I posted this question on another web site, but thought you guys would like to take a shot at it over here. The more knowledgeable people I have looking at it the better.

I have barrel leading problems after shooting 20+ rounds. I attributed this to the bullet alloy being too soft and asked if there was a way of "heat treating" them to obtain full hardness.
Several of you said that my problem was not with the hardness, but with the fit (or size) of the bullet and suggested that I slug the barrels.
Before I get to that, I will rehash my story for those who have not read it.

I have 4 .45-70 rifles, 1 H&R 1873 trapdoor carbine, 1 original Springfield 1884 Trapdoor, 1 Pedersoli Sharps and 1 Uberti High Wall. The bores in the newly made guns look to be in excellent condition. The High Milage gun is the Sharps with over 400 rounds thru it. The 1884 bore is "good" with no rough spots or pitting in it.

I cast my own bullets using Meister lead Alloy which is supposed to be SAECO 10 and when I drop the bullets from the mold I have been letting them air cool. I do not have a lead hardness tester so I don't know what the air cooled bullets actual hardness is.
I am using Lee # 457-340F molds which cast a round nose 3 groove bullet and have been sizing them in a Lyman .457 Lub/Sizer. The sized bullets measure .4565-.4570. They are lubed with SPG.
The loads I've been shooting are 30.3 grains of IMR4198 which should be developing about 1150-1200 FPS. I have not shot them over a chronograph though so I don't know. This low velocity about duplicates the original Black Powder loads and thats where I want it because 1. my shoulder doesn't like hot loads and 2. because I don't want to damage the 1884 Trapdoor.

I have never been able to get under a 2 1/2 inch group at 50 yards even using the set trigger on the Sharps.

I slugged the barrels using a pure lead .50 cal roundball and then measured the grooves and the bore diameters this process produced on the slugs. The following is the results of this process.
H&R TRAPDOOR CARBINE: 8 GROOVES, BORE DIAMETER .4460 GROOVE .4562

UBERTI HIGH WALL: 6 GROOVES, BORE DIAMETER .4490 GROOVE DIAMETER .4545

PEDERSOLI SHARPS: 6 GROOVES, BORE DIAMETER .4490 GROOVE DIAMETER .4560

SPRINGFIELD 1884: 3 GROOVES, CANNOT GET GOOD READING. DIMENSION FROM 1 GROOVE TO 1 BORE IS .458. I am not really expecting much from this gun and some of the leading may be due to the bore.

As I was told the slug needs to be .001 over groove size and the grooves in the Uberti and the Pedersoli are .001 or more under the slug size do you have any idea what the problem is?

I posted this question on another web site, but thought you guys would like to take a shot at it over here. The more knowledgeable people I have looking at it the better.

...snip...

I slugged the barrels using a pure lead .50 cal roundball and then measured the grooves and the bore diameters this process produced on the slugs. The following is the results of this process.
H&R TRAPDOOR CARBINE: 8 GROOVES, BORE DIAMETER .4460 GROOVE .4562

UBERTI HIGH WALL: 6 GROOVES, BORE DIAMETER .4490 GROOVE DIAMETER .4545

PEDERSOLI SHARPS: 6 GROOVES, BORE DIAMETER .4490 GROOVE DIAMETER .4560

SPRINGFIELD 1884: 3 GROOVES, CANNOT GET GOOD READING. DIMENSION FROM 1 GROOVE TO 1 BORE IS .458. I am not really expecting much from this gun and some of the leading may be due to the bore.

As I was told the slug needs to be .001 over groove size and the grooves in the Uberti and the Pedersoli are .001 or more under the slug size do you have any idea what the problem is?

I'd try re-slugging the barrels with unsized bullets instead of the round ball to verify the measurements.

I'm surprised you have that many rifles with bores below .457.

Even more surprising is a .458 groove to land bore measurement (this may be confusion on my part).

I've measured 5 groove barrels before, but not a 3 groove barrel so I may be off in the weeds, but it doesn't sound right to me. I can't find any 45-70 Springfield bore drawings right now.

If you are sizing the bullets down too far you may be distorting the bullets. What is the as-cast size of the bullets?

Steven

Those bores sound extremely tight for a .45-70.

I'd personally try lubing a few bullets by hand, and shooting them unsized.

The 'trapdoor' guns were intended to be shot with black powder and soft lead bullets that will bump up and fit the bore no matter how clean or filthy it was. For that one, I'd seek out some experts... see if you can find any of the Paul Matthews books.

Last - what did you measure the slugs with? Can you check your caliper / mic against some jacketed bullets? It could be off a bit. When you measure a bullet that you've sized, does it read what you'd expect?

Remember also that the slug shows you the tighest part of the bore. If you can, try tapping one just into the muzzle then back out again and see if you get a different reading.

IS possible to have that many bores under normal size...whoud redo the slugging and verify it, but it's possible.

Describe the leading. IF it's becasue the alloy is too soft, it should get progressivly WORSE towrads the muzzle....it should get worse the faster the bullet is moving. Same thing with lube that's not making the grade...as lube runs out, leading STARTS at the muzzle and works back.

IF the leading is at the breech end, soft alloy shouldn't be the cause...bullet is at it's lowest velcoity, so why would there be no leading at the muzzle were it's at it's fastest? BReech leading is usually an indication of sub-sized hard bullets...usually this kind of leading quickly finds its way through out the barrel length (once gas cut, it's not going to self-heal), but it starts at the breech and usually can be seen as being heavier at that end.

I don't see that load and velocity level over stressing soft bullets. The most important measure for the bullet is the diameter of the barrrel directly ahead of the chamber...that can be a differnt diameter than the rest of the barrel. One lead slug pushed frough the bore will only record the single tightest area of the bore.
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Have a 45-70 with a .461 bore. Can get good accuracy with no leading problems with (1) .458" bullets cast dead soft (1:30), a base wad, and used over FFg BP. (2) nearly any alloy if bullets are .462" or larger.

Have to agree from a safety stand point that any .45/70 you load should be loaded to a level that won't damage the weakest gun of the group...ammo evnetually finds it's way into gun's it's not made for. The above 45/70 is of the same vintage sa your springfield (1883) and while I will use low pressure smokless loads, am as careful as possible.

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I have an antique 1879 Remington rolling block .43 spanish, in which I shoot smokless loads. I have not had this rifle very long, but have worked up a good load which gives surprisingly good accuracy. 370 grn lyman mould home cast bullets, cast from wheelweights. 33.5 grns of IMR 3031, home made bullet lube 50% beeswax 50% lard. 2" groups @ 100yds. I can hit 4ltr plastic milk bottles every time at 250yds with previously fired cases.( I only size 1/4" of the neck ) With new cases the accuracy is not nearly as good, in fact it is total crap by comparison.
I use a 1/4 of a piece of toilet tissue 2"x2" split in two and folded up to keep the powder over the primer, as without this I sometimes get quite a bit of unburnt powder residue left in the barrel. I do not size the bullets as i have found the bullets to only vary one thousanth of an inch either side of .439. The weight averages 376grns with a maximum variation of 2grns either way. I have not had any problems with leading of the barrel.

The rifle is still fitted with the standard issue sights. I have a vernier soule sight and a globe for the front presently on order. It is better than I dreamed it would be now, but with precision sights it should be amazing. The only job left after that will be to do something about the trigger pull, it is at least 8lbs at the moment.

As Mike says, try some unsized bullets. You might also try a vegetable fibre wad under the bullet, a la Ross Seyfried.

zonie

Since I do not work with the powder that you are using I can only offer a suggestion. First, can you find out the hardness of the alloy you are using compared to pure lead? The BN number for pure lead is 5, wheel weight is 9-10. What I have learned while working up cast bullet loads for myself is that a low powder charge against a hard cast bullet, will definitely lead to gas cutting by the burning powder and lots of leading. Sufficient pressure must be available to obturate the bullet base immediately to stop leading and seal the bullet base to the barrel. For example, according to the Lee reloading manual, a BN of 16-18 (most commercial cast bullets) can require 23,000 psi to obturate the base. This is a lot higher than most would expect. My experiments agree and include good accuracy too! Second, try a different lube. Lee offers liquid Alox lube (Bottle comes free with their sizer). I have found that it works well on my 45-70 with both Pyrodex and smokeless loads. In fact, I gave up my Crisco/beeswax lube except on my Trapdoor - experiments continue there.

Try re-slugging that bore using a #8 Oval Egg Sinker (available in the fishing section of most sporting goods departments), this sinker has enough diameter to accomodate even very oversize .45 cal bores, yet the egg shape makes it easy to start down a squeaky clean, lightly lubricated barrel, and doesn't have nearly the bearing surface of a bullet, so once started can be pushed through by hand with a wooden dowel. Too these are pure lead, so are butter soft, and most importantly, they have a longitudinal hole running the length of the sinker to allow a place for displaced lead to go when being swaged down to fit the bore. This should give you an absolute, and accurate idea of barrel dimensions.

I too think your bullet diameter would be suspect. Personally I haven't seen any .45-70 shoot well with bullets under .459" diameter, and best results are usually obtained in our experience with bullets at least .460" diameter to fit the overly generous throats that most typical .45-70's posess, regardless of age or manufacture.

Just a couple of thoughts to try.

God Bless,

Is a "trick" that has helped in some cases. Don't size the bullets. Tumble lube them with liquid alox. Thin application for BP use as you will still fill the grooves with BP type lube after it's dry...thick application for smokeless loads. Stand the bullets on their NOSE to dry for a day. Will still be sticky at the end of 24 hours...dip the BASE into motor mica (a dry white lube...can order it from J.C. Whitney or other auto-supply houses).

The combination of a coat of liquid alox and the dry motor mica stuck to the lube on the base seems to help leading...will be a bit smokely...with BP you'd never notice, with smokeless you will.

The alternative method is to still tumble lube them with liquid alox, stand them on their nose, and apply a .45 cardboard wad directly to the still tacky-wet base. Kind of glues it on...and you'll not have too much worry about wad-bullet-base seperation when you load them.

My Handi slugs .457. I get the best accuracy with .457 sized bullets - don't ask me why, it just does. The loads - bullets 405 gr wheel weight metal and smokeless Reloder 7 to Trapdoor load levels or Pyrodex print 2"- 2 1/2" at 100 yds with open sights. Liquid Alox (one coat before sizing and one after) leaves no leading in my barrel. Just "swirl" the bullets in a margerine tub, pour onto wax paper and separate, and let dry overnight. I do not use spacers, wads, cream of wheat or other fillers except 1/2 gr of dacron fiber in the smokeless loaded cases. Bottom line, keep experimenting. Read the threads on web pages like this one to get ideas. Ask 5 of us to answer a question, and you will get at least 8 non-negotiable answers. Lots of material to digest,but all valuable.

Dave

The suggestion to read some of the Matthews books is a sound one. Bear in mind that the 45-70 Govt was developed with BP and shoots best with that propellant. It is nothing to get 4" 200+ yard groups with BP and a prperly "cast" bullet. Be aware, I said cast not sized.. Sizing a bullet just maks a off center bullet far worse. BP requires deep grease grooves filled with SPG or similar lubricants. Fouling is minimal with the proper load and lube. The Lyman 457125 bullet is the perfect choice for the "average" 45-70. The rather rapid twist will stabilize some pretty long bullets. Go with BP as the cartridge was intended and you will be much happier.
I use 1:20 or 1:30 alloy depending on the rifle bore condition.
Older worn barrels need a softer alloy to "bump up".