Suggested loads for Marlin Microgrooves

[cp1969]

Hi, I've got two Marlins I'm considering switching over to cast. Both have Microgroove barrels.

M336C, .30-30 Winchester, no idea of bore diameter.

M1894CS, .357/.38 Special, no idea of its bore diameter either.

The molds I have for the 1894 are handgun--RCBS 150 SWC, which works very well out of an M586 S&W, and a Lee 158 RNFP which has not been tried on anything yet.

The molds I have for the 336 are an Ideal single cavity marked "308291" "52" and an Ideal single cavity marked "154 GR" "896" "308241" These two molds have been bead blasted down to bare metal. Both are plain base.

Thanks. Any advice or recommendations will be appreciated.

[Baja_Traveler]

The most important thing you need to do is slug those bores and use a micrometer to measure. The particular mould you use is half as important as sizing to the correct diameter. My microgroove likes them tight, so I size my 30-30 to .310

[EDK]

MARLINS like hard alloy, oversized for caliber, gas checks, lots of bore contact, and higher velocity.

i run 360 diameter in my 357 COWBOY RIFLES. 180 grain round nose flat point NOE.
My 30 30 gets 311 and LYMAN 311041 gas check. I have a plinking load I'm working on with a plain base clone.

Your bead blasted molds are probably ruined by the bead blasting.

[Rapidrob]

The microgroove barrel needs a hard cast gas check bullet for one reason only. Leading is a bear to remove.
Other than that, any bullet that fits the bore should be fine.
My 1895 .45-70 fouled badly when I shot soft cast bullets for the Trap-Door Springfield rifle out of it decades ago,now I know better.

[cp1969]

Your bead blasted molds are probably ruined by the bead blasting.

I was afraid of that.

[FredBuddy]

Learn to powder coat. It gives you the ability to
use softer lead as in wheel weights, plus it
allows you to increase the diameter of the
boolit to match your bore. It does, however,
cause nose diameter problems (too big) for
some designs of boolits in chambering.

Use expander plugs that are just .001-.002-.003
smaller than your boolit so you don't reduce the
diameter of your boolit less than what you plan.

Especially for my Marlin 30AS, I found that a
taper crimp die solves lots of chambering issues.

So, in my 30-30 microgroove, I use the NOE 127
RNFP, powder coated and gas checked, 1600 fps
and get excellent accuracy. Not a deer load normally,
but good for anything else in my area. (Took me
2 years to get here!)

My Marlin 1894 does best with the Lee 125 RNFP,
powder coated and sized just under .360 at about
1400 fps.

Enjoy the chase !

[Mk42gunner]

It has been a few years since I played with, um I mean worked with, my cheap 336 aka Model 30AW Marlin. It tended to like .311" boolits. I loaded everything with a plain old set of RCBS .30-30 dies and neck expanded with the expander from a set of RCBS .30 Carbine dies.

Now, later in my cast boolit shooting journey, I would use a Lyman M die to neck expand since I now have a set of Lyman dies for the various .32 handgun cartridges.

Robert

[ulav8r]

Try the molds before dismissing them as ruined. They might work as is, or if not too oversized the might respond well to a light lapping.

[cp1969]

Try the molds before dismissing them as ruined. They might work as is, or if not too oversized the might respond well to a light lapping.

I will. Somebody gave me these molds years ago, so I've got nothing to lose by trying them. They're both round nose and I don't know if that's OK for use in tubular magazines?

[cp1969]

It has been a few years since I played with, um I mean worked with, my cheap 336 aka Model 30AW Marlin. It tended to like .311" boolits. I loaded everything with a plain old set of RCBS .30-30 dies and neck expanded with the expander from a set of RCBS .30 Carbine dies.

Now, later in my cast boolit shooting journey, I would use a Lyman M die to neck expand since I now have a set of Lyman dies for the various .32 handgun cartridges.

Robert

Thanks. What mold did you used that cast .311 or bigger?

BTW, I live about 40 miles NW of Butler. Get down to the Koehn bakery every now and then.

[Chihuahua Floyd]

Round nose lead is fine for tube mags. Pointed bullets not so much.
CF

[toallmy]

Polish up the cavities and give the molds you have a shot . You might be pleasantly surprised ......

[smkummer]

I have a microgroove 1894C. it loves Lymans 358430 190 grain UNSIZED. When I sized that bullet to .358, my accuracy went south. I can shoot that ammo in my revolvers until its gone. can't remember what its dropping out of the mold but obviously fatter than .358.

[Maven]

I don't go to any extraordinary lengths to create a "hard" alloy for my guns, which include a Marlin #336 Microgroove .45-70, but I do size my CB's to fit the bore. That means .459" for the .45-70 and .310" when I still owned a [336] .30-30. Surprisingly, I got little to no bore leading from either rifle, but a pc. of copper Chore Boy wrapped around a bore brush (wet or dry) remove what little there was. In the .30-30, Lyman #311466 and Saeco #315, sized to .310" were the best performers.

[popper]

Try 16gr 2400 with the PB (PC helps) sized 311. Pushing harder will require GC.

[ABJ]

Marlin micro's are no different for loading and sizing than any other barrel. I have load tested dozens of 30-30 marlin's. They all preferred .310 to .311 boolits. .311 most of the time. The alloy does not have to be hard. Mine is about 13.5/14.0 brinell. 2 percent tin and just shy of 4 percent antimony. You said your molds are plain base so I suggest a velocity below 1200 fps. I do not have a 357 but I do load for three 35 Remington's in a 336. No accuracy difference in either .358 or .359. Same alloy but gas checked and loaded to 1800 fps.
I wish these old Marlin wives tales would die. That is not to say your gun might not prefer a .359 because some do not because of micro groove but different tolerences just like in any barrel.
Tony

[Mk42gunner]

Thanks. What mold did you used that cast .311 or bigger?

BTW, I live about 40 miles NW of Butler. Get down to the Koehn bakery every now and then.

Several different .32 handgun molds and the Lee 312-185. I just single loaded the 185, I figured if I were to take it hunting, I would either bump a flat nose on it or file the meplat on a few rounds. Then I hurt my back and haven't done much of anything for a few years.

Pretty close to Paola, KS then?

Robert

[cp1969]

Thanks for all the tips.

Mk42gunner, yes, about 7 miles northeast of Paola.