RCBS .50 cal Adjustable Minie Ball Mould Help

[Pelicannon]

It seems I'm at my wit's end here gang and need more experienced minds to help:

The Rifle-
Lyman (Investarm) Great Plains Hunter, 50 cal, 32" barrel, 1:32 twist, ~.506 lands and ~.510 grooves, Percussion with Hi-Lux 6x long malcom scope.

Ignition-
CCI No 11's, CCI No 11 Magnums, Remington cleanbore 209's, federal 209's, Winchester 209's

The Mould -
RCBS Hodgdon .50 Cal Adjustable Minie ball, Lee 320gr REAL

The powder-
Pyrodex Select FFg substitute (I ended up with a case of this stuff a while ago so I need to stick with it)

The Problem -
I have tried 320 gr REAL's (Pure Pb and WW) with 3 different lubes and with/without Wonder Lube Felt wads. I've tried the aforementioned mould configured to throw Pure Pb at 300gr, 325gr, 350gr, 375gr, 400gr, and 420gr. All the above Minies were tested with 3 different lubes starting at 60gr (Vol) and working up. I've tried dry-swabbing between shots but that didn't work. My normal procedure of alcohol patch-then dry patch cleaning every 3 shots doesn't seem to make a difference either. EVERY range day ends with a dish soap and HOT water scrub of the bore followed by a thorough drying and ballistol wipe.

NOTHING IS EVEN REMOTELY ACCURATE!! The best I've gotten with the Minie's was 3.5" at 50 yds.
I finally got frustrated enough to try stuffing a lee 452-300-GC that I use for 45LC and Casull into a Harvester sabot and that got me 3" at 50 yds.

I really want to make this mould work for me as it keeps cost to a minie-mum and makes reloading in the field significantly easier.

Here in Wy, getting within 75yds of your intended animal is doable but INCREDIBLY difficult, so a load that can get me to 125+ is what I'm after. I'm acutely aware that many ML's are capable of 2" at 100yds, which would be MORE than adequate for my intentions. If y'all could send a few ideas to help me conquer this cantankerous beast, it would be greatly appreciated!

[Gtek]

.506/.510, .002" land depth? Also you do not say what the minie comes in at (diameter). How tight is the start and trip to the bottom?

[charlie b]

For mine I have used several different bullets. I suspect the fast twist and shallow rifling grooves are to blame for your trouble. The GPH barrel was designed for sabots.

1. Hornady Great Plains. Size to .502 (it does not engrave on loading). Use lubed felt wad or card and felt wad. 100gn powder. 2-3" groups at 100yd (some of that is me ).

2. Lee 500S&W (C501-440-RF) soft lead (1-40 or 1-30 alloy). Size to .496. Paper patched. Size again to .502. Use card and lubed felt wads. 80gn powder. 2-3" groups at 100yd.

3. BACO 450gn PP bullet. Paper patched. Size to .502. Use card and lubed felt wad. 80gn powder. 2" groups at 100yd.

4. Silver and black base Powerbelt bullets. 100gn powder. ~2" at 100yd and still decent at 300yd. Flatter trajectory than the other three.

PS if you have recoil issues then the Hornady or Powerbelt might be better. The 440 and 450gn bullets are hard on the shoulder.

PPS watch out for the butt plate on that thing. I made the mistake of shooting it once with just a shirt on. Cut the skin and left a nice bruise. I filed the bottom edge a bit rounder and still always use a shoulder pad with it (PAST).

[Pelicannon]

Gents thank you for the quick replies!!!

Got home and did some more measuring;
I shoved a REAL down the bore and measured it like a slug once I got it back out;
.512” groove to groove
.507” land-to-groove (the 5 land rifling makes measuring a hint tricky)
So… I’m guessing it’s a .502” land to land measurement!

These figures would make a lot more sense as my minie’s (at least this last batch cast HOT) drop at .498”

Gtek- thanks for making me confirm those numbers! The muzzle is tight and there may be just a tad bit of taper as it gets a smidge easier toward the breech.

Charlie B - thanks for the recommendations!!!! I haven’t run across anyone around here that has a similar rifle so I appreciate you sharing your loads! I second the sharp butt plate problem; took a grinder to mine before I even took the first shot! Thankfully I’m not too recoil sensitive, so I’ll be looking into those 400+ gr freight trains too.

[megasupermagnum]

Neither of those molds are known for being precision shooters.

TC Maxiball, 370 grain. Send it hot, start at 100 gr of powder and go up from there. Only lube the small bottom groove. Use a felt wad under it. If it wont shoot that good, it won't ever shoot.

https://www.trackofthewolf.com/List/...1/BALL-50-MAXI

[Fast Asleep]

I would offer that your bore diameter at .506 may be the culprit. All of those bullet and sabot combinations are designed to be used in a .500 bore. I shoot two .50 cal fast twist muzzle loaders and have easily attained the kind of hunting accuracy you seeking—as long as the projectile diameter is properly matched to bore diameter.
My first rifle is a self-built undehammer with a Green Mountain barrel with a 1/28 twist and .500 bore that shoots both the Lyman Great Plains and Lee REAL bullets (pure lead only) very well. It also shoots well with the Harvester >300 grain sabot with 300 to 520 grain pure lead 45-70 cast bullets that have been lubed and sized first at .460 and then step sized down in NOE dies to .457,, .454 and finally .451.
The second rifle is an early White Bison in line with a .503 bore diameter. The Lyman and Lee don’t do well in this barrel (due to the .503 bore diameter), but the Harvester sabots do REALLY well with pure lead bullets sized no smaller than .454”. The key here is to size the bullets no smaller than needed to be able to load them. I have taken 5 deer and 5 elk with these rifles with 10 shots at ranges between 20 and 170 yards here in wide open Nevada utilizing 100 to 120 grain loads of 777 3F powder.
I suggest you try the following:
1 The Harvester >300 grain sabot with a pure lead 45-70 bullet sized down to .458 or .457
2 The Lee 450 or 500 grain bullet intended for the 50-70 cast in pure lead and sized down to just barely slide down the barrel. I lube this type of bullet with something like Carnuba Red that isn’t as messy to load in the field.

[Fast Asleep]

One more thought—does your rifle have a hooked breach plug to permit easy removal of the barrel for cleaning? Years ago I had a TC Renegade .54 with such an arrangement that gave poor accuracy. I noticed that the barrel/tang fit was quite loose in the stock and remedied that by first soldering the tang to the breech plug and then glass bedding the barrel in the stock channel. After that the rifle was very accurate with both patched round balls and full diameter pure lead bullets.

[charlie b]

FWIW, I seem to remember the Lyman manual saying the bore was .502 and groove .508 with a 1:32 twist. That's why I size my bullets to .502. The shallow grooves were advertised as being optimal for sabots. They certainly work well with soft bullets and stout charges. The manual did list an upper charge limit of 100gn with up to 430gn bullets.

These were the BACO 450gn on the left and Hornady GP on the right. 100yd into sandy target berm.

[Pelicannon]

All,
I apologize for the lengthy delay between posts, holidays started to occur, and the semester is winding to a close, so things have been more chaotic for me.

THE 370gr MAXI BALLS WORKED!! Factory maxi-ball, wonder wad underneath, 90 gr of Select with a CCI No.11 shot 1.18" at 100 yds with an MV of 1400 fps.

Unfortunately that has been the only thing that worked. As I have been incredibly cramped for time on the range (its been dipping into the -F here) more testing will have to wait. A friend did walk me through paper patching and while incredibly fun, it did not serve to solve the issue of the undersized Minies. As I am hesitant to lap out a $120+ discontinued mold, I purchased a Lee Improved 500-534-Minie mold to alter if necessary in hopes of finding a more permanent solution.

I have started lubing with the old ordnance manual mix of beeswax and tallow to lube a friend's ticking strips, hope to try it out on the new mold as well. I will keep y'all appraised of any progress.

Thanks again!

[BLAHUT]

Try pure lead. You can bilge the mold, can be easily undone. I use the lee Maxie/Minney ? ball, 360 gr ? hollow base, Lee real bullet 340 gr ?, A 500 gr bullet, in a wolf .50 cal, all in pure lead, very accurate at 100 yds. have not tried it longer.

[megasupermagnum]

There are plenty of 50 caliber maxi ball molds around. TC hasn't made molds in a while, but they are available all over for cheap. Lyman still makes one, but it's over priced and single cavity. Arsenal still makes them for a good price, you can choose 1 through 5 cavities. Also on Track of the Wolf, they have a custom run Lee 6 cavity maxiball mold.

I say buy a maxiball mold and run it. It's a fantastic design that shoots good in a lot of guns. Whatever bullet you use, pure lead is generally the most forgiving in a muzzleloader.