Here is a simple outline of what we've done with
our project we call the 12GA From Hell.
Some folks have asked us to do this.
A. The idea for this and the name was by
Robgunbuilder on the AR forum. We figured out how
to make a long brass case, from BMG brass by
machining rims and the case to screw them on.
We ended up with case after mouth was expanded
that was 3.85" long, with a big BMG primer.
B. Rob put his in a big Borchardt falling block,
a gun that can take full BMG type pressures.
It had firing mechanision that fired primers ok.
Example top load is a 1000gr turned brass slug at
3100 plus fps, and a 7/8oz 12ga sabot at
4300 fps.
C. First of mine in a Savage 210 bolt shotgun with a
heavy rifled 31" barrel. My loads in this were kept
below 35,000 psi. Giving loads of 2700 fps with
a 730 gr hard lead slug, and 3900 with 3/4oz sabot.
Second gun was a NEF Ultra that I lengthened chamber
to take long case. Top loads are 600gr hard slug
at 2500 plus fps.Both Savage and NEF had to have
firing mechanisions beefed up to fire BMG primers.
D. We cut cases back to use in 3" chambers but
all guns have to have beefed up hammers, etc,
to fire the big BMG primers.The BMG primers
fired the slow rifle powders ROB and I
were using very well, no misfires.
So tried 3" RMC brass cases, regular plastic cases,
our cut back cases with primer bushings, all with
smaller regular rifle or shotgun primers,
that regular hammers or firing pins fire ok,
and found out that our slow rifle powder loads
wouldn't fire reliably with small primers.
E. Which lead to much more research. We found that
slow powders could be fired with a 10 gr of a
fast shotgun starter powder, under the slow powder,
using small primers. We also searched for rifle
or pistol powders slower than shotgun powders,
that would fire with small primers and no starter,
that didn't up peak pressure to fast as
we increased loads to increase velocity.
We found three- IMR 4759, VV-N110, and 7383 surplus.
These powders are easier to load for slugs without
the problems of fast shotgun powders pushing up
the peak pressures to quick, as you try to increase
loads to up the velocity. We use a minimum
thickness overpowder wad or other wads in the loads
under the slugs as needed. We had lab test 4759
loads with 600gr slug and pressures were little less
than the magnum REM Buckhammer factory loads, but
we got 400 fps more velocity. The Buckhammer
slug and locked on wad is about 600 gr.Both our tested
loads and Rem loads are 3" plastic.Our loads are for heavy
barreled guns only. IE; all slow powder loads whether
with starter powder or 4759,N110, 7383, heavy barrels,
as the pressure curve is higher down the barrel
and might split regular skinny shotgun barrels.
F. We plan on heavy barrels for testing 1887 Win
leverguns, for Mossberg 695 bolt guns, for
various heavy double shotguns, for various
O/U, for modern alloy guns, etc.We are helping to
design a big falling block for 12ga diameter cases
that is reasonably priced.. We plan on testing
other powders, for use with small primers. We
plan on setting up pressure testing barrel for
the long 3,85" case, to test the whole range
of slow powders and bullet weights, in the future.
We have found heatreated Dixie slugs that can
take super velocities, we found brass slugs with
relieved grooves that run same pressures as lead,
or copper jacketed, at same velocities.
This research and work is super great fun,
we are glad to share.We will get pictures soon of
the muzzle blast with long case, and pics
of pentration tests. Ed
