Home Forums Reloading Bullet Casting Cast Bullets in Microgroove Barrels

The Gunsmiths I've asked say I can't expect any kind of accuracy.

Cast bullet makers claim their bullets will shoot as good a jacketed bullets in Microgroove barrels.

My experience has proven the Smiths to be correct.

I'd love for one of you to prove them, and me, wrong.

MG barrels can do OK with cast, but fit and alloy in relation to pressure is critical.

What have been trying to work with? Bullet, cartridge, alloy, lube, etc. etc. ad nauseum.

Details...all of them...

I wonder how many have actually tried it? I've been casting for about 50 yrs, this statement IMO is erroneous in nature and subject to hearsay not so much based on actual experience. Having cast and shot hundreds of rds via MG barrels in the early days Dan's question of certain SOP variables certainly come into play for MG accuracy.

The only microgroove I shoot cast in is my Marlin 30-30 and it does just fine. But I cast a very hard bullet for it using wheel wieghts and 5% babbitt. I also don't try to achieve world speed records with my loads.

I have killed two deer with them at about 100 yds, and punched clean through both of them. If I didn't have so many other rifles waiting on thier turn to hunt, I would take it elk hunting.

Curdog, There's some dialog on the matter in the following link and if you search the site you'll find quite a bit of discussion on the topic.

http://castboolits.gunloads.com/sho...th-Shooting-Cast-in-a-Microgroove-Barrel

My personal opinion, fit is more important than your chosen alloy. Dunno what you plan to do with the loads, but for general purposes I'd start around Lyman #2 alloy, sized minimum .001 over groove, and .002 over groove won't hurt. A rifle powder, not a pistol propellant and look for around 1,800 fps +/- for starters. Might be you could do straight wheel weights and ballpark factory velocities if all is up to snuff with your loads.

Little research is a better path than urban legends. One of the things I've seen repeatedly in this discussion is that Marlin bores tend to be a wee bit oversized and that determination is critical to success. Slug or pound cast your barrel before you do anything else. It's 90%+ about fit more than anything.

What you contemplate is no stranger than shooting 4mm lead BB's in a 7.5" twist 12 groove barrel....well.

My best accuracy was always cast no softer than 20:1,.002 over if possible, rifle powder only unless a pistola chambering of course. Lastly I never even pushed GC velocity envelopes much above 1650 and kept plain base bullets around 1300-1400.

Slugging the bore saves time to taylor your load so I always treat each barrel as an unknown quantity with its own personality.

I have two Marlin lever actions, a recent vintage 444P and a 1972 1895 in 45 70. The 45 70 is the one I've tried the hardest to shoot cast in.

From research I find that the '72 model has bastard rifling......8 grooves but depth is supposed to be the same.

I had the barrel cut down to 20 inch length a few years ago and accuracy with the 350 gr Hornady became really great with three shot groups at 100 yards never going over three inches. The only reason I want to shoot cast is because of their reputation of not tearing up meat while still producing an exit hole in good sized hogs.

I've tried bullets from five sources..... six if you count the 500 gr that Sharpsguy sent me... and there is no difference in the results. I've tried three different rifle powders and varied the weights to get from 1300 fps to 1700 with each one.

Even calling some of the shots "flyers" forty yard groups of four to five inches are the norm.

Y'all have pretty much confirmed what I have come to expect which is that my bore is o s for the bullets I've tried.

One final question...... I have not seen any rifle bullets with gas checks while some of my revolver bullets do have them.

Are they not effective even if velocities are kept in the range I've mentioned.?

Most Lyman moulds are notorious for throwing undersized bullets which can make them a bear to shoot accurately even with mass quantities of tinkering.Been there done that more than a time or two myself. A personal opinion here if your're so inclined would be to slug the bore and have a custom mould cut to the bore specs +.002.

Lots of good companies to choose from these days NOE,NEI and Accurate are just a few the latter being my choice of pref simply because of a very diverse catalog with many custom designs..I've had six cut by them so far, all drop exactly like requested so it's doubtful you couldn't find what you're looking for to tighten up that 45/70.

http://www.accuratemolds.com/catalog.php?page=all

Another good article on the subject of shooting cast in MG bores. http://www.lasc.us/FryxellMarlin-MicroGroove.htm

My hunting pard switched to a 1980's vintage Marlin .30-30 and asked me to cast bullets and help him work up a load. Knowing that we were opening a can of worms, I forged ahead, but didn't get too far. I tried my standard hunting bullet/load and got good results right off the bat.

We found his throat to be .3095, with bore diameter of right at .300. (I won't mention groove diameter as it's totally irrelevant.) The 190 grain FN bullet out of my old custom Saeco mold drops at .310 with a .300 nose riding portion, using straight air cooled WW alloy cast hot hot hot- 850-900º. BHN 12 is the average. I lube them unsized for in my generously throated Savages and old Winchester 54, but I squeezed them to .309 for in his Marlin. (Rule of thumb: size .0005" under throat diameter, come what may. Yes, that's not a typo. 1/2 thousandth.) Seating depth had to be adjusted down a tad for his gun as the throat in my M54 is long and the leade is a shallow 1½º included angle- it allows for long COA and gentle introduction of the bullet into the rifling. I re-throated the rifle myself from its original abrupt throat/leade configuration.

We tried my 28gr. 3031 all time bestest proven hunting load of 28 grains first, as a starting point and to start gathering data. We went no further. The initial testing at 50 yards (original factory open sights, no less) yielded several 1" 3-shot groups, and a ragged 10-shot group that went about 1½". Apples and clay pigeons set up at 100 yards exploded. The azzhat even smacked a bunch of apples at 150 yards, after bumping the sight ladder up a couple notches. 28 year old eyes. What can I say that's polite for mixed company?! We stopped right there. I loaded him up with 120 rounds and sent him forth into the world with a smile on both our faces.

Woody sent me some of his bullets and I just tried 3 with 4198 and 3 with 3031.

First two with faster powder touched at fifty yards then a bad flyer. I suspect a bad crimp as I was crimping on a band per his suggestion.

Looks promising.

I suppose it's been covered adequately already but piling on. The Marlin Micro Groove rifling form can do well and even very well with cast bullets. That said the successful cast bullets will be fit to the Marlin Micro Groove and likely enough those that work with the Marlin will not work very well with other rifling forms. Both bore and groove dimensions are different for Micro Groove. As noted Marlins have shipped with a wide variety of rifling over the years. The 444 generally has a very slow twist and is picky about what can be stabilized.

Expecting to vary bore and groove without changing performance falls in the category of never was and never will be.

That means cast bullets that perform well in the marketplace likely fit the majority of rifles but do not fit Marlin Micro Groove rifling forms. That can reasonably lead to a decision not to bother as it can be more trouble than it's worth.

Temper and gas checks will need optimizing for desired speeds or vice versa speed can be optimized for temper and gas check forms on hand.

This implies ideally getting a feel for throat dimensions and bore dimensions and groove dimensions with lead slugs or preferably chamber casts. Followed ideally by varying dimensions by alloy and sizing on your own bench. supposed to be is a recipe for disappointment.

When you get it down then try plastic coating or paper patched.

I cast the 311041 and size them to .310, with a Hornady gas check and LBT lube, In my Marlin .30-30, over 22 gr. of IMR 4198, they will do 2" at 100 yards for 5 shots. That's good enough for me.

Old70.