I have a bunch of 405 grain bevel base bullets that I am trying to make work in my Marlin 45/70 rifle. Every load I have tried with Trail Boss, Unique and 3031 powder (900-1200 FPS) causes the bullet to tumble, very poor accuracy. With 405 grain gas check bullets, the rifle shoots good (1" at 50 yards, 1.5" at 100 yards), so the rifle will shoot cast lead.

I'm thinking these bullets may shoot OK if the base of the bullet is protected by some sort of wad, maybe cardboard? I tried toilet paper and that was no good, bullets still tumbled. I have around 350 of these bevel base bullets and I'd love to be able to use them for 50 yard target shooting, plinking, maybe medium size game....

Any ideas?

You could try a plastic wad cut from coffee can lid. There is not enough info to analyze why you are getting a tumble but it sounds like the bullet is too small and/or powder charge is too light.

I am with Dan, I would mic the bullets and see if they are cast too small.

Another consideration is if your gun has Micro Groove or Ballard type rifling. The old MG rifling was not conducive to good accuracy with straight cast bullets which is why Marlin went back to the Ballard type.

The rifle is a new Marlin with Ballard cut rifling. I have miked the bullets as best I can with a cheap Sears Micrometer, with that tool they mike .460, so I am sure they are the advertised .458 diameter.

I had not thought about trying a faster load, I'll load up some with a mid-range velocity, say about 1500 FPS using 3031 powder...

That and I'll try some sort of over powder wad.

I'll tell you, there are few things funner than smashing targets with a 405 grain bullet! I was shooting some of my good, 405 grain gas checks this morning, shooting square cut bits of 2 X 4's at 50 yards, and some clay birds. When they hit the bits of 2 X 4, they make a very satisfying "Plunk" and the wood bits go flying. The clay birds they just pulverize. I am thinking of getting my welding guy to make me some steel targets to shoot, some 8, 6, and three inch circles to shoot at different ranges, maybe a steel swinger to shoot at 200 yards...

A hard wad down over a load of smokeless powder with an airspace under the bullet is at great risk of ring-bulging your chamber. Don't do it. Some say a soft wad like a ball of Dacron or kapok big enough to fill the case will be ok... some say not.

Me?
I fill the case up with powder... black powder.

my Ruger #1S in 45-70 won't shoot plain based lead bullets worth a ****. with gas checked bullets it shoots very good. I got tired of trying to figure out what caused it. one of my favorite loads is 18 grains of Unique with the Remington 300 grain hp and no filler. there is a lot of room for the powder to shift but it doesn't seem to matter. this load chronographs at 1,450 fps and shoots into 1.5 inches or less at 100 yards. a filler with the plain based lead bullet had no affect on the groups. they were always terrible as in 6 inches or more at 100 yards.

Try using a powder that was made for your mission. IMR's 4759 or AA 5744 will allow you to eliminate the air space and get the bullet to a velocity fast enough to stabilize the bullet. Data is in the Lyman Handbook or on the powder manufacturer's web site. Both powders are designed for cast bullet loading in big cases. Bob!

Be very cautious in using any kind of wadding inside a rifle cartridge like the .45-70. I know that some people swear by Dacron batting as "wadding" to keep the powder toward the bottom of the brass- but a friend of mine here in the gun club put a good "ring" in the chamber of Pedersoli rifle doing just that.

If you want something to protect the bullet, get some vegetable wads that are lubed from Circle Fly, or get some Durofelt and cut and lube your own- both of which are cost effective and keep the bottom of your bullet from scorching. However, as suggested try a bit heavier load first.

On the wads, be certain that they are right up against the bottom of the bullet. Do not use them to hold powder in the bottom of the case which creates an air space between the wad and the bullet- a very dangerous condition indeed.

__________________
Lost it all in a boat accident

I had a similar problem with my Mod. 1895 Marlin w/micro groove rifling,what worked was using .460" dia. with the Lyman 405gr.and hard alloy(can't scratch with thumbnail.
Tightened the groups right up.Shot a Russian boar end for
end,fell over in his tracks.

try to use 462 bullets if they chamber is ok ,dont put hard filler
paper toillet, dacron or kapok works fine
i always put kapock in reduced loads.
have a nice day
ANDRE

I guess I'll not try using a hard wad under the bullet, I'll experiment with different velocitys instead. That, and be happy with my gas check bullets...

Thanks for the heads up about "chamber rings", never heard about that phenomenon before.

Hey Canoeguy;
I have a trapdoor that has same problem with keyholing.
I used 36.0g. 3031 behing Magnus 405g. bullet.
at 25 and 50 and 75 yds. everything OK. At 100 yds, keyholing
I raised powder charge to 38.0g 3031 and no keyholing.
I used mag primers for all loads.
This keyholing probably due to lower powerder charge and longer twist. A more modern rifle, like a Marlin 95 or Ruger
has a faster twist.
Remember the trapdoors , at end of their career used 500 grain bullets, especially for long range shooting.
Hope this helps...
Smikem

Rifle Magazine Nov/dec 1977 45/70 at Two Miles: The Sandy Hook Tests of 1879........405gr bullets bombed then...500 and 535 were what did the job at ultra long range the 45/70 needs the weight.