How much oversize is recommended?

[Prs61109]

I have slugged the bore of my Pedersoli 45/70. My preliminary measurement is .454 at the muzzle and .4545 at the breech end with a dial caliper. I'll get better measurements tomorrow. My electronic micrometer needs a new battery. Is .002 oversize the diameter I should cast/size my bullets?

I plan to cast 500 grain bullets from Lyman and RCBS. Should these be seated out to touch the rifling (using BP)? The cartridges will not be carried for hunting only to the range.

This is a wonderful forum for a new BP shooter. I'm learning a lot from the experienced riflemen here. Thanks!

[JSnover]

Plus .001"-.002" is fine. You're sizing over groove diameter, right? Touching the rifling is as good a place as any to start. After you get some decent targets, try loading some a few thousandths off the rifling. Your rifle will tell you which is best.

[Don McDowell]

Is that the groove or the bore diameter?

[detox]

Is that the groove or the bore diameter?

Groove diameter.

[Don McDowell]

Groove at .454? That's going to squeeze the snot out of most 45 caliber rifle moulds, but going .001 to .002 over groove is the place to start. Not all rifle like the bullet to enguage the lands, that will have to be determined by what you and the rifle decide.

[JSnover]

Groove diameter.

That sounds a little small but it could be true. Make sure you haven't gotten your terms mixed up. The bore would be the smaller of the two, measured on the lands. Don't size to that one.
You probably knew that but some folks have been confused.

[Prs61109]

I rechecked the slugs with a micrometer and got a groove diameter of .455 and a bore diameter of .450. I am going to use the Lyman 457125 mold (500 gr. round nose). My lead supply is mostly range lead so I'll see what size these drop from the mold. I may need a .457 sizing die. I plan to pan lube with SPG and use a grease cookie. This will be the starting specs for reloading my 45/70.

[Don McDowell]

Going to be interesting to see how thing works with those shallow grooves.

[montana_charlie]

Prs6109,
What was the diameter of your slug before you knocked it into the breech end of the barrel?
How far down the bore did you drive it before punching it back out through the chamber?

CM

[Prs61109]

I used a pair of soft lead, .50 cal. mini-balls. I cut off their hollow bases and rolled them between two steel plates to reduce them to about .465. I drove one completely through the barrel (breech to muzzle) and the second one about a foot up the barrel from the breech. Both slugs measured exactly the same... bore .450 and groove .455.

[montana_charlie]

Thanks for the details.
A foot is a bit far to go ahead of the chamber, but the difference may not be important.

Pushing a .465" slug into the bore (with little difficulty, I presume) shows that a 'large' bullet diameter will work in that gun.
If a case with a .460" bullet will chamber freely, that is what I would use to start with.
But, if you happen to come up with a mould that only throws .457", it will probably work out okay if you stay with black powder and a 'soft' alloy.

CM

[bigted]

I agree ... .455 seems tight at any place in a 45 caliber barrel. my 45-70's all shoot well with the .460 inch boolits. I always try to shoot boolits that are finger seated in a fire formed case neck with just the slightest flair so as to not shave lead. this system seems to work well and allows me to seat out so as to engrave the rifling with a fully chambered and action closed cartridge.

black powder is a wonderfull powder and the only advise I have for you is to ;

-fill the throat
-lube with BP lube
-handle fouling with complete thoroughness
-use soft alloy
-handle the fouling
-do good fouling control
-watch the fouling
-ensure fouling does not contaminate your accuracy
-keep fouling soft n gone
-on n on n on ...

[Prs61109]

Thank you for all the comments and suggestions. I don't want to make too big a deal of this since I won't be shooting competitively (I am too old to begin that).

[montana_charlie]

Thank you for all the comments and suggestions. I don't want to make too big a deal of this since I won't be shooting competitively (I am too old to begin that).

You want a load that hits where you aim, and doesn't fill the bore with lead.
That IS a big deal ... even if you are only 'plinking'.

Everytime you go out with the next load to try out, you are competing with the results of the previous trip.
That IS a big deal ... even if you are only plinking.

So, don't be embarrassed to treat it like it's a big deal when you ask for advice.

CM

[bigted]

I agree with the sentiments ... every load IS a BIG deal to me. I don't shoot competition either but I do compete with myself all the time.

[Prs61109]

I understand what you mean and I agree with trying to improve each time, experimenting, keeping good records, etc. I don't want this quest to become more frustration than fun. Getting good advice and suggestions should minimize the former and increase the latter. I thank you all for sharing your experience and recommendations.

[Larry Gibson]

How many grooves? Pedersoli does make a 3 groove TD.

Larry Gibson

[Outpost75]

If the barrel has an odd number of grooves, before measuring wrap the bullet with one full turn of paper or tape, measure over that, then subtract TWO thicknesses of the paper. This gives a more accurate measurment than meazuring across an upset groove and a land indent, unless yoy have the proper V-anvil flute micrometer, as used for checking cutting tools with an odd number if cutting edges.

[montana_charlie]

How many grooves? Pedersoli does make a 3 groove TD.

If the barrel has an odd number of grooves, before measuring wrap the bullet with ...

He has a Pedersoli 1874 Sharps 'Quigley' in 45/70.
The bore has four lands and grooves.

[hiram]

.002 larger than groove diameter is a good place to start.

BUT, load a dummy round with an unsized bullet. If it chambers, try it that way. It will fill the throat more.

The barrel is your final sizing die. This may not worked with a gas check bullet. Pressure will not zoom up because the bullet is lead alloy. It will squeeze down.