Home Forums Lever Action Central Marlin 336 Lever Actions 336 micro groove and cast bullets.

As the title says how do they work in micro grooved barrels.. I have heard yes and no. I am really looking for jacked bullets but a friend pointed these out to me. What is the story. Will they work or move on. Mostly I wanted these loads for shooting rocks, p. dogs, jacks, etc. Thanks!

I have an 1894 in 357 with a micro grooved barrel. It shoots excellent with a cast bullet. I am using a gas check.

Am shooting a 336 30-30 with microgroove barrel. 160-170gr cast with gas checks. sized to .309, some are even .310. If you go .308 (like Jacketed bullets), they wont work. I shoot a lot of silhouette, and they group in 2" at 100 meters. 19gr of Accurate 5700.
John

The only problem is Marlin's tend to have very short throats and steep leades. It's easy enough to have it reamed out, which I what I've done.

I have a first year of Microgroove 336SC in 30/30. With cast bullets sized .309 and seated to just kiss the lands it will shoot circles around my Ballard rifled 336SC. I have never tried to load them to factory speeds but over Trailboss or a mild load of 3031 they shoot great.

It does have a very short throat but it makes it easy to get an OAL that puts the front driving band into the rifling.

They work fine but often not the same bullets. A typical rifle cast bullet will have a bore riding front section and a groove size driving band section toward the rear. Micro groove runs a slightly larger bore and a slightly small groove diameter. Anything bore size has to be a tad larger to fit the bore and a tad small to not be oversize for the groove. Proper temper and bump up may help.

I have a few rifles with microgroove barrels and once you understand the issues it’s not hard to get them to shoot cast bullets.

In general, cast bullets that are cast hard, larger than groove diameter (2-3 thou) and are fitted with a GC is a generally fail safe combination in microgroove barrels.

The problem is that the shallow rifling needs to get and maintain a decent grip on the bullet. Undersized bullets rarely work and you may get by with a softer alloy and no GC but experimentation is key.

To get over the throating issue use a Lee FCD - they are very handy as most leverguns in rifle calibres have no throat.

I shoot a lot of these without a gascheck at reduced plinker velocities through a microgrooved Glenfield 30-30: https://oregontrailbullets.com/xcart/?target=product&product_id=3

Over Unique, 2400, and Blue Dot, they do minute of soda can, even using a Williams peep. They're a lot of fun.

15 to 16 grains of 4227 with a bullet that fits is as accurate as any 30-30 I have. I had Tom at Accurate molds make a custom mold for me that fits Marlin throats very well. I believe it is the 31-180R but don[t hold me to that. I'm not at home and can't check. For a production mold the Saeco 315 is an excellent generic bullet. I believe the 315 number to be correct. The Lyman 311467 (?) should work as well.
Good Luck,
Rick

I've heard that longer heavier cast bullets work better than the shorter lighter bullets in micro groove barrels. I've never tried lighter bullets so I can't claim this is true.

For years I've been shooting .30 cal 175gr cast bullets sized .310 diameter with a gas check out of a Marlin 336 with excellent results. I have not found the micro groove barrel to be a problem. Years ago I used these bullets in metallic silhouette matchs. Today I use them mostly for informal target shooting.

Go ahead and give them a try I don think you will regret it.

My 45-70 shoots Lee 340 grain bullets fine. Never an issue.

LOTS of info on the web about shooting cast bullets in micro-groove Marlins.
Try the MarlinOwners.com