Handloads - bullets disappearing...

[Goosebrown]

So had the most unusual experience with load development yesterday.

I worked up two audette ladders for my 22-250 1/12 bolt action. I used 50gr Sierra Blitz bullets. I checked them on the Berger Bullet Stabilization Calculator. (http://www.bergerbullets.com/twist-rate-calculator/). They were right in the stable range. I loaded them with a small jump to the lands. I used the Sierra Loading Manual for 22-250 (http://accurateshooter.net/Blog/sierra22-250loads.pdf). It stated that the maximum velocity for the 50gr Blitz was 3600 fps.

I loaded two batches four times each so that I could shoot the same ladder 4 times with each load and compare the results.

I used IMR4064 and loaded at about 3600, 3620, 3640, 3660 and 3700fps.

For the second batch I used RL15 and loaded the same velocities 3600, 3620, 3640, 3660 and 3700fps.

All Lapua brass from the same lot.

I know that that is over the maximum recommended, but it looked like it was going to find an accuracy node and the stability calculator confirmed that.

All case prep occurred at the same time in one batch with CCI primers.

Shot all 8 groups. Four with the IMR4064 and four with RL15.

The four groups of RL15 shot a little weird in that the second shot was lower than the first, but it happened all 4 time. I found an accuracy node at 3680-3700fps and will experiment there next.

The weird thing was the other batch with 4064.

I had totally clean targets out and was using a backing of a 300 yard target so there was fresh paper all over the target. Then I put up four smaller targets and started shooting at 200 yards. In each set of loads with the 4064, the firs shot was identical across all four targets. That is slightly down and to the left of an unzeroed scope.

However, not a ONE of the other bullets even hit the paper. Not. One. Bullet.

Low velocity was where the RL15 low velocity had hit more or less but all of the higher velocity bullets simply disappeared. The were either RADICALLY off course or they disintegrated in flight.

This is the mystery. In the same gun with the same scope in the same weather on the same day at the same time with the same velocities and the same bullets, RL15 delivered and 4064 just made them disappear. (unless all 5 were in the same hole every time... which I really doubt.)

I am happy with the results in that I have an RL15 load to look at, but I am really stumped as to why the bullets disappeared?

Any ideas?

Oh... no flattened primers. Perfect primer strikes.

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[Velzey]

I've had similar experience with 50gr Blitzkings and 4064. I was loading in a .220 swift and there was a magical velocity that the bullets would shed their jackets and be set free. And it was right would the 3750 fps mark.
At the time I talked to Sierra about it and they thought it was possibly their fault and had me send in the remaining bullets for inspection. They sent me a coupon for several boxes of free bullets for my trouble.

 

[ageingstudent]

It doesn't seem likely you would have trouble with that projectile with a 1/12 twist. From what I read in your post you are operating at the limits of that projectile right? Any chance you can get a chrony reading? Perhaps they have more velocity than projected.

If you want to see if the projectiles are disintegrating try putting up a large sheet for a target or find a large dirt bank you can scan for hits. Someone spotting for you could help.

 

[Goosebrown]

It was a large clean target at 200. I might try at 100. Might try lower velocities as well. However I am happy with the rl15 load.

I love mysteries and reloading.

 

[ageingstudent]

Yeah I thought of bringing the target in to 100 after I posted. I have heard of 250 projectiles disintegrating but never seen it yet. I have a 1/12 also but never used that powder. Be interested to hear what you find...