GuitarmanNick
Ultimate Member
The firearm in question is a Yugoslavian M-57 pistol in 7.62x25mm. It has been quite accurate with surplus and my hand loads until yesterday.
The hand loads have an X-treme 110 grain .30 carbine plated bullet. The same load with a FMJ has been very accurate in the past and is relatively light at ~1150 FPS.
As I was testing the latest hand loads, it appeared that the majority of the rounds were key-holing or tearing apart, and grouping was not good at all. The target was supported, but not completely. It did have some "round" holes, but most were jagged and shaped differently.
Since I had not previously slugged the barrel, I did so a few minutes ago and was a little perplexed at the measurements. I double checked them, and triple checked them.
The lands are .303" and the grooves are .313". Bullet diameter is .308".
Could the bore be too tight for the plated bullets and causing them to ripped apart or damaged? Am I crimping the round too much(I only use a light crimp but did not change it from the FMJ setting on my die)?
Any helpful input from the MDS collective would be appreciated.
The hand loads have an X-treme 110 grain .30 carbine plated bullet. The same load with a FMJ has been very accurate in the past and is relatively light at ~1150 FPS.
As I was testing the latest hand loads, it appeared that the majority of the rounds were key-holing or tearing apart, and grouping was not good at all. The target was supported, but not completely. It did have some "round" holes, but most were jagged and shaped differently.
Since I had not previously slugged the barrel, I did so a few minutes ago and was a little perplexed at the measurements. I double checked them, and triple checked them.
The lands are .303" and the grooves are .313". Bullet diameter is .308".
Could the bore be too tight for the plated bullets and causing them to ripped apart or damaged? Am I crimping the round too much(I only use a light crimp but did not change it from the FMJ setting on my die)?
Any helpful input from the MDS collective would be appreciated.