Micro groove barrel and cast


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Mac2
September 24, 2011, 09:43 PM
I've cast and loaded pistol calibers for years, but recently wanted to dabble in casting for rifles. Thought I would start with 30-30. I have a Marlin 336 with the micro groove barrel. I read over in the rifle section a post about the micro groove barrel not being compatible with cast bullets. Any experience with using cast in the Marlins? I've got a 170 gr TL w/ GC mould. Thanks for any experience before I cast a thousand or so. Mac.

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jerkface11
September 24, 2011, 09:55 PM
Gas checked bullets should be fine with micro groove.

Raymond Bob
September 24, 2011, 10:34 PM
Cast bullets that are a little over sized to better in the Marlin 336 with micro groove. You can slug your barrel and size bullets .002 over the groove size. I have found that the best result is to size to fit the throat. Basically, use the largest size you can chamber.
You will find a lot of Marlin's, including mine, do best with a .311 bullet. Many do fine with .310.

Bob

Mac2
September 24, 2011, 10:57 PM
My mold is a .309 as is my sizer. Too loose or will it still work? Thanks for the replies. Mac.

PO2Hammer
September 24, 2011, 11:35 PM
The Marlin Owners forum has a few very in depth threads on this subject.
http://www.marlinowners.com/forums/index.php?PHPSESSID=07b52sn64rkee8a5ruuhdcvlo0&board=5.0

the Black Spot
September 24, 2011, 11:38 PM
My marlin 444 will group under two inches at 100 yards with cast 310 gr from lee mold using varget powder. I think slower powders help when shooting cast bullets.

jcwit
September 24, 2011, 11:38 PM
Marlin also has micro-groove in their .22 rimfire barrels and lead .22 bullets just fine, ssooooooooooo?

tackstrp
September 24, 2011, 11:46 PM
check with Ranch dog http://www.ranchdogoutdoors.com/ he sells a custom mold for marlin rifles. Sadly all tumble lube.

GooseGestapo
September 25, 2011, 02:53 AM
I think you'll find that your .309" moulds will cast to .313-.314".

All of my Lee .309" moulds do. The .309" is the nominal size-too size, not exactly what they cast out at.

I've shot my .309" sized moulds to .311" through not only my .30/30 MG barrel with excellent accuracy, but have also shot them through a .310" SKS, and even several .303British rifles. I have a .314" Sizer for the .303's, but find that the die only lightly touches parts of the bullet, and dosen't completely size them. It does however apply the lube properly (Lyman 450 die).

Sport45
September 25, 2011, 03:07 AM
My marlin 444 will group under two inches at 100 yards with cast 310 gr from lee mold using varget powder. I think slower powders help when shooting cast bullets.

What diameter are they sized to?

the Black Spot
September 25, 2011, 06:59 AM
.432

Sport45
September 25, 2011, 12:10 PM
Thanks!

Mac2
September 25, 2011, 10:16 PM
Thanks to all for the replies. One of my C&B pistols is .31 cal, so I have a supply of .311 rb that is pure lead. Slugged out to .309, so I'll be going with a .311 sizer. These will also be tested in my SKS and Mosin. I'll check the 308 model 788, but they may work in it also after I check it's bore. Again, thanks. Mac.

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