I've been now working on and off with my latest rifle, a BSA martini model 12/15 converted to CF and rebarreled with a Lothar Walther .308 1 in 12" twist barrel
The overall goal has been to develop the rifle into a short-range BPTR, and I'm slowly getting there...

I've been finding out what it likes, and what it doesn't like, and how to do fouling management between shots - a pretty important factor, it seems; more so that with the big .45's.

Yesterday evening, I managed to shoot the target below:
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This was shot prone, with slings, unsupported, at 75m.  The target is a 100 rifle target reduced to 75m.

Load data as follows:
Case: Remington 32-20
Primer: Fed. SP
Bullet: 151gr 30:1 RN bullet of my own design, made by Boomer's, cast 30:1
Card overpowder wad
18.4 grs of Swiss 1 1/2Fg

Wiping between shots with 2 patches, moistened with WD40, pushed through in a single pass from breech to muzzle.

The 1st shot from the clean barrel was a low 8 at 6 o'clock, and I also pulled the other 8  .

Still, the rest seems pretty promising, especially with the nice cluster in the 10-ring.

The bullet is not the typical .32-20 bullet, but is quite a bit heavier - I designed it myself as I am a firm believer is the use of heavy-for-cartridge bullets for optimum accuracy with BP.

Now some more experimenting with seating depth, some 2Fg swiss,....

Is a Martini legal to compete in BPTR?

Target dimensions:  10-ring about 24mm (0.94 inches), each consecutive ring will add the same.  So the 9-ring would be 1.88" etc.

The goal is to use this from 50 to 300 meters, 50 m standing, 100, 200 and 300 prone.  Most matches here are actually shot at 100.  For longer range, I need to go to the UK.

And yes, a Martini would even be legal in BPTR in the US, not in BP silhouette though.  But then again, I'm not shooting in the US.

Greg,

That's the reason for the heavy-for-calibre bullet.  Although, to be honest, beyond 300 would be really stretching it.  I'm not really expecting any benefits when compared to the .45's at 300.  At 100 and 200 it will give me a clear advantage, but at 300 it will be at best at equal terms...

Good evening gents,

I had another go yesterday evening with the little rifle - still shooting prone with sling, no support at 75 meters (82 yds). 
The only variation is the powder: this time I used Swiss FFg instead of 1 1/2Fg, same volume - which came out at 18.2 grains; so 0.2 grains lighter than the same volume of Swiss 1 1/2Fg.

The target below shows 10 shots fired, no fouler, and wiped between shots with 2 patches moistened with WD40. I'm pretty happy with the results, obviously... The group measures 1.58 inches at the outer edges, so 1.27 center-to-center, which makes it slightly under 2 MOA.

This is with the original BSA peep sights, aperture rear and front.
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I just read your post and happened to remember this.
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                                                                        Tim

I just wish my orig. Rem Hepburn 32-20 had a faster twist.
beltfed/arnie

BSA martini model 12/15 converted to CF and rebarreled with a Lothar Walther .308 1 in 12" twist barrel

Your first line made me think (wow) there's a brave man and other thoughts.