bullet tumbling in flight
Topic got locked before one very common cause for bullet tumbling from lever action rifles was mentioned. That's the condition of the bore just inside the muzzle. A lot of lever guns get cleaned from the muzzle end. His is a Marlin which are much easier to properly clean from the chamber than a Winchester but a lot of Marlins still get a rod shoved down the muzzle. With 1500 rounds fired,and if cleaned often, the rifling just inside the muzzle could be very worn even if the rest of the bore is pristine. It happens a lot. I've seen them so worn that a bullet will fit into the muzzle butt end first.
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Customer called about a Marlin 336, 30/30 , saying that the bullet is tumbling at 50 yards. Gun is about 30 yrs old, and bore looks good. Using 160 gr. in the new lever hornady rounds. Any suggestions? I am going to check out the bore and the riflings when it gets in also trying some other rounds and grains. I will probably lug the barrel for a measurement . He says about 1000 - 1500 rds fired in lifetime. Is there anything else. thanks 0 -
Check the crown of the muzzle with a loupe. At fifty yards, the crown or an extremely unbalanced projectile are about the only things that could cause the tumbling at such a short distance. 0 -
How does he know it is tumbling? What does he say is happening? 0 -
The rifling might be the wrong twist for the weight of the projectile. If he is using a different size bullit it may have this affect. 0 -
Just last week I got a Browning BAR (30-06)into the shop with 5 rounds of new factory ammo and a 12" paper plate with 1-1/4" X 1/4" tears in it... Customer says "bullets tumbling @ 115 yds." I believe him...I touched up the crown of the barrel just a touch... Fired the 5 rounds @ 100 yds... bullet holes are round, but no group whatsoever...Plan on touching up the crown some more and try again...
Good luck with yours...
JIM..........0 -
Thanks for the suggestions, I will be checking the crown out. Thanks again, 0 -
THE CROWN WILL NOT CAUSE BULLETS TO TUMBLE(OPEN UP GROUPS A BIT SURE), AFTER A VERY GOOD CLEANING TRY AGAIN WITH LIGHTER WEIGHT BULLETS. ALSO CHECK THE END OF THE BARREL FOR A 'BULGE', I'VE SEEN A BUNCH OF RIFLES THAT HAD THE SNOW/MUD CLEANED OUT OF THEM BY SHOOTING = INSTANT BULGE. 0 -
Bullet tumbling? There really aren't many choices, all already mentioned. To expand a bit:
a. Damaged/bad crown.
b. Severely worn rifling (though if so, you should see this easily with bore exam).
c. Bad ammo:
1. Wrong bullet type for gun (either bullet too heavy for rifling rate of twist, or bullet diameter is too small for bore).
2. Outright defective ammo (eg insufficient powder/ bad handloads/ defective bullets, etc).
Assuming the bore is OK, and you're using quality factory ammo, you've eliminated b and c2.
New 160 grain Hornady rounds ought to work fine in a standard 30/30, and I think probably eliminate c1. So assuming the bullets actually are tumbling here, I doubt its the ammo.
I'd say check the crown carefully, and assuming you don't see a problem, try some different ammo.0 -
I think thye "key" lies in the words "new Lever Ammo" wherein the new style bullet & weight combo doesn't like the old style rifling meant for the stocky fat projectiles. I base this on having major grouping problems with the new stuff in the older lever guns. Didn't have any tumbling but played hell trying to keep them on the paper at 50 yds! Try the old stuff, can't hurt! 0 -
The standard weight bullets for the 30-30 are 150 grain, and 170 grain. The new Leverevolution ammo is 160 grains, so the rifling should stabalize that. But, I suspect the 160, being pointed and all, to be a bit longer than the flat or rounded nosed 170's. I am not sure but what Marlin might have tightened the twist in their newer rifles for this hopped up ammo...probably the same twist as the 308 Marlin Express.
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New bullets are too long for the rifling pitch to stabilize.
Try lighter weight bullet if you want to use the new Hornady bullets.
Also check for ringed barrel and Microgroove rifling which was a bad idea from the get-go.0
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