I finally got a chance to try breech seating my 45-70

It was quite a long drawn out affair. I decided to give it a whirl on an inexpensive Buffalo Classic before I tried messing with one of the more spendy toys. 
Now as some may know the BC is not a good candidate for this as it has zero throat and most of them have a reverse taper in the bore. ( gets bigger at the muzzle)
So I lapped the bore out until I had it suitable then made a throating reamer that tapered in slightly. At the entrance to the throat it's .0015 over bore tapering to .0005 over bore at the start of the leade. The leade is 2deg included and the throat is approximately .6" in depth
Then I grabbed a cheap Lee mold and lapped it out using progressively cast bullets until it was dropping tapered bullets that matched the throat dimensions. 
Being a Lee mold the bases are less than perfect so I made a soft collet to hold the bullets and faced .002 off the end to get a perfect square base. 
This whole project has taken weeks but I finally got to test today. I loaded cartridges at case full with room for a wad(79gr) downwards in 2 gr steps drop tube but no compression. 
Shoot groups at 100yds and to my surprise first string was .700" CTC. I cleaned 1 wet 1 dry every shot. 79 and 75 gr gave very good consistent groups. 
Where would anybody suggest I go from here
Add compression in steps
Or 
Move the seating depth
Or 
Toss the Lee mold and get something decent. 

In immediate terms I'm trying to learn about breech seating and how that applies to what I like doing best. Getting rifles tuned and loads developed to shoot as accurately as they can. 
The 45-70 is a reasonable single shot to make the mistakes on before venturing onto the 38-55. 
Ultimately though I just simply enjoy shooting at distance. I have always done it informally but I am looking at pursuing it more formally.
I intend to check out the match this summer at the Connaught range in Ottawa

   Hi Sea Nmp --- That is a great start out of the gate if you'll pardon the horse reference.

Our "big bore" matches are ten (10) shots @ 200 yards.  I hope you can go the distance of one furlong.   

C.M.M.

Well I did not get a chance to chronograph the loads today as the ball clamp on my tripod needs some repair so I just fired groups

Let me say that if someone had asked me if a cheap Buffalo classic was capable of this I simply would have laughed

Best group of the day was 79grFFg Goex with 0.100" compression and a 0.060 wad. This was the load that left the casings absolutely clean as well.

Shot with factory sights

The cluster is 4 of 5 shots

Quote:


  Hi again -- Sea Nmp

The H & R rifle know as the "Buffalo Classic" was avaialable in both 38-55 and 45-70 when they were first introduced to the marketplace.  My understanding is that the 38-55 version was dropped by H & R.

Your B.C. would be most welcome at the matches were I shoot in Maryland, which is an ASSRA sanctioned club, named "Columbia Schuetzen Verein".  We shoot at a range just on the fringes of Thurmont, in Frederick County, Maryland, which is accessible using the U.S. Route 15 corridor going north & south along the Catoctin mountains.

I have witnessed a gentleman with a 45-70 H & R - B.C. rifle beat some very expensive hardware at a "rifle side match" during a very large regional cowboy action shoot several years back which impressed me very much.

We can get you more info about the C.S.V. if the travel is doable for you.  If not the C.S.V. matches, there are many other opportunities through the A.S.S.R.A. on a national basis.
 
Keep up the good work !
C.M.M.

   Sea-Nmp   
                I will be back in touch RE: Columbia Schuetzen Verein later today.

I would also suggest you consider the ASSRA matches put on by the Western New York folks, namely, Jeff Schultz.  They compete in Alabama, N.Y and at Bath, N.Y.; both would be a much shorter drive for you.

If you were to send Jeff a P.M. to "Jeff_Schultz", his Forum name or find their schedule under the "Announcements" heading you will find the 2014 shoot dates.

Hope this helps.    

C.M.M.

Thank for the info CMM. I was going to get in touch with the Eastern and Western NY groups and go check out a match or two. 
Today I'm pondering ES. I got an opportunity to get and chrony loads while shooting groups. It seems the more compression I add the more erratic the velocities get. 
Group 1 
0.075 compression
ES 29fps

Group 2 
.100 compression
ES 16fps

Group 3
.125" compression
ES 71fps

Group 4 
.150" compression
ES 60fps

.100 to .125" of compression yield great groups so the velocity and barrel harmonic are probably in tune however I get some twitchy velocity spikes that would concern me at distance. 

Questions
What is my best option to pursue to get this velocity smoothed out a bit
1) can playing with seating depth affect the velocity peaks? 
2) Primers? How much of an effect do primers have from experience? I've been using WLRM because that's what I could get. With an over primer wad of .005 drafting paper. 
3) what is a typical, acceptable ES?
I'm using Goex and I don't know of anyplace in Canada that regularly carries Swiss.

Sean, are you certain that your chronograph is not too close to the muzzle?  The only time I've ever seen extreme spreads greater than about 25fps on 10 shot groups is when my chronograph was set too close.  I think all of the junk coming out of the barrel causes wild readings.  I'll bet that this is what you are seeing.  I run my chronograph as far away as the wire will let me.

With respect to improving SD I think that playing with powder charges is the ticket.  Once you get a powder charge that you like, play with fouling management to reduce it further.  I wipe between shots and found that you can learn a lot by experimenting with fouling management while using the chronograph.   

Chris.