A good friend has an H&R 1871 Buffalo Rifle in .38/55. The judge shoots a load of 21 grains of H4198 with a 244 grain hard cast bullet. He said last weekend the bullets began to keyhole when he could find them at all on his target. There is about a 30 degree lower difference in temperature in the area he shoots now compared to the same area three months ago. His load was way at the lower end of the scale, giving him about 1,300 fps. I told him to try increasing his powder by a couple of grains with the same bullet. Any suggestions as to what the heck is going on? Thanks ... Tom Purdom

His rifling twist is possibly a bit on the slow side for this bullet weight (lenght) and he added to the problem by driving it slow, The keyholeing might go away with a little more velocity but the problem still remains that the twist isn`t right for this slug. I`d try another bullet of a shorter lenght, and speed it up some.
I doubt the temp had anything much to do with this.

I don't know if this relates to rifles, but I shoot a lot of lead bullets in 38 special and have found shooters will get keyholes sometimes when their barrels are leading real bad and have not had the lead removed. Lewis lead removers work great for pistols. Just a thought.

Tom..
I have no hands-on experience with that round but am aware that there are a variety of bullets listed for it, but in different diameters. Apparently some years ago Marlin and other mfrs. used slightly different bore specs for this round. Rather like some of the rifles available in 7.62X54 with variances between .308 and .311.

Also, isn't this a blackpowder cartridge? Twist rates are going to vary depending on whether the intention is for BP or smokeless.

Also, check the crown for damage.

twist...
either the barrel is too slow or the bullet is too long

velocity
too low, then it wont stabilize

bore diamater
bullets undersized
bore over sized

jeffe

I have two rifles that keyhole:
1)Enfield No. 4 mark I 303 Brit with .318" grooves, will keyhole 303 Brit ammo with .309" bullets.
2) Ruger 44 mag with end of the barrel blown off due to leading. A piece of smooth bore was welded on, and now it keyholes 240 gr bullets. Can't stay on the paper at 25 yards.

IT COULD BE HE IS USING TO HARD OF ALOY FOR HIS BULLETS TRY 30-1 TO 20-1 LEAD TIN NO ANTIMONY OR TRY A FASTER POWER IE 2400 296 H110 START AT 10.0 GR AND MOVE UP,ALSO TRY A SOFTER LUBE LIKE SPG IF YOU ARE NOT GETING A LUBE STAR ON THE MUZZLE OF THE BARREL YOU NOT GETTING ENOUGH LUBE. THIS IS WHAT I HAD TO DO TO GET MY 32-40 TO SHOOT WHEN I SHOT SHUTZEN RIFLES. HOPE THIS HELPS WELLS

wells,
please turn OFF you capslock key, as all caps is considered to be "shouting"
jeffe

Like Bob and Clark said, maybe he's got the wrong diameter bullets. John Sweeney's book says original 38-55 caliber rifles had groove diameters between 0.377" and 0.382". Do you know what diameter bullet your friend is using, and does he have the option of sizing it down less when he lubricates? If he's a whole 0.004" under groove diameter and doesn't want to buy a whole new mould, maybe he could paper patch these up to groove diameter.



H. C.



(edit)

P. S.



He could find out whether the bullets are too small in diameter by shooting them into dirt and digging them up. If the rifling looks washed off by hot burningn powder gases getting past the bullet, he may need a bigger diameter bullet. If the rifling marks on the sides are clean, maybe diameter is not the problem. Bullets can be bumped up to a slightly larger diameter, but don't ask me about the technique or equipment.

I think the culprits have already been defined, but I doubt it is a problem of twist rate. IIRC the 38-55 normally used a bullet heavier/longer than a 240 grain thing would be, so I'd investigate elsewhere. First thing I'd do is slug the bore to check groove diameter. Hard cast does not obturate hardly at all with low pressure loads, if his bullets are undersized they are likely not engaging the rifling enough.

Clark!

Quote:

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Ruger 44 mag with end of the barrel blown off due to leading. A piece of smooth bore was welded on, and now it keyholes 240 gr bullets. Can't stay on the paper at 25 yards.

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Please tell us that story!POTKB!