Guys,

Range day yesterday. Just got a Ballisticast 1431 mould to make a 500 gr FPGC slug for the 470 NE Searcy.

Had played around with the same bullet made by Sean Harper in Houston to get an understanding of the way the rifle works.

The first load for this test was 40.0 gr of XMR-5744 and Fed 215 primers. No filler.

The slugs were WWM, sized to .476, and had 3 groves lubed. (Experienced no fouling by the way.)

The first group at 50 yards on cold, clean barrels gave me a perfect center with the right bbl in the top of the 2" bull and the left bbl in the bottom of the 2" bull. Center to center spacing was 1.48". A 42.0 grain load was not quite as good, with the impact point moved to the left an inch or so, and the center to center distance growing to 1.75"

Chrono'd the loads today. Velocities ran:

rt bbl 1475 fps
left bbl 1495 fps
(a break with another load being fired)
rt bbl 1506 fps
lft bbl 1506 fps

The barrels were warm but not hot for the second pair.

Now ... how to interpret the information.

1) Would it be reasonable to assume that the cold shots might be closer together in velocity if there was a filler in the cases?

2) Load is very comfortable to shoot, and these big flat points should do reasonable well on game. Is a 1500 fps round reasonable for use on eastern deer and black bear?

3) If the loads never get any better than this (and I find the groups have improved as I relearn how to use iron sights with my old eyes), is this in the acceptable range for an open sighted double rifle?

Thanks for the help guys!

First- you don't need any filler with XMP 5744. The major issue I had with my 470 NE was getting a mold to cast bullets .001 over the groove diameter. I had to actually enlarge the lube grooves of my RCBS mold on the lathe. Sounds like your gun is shooting optimally. Don't change a thing!-Rob

Have you heard of the Beagle method for opening up a mold?
Take some sticky backed aluminum tape, like for duct work. Cut it into small strips and put on one side of your mold to hold it open slightly. Cast a few to get it hot, then measure. Apply more if needed. You can go out pretty far without getting wings if you let the mold cool inbetween pours and pour from a short distance.
Or you could hone the mold out to make it larger. Cast a bullet, put a screw in it, apply lapping compound and spin with a drill inside the mold. Clean and cast a new one for measurements, use the new one if it needs opened up further.

Mike, have you tried any of the 500gn cast at normal velocities? Sean sent me some of the 500's to try also. I'm ready to load and proof my gun now, then I'll start on loads and regulation. When I get a chance, I'm going to try and make my own jacketed bullets. I'll make a die to swage some copper tubing, then try to pour WW into the fluxed jacket. It might just make a mess, but I'll try it anyway. I have a couple of boxs of Barnes XLC's for the regulation.

Haven't tried any of the ones I cast at higher velocities.

Have gone to 55.0 gr of XMR-5744 with Sean's slugs. Velocity was 1806 fps with the MAD of 22. Showed a light leading. Accuracy results were not impressive, but I can't find my notes on that run. Could be that I was learning the sights still and the results reflected that.