Klassic Keyholing 6.5x55 m/96

[Dutchman]

Yesterday I had a lot of keyholing in several rifles... pretty indicative that I've not slugged the bores. But it was a scope testing day more than a paper punching day. But one particular cast bullet delivered some strange results.

I had some 108 gr round nose gas check bullets from some unknown source. I loaded all 80 rds of them with 10.5 grs Swede Gallery Powder (like Unique). Mild load but very accurate with 140 gr Loverin .266" in several of my m/96.

Three went straight... well, mostly straight. I see they have a slight bit of canting to them. Three went sideways. At 50 yds. Strange that the keyholing bullets hit the target higher than those that flew straighter.
http://images50.fotki.com/v1570/photos/4/28344/7865574/DSCF8944rd-vi.jpg

The cases came out very hot and very sooted. With all of these there was some back puffing, gas leakage. I could feel it hit my face (around my glasses).
http://images52.fotki.com/v1568/photos/4/28344/7865574/DSCF8975rd-vi.jpg

At 100 yards these bullets were hitting: 6 feet to the right, 2 feet high at 11 o'clock, one foot low at 6 o'clock, etc. Flying all around. I don't have any more of them, thankfully. I can't recall having such strange results with a cast bullet before.

The rifle shoots very accurate with .266" cast bullets so its not a case of the bore being oversized. The Lee 170 gr at .268" consistantly hits tilting at 50 yds.

http://images51.fotki.com/v1550/photos/4/28344/7865574/DSCF8942rd-vi.jpg

All fired from the same rifle. This is 5 shots. Those .266" 140 gr Loverin are nice.

http://images50.fotki.com/v1571/photos/4/28344/7865574/DSCF8943rd-vi.jpg

Dutch

[StarMetal]

Yesterday I had a lot of keyholing in several rifles... pretty indicative that I've not slugged the bores. But it was a scope testing day more than a paper punching day. But one particular cast bullet delivered some strange results.

I had some 108 gr round nose gas check bullets from some unknown source. I loaded all 80 rds of them with 10.5 grs Swede Gallery Powder (like Unique). Mild load but very accurate with 140 gr Loverin .266" in several of my m/96.

Three went straight... well, mostly straight. I see they have a slight bit of canting to them. Three went sideways. At 50 yds. Strange that the keyholing bullets hit the target higher than those that flew straighter.
http://images50.fotki.com/v1570/photos/4/28344/7865574/DSCF8944rd-vi.jpg

The cases came out very hot and very sooted. With all of these there was some back puffing, gas leakage. I could feel it hit my face (around my glasses).
http://images52.fotki.com/v1568/photos/4/28344/7865574/DSCF8975rd-vi.jpg

At 100 yards these bullets were hitting: 6 feet to the right, 2 feet high at 11 o'clock, one foot low at 6 o'clock, etc. Flying all around. I don't have any more of them, thankfully. I can't recall having such strange results with a cast bullet before.

The rifle shoots very accurate with .266" cast bullets so its not a case of the bore being oversized. The Lee 170 gr at .268" consistantly hits tilting at 50 yds.

http://images51.fotki.com/v1550/photos/4/28344/7865574/DSCF8942rd-vi.jpg

All fired from the same rifle. This is 5 shots. Those .266" 140 gr Loverin are nice.

http://images50.fotki.com/v1571/photos/4/28344/7865574/DSCF8943rd-vi.jpg

Dutch

Dutch,

What do you think the velocity might have been on the bullets that keyholed?

I have a 260 Remington with a 9 twist and wanted to see how slow I could go with the 170 grain Oldfeller cruise missle. It was the mid 1300's fps. Soon as I got up to 1400 fps and little over they flew straight. I feel that's pretty slow even out of the slower 9 twist then what your Swede's much faster twist.

Some of the shoulders look funny on your brass, but it may be from the soot making it look different.

Joe

[SierraWhiskeyMC]

I'll venture a guess here that those "unknown source" 108gr boolits were undersized for your barrel.

First few rounds might've just barely been hanging to the rifling until the barrel got warmed up a bit and expanded (or started warming up lube in subsequent boolits); after that it was like throwing a hot dog down a hallway.

Supporting that assertion is the heavy soot on the cartridge cases. There wasn't enough of a seal 'twixt boolit and barrel for the cartridge cases to expand and seal against the chamber wall; indication of very low chamber pressure.

The next is the keyholing. You're drilling them in there pretty good with both the 140gr and 170gr boolits. Since you were using the same amount of powder behind the 108gr boolits as the 140gr boolits, the lighter boolits would have been a whole lot more stable if they'd bit into the rifling - that is, if the 108gr boolits were correspondingly shorter in length than the 140 grainers (about 77% to 80% the length of the 140gr).

[45 2.1]

Most all the swedes have long throats. If you noticed and compared all the different heavier designs, they have about the same body length irregardless of how long the nose is. Your light boolit probably won't get to the rifling if its in the case neck. A real good way to tip a boolit into the rifling.

[Bret4207]

Agree with 45 2.1 and SWMC. Light load, small boolit, good chance of tipping. As Joe said, a little more oomph might have helped too.

Funny thing, my wife was looking over my shoulder at Dutchs pics and said that some of the designers on those home designs shows would love the targets. They'd call them modern art and ooooh and aaah over them.

[Calamity Jake]

You have the "Need for Speed", a little more anyway, there not stablized, push um faster.

[sturf]

Check Greenhill. Your bullets are too light ( actually it's too short ) for the fast twist of the 96 sweed. 140 to 170 gr would be much better.

[SierraWhiskeyMC]

Check Greenhill. Your bullets are too light ( actually it's too short ) for the fast twist of the 96 sweed. 140 to 170 gr would be much better.

Actually, for a given boolit alloy, caliber, velocity and twist rate, the shorter the boolit, the more stabilized it is.

Greenhill's formula is really a bit too simplified to be of much use with cast boolits. A fellow by the name of Don Miller came up with a much improved stability calculation. It's reportedly accurate to within about 7%.

There is a Microsoft Excel spreadsheet with Miller's formula in it available about halfway down this page:
http://accurateshooter.wordpress.com/2008/06/03/calculating-bullet-rpm-spin-rates-and-stability/

If you don't have MS Excel installed, you could download OpenOffice from http://www.openoffice.org - it's freeware.

[Nora]

As far as the sooting goes I'd also suggest that there wasn't enough charge to properly expand the brass to seal the neck in the chamber on launch. Whether it be from work hardened brass or just not enough bang a little more powder should take care of the sooting.

my .02

Nora

[augois]

I had the exact same keyholing at 50yds. with my Swede the last time out to the range With the 140gr. Lyman Loverin design sized .266. I had never shot this boolit before. I guess I have to slug the barrel, and maybe get a .268 sizer die. I don't remember off hand, the powder or charge, but would an under powered charge really cause so much instability.

[jim4065]

I had the same keyholing in my 94 Swede until I kicked up the speed. Low fps means low RPM's, and the spinning top falls over. Just my experience.

[Dutchman]

Some good feedback, I appreciate it.

The 108 gr were seated out far as I could go and still have some good support for the bullet.

While the brass I was using was Swedish once-fired and I'm sure is somewhat work hardened, this extreme sooting didn't occur on all the cases. This part of the mystery is really strange far as it goes. Since I have no more of these light bullets it won't be a further problem.

I've shot the 140 gr Loverin .266" in 3 m/96 Swedish Mausers. None have tipped or canted or tumbled. One of the rifles that shot the above target has quite a worn bore but still shoots pretty good.

The Lee 170 gr. My first load with it was 13.8 grs 2400 since I had no data I winged it. I use Lee dippers for a lot of cast bullet loading for some strange reason. This 13.8 gr load did have consistant tipping. But they were also very accurate. So I upped the load to 17 grs 2400. This is a much more substantial load. But still tipping. The bullets are seated to hit the leade with a slight crush fit. As long as you don't open the action before shooting its ok as the bullet would probably remain stuck in the barrel. I like the 170 gr Lee. I can try upping the charge again but I'll have to research comparative load data first. The 17 grs was a pretty nice load. And since the same rifle shoots .266" 140 gr well its not a matter of bore size being too big.

I have some SR4759 and Re7 so I'll work up a load for the Lee 170gr in 6.5x55. The bullet is very capable so its worth the effort. I bought the mold for this and the Lyman 140 gr Loverin and the 150 gr Lyman which is apparently a rather new mold. I'm anxious to try it out.

I need to put a little more care into matching cast bullets with particular rifles. All bores aren't uniform. I've been lucky so far but wednesday I was shooting a bunch of rifles I don't normally shoot so I had no history shooting them with cast bullets. This was the 1909 Argentine and the 1908 Brazilian. I have better examples of both those rifles so they'll be the ones I slug the bore on.

I'll refer back to this thread as there's some good advise. Thanks.

Dutch