Marlin 45-70 Bore dimensions?

This is almost like backwards engineering because I'm already successfully casting and shooting a PCed Lee 340gr boolit from my ported 1895 45-70 Guide Gun but I'm not real familiar with the typical bore dimensions of the 45-70 like I am with various 30 calibers.

To add to the confusion is the fact that the Lee mold is marketed as a .457" as is their sizing die. I thought a 45-70 was supposed to have a .458" groove diameter so something isn't making sense here.

I'm sure the reason my boolits are working is because the PC and I'm not sizing them but I'd like to size them if for no other reason than to have them starting all the same size.

So my question is for those of you shooting the Marlin 45-70 (standard 6 groove rifling) if you have slugged your bore what dimensions did you get and whether you slugged it or not what diameter are you sizing your cast boolits? Thanks,

Motor

Mine slugged .4575. I'm sizing .459. 25+/- year old Marlin 1895.

Attachment 210984
Attachment 210985

Mine is 2010 Remlin . It'll take a .461 .
The gross barrel slug is .451-.4505 X .457+ <.4578 .
It isn't egg shaped but it's not uniform , balanced but not uniform .
It's almost like the bore was tapered small then pushed back out with the rifling button .
It is also 6 right .

The rifle delivers about what I would expect from a heavy cal , light weight lever action and I blame the last half inch of every group on me and bad gravity .

My 458193 Lyman has been the best bullet to date , dropping @.459 shot as cast groups have visited <2.5" live CTC for 5 shots same load different days . Because it is a work in progress with 3 correct bullets and 3 for fun I haven't shot long strings .

17nut, I can't make out the numbers on my phone I'll see if I can read them later on my home computer.

Thanks for the relies. It makes me wonder even more why the Lee stuff is .457" I just got a good deal on a .457" size die. When it arrives I guess I'll have to size a couple and see what they measure then go from there.

It wouldn't be the first Lee die that I polished to increase size. ;)

Motor

Have you measured a boolit to see what your lee mold is actually dropping them at with your alloy? What do they measure after powder coating?

.460" in both my regular 1895 with MG rifling and the Guide with ballard rifling.

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Originally Posted by starmac

Have you measured a boolit to see what your lee mold is actually dropping them at with your alloy? What do they measure after powder coating?

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I couldn't remember so when I got home from work tonight I grabbed my 0-1 Mic and the boolits and measured a few.

I got from .4585 to .461 but the .4585 was only on the small side. None of this is surprising to me since they are as cast and as powder coated (shake and bake method).

I do know they shoot good but I would really like to round them out some. LOL

Judging by the posts so far it seems opening up the .457 die is almost a certainty.

Motor

I bought a .459 sizing die from TrackOfTheWolf for mine

Quote:

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Originally Posted by Retumbo

I bought a .459 sizing die from TrackOfTheWolf for mine

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I went with a .460 from them and use it in my H&R BC. Before powder coating that Lee mold dropped too small, but powder coating gets it up plenty large to size down to .460 in the die. Now I am ringing the 500 yard gong with no leading and no smoke. :)

Quote:

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Originally Posted by Motor

17nut, I can't make out the numbers on my phone I'll see if I can read them later on my home computer.

Thanks for the relies. It makes me wonder even more why the Lee stuff is .457" I just got a good deal on a .457" size die. When it arrives I guess I'll have to size a couple and see what they measure then go from there.

It wouldn't be the first Lee die that I polished to increase size. ;)

Motor

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Pics get bigger if you click on them!

Thanks for all the great replies. Judging by current success and current un-sized boolits and the information you guys provided I now have a very good idea on what will be best.

You guys are awesome, as usual. :)

Motor

If you are casting from a relatively soft alloy, say 19:1 Pb:Sn. the bullet will
obturate (bump up) to till the grooves on firing.

big fat bastige... honestly, no clue what mine slugs. I just went with Lee 405 HB mold and 460 Lee sizer. Works great and stopped there. I do have a couple RD molds, yet to cast, but they should drop at ~460 too so don't plan to pound a slug thru the bore.

Well the last few Lee molds I bought drop either just on marked size or small. My older Lee molds drop a little big which is better. These 340gr drop right on .457" (and a little out of round) then I powder coat them which adds maybe .002" at most.

The alloy is between 12 and 14BHN. These do work with starting trap door loads using IMR-4198 I polished my die so a .459" gauge pin just fits. I ran all of the boolits I had through the die some barely made contact 5 did not touch at all.

I'm going to purposely load these 5 and shoot them from a clean bore and observe accuracy and fouling. If these work .459s should absolutely trouble free. It does appear that I'm going to need to massage yet another Lee mold though which really isn't a big deal anymore. :)

Motor