Getting a lot of lead in chamber of 38/40 1873 Uberti

I have been shooting my original 73 Winchester at CAS matches for 20 years and in the past 7 years I noticed that I was getting a lot of lead buildup in the chamber all along the length of the brass. By the end of a match it would net tight when chambering a round. I would have to take the whole gun apart and scrape out the lead flakes with a dental tool. Several months ago I bought a new Taylor's / Uberti 73 also in 38/40 so that I could stop shooting a gun that was made in 1885. I have shot the new rifle in 2 monthly matches and found that it too was doing the same thing. in fact It had more lead in it. I created a tool with a brass case a brass jag and casting resin to get the lead out, I works well but I am trying to figure out why this is happening in the first place. I have been using the same loading specs for 20 years,


MikeAttachment 200198

Have you cast your chamber and if so, how large is the unrifled portion of the origin of rifling before the lands start?

How does this dimension compare with the diameter of the bullets you are shooting?

What is the difference in diameters between the ball seat at origin of rifling and barrel groove diameter?

Are you shooting black or smokeless?

If you are sizing bullets to barrel groove diameter and not to fit the throat at the origin of rifling, AND if bullets are harder than about 10 BHN, this would explain the leading, regardless of whether you are shooting black or smokeless.

My advice is to shoot SOFT bullets no harder than 10 BHN, with 6-8 BHN being better, using 1:40 or 1:30 tin-lead with SPG lube. Use the largest bullet diameter which will chamber and extract freely, using either black or Trail Boss.

What alloy and lube are your bullets made with?

What diameter are they?

Greetings
Well stated Outpost.
We presently own several 38-40 and 44-40 Winchesters and Marlins. Have not seen any leading to the effect that photo depicts but we had been advised through suggestions and experience that the throat is the primary diameter to deal with.
Soft (1-40) was advised and adhered to.
We begin all our shooting with BP cartridge firearms using BP to establish the "accuracy potential" of that particular firearm. Then move to smokeless in an attempt to beat the BP "best load".
Mike in Peru

I thought of this but it is happening on both guns and one is old and the other is new.
I have not slugged the bore(s) or chamber(s) and I will have to measure the bullet. I get my bullets from a guy in my club who does it professionally so I will have to ask him about the hardness. I am shooting smokeless powder. It is a load that I got from a fellow club member years ago that owned a cartridge loading company whom I bought rounds from before I started reloading. I have not choreographed them but they are not light loads

thanks,
Mike

My best guess is that the bullets are undersized for both guns and that the alloy is too hard.

If you cannot gouge the nose of the bullet with your fingernail, it is too hard.

If you cannot deform the bullet lube in the grooves with thumb pressure alone, it is too hard.

The great majority of commercial cast bullets are too hard and the lube is too hard. They make them to withstand rough handling in shipment, not to shoot well in light cowboy loads.

Matt's Bullets can provide softer bullets with softer lube which will do much better for your purpose.

The loads that I am using are somewhere in the middle of the manufacturer's recommendations. According to there specs they should be around 840 fps. The bullet is 0.401 " and with my CabineTree Lead Hardness Tester the lead looks to be around SAECO 10 or Binell 22. Years ago I made some rounds without powder or primer that I use for testing because the I suspected the old Winchester of shaving lead off when cambering rounds. When I operate the gun with them I don't see that happening. I have always used Redding Dies on the recommendation of the same person that I got the loading info from. I used the crimping that was built into the bullet seating die and had no problems with that with my Winchester. When I got the Uberti which is 4" shorter I found that using the die crimp was not enough when loading 10 cartridges into the gun the mag spring was pushing the bullets
back into the cases so I now use a Lee Factory Crimp Die to crimp the bullets in. When I used the bullet seating die to crimp in the past sometimes I would get a small shaved ring of lead where the edge of the brass met the crimping groove but I usually removed the ring with my fingernail and it would fall off. I have not measured the chamber(s) or bore as of yet. I will have to find out the best way to do that.

Mike