How much needed in the .45-70 to obturate hard Laser Cast bullets?

[tacotime]

If I read correctly, these 350g and 405g bullets are high on the hardness scale... thought I read 18bhn (or more?). How much velocity is likely needed to keep these boolits from leading up the barrel?

I was shooting a light 4198 load with a 350g and later found it had been leading up a bit at the breech in the Ruger #3. I think it was 29 grains and obviously not high velocity then. Accuracy was good.

Also using 3031.


Thanks.

[Harter66]

Lead at the breach is dia , lead at the muzzle is lube .

That hard and under sized I don't think you can hit them hard enough to seal the throat. Maybe a plain base gas check or a wad card treating them like BP w/o the lube cookie .

[RickinTN]

The LASC link which used to be at the bottom of the page has a wealth of information. It is not speed which obturates a bullet, it is pressure. I think the factor is about 1,422 times the BHN of the bullet, so if the hardness of the bullet is 18 it will take about 25,596 PSI to obturate the bullet. Not sure what kind of 45-70 your shooting but that would be a push for many as I recall. I like my 45-70 bullets to be in the 10-12 BHN range. I shoot a few Marlin levers and a couple of Browning 1886's.; My rifles can stand more velocity than I can.
Good Luck,
Rick

[rintinglen]

Those hard boolits need a pretty good kick in the pants to get them to play nice. It helps to give them a coat of LLA or BLL, but you still are going to have to hit them hard to obturate. The 350 will need something on the order of 50 grains of 3031, or 41 grains of 4198 to get where you need to go.

[tacotime]

Dang that's a lot of 4198 for the light afternoon I had in mind...

The boolits are ALOX coated by me.

I got these hard boolits before I knew there could be a rifle bore leading issue. I really had only thought of leading as a handgun issue. Doubt a bore size issue with the #3 but possible I guess. Never really have heard anyone complain about #3 bore sizes. But Ruger can make mistakes. I have history on that.

Guess I will have to bump it up.

Thanks and more opinions welcome.

[elk hunter]

I've not shot the Laser Cast 350 in a 45-70 but have shot a lot of them in my 500-450 double ahead of 54 grains of H-4198 and 12 grains of Dacron. They're going right about 2000 fps and shoot great with no leading.

Of course your mileage may vary.

[tacotime]

Was hoping for some pretty light loads...

Can I put gas checks on these?

[Larry Gibson]

I used to live 40 miles north of Laser Cast Bullets and also contracted with Powder River Cartridge Company for load development using Laser Cast bullets. I've shot thousands of their bullets including their 45-70 bullets. The Laser cast bullets you have should be .458 or .459 and if your barrel's groove diameter is .459 or less then it isn't the alloy causing the leading in the throat, but the lube is the cause. You are getting a bit of gas blowing by the bullet before it seals the bore.
The bullets do not need to obturate.

I suggest a light coat of LLA on the bullets over the lube already there and let them thoroughly dry before loading. That should cure the leading problem. It did with all the Laser Cast Bullets I used that caused similar leading in the throat. Not all the bullets caused leading with all loads, but some did, especially those in larger cases such as the 45-70 with light loads.

[dla]

I bought a lot of Oregon Trail 405gr unsized/unlubed. They ran about .461" and I'd pan lube them with the concoction of the day - shot great through my Guide Gun. I ran them at about 1800fps.

More LLA is your best bet, otherwise I don't know of a trick to cure leading from undersized bullets. Btw, I suppose I should ask how you know the leading is significant?

[FredBuddy]

I'd try the LLA route first. If that's not satisfactory then
clean the factory lube off (as described on this site
in several places) and powder coat up to size.

I started using store-bought cast bullets years ago.
Didn't know better till I found this cast boolit web site.
Now I have 1/2 ton of wheel weights and pure lead
to melt down and only shoot my own cast boolits.
Talk about good therapy......