Micro-Groove Barrels and Lead Bullets....

[SSN Vet]

this was posted in a thread comparing Marlin vs. Winchester lever action rifles in .30-30 win, on the Rifle forum the other day....

if you shoot cast in the micro-groove barrel it can be a real pita to get it to shoot straight.

Have other's reloading .30-30 with cast lead bullets had similar experiences in their micro-groove Marlins?

 

[enkindler]

Use the slowest powder that will get you to the speed you want and slug your barrel to make sure that your bullets are at least .0005" over maximum groove diameter and it will shoot fine.

 

[LHB1]

No experience with .30-30 but had no problems with my Marlin 1894 shooting full power .44 Mag ammo with hard cast lead bullets from H&G mold lubed with ALOX-Beeswax lube. Extremely accurate and no leading. YMMV

Good shooting and be safe.
LB

 

[ClarkEMyers]

Microgroove by definition has shallow grooves and larger bore -

Microgroove by definition has shallow grooves and larger bore - people who match the bullet to the bore and throat report fine results in a Microgroove barrel - but the same bullets that work in the Winchester may not work as well in the Marlin.

Some folks who just want to buy cheap bullets report that bullets available to them don't fit the Marlin with Microgroove that well.

 

[GooseGestapo]

Like another stated, the microgroove barrels tend to run a bit larger in bore diameter than conventional bores.

My first attempt at loading cast bullets in a microgroove barrel didn't go well. It was a Marlin M1894 in .44mag. I was loading and shooting an S&W M29 that shot real well with my Lyman 429421 bullets, sized to .429".

The rifle shot patterns not groups. Groups at 25yds ran 5"+. I parted with the rifle and went on to other pursuits. (I found later that these can need bullets running from .431" to .433" to shoot well. Ditto the .444 Marlin)

Later, I became interested in loading for a Marlin M336 in .35rem. It shot well with some 156gr HPGC bullets at .358" but ran out of accuracy at above about 1,700fps.

I later started playing with a Glenfield M30 (Marlin 336 w/birch stock and half-magazine). It showed promise with .309" bullets but above about 1,700fps it too started throwing it's groups.

Then, I read an article in the American Rifleman by C.E.Harris about loading for the various SKS's, and the variation in the bore diameters, and he made an anectdotal comment about the Marlin bores running larger. This got me thinking, and I tried some of my Lee 150gr FNGC sized to .311" through my .30/30. (I'd been playing with some SKS's too).

Voila !!! My groups at previously "jacketed bullet" velocities were as good and often better than the jacketed bullets.

My .35Rem has responded well to larger sized bullets, but I don't have a suitable mould for duplicating factory 200gr ballistics. I plan to some day however. (I'd try the RCBS 200gr FNGC first)

Now, I just size all my .30cal bullets to .311 as I've found that my .30/06 likes them better this size too.

My Marlin .45/70 guidegun shoots very well with it's bullets sized to .459", or not sized at all with the case of a .459 HollowBase 405gr FN (Lee). I just hand lube the cooled bullets with SPG, load and shoot them. I suspect it just might do better at .460-.461" however.

However, for max velocities and flattest loads, I use the 300gr FNGC (RCBS) over a heavy charge of H4198, for about 1,900fps. This will take care any use I'll ever have for this rifle. At these pressures, it seems to be obturating sufficiently to get a tight bore, and accuracy is quite good.

So, run your .30cal bullets for your Marlin at .311" and It'll do just fine.

For more info, check out www.marlinowners.com