Sierra 50gr Blizking bullet

[Vet66]

I'm at a loss, I can't seem to get these looking any better on the target than a shot gun blast. Two rifles used, one is a .220 swift the other is a .222 Sako. Tried a half dozen powders, different col, you name it I tried it. Anyone have any luck using these bullets? I wonder if I'd have better luck using the 22-250?
By the way all barrels on these rifles are 1:14 twist.

[Unclenick]

You've already identified the problem. Most 50 grain bullets are only abut .65" long. That BlitzKing is almost 0.79". The stability calculator at the JBM ballistics site shows that at 3500 ft/s you would need about a 10.5" twist to get best stability for it, and about 12" just to prevent it from tumbling and fanning out all over the paper.

Most people are mislead by manufacturer's tables to believe bullet weight determines the rifling twist, but such tables assume all bullets of the same weight have the same length. It is actually length that is the much more critical to determining how fast a bullet has to spin.

For best precision you want a gyroscopic stability factor (the number that calculator estimates) of about 1.4 to 1.7. For your 14" twist, the longest 50 grain bullet at 3500 ft/s would be 0.64" long, like the Sierra Semi-Point Varminter.

[Vet66]

Thank you for the informative reply. I'll try another bullet for sure.

[wileybelch]

I can verify UncleNick's response. And the 55gr BlitzKings are 0.822" long! Years ago, I tried the BKs when they first hit the market. Almost none of them found the target at 200yds. Then one day I saw a 'puff' of smoke around 100yds out - it was the BK blowing up! My .22-250 has a 1:12" barrel from long ago, before modern bullets were available. I probably should rebarrel.

[Vet66]

Well, I decided to try these in my Winchester Model 70 22-250 (1:14) just for the heck of it.....I was taken aback...it likes them. These are preliminary loads and, they look like they have potential. Range 100Yds, mild wind. Target triangle is 3/4".

[Longshot4]

Vet66 is that a bedding problem or a primer problem your group has?

[Vet66]

longshot, neither. These are preliminary loads in this rifle using the 50 grain Blitz king bullet. I need to fine tune the col and powder charge. This rifle normally digests 52 gr A max bullets.

[Saint Dennis]

I have gotten excellent results with both the Blitzkings and the Amax in my .220 swift (1 in 10 twist).

[Vet66]

Saint Dennis, I can not get these to shoot in either my 222 or 220 rifles, both being 1:14 twist. I have to agree with Unclenick and, wileybelch that the bullets are too long for the twist, however, I am perplexed that it does so well in the 22-250 with the same twist. Of course the 222 and 220 swift do very well with 40 grain bullets. I'll stick the blitz kings in the 22-250 and, fine tune the loads.

[Colorado Redneck]

Do you have any idea of the velocity from the 22-250 using the 50 gr. BK's? I used to shoot 55 gr. Hornady Sp. Points in a 22-250. At 100 yards they were good to great. At 250 yards they were crap. Evidently as they lost velocity the rotation slowed enough to destabilize.

[Vet66]

Colorado Redneck, I can't give you an exact number (my chrono is broken at this time...don't ask)but according to the reloading manual it should be pushing about 3600-3700 fps using the 4064 powder and, 3700+ using H380 this is not carved in stone however. I seem to lean on your assessment on the extended range, I'll test that next time at the range, limited to 150 local here but, will travel to the hills if need be. I'll let you know. Before Twin "S" closed (due to yahoo *******s) range was 500 yards...gee I miss that club. I am disappointed at the performance of the 222 (Sako L 46) and 220 Swift I'm ready to take a saw to both of them. I'll update the progress of this round.

[Longshot4]

The 50Gr Blitz King groups well in my Rem 700 Varmint Special. I can't tell you why your 222 isn't doing better but you might want to try some different primers. According to Sierra 3600 Fps. is max for the Blitzking. That might explain the problem with the 22-250.

[Colorado Redneck]

I hear ya on disappointment. Sometimes it gets downright disgusting. Keep working on things, you will find something that works for you. Rifles are a lot like the fair sex---they are all different, and sometimes obstinate. A rem 700 in 204 Ruger was my waterloo. Finally gave up. Got a different rifle (Ruger Hawkeye Predator) and am a lot happier.

Trying a shorter bullet might make your 220 Swift and 222 Remington work better. I have a CZ in 222 Remington that really likes 40 gr. bullets, except for the 40 gr. V-max. For some reason that bullet will not shoot worth a dang in that little rifle. But Nosler BT's in 40 grain works wonderfully. On a positive note, trying different components gives you lots of reason to load rounds and go shoot.

[Unclenick]

Vet66,

I note a labeling inconsistency. You sometimes refer to the 50 grain BlitzKing, and some targets are labeled 50 grain Sierra Blitz. Both bullets are made by Sierra and are not the same. The BlitzKing is a longer 0.786" boat tail design. The Blitz is part of the Sierra Varminter series and is a shorter 0.656" long flat base design and is nearly ideal for a 14" twist at muzzle velocities of 2000 fps and higher.

If the Blitz is what you actually have, it should do very well in all your guns except the 220 Swift, which can push it fast enough to strip the core. The triple deuce then may have some other issue like a shot out barrel or a bedding, lug engagement, or crown problem.

If you are actually using the BlitzKing, then it defies both the JBM and Kolbe ballistic stability calculators, and I would then take the 22-250 out to 200 yards and see if it still groups. If understabilized bullets are especially well aligned with a bore by how they enter the throat of some chambers, they can fly for a distance before they begin to fan out.

[Vet66]

Unclenick, You are correct, these are Blitzking #1450 and, they measure .782 on average. I really appreciate your input, great value for me. I never realized the difference. Thanks.

[KEYBEAR]

Do a test and slow three down for group (2800) or less
I really think you will find they (the bullets) shoot very well .

I shoot a 223 IMP and never go past 2600 fps and can do a good 1/4 inch at a 100 yd .

[flashhole]

KEYBEAR - that's an interesting comment. My 223 Kimber bolt gun 1:9 twist would not shoot mid weight bullets (50-60 grains) worth a darn. I never thought to slow them down. I switched to the 63 grain Sierra Semi Spitzer and had a one-holer. I still have some of those bullets so I think I will try your suggestion.

[Unclenick]

It's usually an issue with core stripping when that happens. If it's not a bonded core, the jacket can accelerate so fast the core under it slips. That ruins symmetry of the mass distribution, resulting in fliers. The bullet makers can usually give you a maximum MV, but don't forget to ask them what the twist rate was and what the peak pressure of their load was. The stripping occurs during the pressure peak when the bullet is under maximum acceleration, so the length of the barrel and therefore MV aren't really the issue. Peak pressure divided by rifling pitch will give you a scaling number you want to avoid exceeding.

BTW, this is one of the things gain twist barrels are supposed to avoid. They would give you lower rotational acceleration at the pressure peak, and thus should theoretically give you a much higher no-stripping velocity, but I've not heard anyone report doing the experiment.


Vet66,

What I missed before is the plastic tip on that bullet. I didn't allow for it and on the JBM calculator that makes enough difference to put you just over the stablility line and into the low acceptable stability range at .22-250 velocity. It's not quite up to an optimal amount of stability, so I'd still be looking at what happens at 200 yards and beyond, but it would certainly explain why you can shoot it at all. At a lower velocity with the same 14" twist, that stability factor goes down and gets much closer to crossing the line, and that probably explains the .222 not working with it. The .220 Swift should make it even more stable, but I suspect it of stripping the core, as mentioned earlier. Anyway, we now have a reasonable set if explanations for why it only works with the one 14" twist chambering.

The reason the plastic tip matters is, even though it doesn't reduce the overturning drag trying to make the bullet tumble, it does put less mass at the front. The bullet tip describes circles (coning motion) as it settles the bullet attitude over from bore axis spin to its yaw of repose in flight. With the lower tip mass, these circles have less centrifugal effect trying to pull the nose off axis. That's why the stability with a plastic tip bullet is better than a same-length bullet of more conventional construction.

Incidentally, it is a factor even with hollow point bullets that their mass is a bit lower at the nose due to the lead core not going all the way to the tip, as it does with a FMJ design. So, often, they can work with slightly slower twists than the stability calculators show, because the calculators assume uniform density.

[flashhole]

Thanks Nick, I was not aware of that but I will pay attention to it in the future. And thanks for always being helpful. I enjoy your posts.