I recently bought a 629-5 mountain gun that after 18rds. of my cast bullets the rifling is almost filled in. Now I have been shooting these same bullets that I have casted myself in my 2 m-29's with no more than the usual leading . I shoot 4.5 gr. and 7.5 gr.of titegroup for lite and midrange loads and 22.5 gr.of w296 for deer loads .The mountain gun leads moderately with the 4.5 and is asmooth bore after 18rds.of the 7.5 and well I have'nt shot enough of the 22.5 loads to see how fast it will lead up . I also tried some commercial lead bullets with the same affect . Could it be a defect in the gun ? Its a challenge to clean and if I don't use my lewis lead remover every 6 shots I won't be able to pull the lead remover through . Suggestions?

Leading is usually caused by poor bullet fit. Check your barrel and chamber throat sizes to make sure they are correct for your bullets. It sounds like that gun may be out of spec somewhere.

Bad hammer spring.

Several questions.

You say "My cast bullets", how much experience do you have casting bullets? What alloy? What Lube? What diameter are they sized? What are your gun's throat and groove diameters? Gas checked or plain base?

Does the leading start at the forcing cone and go forward? Worse at the muzzle and works backward? Is the area from the breech to the frame face pretty clean and the leading get worse from the frame face forward?

Is it a defect in the gun? Not likely, but you have to match bullet dimensions to the gun, not just assume it is .429 and shoot bullets that diameter. Just for interest, my first 629 Mountain Gun had a groove diameter of .435! Throats were close to .430. Guess what, it leaded like a real b..ch, and wouldn't shoot in a bucket.

Give us a little more information, we need something to start with, not simply that the gun leads.

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Gunsmithing since 1961

The first thing to check is whether the bullets you have will just fall through the cylinder, without any help. That will tell you if they even fit the throats. It should take a little pressure to make them go through the cylinder, like pushing them through with a pencil.

A five groove barrel is a little more of a challenge to measure.

The leading starts at the forcing cone and moves forward . The cylinder face looks splattered but not for several rounds. I have been casting 240 gr. Lee tumble lube for about 15 yrs. now without a problem . The gun shoots pretty acurately right away ,so I figure its not out of alignment . I will try the bullet through the cylinder . Wheel weights are what I use for lead .I will try to get throat and forcing cone measurements and get back with you.

I had a similar problem. I went from 7.5 grains of unique to
11 grains problem solved. I was shooting 200 gr. lrnfp ( my cast ).

Pat

A lot of the Lee molds tend to cast undersize for what is really needed. Measure the bullets before and after you try them through the throats.

I have a couple 29s and a 629-2 mountain revolver all of which have chamber throats in the .431-.432 range. If your bullet is smaller than your throats you will get some gas cutting of the bullet and some serious leading.

THis^ Leading is almost always about bullet fit. If the cyl throats are smaller than groove dia, the bullet is going to lead, regardless of alloy or lube. Early leading is telling me the bullet is to small as it hits the rifling, you get gas blow by & leading until the bullet bumps up & seals the bore, about 2" or so down the bbl & leading stops. Now some bbls are rough & will just lead, lapping is the only real answer there. Sometimes powder can cause a leading issue, TG is such a powder. Sometimes using the LFCD can cause a bulelt to be sized down, also making leading possible.

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NRA Cert. Inst. IDPA CSO

As others have said here, you can not answer your question without knowing the exact throat / bore / bullet diameters, and there in will be your answer.

Small throats can be easily opened, with over sized throats, you will have to match the cast bullet diameter as a compromise with the bore diameter. Most guns shoot best with the bullet being .001 / .002 over bore diameter.

Sometimes, there is a constriction where the barrel screws into the frame, or a rough bore, both of which can be improved with lapping.

Bevel base bullets tend to lead more due to flame cutting, and sometimes switching to a gas check bullet alleviates the problem. How does it shoot with jacketed bullets?

Larry

My cylinder throats are measuring .4275 to.428 and I tied to go into the end of the barrel to measure the lands at .429 . My cast bullets measure .430 . The hornady 240 gr. XTPs shoot great . The bore is not near as shiney as my blueed guns . If Titegroup is a cause for my leading what would be a good powder for lite .44 loads ?

Both Universal and Unique work for light-medium .44 loads. Universal is a bit cleaner burning but has more of a pressure spike. Unique is what I use for plinking rounds with cast bullets.
If that doesn't solve your problem you might try some JB bore paste on a mop to polish the barrel a bit and smooth out any rough spots.

I use 17 gr 2400 for light loads and 22gr of W296 for anything other than plinking and paper target killing.
I guess you ought to try some of W296 loads that you have already built up.

EW

Leading that starts at the breech end is a definite indication of undersized bullets. Shooting cast bullets is not nearly as simple as casting a tumble-lube bullet from wheel weight metal, which can vary considerably, rolling it in LLA and loading.

First, the throats need to be larger than groove diameter. Slug the barrel and see if the slug will pass freely, or with very slight resistance, through the throats. If it does, good. If it doesn't the throats need to be enlarged until the bore slug will pass easily.

Once a bore slug will pass through the throats then measure the throats by slugging them. Size your bullets so they are throat diameter to .002 larger. Notice that you don't have to know the groove diameter!

Slugging the bore. Drive a slug into the muzzle and all the way through the bore and out the breech. If it passes through the frame area without extra resistance that is ideal. If you meet resistance in this area your barrel has what is called a frame or thread choke, the bore diameter through the frame is smaller than the front of the barrel. This choke needs to be removed by lapping. So-called "Fire lapping" will do the job. Fire Lapping kits are available from many sources, simply Google it. They come with instructions.

If your barrel has a frame choke, checking and fitting the cylinder throats must be done with a bore slug that has only been into the muzzle of the barrel, not pushed through the frame choke area.

But, before you do anything else, it will make life easier to know the groove diameter at the muzzle since that is the point to which fire lapping will be designed to enlarge the rest of the barrel to. If your barrel is larger than .432-.433 it won't be worth the work and cost for a custom bullet mould and sizing dies to make bullets to fit it properly. Believe me, BTDT, and I have been doing this a lot of years.

If you want a bore slug measured PM me and we can work something out.

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Gunsmithing since 1961

I was doing the long post when you posted this.

Did you slug the throats and mic. the slug, or try to measure them with a dial caliper directly? You cannot accurately measure the interior diameter of a cylinder with a dial caliper, it will give a measurement several thousandths too small. If you did slug them and measure the slug, and the measurement was really .428 that is the answer to your problem.

It is highly unlikely the groove diameter is smaller than .430-431. No matter what size your bullets start out they will be .428 after going through a throat that diameter. If your groove diameter is .431, and the throat sizes them to .428, they are .003 under-sized and allowing lots of blow-by to scour lead off the bullet and deposit it in the bore.

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Gunsmithing since 1961

Thanks everyone , I'm going to follow the instructions and slug the barrel and cylinder than I'll let you know where I'm at .

I would say Titegroup powder is your problem. My experience is it burns too hot for cast lead bullets. I quit using the stuff.

Try Universal for midrange 44 Mag loads, it's a sweet powder for that application.

After slugging the barrel checking the throats ,etc. the conclusion is the powder ,thanks everyone .

I had a horrid batch of leading with mid range 180g 40 S&W in a 610 revolver and Titegroup powder.

I changed powders, after doing everything else to no effect, and the leading went away.

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Dum vivimus Vivamas

That is your problem. The bullets are sizing down passing the cyl throat & then trying to bump up as they go down the bbl. You will get gas blow by & early leading. The onyl real fix is to open up the cyl throats to groove dia or 0.429"-0.430", possible groove dia. FInd a place that does boring or polishing & they can do it as well as a gunsmith.
I agree on the TG, hate the stuff for anything, but really poor w/ lead bullets. It just burns too hot & fast IMO. Unique or WSF, even midrange 2400 loads work far better.

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NRA Cert. Inst. IDPA CSO