Strange cut pattern on paper targets

[schuetzen]

I was curious if anyone knows what causes these strange cut patterns on my paper targets.  These were shot with low powered loads of 110gr Rainier Ballistics 30 Carbine (.308) RN TMJ bullets loaded in .308 WIN with 12 gr of Unique powder.  The Rainier Ballistic bullets are copper plated lead bullets (electroplated copper, I believe).


I've drawn yellow arrows pointing at the strange cuts.  They are like little rectangular cuts (like rectangular flower petals) on the periphery of the bullet whole.  In this picture one bullet hole has one cut (above right) and one bullet hole had three (lower left). Note, other long thin black marks are from a marker pen to mark my shots.

[smokehouserex]

 
 
  I had some tgts. that looked similar to that the other day. Was shooting cast bullets at modest velocity. My target holder was leaning back at the top and the wind was gusting and I attributed it to that?? but I'm not sure what caused it, they almost looked as if they were yawing at impact.
 
  HM

[SHOOTALL]

Maybe they were not going fast enough to stabilize or the rate of twist was to fast for a light bullet . many 308's are 1-10 not sure what a 30 carbine is might be worth your checking.

[Ranch13]

Not uncommon with roundnosed bullets, also can be because the target not fully supported by the backerboard.

[schuetzen]

Not uncommon with roundnosed bullets, also can be because the target not fully supported by the backerboard.

It was a bit breezy out there when I was shooting, but the "not fully supported" theory sounds plausible.  I may experiment with unsupported and better supported targets next time and see if I can see a difference.


The only other explanation I could think of,  was that the copper plating was starting to peel off, but the speeds should not be very high in this case.  Also, I would think that electroplated copper would be more stable than copper jacketed bullets.


I'm not sure about the twist rate.  The barrel is an Encore 15" .308 and has a muzzle brake added.

[Blackhawker]

Any idea of what your velocity is?  You might be shooting just above the velocity and/or pressure limits of the copper plated bullets.  The interior of those copper plated bullets are just soft lead.  They will distort under a lot of pressure.  The 30 carbine round can get up near 40,000 cup or more but even a light load in a larger case like the .308 may be pushing the limit of those bullets.  You might try full jackets or if you want to save some money, try Hornady's 100 grain short jackets.  I think they only cost a buck or two more than the copper plated bullets. 

[SHOOTALL]

30 carbine twist rate is 1 in 16 . if your 308 is 1 in 10 that is a big step .

[schuetzen]

Any idea of what your velocity is?  You might be shooting just above the velocity and/or pressure limits of the copper plated bullets.  The interior of those copper plated bullets are just soft lead.  They will distort under a lot of pressure.  The 30 carbine round can get up near 40,000 cup or more but even a light load in a larger case like the .308 may be pushing the limit of those bullets.  You might try full jackets or if you want to save some money, try Hornady's 100 grain short jackets.  I think they only cost a buck or two more than the copper plated bullets.

I have a friend with a chronograph, but we haven't tried setting it up yet at the range.


I was looking for inexpensive plinking round for .308 WIN.  I may need to rethink these loads.  I have a box of Speer "plinkers" in .308 that I have not tried yet.  I also found someone who has 147gr NATO M80 bullets pulled from Lake City munitions.  In quantity they are very reasonable, about the same price I was spending on Rainier Ballistic bullets.