Queston?

[robertbank]

Well I took my new gun out yesterday and ran 170 rounds through it. FMJ and lead cast boolits. Loads were mixed so I can't tell you what particular load caused my problem BUT on two occassions shooting at 15 yards I had two boolits keyhole through the target. My boolits are 125 gr lead cast from wheelweights. Gun is a new Tanfoglio 9MM and the loads was a soft 4. gr Unique, WPP and Win cases. All other rounds showed no evidence of instability and were accurate. Is this a new barrel thing, could I had a couple of really light loads? Sorry I can't give any more information as I didn't notice the keyholing until I examined the target. Boolits are lubed with a hard lube.

I have this happen once before but only from a gun that was heavily leaded. In this instance there was virtually no leading inevidence.

Take Care

[44man]

There are several reasons for keyholing. The most common is a boolit that is either too short or too long for the rate of twist and the velocity they are fired at does not allow any stability. In other words, you have to get the revolutions right for the boolit in either case. You may have had some loads so light that the RPS were too slow.
The other reason is a boolit that strips the rifling due to being too small or leading in the bore that has filled the grooves. Sort of the smooth bore effect. Still boils down to no RPS.
It is not a new barrel thing. Lube can cause it if it all flew out of one side of the boolit and was still in the other side. One reason I never use a hard lube. I have seen lube so hard that if you drop a boolit on the table, half the lube would break out. It might be OK if it was sticky and stuck to the boolit, a good reason for some lanolin. You can check your lube by taking small stick or toothpick and trying to poke it out of the groove. If it is brittle and breaks out in chunks, it is no good. If you can peel it out all the way around the boolit in a strip, it should work but it should not completely pop free of the grooves.
Lube should either be so soft that ALL of it leaves the boolit at the muzzle or it should be flexable and sticky enough that the only lube missing from the boolit is what was used in the bore or what sheds the surface from spin when leaving the muzzle.

[robertbank]

Thanks for the reply suspect it is a combination of velocity and hard lube. I am going to switch to a softer lube and move up a notch with my velocity and see what happens. Definitely not leading or stripping. I have not had a chance to slug the bore so .355 sizing could still be the culprit. Thanks for the reply,

Take Care