I am certain that the subject of cast bullets and Microgroove barrels has been done to death, but I was not involved. I now have a Marlin 336A (30-30) and want to "give it a go" with cast bullets. I have some ideas and theories, but would like to hear your ideas, theories and experiences.

One of my first cast shooters was said Marlin shooten 170 Lee's treated hard. Just was lucky, LBT blue and it shot as well as any orange slug at max speeds.

--micro's tend to run large. I have a 30 caliber blank here that's 3085 x 3034 or so. I've seen 30's to 3105 and bore dia's that were a tight .300. Go figure, they must vary the button speed per wear or something to get those numbers

--you'll hear pure, rank bullsh** that micros lead. Likely these experiences are soft, undersized slugs blown thru minus any grip on the rifling-- which is generally shallow.

--IMO muti groove barrels like the Marlin grip the bullet more securely, like the fine sharper teeth on a new pipe wrench. Ever use said tool that was old and worn? It slips-- new one doesn't.
Less bullet slugging or none means better groups.

The crap heard about micro's is again more reguritated cast myths from the past. One squeeky wheel has a problem and the world hears about it. It just isn't fact....no more than any other barrel has the potential to give problems in load developement per cast shooten.

Charger, Marshall Stanton on the Bear Tooth Bullets web site has a list of average Micro groove barrel bore diameters and recommended bullet diameters. There's no guarantee that your barrel matches his list, but it's a good starting point.

The average micro groove diameter for a Marlin 336 in 30-30 is .310 with a recommended bullet diameter of .311. The 32-20 is .313 with recommended bullet of .314. In general, all the micro groove barrels are larger than normal and require bigger diameter bullets. Turbo

Be warned that microgroove barrels crop up in NEF rifles. You can also be warned that moulds that cast big enough can be hard to come by. You're lucky in that .30-30. .311 moulds and sizing dies are readily available.

I just halved the group sizes and eliminated bad fliers by lapping a Lee 457-405HP out to .461. Really annoys me that I had to do that.

I am also working on a microgroove Marlin .44 Mag. It did well when I could get enough lino to shoot straight lino bullets, but is crappy with WW.

My opinion, and it is purely an opinion, is that microgroove would be as good as any if Marlin/NEF had the good sense to make their barrels a thou under spec instead of a thou over.

It's just another example in the long list of examples of the firearms industry crapping all over the shooters.

I've been shooting cast boolits in my 336 Marlin chambered for .35 Rem for about 25 years without any leading. I've shot probably a couple thousand rounds loaded with pistol bullets both gc and pb. Plinking accuracy has been about minute of pop can at 100 yards. A few months ago I got a Lyman 358315 mould and even with much heavier powder charges there is no leading and accuracy is fine. My lube for the past several years has been Orange Magic. Before that it was anything I could find.

I've shot the Lee C309-150-F for many years with no problems in my 30AS. Alloy is WW with 1% added tin and dropped from the mold into cold water. I lube with Lee liquid alox, size them .310 in a Lee push through and drive them 1,924 fps average. No leading, accuracy is same as jacketed.

I've got a Microgroove .45-70. I think it's got 12 grooves, but it's been a while since I counted 'em. Groove diameter is .458". No problems with cast.

Once had a Marlin bolt rifle based on an FN action with a micro groove barrel. It was a 300 H&H re-chambered to 300 Weatherby Magnum with the micro-groove barrel. Original owner lived in Illinois and shot a lot of cast bullets with it. I could never get the thing to shoot under 3 inches! Ended up trading it off and the new owners could not get it to shoot either.

I had two 336's in 35 Rem. One had the regular barrel and and one microgrove I slugged both and sized the bullets .002 over and both shot cast very well. My son has the 1950's model with the balard barrel now. I still shot the micro groove with cast and half jacket pistol bullets. The cast are 3 parts WW one part Lino air cooled, lube is anything I have. I am going to cast some after and try some Felix lube. So far it has done very well in the other calibers.

AKA elbStJoeMO

Ed, I shoot the RCBS 200 grainer in a MG 336 35 Rem with FWFL. You will not be disappointed. btw, this is my first and only MG and so far very satisfied. Someone (other than ish) ask Jump if he likes MG bbls. sundog

I've never bought the MG/cast boolit bugbear myth. Almost to the exclusion of all other forms, PPC revolvers use multi-groove or MG copy rifling patterns hereabouts, and those wheelguns absolutely drive tacks with butter-soft wadcutters. Little sister's PPC gun (M-10 with rebated cylinder, slab barrel) is a MG pattern, and she runs around 1480-1485 out of 1500 pretty consistently. Naw, those MG's won't shoot lead worth a darn!

Thanks guys..I think I have a mould that should do the trick. In my 311291 collection there is a DC that throws bullets .302 on the nose and .315 on the body. I have some of these cast up (Lyman No 2) and sized .311. I stuck the nose of one of these in the muzzle and the nose is a hair larger than the bore. I can push the bullet in by hand, and see where the top of the lands have engraved the bullet nose. Seems like a good fit to me. I will give it a go over a healthy does of 3031. Thanks again..

IMASHOOTER2
thats nearly the same as my shooting rig here in england.What powder do you use? I tried reloder 7 but it leaded so badly I couldnt hit a coke can at 25m

marky123,
I always go back to IMR3031 and a Lee dipper for my .30/30 cast loads.

I load for a Marlin .45 camp carbine with a MG barrel. It's not a tack driver, but it does OK, and it doesn't lead at all with 200g SWC's cast from WW.