Marlin #336 .45-70, Microgroove + Scope

[Maven]

My Marlin #336 .45-70 has proved to be exceptionally accurate with cast bullets and microgroove rifling in spite of rumors to the contrary (and I don't even use linotype or heat treat my CB's!). I added a 4x scope to it not long after I purchased it, but removed it for a BP cartridge match my gun club was sponsoring. As receiver sights were permitted, I added one and have been ambivalent about it ever since*, as it was much harder to "zero" when different powders and charges and different weights of CB's were used. Last week I decided to remount the scope, but keep the receiver sight body in place. Well, the CB deities must have been happy with me because sighting in took only a half dozen shots. Final adjustments at 50- and 100 yd. will have to wait until the snow cover melts enough so that I can see the brackets which hold my target frame. Indeed, it is much easier to shoot good groups when you can see the target clearly!

The attached image was shot @ 50 yd. with the 4x scope mounted: LBT ~460gr. FPPB CB + 17g r. WC 820


*The receiver sight looks better on the gun than the scope, but the latter is easier on the eyes!

 

[Chris]

That is a nice group. I have the same rifle and it shoots beautifully, there isn't a bullet or powder that it doesn't like. Of course it has preferences, but across the board if this rifle were female you would marry her.

I have an LBT 405 that shoots like yours at all practical velocities. Back when Veral fitted the bullet to chamber and bore.

I don't buy the prejudice against microgroove bores at all. I own several and they all shoot cast great if I take time to fit them to the bore.

 

[Ian]

Go ahead and try Linotype. I dare you

Ok, just kidding. Don't, because if you do you might find out how some of those ancient rumors about cast bullets and MG rifling began.

 

[oscarflytyer]

only trick to MG bbls (imo, and experience with all mine) is to size .002 over. So .310/.311 for 30-30, .360 for 35 and .460 for 45-70. Works great in mine. All with BLL and WW+2% tin, except 45-70 which is Lee HB and BIG lube grooves, so pan lubing it. And shooting all with Skinner peep sights. and all works almost exactly the same - great!

 

[Chris]

only trick to MG bbls (imo, and experience with all mine) is to size .002 over. So .310/.311 for 30-30, .360 for 35 and .460 for 45-70. Works great in mine. All with BLL and WW+2% tin, except 45-70 which is Lee HB and BIG lube grooves, so pan lubing it. And shooting all with Skinner peep sights. and all works almost exactly the same - great!

Agreed, that works for all mine, too. It is critical.

 

[Brad]

That is a heck of a group. Mine isn't microgroove but it is capable of far better than it should be.

 

[Maven]

Thanks, guys! Brad, you may find this interesting: I was shooting the .45-70 at our range one day when my friend and his brother showed up with another Marlin .45-70 except it had Ballard rifling. Using factory ammo, first in my gun and then in his, I got identical results @ 100 yd. Chance? perhaps, but I think accuracy depends on more than rifling type especially in light, lever action rifles.

Ian, I haven't seen linotype in years. My small stash was the result of good fortune. To wit, a lino pig left at the curb and a small bucket of very small type (used for printing numbers on checks I was told) given to me by a shooter friend. Also, I and others created quite a flap "over there" when we challenged a well-known gun writer's assertion that MG bbls. would only shoot linotype CB's accurately.

 

[Brad]

Microgroove not shooting cast is a fiction perpetrated by the Lyman manuals. Hard bullets at 1600 fps max.
Yeah, maybe with the sizes Lyman suggests. Run a 444 Marlin with a .429 bullet and it is not likely to work out well. Size to .432 and things change rapidly.
My 30-30 is microgroove and I never worry about accuracy due to it with cast. I know what to feed it and never have felt handicapped.

I think that sometimes the writers are too cosy with some manufacturers. Rather than test the assertion they take it as gospel.

 

[Maven]

"I think that sometimes the writers are too cozy with some manufacturers. Rather than test the assertion they take it as gospel."

Brad, That particular writer was a shill for Lyman, which was justly criticized for their molds and customer service. He must have taken those criticisms personally as he convinced Lyman to pull their support for the then new Cast Boolits site.

 

[Brad]

What was it Reagan said? Trust, but verify.
Lyman manuals said microgroove was bad with cast. I read on CB that it wasn't so. I tried on my own and made my own observations.
I don't believe much of what I hear or read until I validate the source, verify the info, and investigate.

 

[oscarflytyer]

MGs will shot cast all day - sized correctly. Just ask Ranch Dog! And may others - mine included! I have a .311 size die for the 30-30, custom .460 die for 45-70 and JUST scored a .360 die machinist reamed for the 35 Rem. 30-30 mold should drop big, 35 die is an RD = big, and 45-70 is a big Lee 405 HB which bumps up, with a 460 RD mold in the wings. Only one in the middle is the Win 94 32 WS - and will also prob bump it up .001-.002. Do the same for my revolvers with cast.

The MG bbl myth is the same as with the Glock bbls. Go .002 over and watch jaws drop!

 

[Rick]

Oscar, .002" over what dimension for the revolvers? Would probably be best to size revolver to the throats, not .002" over groove diameter.

 

[Chris]

This MG myth needs to get done. It has been disproven so many times that I think it deserves a seat with "the earth is flat" crowd. I don't think we should give it anymore time if the caveats are stated. This is getting old after 40 years of reading about it with no credible evidence for the hypothesis.

 

[Rick]

Welcome to the wonderful world of cast bullet old wives tales Chris. Hard Cast. Smoke the mold. Cast will ruin a micro groove barrel and a long list of others. Never will get rid of them because they are far too often repeated, even in print.

 

[Chris]

Welcome to the wonderful world of cast bullet old wives tales Chris. Hard Cast. Smoke the mold. Cast will ruin a micro groove barrel and a long list of others. Never will get rid of them because they are far too often repeated, even in print.

I suppose this is the raison d'etre for this website and its members...

 

[RicinYakima]

History lesson for today: Why size bullets to the diameter of the grooves of the barrel? Well in the 1890's through 1930's the only lead bullet target game was Schutzen. In that the bullet was pushed down the muzzle to a position, fully supported by lands and grooves, just in front of the chamber. Then from the rear a powdered cartridge case was inserted. These shot very well for the day, less than 1 MOA at 220 yards. Gun writers and mould makers from then on said you should size bullets groove diameter because that is what the Schutzen shooters did.

Since there were no target games for fixed cast bullet shooters, they worked out great hunting loads that were sized to the throat. This was actually mentioned in several articles back in the 1920's. In the 1970's Col. Harrison and that puppy cub writer (C. E. "Ed" Harris) began working with Marlin lever guns. They discovered the same thing, fit the throat (on commercial rifles normally .002" larger) and accuracy was fine. The CBA shoots only fixed ammo (and get groups less than 1/4th the size of the best Schutzen records) only and now publish data.

Gun writers do something once, write the article and swear by it for 50 years. Why do more research when nobody is paying you to do it? Like an elderly hippy "Never trust a gun writer of 40, they already been paid for it!"

 

[Ian]

I suppose this is the raison d'etre for this website and its members...

Exactly, Chris.

Some other tiresome misconceptions:
"You can't shoot cast bullets accurately past 140,000 RPM".
"Wax=flux".
"You can't shoot cast bullets in a self-loading rifle".
"Leverguns can't be accurate".
"Fillers are dangerous no matter what".
"Slug your bore".
"When in doubt, add more tin!"

 

[oscarflytyer]

Oscar, .002" over what dimension for the revolvers? Would probably be best to size revolver to the throats, not .002" over groove diameter.

Rick - you, Sir, are absolutely correct! Above worked perfectly fine/same for me/revolvers - throat/bbl/etc was good - until I got the Uberti 44 WCF. While I did not slug the 44 WCF bbl, I DID have to use a cast bullet that worked thru the throat. And that was a .430! Which is supposed to be way big for 44 WCF (.427). And it is a big balancing act to size the case to 44 WCF specs AND stuff with a .430 slug! Looks kinda funny/odd/off/pregnant. But, at the end of the day, it works and shoots well! In the end, Ugly is as Ugly shoots!!!

 

[Brad]

Please don't get Rick started on not using cylinder throats as bullet sizer.

I find that .0005 to .001 under throats dimension works well. Go even a little large and you can get leading in the rear of the barrel. At least that is my experience.

 

[oscarflytyer]

Please don't get Rick started on not using cylinder throats as bullet sizer.

Brad - You mean I am not 'sposed to yank a short hanging chain?!? Dang, what lack of new year's fun is THAT?!?!

Rick - don't just jump on this and get Brad pissed at me!!!! lol!