Marlin 336 Bore

[Bzcraig]

I originally posted this in the lever gun forum but only got two responses, hoping for more here.


I have read numerous posts stating that Marlin 336's w/mirogroove rifling need larger boolits. I finally got around to slugging (thank you fishman for the slugs) the new to me 336. When I put the mic to the slug I got .3084. Has anyone else gotten similar results? I use Lee sizers, so should I size to .311 or get a .309 try it and open up to .310 if needed?

[mroliver77]

My 30-30 is close to same as yours. I have a .308 then .310 size die so went with the .310. It has worked so good I never tried any other. My gun will shoot any alloy! I have never seen one iota of leading. It will loose accuracy fast if you push the alloy strength too far.

If you do a neck/throat impression you will find that there is no traditional throat. I believe this is why these can be cantankerous with lead.

Like most will tell you, go with a little harder alloy than you would in any other gun. I have shot pure lead balls, swaged pistol bullets linotype and in between in mine with good results. I have full throttle jacketed loads with cast that shoot well.

Try your .309. Go on from there.
Jay

[Bzcraig]

Thanks for the info, that is great input. I was going to try straight ACWW then start to add linotype as necessary. This is the first rifle I will cast for.

You mentioned a cast of the throat/chamber, I bought some Cerrosafe from Brownells but am having a hard time trying to figure out a good way to get the alloy into the chamber without making a mess. Any suggestions?

[Pb2au]

I found sizing to .309" for my 336 was successful as well. I use ww alloy, air cooled. I would be willing to bet that adding the lino probably will not be necessary for run of the mill load data.
FYI I am using the Lee 170 grain RNFP with the gas check. I have made gallery loads with Trailboss, up to more conventional loads with IMR 4227. I am currently ready to test some loads with Alliant 2400 as well.
Good luck in your endeavors!

[runfiverun]

my 30 caliber default size is 310.
generally the throat will take this size easy enough and will feed from the tube without difficulty.
in most of my rifle caliber lever guns the nose diameter is what aligns everything and light engraving definitely helps with accuracy.
you know you got it right when the lever just snicks shut with a little resistance but doesn't affect operation.

[blackthorn]

The following came from a disscussion on another topic. Following these instructions will allow you a straight-on shot at your rifle's chamber, making chamber casting much easier. Hope this helps.

"A Marlin model 336 is easy to clean from the breech by opening the lever half way, removing the lever screw, removing the lever, pulling the bolt from the frame and removing the ejector, thus removing any danger of bending it."

Have a great day!

[mroliver77]

I dont use cerrosafe. I do an impact impression. I fill an old case with lead after shortening the neck about 1/8". I roll a heavy .30 cal pure lead slug between two pieces of steel until it is slim enough to fit down a lightly oiled bore. I have a selection of steel rods and use one that fits bore close. A wind of black tape every few inches keeps it from touching the bore. I use a heavy hammer or light sledge and rap it a few times. You can feel the difference when lead is upset as hammer bounces back. It takes a couple light taps to help open the bolt, not enough to alter slug but just enough to help move it. Now you have an impression of the neck/throat area that will never change dimension.
I can get the exact chamber length, the neck o.d., where the throat begins and see the shape of the throat.
I used to do this to every gun. I only do it now for problem children.
runfives post is great too in my opinion.
J