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gunboat57	Check your case length	Lead	[-]
Posts: 311 Mar 2 12 5:21 PM active member Reply Quote More My Recent Posts	Tags : None I got sloppy when resizing my 6.5x55 brass. The necks were getting longer but I didn't notice because they still chambered easily and performed well in one of my Swedes. Took my other Swede M96 to the range today and had some trouble chambering a few rounds. Later I realized the necks were so long they were pinching the bullet when chambered. I should've investigated but went ahead and shot anyway. The loads were mild and bullets were 85gr so no overpressure was noted after firing. The five shot group at 100 yds was tight even though two of the bullets went through the paper sideways. Go figure. Made it hard to calculate the group size. Anyway, I learned my lesson about checking case length. Had my loads been on the hot side there could've been trouble. Also learned that not all Swede chambers are created equal. Tom P.
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fastshooter		#1	[-]
Posts: 260 Mar 2 12 11:11 PM Reply Quote More My Recent Posts	Been there, done that.fastshooter
brass rat		#2	[-]
Posts: 2449 Mar 3 12 3:09 PM Reply Quote More My Recent Posts	Somebody help me out here. I am having trouble trying to picture how a tight throat is going to cause bullets to keyhole when they exit the barrel 29" later. ----------------------------------------------------------------- Why not join us at Milsurp After Hours handloading forum
gunboat57		#3	[-]
Posts: 311 Mar 3 12 7:30 PM active member Reply Quote More My Recent Posts	Tight in the sense that the case neck was too long for the throat and the end of the throat acted like a roll crimper. My theory is that since I'm using 85gr bullets there's a bit of a jump until the ogive finds rifling. Also the bullets are seated in the case with less than one diameter of depth. If the case neck squeezed down on the bullet with even slight asymmetry when I chambered it, the bullet could've gotten cocked as it left the case mouth and didn't engage the rifling coaxially like it should. Evidence that MIGHT support my theory is that I also fired some 140gr bullets, some of which also had long case necks and were hard to chamber. None of them keyholed. They were seated deeper and were therefore guided better? OK, I'll admit it. I'm grasping at straws because I've never had my Swedes keyhole bullets before. Come to think of it, I could try to make an 85gr bullet keyhole by seating it a bit crooked in the case. Shouldn't be too hard since they are not seated deep. Tom P. Last Edited By: gunboat57 Mar 3 12 7:33 PM. Edited 1 times.
fastshooter		#4	[-]
Posts: 260 Mar 3 12 8:19 PM Reply Quote More My Recent Posts	I thought under size dia. bullets caused the bullet to key hole. among some other things. Seems the pinched neck would also cause a pressure spike.fastshooter
Parashooter		#5	[-]
Posts: 2009 Mar 4 12 2:59 AM Veteran member Reply Quote More My Recent Posts	The 85-grain .264" Sierra was once, and still may be, a very light-jacketed, soft-cored varmint vaporizer. I learned many years ago that it was possible to drive these fast enough in the tight-twist Swedish 96 that they actually come apart in mid-air from centrifugal force. When driven just below the velocity at which they disintegrate, they can get pretty unstable. It may be that the increased pressure generated by mouth-pinched bullets added sufficient velocity or in-barrel deformation to produce this effect.
gunboat57		#6	[-]
Posts: 311 Mar 4 12 1:47 PM active member Reply Quote More My Recent Posts	"they actually come apart in mid-air from centrifugal force" I'd heard about that happening but I'd love to see that caught in a high speed camera movie! Tom P.
fastshooter		#7	[-]
Posts: 260 Mar 4 12 5:10 PM Reply Quote More My Recent Posts	I was told by some one from Hornady the bullet made specifically made for the 30-30 would do the same if exceeded very far beyond 2500 fps. I was asking about loading it with a low dose for the 308 for deer hunting. He said if I could keep it below that speed to go for it.fastshooter
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gunboat57		#8	[-]
Posts: 311 Mar 14 12 12:32 PM active member Reply Quote More My Recent Posts	Just as a followup, I trimmed all my cases and went to the range again. Results are below: First shot from an oily barrel keyholed. Next 4 grouped. I thnk my loads are marginally overstabilzed. Note the Williams aperture sight on my 1915 CG. Of course, no permanent alterations were made to the rifle. Target is an 8.5x11 piece of construction paper. At 100 yds the paper appears to be the same width as the front sight post. Convenient! Tom P.
mauserand9mm		#9	[-]
Posts: 1529 Mar 16 12 7:42 PM Veteran member Reply Quote More My Recent Posts	" First shot from an oily barrel keyholed." You mean first shot from a clean barrel?
gunboat57		#10	[-]
Posts: 311 Mar 17 12 4:40 PM active member Reply Quote More My Recent Posts	Yeah, barrel had been cleaned with brush and an oily patch after last shooting. It wasn't sopping. In fact, I usually run a dry patch down the bore before shooting. Didn't do that this time. Not sure it makes any difference. Tom P.
mauserand9mm		#11	[-]
Posts: 1529 Mar 18 12 5:50 AM Veteran member Reply Quote More My Recent Posts	I think that was the reason for the flyer, don't really know the mechanics behind it though. Actually they say that you shouldn't shoot with oil (even a thin coat) in the barrel, and that it should be patched out after storage and before firing the first shot. The theory being that the oil will tend to be an obstruction as it builds up in from of the projectile. My Remington 700 always plants the first shot away from where the rest of the shots go. This is after I dry patch out the oil from storage. It's not a temperature issue as I can let it cool down completely and it will shoot where it's supposed to when I start shooting again. I know dry patching probably doesn't remove all the oil. Actually, next time I take it out the range I'll use acetone or spirits to get all the oil out before firing and see what difference it makes.
brass rat		#12	[-]
Posts: 2449 Mar 18 12 11:27 AM Reply Quote More My Recent Posts	I keep my bores well oiled when in storage so I always pull a boresnake through before I shoot. Enough oil in front of the bullet and your barrel becomes a hydraulic cylinder and far worse things than key holing can occur. ----------------------------------------------------------------- Why not join us at Milsurp After Hours handloading forum
fastshooter		#13	[-]
Posts: 260 Mar 18 12 3:50 PM Reply Quote More My Recent Posts	Maybe I missed the boat. I was under the impression that key holing came from an under size diameter bullet in relation to the bore diameter. (Example) 311 bullet fired through a 314 diameter bore.fastshooter
gunboat57		#14	[-]
Posts: 311 Mar 18 12 8:22 PM active member Reply Quote More My Recent Posts	Undersized can cause it. I had a Martini-Enfield (303 caliber) with a worn out bore. Not much rifling left. 180 gr jacketed bullets would tumble and miss a target by 3 feet at a range of 25 yards! That was due to the bullet being undersized and not taking the rifling. But if you "overstabilize" a bullet, which I think means spinning it too fast for its length, in flight it will continue to point in the same direction as the bore axis even while following its parabolic trajectory. In other words, it doesn't point into the wind like a properly stabilized bullet will. It starts precessing and nutating and eventually aerodynamic forces acting on the bullet suddenly flip its axis perpendicular to its flight path. The fact that my key-holing bullets weren't too far out of the group makes me think the bullets went rogue right near the end of the flight. I've got to do more reading on the subject, that's for sure. Tom P.
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