80 grain SMK's breaking up.

[ovenpaa]

Christel has been very successfully shooting with the .224 SMK 80grain, moly coated bullets for the last three years. She shoots a wildcat 6,5x47 Lapua case necked down to .224 with a no turn neck. The Action is a Savage Match bedded in a BVSS stock with a 29” TruFlight 1:8 barrel and she typically shoots at around 3250 fps with H4831SC with very good results. She and the rifle have shot .019” and better at 100 yards however she uses it as a 600-1200 yard rifle. Yesterday she was shooting at 800/1200 yards with the rifle.

The day was hot for us at around 30C/85F and for the first time ever she had some of the bullets disintegrate, this is typically seen as a small p**f of dust/smoke at around 150-200 yards out from the firing point followed by no hit on the target, we know she was shooting OK as she she was grouping nicely on the 1200 yard target so certainly something was going wrong. Given the ambient temperature her MV would have been up a bit but she was not seeing any significant pressure signs so my question is has anyone heard of this happening with the .224 SMK80 before and does anyone have any view on what the maximum MV and rotation the bullet will run to is? I ask because we are talking about building another wildcat for her based on the same bullet.

She has shot on hot days before so it was really odd to see this happen and is a first for any of her rifles. We have absolutely no plans to move away from the SMK for the bullet as it has worked so well for countless hundreds of rounds.

Does anyone have any views on this?

[dromia]

How many of the rounds disintegrated and how many were fired?

I would email Sierra about this and get their take on it.

I have had reports of this over the years and seen it happen with cast boolits, never with jacketed.

Because of the randomness of this happening I have put it down to a flawed bullet.

If the velocity rpm was too great for the design then it would happen with every shot, surely.

[ovenpaa]

No problems at 800 with maybe 10 shots including a 5 shot group and no issues followed by 15 shots at 1200 and 4 failed to get to the target, the remaining shots were very nicely grouped so I would be very surprised if she had missed the frame. The only problem is she is shooting a .224" bullet at a well used target so the markers do miss them sometimes.. I am still sure I saw at least 2 break up but something is nagging me now as they seemed lower than I would have expected.

[dromia]

You haven't been imbibing, late nights, overwork or just generally loosing the plot to advancing years and a dissolute past perchance?