Just slugged the bore on my Marlin 45/70 Microgroove

[UKShootist]

Greetings all. My first post on what looks to be a treasure trove of information.

I'm having some accuracy problems with my Marlin 1895 45/70 Microgroove barrel. I've just slugged the bore using a plain lead 500 grain bullet. It took some tapping through but seemed fine. I'm guessing that the amount of force needed, reasonably strong but not overly so I felt. The result was .458" / .453" Does this sound about right? Given that the Lee mould purports to provide a .457 bullet, and such commercial cast bullets I can buy do the same, I would assume the bore is a little over size.

[Char-Gar]

Marlin MG barrels tend to run larger in the lands and grooves than most other barrels of the same caliber. Sometimes quite a bit larger. What is needed is a larger sizing die. I have a special .460 dies that I use for my Marlin 45-70. The bullets RCBS 405 FNGC, are .4595 as cast and therefore are just lubed in the die and the GC crimped on. Accuracy is outstanding.

[Chris C]

Get your bullets sized correctly and the micro-groove .45/70 is a very accurate rifle. I don't have any recent or longer distance targets but back when I was first seeking proper bullet fit for mine, I shot this 10-shot target at 25 yds.

168706

[UKShootist]

Thanks chaps.

[osteodoc08]

Bump the sizing die up a little. Should be GTG

[Freightman]

Get the 405 HB mold have had two both dropped at .460 one gave up after many years new are better.

[runfiverun]

just get a mold that pours to 460.
458 is the correct diameter for a 458 barrel.

[Geezer in NH]

I have never had good targets with my Marlin 1895 with 500 grainers.

[OS OK]

Get your bullets sized correctly and the micro-groove .45/70 is a very accurate rifle. I don't have any recent or longer distance targets but back when I was first seeking proper bullet fit for mine, I shot this 10-shot target at 25 yds.

168706

That's nice, looks like all 10 went in at an inch, consistent…only thing is, at 100 yards that's a 4 MOA rifle. Is that standard for a 45-70?

[fourarmed]

My 1895 Microgroove is considerably larger than that. It has been a long time since I slugged it, but I believe the groove was AROUND .4595". I reamed out a sizing die to about .461" so that it lubes only. What was the diameter of your slug before you drove it through the bore?

[Chris C]

That's nice, looks like all 10 went in at an inch, consistent…only thing is, at 100 yards that's a 4 MOA rifle. Is that standard for a 45-70?

At the time, that was pretty good for me................but that was 2 1/2 years ago. I'm shootin' at 50 yds now and many of my targets look like that. Haven't done any target work at 100 yet. I know many people who can do that at 100 yds day in and day out. I'm just not one. The gun always shoots better than the shooter..............so I can't really state what "standard" is.

Haven't shot the .45/70 in over a year and a half as I've gone to a .38-55 single-shot 1885 Highwall for my target work.

[OS OK]

I really like the 45-70 and hope to someday find the one that has my name on it. My guns out shoot me as well, but ever now and then I get all them to conform nicely as you have done there.
Open sights and old eyes!

charlie

[dubber123]

The chambers on some of those Marlins are on the "generous" side. I have an 1895 CB, and a .462" sized hand load will drop right to the rim and bounce.

[wmitty]

The Lee 340 grain I tried was undersized and accuracy non existent. Ordered the Ranch Dog 350 grain and was much happier. Think my Marlin is a .46-70!

[MrWolf]

My 1895 Microgroove is considerably larger than that. It has been a long time since I slugged it, but I believe the groove was AROUND .4595". I reamed out a sizing die to about .461" so that it lubes only. What was the diameter of your slug before you drove it through the bore?

Just checked my notes and that is exactly what mine is.

[quasi]

.460 dia. has worked for me in two micro groove 45-70's. .461 is very slightly better in both rifles. Bore dia. is not as important as throat dia. in my experience.

[knifemaker]

If you size your cast boolits to .460 or .461 you should see a good improvement in accuracy. Most Marlins 1895s I have seen or used liked a .460 boolit. I have a 1895 LTD-V that will shoot 1 inch groups at 100 yards with a Ranch Dog 350 gr. RNFP boolit sized to .460 using 43 gr. of IMR-4198 powder for a velocity of 1850 fps. I will shoot the same size group also using the Hornady 350 gr. RNFP jacked bullet which is also .460 in dia.