Compressed smokeless load (grits) load in .45-70 and BP recommendations

[Tangle Eye]

I know this smokeless stuff is off topic here but if anybody has tried this I'll bet its some of us who hang out here on the dark side.

I've got an pretty consistent load of 13 or 13.5 gr Unique under a 410 grain cast bullet for my 1895CB .45-70. I haven't settled on exactly which load yet. I'm currently using a small square of polyester quilt batting to stuff in front of the powder in the case to keep it back at the primer. I'm concerned that this will slip under recoil (in the magazine) and cause position sensitivity in this light load. Also - I have found that 28 grains of H4198 produces good groups but it is very position sensitive (I guess because its fairly slow) and putting the wad in front of the powder caused velociites to swing over 200 fps from load to load.

Now - what I'm thinking is this: Use my wad cutter to cut an actual size wad for the .45-70 from felt or the quilting material I have. Put this over the powder. Then fill with grits to the bullet base so I'd get just enough comression to guarantee nothing moves around in the case. This is, of course, how we do it with black powder but I'm wondering if this would work with Unique or H4198. Anybody ever try this?

If this doesn't work - I'm seriously thinking of going back to the Holy Black for this rifle.  So with this in mind -- what is your favorite load for the Lyman 405 grain bullet (410 as cast by me) with black powder?  I'm looking for 200 yard performance or greater here for cowboy side matches.

[Grapeshot]

Normally you don't need a wad or filler with that 13.5 grains of Unique.  Paul Matthews, the guru on the .45/70 wrote in his book, "40 Years with the .45/70" that his utility load with the .45/70 is 10 grains of Unique and I've used as much as 16 grains of Unique with the 405 grain cast Lee bullet.

Grits, Super Grex, or any of the granulated shot shell buffers have a tendency to increase pressures, and recoil, even with that low charge of Unique.  With a wad and a slightly compressed column of filler, the volume of the case is reduced and the violent burning of the powder increases pressure dramaticly.  This is tranlated into recoil as the filler and the bullet have to be pushed out the barrel without the larger volume of free area for the powder to burn when you do not use a filler.

You're kapok, or poly batting, is probably the best choice as it won't become a projectile that will be stopped by the base of the bullet.

In other words, it may be safe to use a filler, but I'm guessing that you will experience a stiffer recoil than if you do not use it.

[Tangle Eye]

Grapeshot - you echoed exactly what my thoughts were on the filler but I wanted to bounce the idea off somebody else.  I may well try that Unique without the wadding.  I'm also gonna try black in it since that is a legitimate black powder caliber.  I really wanted more velocity than I'm getting from the Unique load so I can reach out to 200 yards with my Marbles sight.

An interesting thing I noticed which I'm sure has to do with internal ballistics. 28 grains of H4198 gives an average 1022 fps velocity and 13 grains of Unique gives 1140 fps. But - the H4198 load hits almost 6 inches higher on the target with the same sight setting.  My bet is the H4198 is still burning down the barrel and developing velocity whereas the Unique burns really fast and is not gaining any velocity as it travels down the barrel.

[Grapeshot]

From my experience and answers I've gotten from the boys at the Army Ballistics Lab is that the longer a bullet is in a barrel after the trigger is pulled, the higher it will print, compared to a similar bullet that exirts the barrel in less time.

The gist of this is the faster a bullet travels through the barrel, the less time recoil has to affect it as it leaves the muzzle.

So, your bullet backed by the H4198 is travelling slower than the same bullet powered by Unique.  So, even though we're talking in thousandths of a second, the muzzle will be at a higher angle with the H4198 as the bullet exits.