Unlimited is likely a version of one of these. I'll have to compare results to see.
Note that if you need a more accurate number it can be done via equations in McCoy's book, Modern Exterior Ballistics or a six degree of freedom ballistics program (code for one is at the back of Harold Vaughn's book, Rifle Accuracy Facts). The problem is this requires information you won't find in a list somewhere, including each bullet's center of mass and its transverse and axial moments of inertia. It takes a bit of work to measure these things. Geoffrey Kolbe's small book, A Ballistics Handbook, has an illustrated description of how to make and calibrate and use a torsion pendulum for finding those moment of inertia values in Chapter 8.
The reason all this added information is required is that some bullets have empty space in the nose (rifle target bullets, for example) or a less dense plastic insert that affects drag at the tip, but let the center of mass, about which the bullet turns in flight, to move rearward as compared to an FMJ design. Others may have a thick copper base that puts the more dense lead core farther forward than others, moving the center of mass a little forward with it. Both things affect the net bullet density which affects those moments of inertia, which determine how much gyroscopic stiffness the bullet can develop at a given rate of spin.
Note that if you need a more accurate number it can be done via equations in McCoy's book, Modern Exterior Ballistics or a six degree of freedom ballistics program (code for one is at the back of Harold Vaughn's book, Rifle Accuracy Facts). The problem is this requires information you won't find in a list somewhere, including each bullet's center of mass and its transverse and axial moments of inertia. It takes a bit of work to measure these things. Geoffrey Kolbe's small book, A Ballistics Handbook, has an illustrated description of how to make and calibrate and use a torsion pendulum for finding those moment of inertia values in Chapter 8.
The reason all this added information is required is that some bullets have empty space in the nose (rifle target bullets, for example) or a less dense plastic insert that affects drag at the tip, but let the center of mass, about which the bullet turns in flight, to move rearward as compared to an FMJ design. Others may have a thick copper base that puts the more dense lead core farther forward than others, moving the center of mass a little forward with it. Both things affect the net bullet density which affects those moments of inertia, which determine how much gyroscopic stiffness the bullet can develop at a given rate of spin.
Thanks nick. These calculations require me to have samples of the bullets so I can perform the measurements. This is the reason I was interested in quick load, I figure if it has the database with these metrics and if I can provide some input, twist, cartridge, environmentals, I can avoid purchasing a bunch of bullets that may not work out.
1stMar,
What are you trying to do?
Optimal stability means different things at different ranges. Short range benchrest shooters want as slow a twist as they can get away with to minimize any bullet imbalance. For shooting 200 yards and under this works out really well for them.
Palma shooters want a twist that ensures bullet stability throughout 1000 yards, and twist rates are generally slower, but it depends on whether the shooter is going by US Palma or International rules as far as bullet weight goes.
The most accurate bullets you'll find for a 1:12 22 caliber barrel will likely be the 52 to 55 gr match bullets. For "longer range" shooting the Nosler 60gr ballistic tip boat tail comes out with a 1.25 stability factor, at least at reasonable velocity. I know that is slightly higher than a Sierra 155 Palma (2156) bullet being launched at 3k from a 1:14 twist 30 cal barrel.
So depending on what you want to do, really narrows down the range of bullets that people can recommend.
Jimro
What are you trying to do?
Optimal stability means different things at different ranges. Short range benchrest shooters want as slow a twist as they can get away with to minimize any bullet imbalance. For shooting 200 yards and under this works out really well for them.
Palma shooters want a twist that ensures bullet stability throughout 1000 yards, and twist rates are generally slower, but it depends on whether the shooter is going by US Palma or International rules as far as bullet weight goes.
The most accurate bullets you'll find for a 1:12 22 caliber barrel will likely be the 52 to 55 gr match bullets. For "longer range" shooting the Nosler 60gr ballistic tip boat tail comes out with a 1.25 stability factor, at least at reasonable velocity. I know that is slightly higher than a Sierra 155 Palma (2156) bullet being launched at 3k from a 1:14 twist 30 cal barrel.
So depending on what you want to do, really narrows down the range of bullets that people can recommend.
Jimro
Jimro trying to find an optimal load at short distances. Unfortunately I don't have a range thats more than 100 yds. I recently have gone from 1:14 to 1:12. At 1:14 it shot 52-55gr extremely well. Never tried anything heavier or anything lighter than 50gr. Since going to 1:12, I haven't been able to find a satisfactory load. The faster twist pushed me towards 55-60. I've tried several bullets at 55 and vmax 60gr. I think I tried some 53gr Sierra (1400). Nothing has really stuck out. I do have some 52gr amax but rather than jumping round a burning powder, primers, cases, bullets I thought I'd take a more scientific approach to it.
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For accuracy at shorter range, try the 60gr VMAX flat base bullet.
A lot of folks have gotten them to shoot nicely from 1:12 twists using the 22-250. If that doesn't shoot for you, try the 53gr SMK as the old standby, if that doesn't shoot for you odds are its your barrel that's the problem and not the bullet.
Jimro
A lot of folks have gotten them to shoot nicely from 1:12 twists using the 22-250. If that doesn't shoot for you, try the 53gr SMK as the old standby, if that doesn't shoot for you odds are its your barrel that's the problem and not the bullet.
Jimro
Jimro been using 60gr vmax ^^^ and I tried the 53 (that's Sierra 1400) ^^ trying the 52gr amax today. The 60s look like they want to shoot, I usually get 5 shot groups that result ineither 4 shot under a 1/4 and a 5th that brings it to .5-.7 or a cluster of 3 and a cluster of 2 that's .5-.7. Can't seem to et 5 under a half. New barrel. Not expecting anything different from the 52s but I'll try them today.
1stMar,
The 52gr SMK is a boat tail design, the 53gr SMK is a flat base design. At short ranges flat base designs seem to shoot more accurately than boat tail designs based on who uses what to win matches.
Sierra's accuracy load for the 53 SMK is 34.9gr of Reloader 15, using a Federal Match primer.
Out of curiousity, what components do you have available?
Jimro
The 52gr SMK is a boat tail design, the 53gr SMK is a flat base design. At short ranges flat base designs seem to shoot more accurately than boat tail designs based on who uses what to win matches.
Sierra's accuracy load for the 53 SMK is 34.9gr of Reloader 15, using a Federal Match primer.
Out of curiousity, what components do you have available?
Jimro
Sierra 1380 (69grhp)
Sierra 1390 ((55gr hpbt)
Sierra 1400 (53gr FB)
Hrndy 60gr vmax fb
Hrbdy 52gr amax bt
Hrndy 55gr fmj
Imr4064
Imr 4895
Aa 2230
Imr4350
W748
8208
Fed 210
Cci lr
wlr
It does seem to like fb the best. The vmax and the Sierra 1400 seems to shoot the best. It likes 4064- 35.4gr for the vmax.
Sierra 1390 ((55gr hpbt)
Sierra 1400 (53gr FB)
Hrndy 60gr vmax fb
Hrbdy 52gr amax bt
Hrndy 55gr fmj
Imr4064
Imr 4895
Aa 2230
Imr4350
W748
8208
Fed 210
Cci lr
wlr
It does seem to like fb the best. The vmax and the Sierra 1400 seems to shoot the best. It likes 4064- 35.4gr for the vmax.