Bob Kingsbury
New member
Thanks fellas
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squeakie
Guest
I've never used the ballistic tip Noslers in any 22 centerfire rifle, so I cannot compair them. But as I said before I shoot the Vmax bullets all the time in my .223's without a hitch. How much different are they? I would like to think that with 300 fps faster velocity in the same twist barrel they'd also stabalize.
gary
gary
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nhkuehl
Guest
Stability
From what I can tell, the benchrest crowd shoots at the ragged edge of stability (Sg 1.00) and the long range crowd shoots fully stabilized (Sg 1.4). It seems velocity can compensate for lack of stability at short range, but if the bullet isn’t fully stabilized at the muzzle it will not stabilize further down range and that shows up at longer distances. If you shoot the same bullet, say a .224 55 gr V-Max (nominal length .816”) at 3140 fps in a 1:9 twist (Sg 1.82), a 1:12 twist (Sg 1.02), and a 1:14 twist (Sg 0.75) with everything else equal the difference in the group size should increase over distance (and a bullet may keyhole). If you increase the velocity to 4000 fps with the 1:14 twist, the Sg is still only 0.81. The optimum twist would be 1:10. Your choices of twist are somewhat limited with factory rifles.
I won’t even pretend that I understand the calculations, and there may be some exceptions, but it has worked for me. I shoot both a 1:9 and 1:12 twist .223 so I’ve been able to compare the same bullet at two different levels of stability and there is a difference.
I’ve been developing loads for a friend. He gave me an assortment of 6mm bullets and the first thing I did was measure the length of each and calculate the Sg and ranked them from highest to lowest for a 1:12 twist with 1.40 being the cut-off and only worked with the bullets of 1.40 and above. He was able to shoot a 0.25” group at 200m.
German Salazar did a test of varying Sg over distance and you can read the article and links at: http://riflemansjournal.blogspot.com/2010/06/ballistics-heavy-bullets-in-113-twist.html
- nhk
From what I can tell, the benchrest crowd shoots at the ragged edge of stability (Sg 1.00) and the long range crowd shoots fully stabilized (Sg 1.4). It seems velocity can compensate for lack of stability at short range, but if the bullet isn’t fully stabilized at the muzzle it will not stabilize further down range and that shows up at longer distances. If you shoot the same bullet, say a .224 55 gr V-Max (nominal length .816”) at 3140 fps in a 1:9 twist (Sg 1.82), a 1:12 twist (Sg 1.02), and a 1:14 twist (Sg 0.75) with everything else equal the difference in the group size should increase over distance (and a bullet may keyhole). If you increase the velocity to 4000 fps with the 1:14 twist, the Sg is still only 0.81. The optimum twist would be 1:10. Your choices of twist are somewhat limited with factory rifles.
I won’t even pretend that I understand the calculations, and there may be some exceptions, but it has worked for me. I shoot both a 1:9 and 1:12 twist .223 so I’ve been able to compare the same bullet at two different levels of stability and there is a difference.
I’ve been developing loads for a friend. He gave me an assortment of 6mm bullets and the first thing I did was measure the length of each and calculate the Sg and ranked them from highest to lowest for a 1:12 twist with 1.40 being the cut-off and only worked with the bullets of 1.40 and above. He was able to shoot a 0.25” group at 200m.
German Salazar did a test of varying Sg over distance and you can read the article and links at: http://riflemansjournal.blogspot.com/2010/06/ballistics-heavy-bullets-in-113-twist.html
- nhk
Not really. While the BIBs page was created for Randy's bullets, since the jacket lengths he uses are the same as for most everybody, the stability numbers he give should be about right for all bullets of the same form -- i.e., flatbase (unless a boattail noted), no tip.
http://www.bibullets.com/products/
I'm not sure if Randy uses the same modeling as Berger. Think so, or at least close. Fr boattail bullets, esp those with a VLD design, you can use Berger numbers.
http://www.bergerbullets.com/Products/All Bullets.html
Neither of these include tipped bullets. If you want to do your own computations (not that hard, but also not that easy) the JBM page will do that.
http://www.jbmballistics.com/cgi-bin/jbmdrag-5.1.cgi
Anyway, most BR shooters are close to 1.4 Sg
FWIW
Edit: Oh, I see Randy didn't give jacket length on the 6mms. Best I remember, the 65-grain are on a .790 jacket, and the 67 grain are on a .825 jacket. These would be considered typical for BR.
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squeakie
Guest
I agree but with reservations. The spin of a bullet going thru air gives it a gyroscopic effect. But if the rotation is past a certain point it actually causes other problems down range. I think this is why bench rest shooters tend to use slower twist barrels as much as anything else. A few years back somebody in P.S. magazine stated that an error of .0001" in the bullets C/G gives a displacement of .093" at 100 yards, but the faster you spin this bullet the further the displacement. Now I'm not the brightest person here by a long shot, but this all makes sense to me. And it falls right in line with what all the guys shooting competetion benchrest are doing.
gary
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nhkuehl
Guest
Over rotation
Yes, I think that sums up the thinking and I believe Bryan Litz's recommendation is a minimum of 1.40 and that if the Sg is >/= 2.00 you should use a slower twist. Sg 1.00 is considered stabilized, but if the temperature goes down or barometer goes up look out.
I'm shooting a 1:10 twist .308 Win with the 168 gr A-Max at 2800 fps for F-Class F/TR and that is an Sg of 2.06 and it is very accurate and consistent at 600 and 1000 yds. A 1:12 twist (Sg 1.43) would probably be a better choice, but I can't complain. nhk
Yes, I think that sums up the thinking and I believe Bryan Litz's recommendation is a minimum of 1.40 and that if the Sg is >/= 2.00 you should use a slower twist. Sg 1.00 is considered stabilized, but if the temperature goes down or barometer goes up look out.
I'm shooting a 1:10 twist .308 Win with the 168 gr A-Max at 2800 fps for F-Class F/TR and that is an Sg of 2.06 and it is very accurate and consistent at 600 and 1000 yds. A 1:12 twist (Sg 1.43) would probably be a better choice, but I can't complain. nhk
The link/formula I posted above includes Ix/Iy ratio. Henry Childs tested(into destable) PB BR bullets - vs- LR BR bullet's specifically in this regard. His conclusion was that PB BR bullets could get by with considerably lower Sg than LR BR bullets, -because of this ratio. This supports Bryans notion to use higher Sg with LR bullets, but PB BR shooters know they can and should use the lowest twist they can get away with.
It's an example of things missed with rules of thumb. There are other things.
Also, you can be assured that Sg increases downrange, with any bullet that is dynamically stable(Sd). If it ain't whacking paper sideways by 50yds, it won't furrther. This because a dynamically stable bullet(which cannot be assumed, but must be tested as such) is disturbed most in flight by muzzle release, while at the very point of lowest Sg.
It's an example of things missed with rules of thumb. There are other things.
Also, you can be assured that Sg increases downrange, with any bullet that is dynamically stable(Sd). If it ain't whacking paper sideways by 50yds, it won't furrther. This because a dynamically stable bullet(which cannot be assumed, but must be tested as such) is disturbed most in flight by muzzle release, while at the very point of lowest Sg.
Boyd Allen
Active member
Just a little heads up for you stability guys....Years ago, the first time that I took a tight necked .222 to the range, with loading equipment. I took along some of an odd lot of 55 grain Nosler Ballistic Tips to fire form the cases, before getting down to serious business with some "real" match bullets (52 gr. FB HP) They shot into nice little groups. The barrel was a 14 twist Hart. Unless the twist of the problem rifle is slower than it is supposed to be, I doubt that the problem is its twist.
Doug Kennedy
Hemi Road Runner
Gary, if you would like to try some nosler bt let me know. I prefer them over the Vmax.
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Montana Pete
Guest
I know this is not what you asked, but my Savage Model 12 Varminter in the 22-250 comes in 1/12 twist. This is supposed to stabilize bullets up to 64 gr. I even shot half a box of 68 gr and they seemed to do okay.
This twist might be a little better, since it does give the owner a little more flexibility.
Again, apologies that this is not a direct answer to the problem you have put to us.
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squeakie
Guest
when I get off here, I'm going over to Gander Mountain and buy a couple boxes of them as well as the Seirras I like so well. The strange thing about those two 22-250's is that I simply can't make the 52 & 53 grain Seirras shoot all that well in them, and only fairly well in the .223. I couldn't get the Amax bullets to work in any of my rifles, and that bugs me, but they did shoot better in the 22-250's (.50" groups). What I'd really like todo is to find a 60 grain bullet that grouped .50" or less in the 22-250, and yet work well on coyotes.
you come thru the storms OK yesterday? We had eight tornados north of me
gary
I offer a data point: My Ruger #1 will not shoot well with the 55 gr Nosler Ballistic Tip. Most of the time. When I went to Berger 52's, Sierra 53's, Starke 52's, all was well. One exception - the 55 Nosler did shoot well out west at 4000 feet on an 80 degree day. Correcting Greenhill calculations (still using the simple form we see published a lot) for air density and bullet specific gravity shows how this may be so.
Gary, the 60 gr. Nosler Partitions are serious coyote bullets. The ones I have measure .790 long...shorter than both the Nosler 50 gr. BTips (.800 long) and the 55 gr. BTips (.810 long). They've shot well in both 223's and 22-250 twisted 1:14.
Good shootin'. -Al
DR4NRA
New member
Gary, I have a #1 V stainless in 22.250, and a Cooper in 220 Swift, both with 1 in 14 twist. The swift digests the 55 gr Sierra Blitzkings extremely well low to mid 2s for 5 shot groups in 3 diffrent nodes, 3300, 3500, and 3750 fps. The 22.250 will also shoot these extremly well, but likes to be pushed towards the top end, and seated about 15 thou longer than what Sierras manual states. If I seat them to manual specs and slow them down a couple hundred fps, I do get a little bit of keyholeing.
As far as the 52 and 53 gr the 250 really shines when loaded at the middle to top and seated out a little, whereas the swift likes them just about any velocity and seated to 5 thou under touching the lands. But then again my swift has a very tight chamber, and touches the lands at manual stated seating depth. My 250 has a chamber with a very long throat which gives me alot of jump unless seated out.
As was stated by another poster, I really doubt that twist is the problem, as the 55 gr bullet is considered the optimum weight for both in a 1 in 14.
I dont put much credence in twist calculators as I use the Sierra infinity program which has one and it is based on the greenhill formula. I have never been able to come up with a bullet to velocity that matches the twist rate for any of my rifles, unless I go to a 100 to 200 fps overload. And this is plugging in data for Sierras own bullets. Real world results from the field is more reliable.
And to back my statement on this if you can find a copy of F.W. Manns book The Bullets Flight, From Powder to Target, first published in 1908, then again in 1947, you will gain alot of knowledge as this still is considered a must have for any ballistition. 38 years of actual test data, and the first real definitive look at real world external ballistics.
Good Luck
DR
As far as the 52 and 53 gr the 250 really shines when loaded at the middle to top and seated out a little, whereas the swift likes them just about any velocity and seated to 5 thou under touching the lands. But then again my swift has a very tight chamber, and touches the lands at manual stated seating depth. My 250 has a chamber with a very long throat which gives me alot of jump unless seated out.
As was stated by another poster, I really doubt that twist is the problem, as the 55 gr bullet is considered the optimum weight for both in a 1 in 14.
I dont put much credence in twist calculators as I use the Sierra infinity program which has one and it is based on the greenhill formula. I have never been able to come up with a bullet to velocity that matches the twist rate for any of my rifles, unless I go to a 100 to 200 fps overload. And this is plugging in data for Sierras own bullets. Real world results from the field is more reliable.
And to back my statement on this if you can find a copy of F.W. Manns book The Bullets Flight, From Powder to Target, first published in 1908, then again in 1947, you will gain alot of knowledge as this still is considered a must have for any ballistition. 38 years of actual test data, and the first real definitive look at real world external ballistics.
Good Luck
DR
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nhkuehl
Guest
Stability and keyholing
I don't have a .22-250 or 1:14 twist barrel, but I wanted to shoot a load that was Sg 0.80 or less so I loaded a .224 68 gr BTHP (.985" long) at 2616 fps and fired it in a 1:12 barrel. The Sg, unadjusted for temperature and elevation was 0.69; adjusted for 70 degrees and 4800 elevation the Sg was 0.84. I fired 10 rounds at a 28" square at 200m and 8 of 10 rounds hit the target and those 8 were 17" across. All the holes were oblong as you can see by three closest together ones that I scanned (pic attached). Besides keyholing, an unstable bullet will not group. The manufacturer's recommended twist for that bullet is 1:10 (Sg 1.00) to 1:7 (Sg 2.03)
Now I'm going out on a limb and say a stablized bullet can still keyhole, but it will group (second picture). Those groups were shot from the right twist, at the right velocity, through a barrel that had a defect. - nhk
I don't have a .22-250 or 1:14 twist barrel, but I wanted to shoot a load that was Sg 0.80 or less so I loaded a .224 68 gr BTHP (.985" long) at 2616 fps and fired it in a 1:12 barrel. The Sg, unadjusted for temperature and elevation was 0.69; adjusted for 70 degrees and 4800 elevation the Sg was 0.84. I fired 10 rounds at a 28" square at 200m and 8 of 10 rounds hit the target and those 8 were 17" across. All the holes were oblong as you can see by three closest together ones that I scanned (pic attached). Besides keyholing, an unstable bullet will not group. The manufacturer's recommended twist for that bullet is 1:10 (Sg 1.00) to 1:7 (Sg 2.03)
Now I'm going out on a limb and say a stablized bullet can still keyhole, but it will group (second picture). Those groups were shot from the right twist, at the right velocity, through a barrel that had a defect. - nhk
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squeakie
Guest
I bought two boxes of the 55 grain BT's a couple days ago, and they had the partitions sitting right beside them. So I'm off to Gander Mountain again! Thanks for the advice. So far the hardest thing I've ever found for coyotes is the 80 grain Sierra Blitz at about 3400 fps. Very terminal!
gary
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squeakie
Guest
good post! I will hunt for a copy of that book. Can you post the ISBN catalog number?
gary
keithcandler
New member
I have shot thousands of 55g nosler BT in Rem 700's in 22/250 with a 14 twist, not in just one rifle but multiples. I would look at the crown first, and make sure that the barrel is not full of copper, second.
DR4NRA
New member
Gary, Sorry but getting ready to go on a hunt, not alot of time to shoot. Went out and got some nosler 55 gr BT, still got sierra 55 BK, and a bunch of 52 sierra match. Will run a test with both the 250 and the swift. I plan on running data as to velocity and seating depth. The book you are looking for is available on CD rom, or quite expensive in original form.
DR
DR
Sounds like you do not have enough Velocity,i don't know what powders/loads you are using,but i have never had a problem shooting 55 and 60 grain bullets in a Remington 22/250 if i keep the velocity up above 3400 fps.
14 twist will give the best accuracy with 52-53 grain bullets,but my rifles shoot 55 grain nosler bat-tips very good.
14 twist will give the best accuracy with 52-53 grain bullets,but my rifles shoot 55 grain nosler bat-tips very good.