Lyman round balls.

[longbow]

Goodsteel:

Two things I would do is to oven heat treat or at least water drop when casting and also fill the hollow base with hot melt glue.

One other comment ~ and I can't absolutely confirm this but I think that big flat nose might be too much of a good thing.

I tried full wadcutter hollowbase slugs (more like a flat nose Foster than your pellet design) and they did not give very good accuracy at 50 yards where simply changing the nose to TC style with a large meplat but also the conical bevel seemed to improve accuracy noticeably. I fiigured the big wadcutter nose disrupted too much air flow around the slug so it wasn't stable. Whatever, they didn't work well for me.

Also, my understanding of the Lyman sabot slug with the big flat nose is that they become unstable when dropping to transonic velocity and can tumble when shot from smoothbore. Okay when shot from rifled bore but unstable without the spin.

Something you might try is to make a simple form out of CPVC pipe or pipe coupling (or metal if you want) so that you can slide the slug in leaving a 1/2" or a little more empty "tube" behind the slug then fill the skirt and form with hot melt glue. You will need to use some grease or something as a release and since yours is bore size you might want to add a one wrap paper tube to cover the glue. This gives you an attached wad slug with longer, lighter "skirt" and support for the skirt as well (I see in the photos that the skirt has squished up a bit). The longer "skirt" will provide some more drag which may help. It is easy to try anyway.

I have been doing this with home made hollowbase slugs sized to fit into a shotcup and it seems to be working well. Call it a home made "poor man's" Brenneke or AQ slug. Simple to make and they are giving me pretty good accuracy so far though there is testing yet to do.

Longbow

[MBTcustom]

Thats a good idea, although I still want to use the shotcup as a sabot. I put a lot of design into that pellet in order to make it ride in the shotcup with the right pressure on the base and the driving edge. What I may do is build a form that will allow me to build a nose out of HM glue as well as fill the base. I think I am close here because not all of them went squirly on me, there were quite a few that flew strait all the way to the target 150yrds down range. If that doesn't work, I think I will take your advice and open the leading edge and skirt up to bore diameter and build a tail-wad of sorts out of HM glue and use a card wad to protect it from the powder.
You might be surprised to know that the pellet made it through 3" of phone book before stopping. I think it would do quite well on a deer 50 yards away, although they might here the impact in the next county!
More testing is definitely required but I am still pretty taken with the bore diameter RB so that is going to get more of my attention in the coming months. Those things are going to be a big hit around here I can tell you! My buddy Jason got with some friends and took the 25 I gave him to the pond and blew up some turtles. Everybody thought they were amazingly effective and I could probably make a few bucks loading them for the locals, (after I get my FFL of course).

[MBTcustom]

You know these .735 RBs are the biggest boolits I have ever cast. If they get any bigger, I may have to screw a bumper to them and install headlights!

[longbow]

Goodsteel:

Sorry, I skipped a groove there and forgot you made the "pellet" to fit into a shotcup. If all you want is to support the skirt, just fill up the skirt with hot melt glue and leave it at that.

If you want an added "skirt" length then just bore a CPVC pipe coupling or whatever to a sliding fit for the "pellet", wipe a light coat of grease or other "release agent" on the inside then slide in a pellet and fill away leaving an extended skirt. The whole works will push out of the tube after the glue hardens. I made up 10 forms from CPVC couplings so I fill 10 up and by the time I am doing the last one the first is ready to come out.

Another trick to get nice full skirts or sharp edges on an extended skirt is to wipe some grease onto a steel slab, fill skirt or form a little bit overfull then press the slug/form down onto the steel and squeeze the extra glue out. That leaves a full cavity/form and nice clean edges on the skirt. The glue just lifts off the greasy steel.

I wipe with grease onto the glue skirt before loading into a shotcup just to make sure any gas leakage doesn't melt the glue to the shotcup. So far it has worked fine.

I was thinking yours were full bore and you don't want glue rubbing on the bore! That's why I suggested the paper tube. I have done that with full bore slugs too and it worked quite well. I just find it easier to load using shotcups so have stayed with that so not quite full bore slugs.

Sorry, I had an old brain misfire. You are good using shotcups.

Longbow

[excess650]

I picked up somne BPI BP 12 wads and BPGS gas seals to load some buckshot and found those also used for 2-3/4" 1-1/2oz loads in AA cases. I checked the length and diameter and went to experimenting. I ended up loading 21gr SR4756 just to err on the light side, and slit the BP 12 full length to create (2) petals. I put a 1/8" 20ga felt wad in the bottom. In that the BP 12 has some taper, I used a single, full length wrap of .020" carboard inside the cup, pushed a .605" RB to the bottom (snug) and put a .615" RB on top (snug). The combination made a perfect fold crimp.

In that this is just over 1-1/2oz I was a bit leery of shooting these from my 6-1/4# double. I made sure I had a firm grip on it and shot at my targets at 25 yards. The pairs of balls typically printed 2-3" apart with L-R barrels shooting similar point of impact. They print higher than single .615" RBs, but lower than single .678", and better centered than the .678". Recoil wasn't as harsh as anticipated, but then again, I wasn't burning Blue Dot.

I tried some #1 buck loads at 25 yards but wan't impressed. They look great at 15 yards, so a RB load in the R barrel and either shot or buckshot in the L should get the job done.

[Catshooter]

How about just making your base plug different? Make it to cast a solid base.


Cat

[longbow]

He is shooting from smoothbore so solid base won't be drag stabilized... unless you mean sold base with attached wad.

[nanuk]

6" groups or better at 100 yards was my goal ...... Not tack driving but consistent 6" or better groups at 100 yards is good enough for me.
Longbow

I think Canadian Tire has "Tacks" with 8" diameter heads..... should be just what you need!

[nanuk]

GS: do you make your own RB moulds as well?

[MBTcustom]

No, that would be a real trick wouldn't it?

[excess650]

I tried more combinations in my 20" double. I found that a .690" roundball was too large to work in a shotcup, so cut the petals back to ~1/4" on Federal 12S4 (brown) wads. I used .020" carboard 1-1/8" x 2-3/16" to form a shotcup to sit in/on the 12S4. Once in place a 1/4" felt wad goes in the bottom of the carboard shotcup, and a .690" RB on top, fold crimped in WW AA cases. The charge was 17gr Red Dot (1-1/8 oz target load). 3 shots each right/left barrels at 25 yards produced a fist sized hole with only a bead front sight.

While not particluarly HV, estimated 1100fps, the above load with a WW alloy ball just under 500gr should make an impression on whatever it hits.

.678" RBs in a 12S0 wad with a bit of cornmeal under the ball didn't produce particularly good results. I suspect the combination is too loose.

[MBTcustom]

My experience exactly.
I needed to find a good fit in the bore first, and then find a hull that will fit that combo, and finally, find a powder that will produce an accurate result. I really think that the powder selection has as much to do with fine tuning accuracy into a shotshell as it does with metallic cartridges.
Try SR4756 and 700X. I got the best results with SR4756 so far.

[MBTcustom]

Now fellers, I'm not one who is given to wild exageration, but the .738 RB load I have developed is absolutly amazing. I'm getting almost pie plate sized groups @ 130 yards with this load!
Here it is:
Win AA hull (the old kind)
Remington 209 primer
29.5 grains of SR4756
Federal 12S4 wad (petals cut 1/16" tall)
1.6cc COW
.738 diameter round ball (WW alloy lubed with 45/45/10)
8 point fold crimp

This load is using vintage hulls primers, wads, and powder from the 70s, so be careful if you decide to work this one up with modern components.
I can hit a pop can every time @ 50 yards with this load in my cheap $10 S&W 916 shotgun with a 21" barrel. @ 130 yards, I can hit an archery bad target every time in the center! I was scarring the heck out of some pop cans that were hanging from a beam in front of the backstop! I never would have believed that this level of accuracy was possible out of a smooth bore. every single shot leaves me shaking my head in disbelief at what I just did. At 130 yards, I would be amazed if I even hit the backstop, but on the contrary, these balls go where I point them every time.
After boosting the charge to 29.5 grains of SR4756, the recoil is stiff, but manageable.
I believe this is now my go-to gun and load for deer and hog hunting.

[longbow]

I am going to have to try the 0.735" balls a longer range. My 50 yard groups have been quite good but I really haven't stretched out the range at all with the big 'ol RB.

I got some IMR4756 a while ago but have not loaded any with it yet. I have RB's and a couple of designs of attached wad slugs to test.

Winter is done so it is time to head out to the range or bush.

[missionary5155]

Good morning
Sounds like a winner.. Looks like I ned to get a can of 4756 and roll out some full bore RB for the Fox B next time up north there.
Mike in Peru