Getting around the no throat chamber

[charger 1]

Whether its in my 45/70 or my 45/100 I have the sharp 45 degree lead with no actual throat. Even when I trim brass to the very dead end of the chamber I find that by shot 4 I'm forcing things closed and accuracy is starting to go wild. Wire brush the chamber and I'm off again. Shooting smokeless, I'm wondering about lapping that first little bit to knock some of that edge off?

[barrabruce]

You mean maybe soften the angle a bit??
so it just goes.
Cartridge chamber..45 degree...start of lands ???

I done this on my 30-30. it had a sharp shoulder on the end of the freebore to the lead of throat/forcing cone as some may say.
My PP offerings have shot better as well as my cast a bit.
No more bits catching on the sharp shoulder anymore.

I would rely on the "experts" for this thou as I have no idea of these calibres and what makes 'em tick.

[charger 1]

45/70's dont even have the freebore so its right into the sharp ball throat

[largom]

I would shoot several fire-lap boolits through it.

Larry

[BABore]

I would think 10-15 low velocity firelapping rounds would do wonders.

[montana_charlie]

Whether its in my 45/70 or my 45/100 I have the sharp 45 degree lead with no actual throat.
Can you make a drawing of that chamber, and the beginning of the rifling, which will better explain how you believe it's shaped?
What brand are the rifles?

This drawing is not to scale, but the dimensions are about right for the average 45/70...45/100.
It depicts what it sounds like you are saying.
It is a 'no throat' chamber with a forty-five degree chamber step that also forms the beginning of the rifling.

It illustrates a barrel that was bored and rifled...then the chamber was cut in one end...with no other shaping in the 'throat' area.

With a topography like this, your (groove diameter) paper patch could not peek out the end of the case mouth more than 25 thousandths of an inch...if that much.

http://castboolits.gunloads.com/picture.php?albumid=88&pictureid=1276

Do you still believe your chambers are shaped this way?
It is similar to a type recommended by some PP shooters.
But, you need to shoot a bullet with a patched-to diameter of ~.450"...with most of the bullet shoved up in the bore...and only a short portion of the shank held in the case.

CM

[Red River Rick]

Charger 1:

I'm experiencing similiar problems with both my Pedersoli's, 45-70 & 45-90. So I did a chamber cast of the 45-70 and mine sounds identical to your, no throat or leade, just a 45 degree chamfer.

Does your chamber look like this:

RRR

[montana_charlie]

Rick,
Isn't your 45/70 a Rolling Block with a few years on it?
Can you post a chamber cast from the Sharps, for comparison?
CM

[Red River Rick]

MC:

Yes it is! The information that Pedersoli sent me, indicates that the rifle (cataloge # 3514) was made in late 89', and was shipped to Canada in the spring of 90'. The pic of the chamber cast is from the rifle mentioned.

I'll have to make a chamber cast of the 45-90 and post it later.

RRR

[405]

Those throats look a lot like some of the old originals. Got one in 43 Span RB and one in 1874 Sharps. I've found they have a tendancy to gather paper rings or other junk when firing PP bullets sized up to normal dimensions and of normal GG shapes. I think Mt Charlie's idea of patch to bore diameter (or maybe a little larger) and seat way out would be worth trying. The best type bullet for that task would be soft lead and the smooth-sided, tapered type. You could even go up to about 2 thou larger than bore. That usually leaves enough room to seat the cartridge fully while lightly engraving the lands into the paper. By loading that way any bullet obturation at firing would happen while most or all of the bullet contact shank was within the bore and not trying to size itself twice as it passed thru the throat. $.02

[charger 1]

charger 1:

I'm experiencing similiar problems with both my pedersoli's, 45-70 & 45-90. So i did a chamber cast of the 45-70 and mine sounds identical to your, no throat or leade, just a 45 degree chamfer.

Does your chamber look like this:

Rrr

bingo

[montana_charlie]

Charger1,
You say "Bingo" when Rick asks if your chamber resembles his, but look at that angle on his...

It is certainly not a 45 drgree taper. It is more like twenty degrees.
It resembles chambers cut a hundred years ago...probably because Pedersoli used an original as their production standard.

Once again...what brand rifle are you dealing with? How old is it?
CM

[charger 1]

Right you are. I make the step with no throat but it is closer to 45. It is a Douglas barrel chambered with a PTG 45/100 reamer. I just fired 10 400 grit fire lap. Now I gotta patch a few up and try

[leftiye]

Stick a 1 or 2 degree (0r 5 degree - whatever you like) .45 cal throater/leade cutter in it. Make the freebore whatever you like too. Except for too much freebore for some given boolit designs, you can't go wrong.

[charger 1]

Stick a 1 or 2 degree (0r 5 degree - whatever you like) .45 cal throater/leade cutter in it. Make the freebore whatever you like too. Except for too much freebore for some given boolit designs, you can't go wrong.


Got one ya wanta rent out?

[Nrut]

Here you go charger 1
http://castboolits.gunloads.com/showthread.php?t=18409

[charger 1]

Here you go charger 1
http://castboolits.gunloads.com/showthread.php?t=18409

Using that method I wonder how one keeps the lapping compound from also lapping chamber? Any bell in chamber and there goes extraction

[garandsrus]

Charger,

Unless I am missing something, the only contact between the rod and barrel would be the small spot where the taper on the rod touches the barrel, which would be at the transition from chamber to barrel. The small end of the taper that is taped would also touch the barrel, allowing the rod to center itself.

John

[charger 1]

Charger,

Unless I am missing something, the only contact between the rod and barrel would be the small spot where the taper on the rod touches the barrel, which would be at the transition from chamber to barrel. The small end of the taper that is taped would also touch the barrel, allowing the rod to center itself.

John

Upon further thought it looks as though thats the idea alright. Well one atep at a time. I slow fired 8 400 gritters in total, so now I'll seat a bit deeper and give er a go. If that still has be grunting at shot 5 I'll switch to the lapp rod. I'm trying to go easy cause this things about the price of 6 H&R's now and untill things get stopped up at chambers end its as accurate as he11 is hot. I think whats going on from slugs recovered from water is that the fresh cut chambers 45 gegree short lead to rifling is so sharp on top that when I take 420 grains of air cooled wheel weights and shove em out at 2350 the obturation is pressing against the top of that short sharp lead enough to take a bit of paper till after shot 4 I've got a build up

[405]

I think you're firelapping first approach is best. Going slow is good. Can't put metal back once it's gone and setting back and re-chambering those barrels is a PITB. Once the "sharp" entry edge into the bore is radiused a little you still might try soft bullet patched to bore dia. or a little over and seating bullet way out.

[charger 1]

Sorry for not getting back sooner. Finally pounded some lead into that chamber properly and found things to be VERY VERY tight. I start at bore, when I'm wrapped with old mimio paper and resized I'm 460. That just wont do. So after months of looking I discovered something yesterday. Telephone books. Thats right fellas, a 100 pages of the best patch material get turfed every year. Wrapped ten up, the tenth went in the same hole the first did and was just as easy to load, No tearing

[leftiye]

Are you sizing the patch down? I concur on the pulp paper. It sizes down real good too. Just size it to where you want it to be. When the paper stops compressing, the lead will size down as much as you size it. Obviously, some pre calculating is wise.

[Woodtroll]

Charger 1,

Did you ever fire lap or modify your chamber, or did you settle on just using the phone book paper? I have a similar issue with one of my rifles, and am considering "knocking the edge off" just as you were thinking of doing.

Thanks,
Regan