10ga foster slug mold thoughts?

[bikerbeans]

Hi All,


I have contacted a mould maker who appears willing & able to make a Hollow-base, fullbore, foster style 10ga slug mould. I have in my mind what I want made, but I would like to here from others who have considered this project. What I would like to hear is if you were going to spend the $$$ for a 10 ga foster style mould what would be your design parameters? I am just looking for backup in case I have forgotten something.

This slug has the following usage;

1. My amusement
2. Maybe a deer one day but not likely
3. Fired in my 10ga H&R 24" barrel cylinder bore
4. Minimizing recoil is NOT a concern

thanks


BB

[bikerbeans]

anyone have a 1 3/4oz slug that they have removed from a Federal 10ga shell? If you do I would like to know the weight, length, diameter, both outside the hollow base. I have a few but I don't want to sacrifice a $2 slug if someone else has already cut one open.

thanks

BB

[jmort]

For the record, your idea sounds fun/awesome. I wish I could help but I want to watch you make it happen.

[longbow]

This probably won't be a lot of help but maybe some.

In general, Foster slugs have been poor performers for me. Mostly due to skirt distortion/slug up resulting in cocked nose, flared skirt or some other distortion ruining accuracy.

To 50 yards or somewhat beyond, round balls have been more accurate and more consistent than almost any hollow base slug I have tried.

There have been a few exceptions but not many. I have had better results with Brenneke style attached wad slugs than Foster slugs for drag stabilized slugs.

What you might do is look up turbo1889's posts. he had a custom (Brooks?) mould made up in hollow base and it had a very thick skirt. It worked pretty well for him.

If you plan to use a Foster slug my recommendations are:

- do some digging to see if someone else has designed a 10 ga. Foster slug that was successful and ask if they will share
- for bore size slug add lube grooves and make it at least exactly bore size or better, a thou or two over
- use a design with a thick skirt ~ I am thinking at least 0.125"; possibly a variety of hollow base pins would give options for hollow base cavity size and skirt thickness
- I was going to say it might be a good idea to go with a Lyman sabot slug clone or a Lee Drive Key slug clone but you say "full bore"
- don't use too large a meplat as the slug may become unstable like a wadcutter boolit
- maybe use a Lee Drive Key slug as a model and scale it up to 10 ga. full bore + add lube grooves ~ the Lee Slugs seem to work fairly well in smoothbore... or scale up turbo1889's 12 ga. design

I would be inclined to try a 0.735" RB in a shotcup ~ TOW sells them so no mould investment to try them out.

Maybe something useful there.

Longbow

[smkummer]

I would add that any 10 gauge slug should be safe to shoot out of a full choke barrel and not only just because I own a H&R 176 with a 36in. tube.

[6pt-sika]

I would add that any 10 gauge slug should be safe to shoot out of a full choke barrel and not only just because I own a H&R 176 with a 36in. tube.

Yes they are !

I shot a few out of a pair of Ithaca MAG-10's with 32" full choke barrels and the guns suffered no ill effects .

[Marine Sgt 2111]

The Federal 10 slug is actuall a long 12 gauge dia foster slug. I cut one open years ago and was disappointed when I measured the diameter. I made up a double cavity RB mould, it drops a 660gr ww alloy ball, just haven't had the time to try it out.

[bbailey7821]

I own a Browning bps and would love to try out one of these in it. If this thing goes to fruit, please count me in send me a PM and I will get you my details.the pigs in South Texas won't know what hit them.

[6pt-sika]

The Federal 10 slug is actuall a long 12 gauge dia foster slug. I cut one open years ago and was disappointed when I measured the diameter.

That may very well be true .

But at the same time I was trying them in the two Ithaca semi auto's I also tried them in a Browning BPS with the IC choke in place and they shot relatively well at 50 yards compared to what I was getting from the Ithaca full choke barrels .

[bikerbeans]

Getting closer to placing an order for the 10ga foster mold, hopefully this week. My right shoulder can hardly wait.

BB

[bbailey7821]

where are you planning to order the mold from biker beans?

[bikerbeans]

Brooks. One more decision to be made and I will then make the payment.

BB

[bikerbeans]

Attachment 83787

This design is the work of another who has allowed me to use it.

BB

[longbow]

Now that looks like a nice slug design!

Not sure if the skirt is quite beefy enough but filling with hot melt glue should sort that out if you have any problems. I have had some pretty thick skirts distort! Oven heat treating wheelweights will fix it too.

That does look substantial though.

Has this slug been made and shot or will yours be the first?

I will be interested to see the mould when you get it and of course range results.

Looking good for sure!

Longbow

[bikerbeans]

longbow,

As far as I know, I am the guinea pig on this mould, but the gentleman who designed it has had success with his designs in 12 & 20 ga. I plan on trying the slower powders that Mr. Hubel has used in his slug loads in an effort to keep the pressure down an take advantage of the large capacity of the 3.5" 10ga hull. There is approximately a 4 week lead time on the mould and Ohio's whitetail season is rapidly approaching so I doubt I get to put much into the load development until the end of the year. Of course, if I wait till January I can shoot milk jugs full of ice with the big slugs, this to me is great amusement! I like to add a bit of food coloring to the water in the jug, you can get some really nice looking color displays when you vaporize a gallon of color ice with a large lead projectile.

BB

[SuperBlazingSabots]

Hello Brother BikerBeans, I am broke so I'll share my last 2 cents:

Give it a solid firm base by adding 1/4" nitro card below the slug from Circle Fly and you are ready for Polar bears and Brown bears.
Keep the slug weight down to be able to push it faster.

" A happy man is one who loads his own slugs and burn's powder at the range" - Super Blazing Sabots!

"An inventor fails 999 times, and if he succeeds once, he's in.
He treats his failures simply as practice shots. ~ Charles F. Kettering

Best regards,
Ajay
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[turbo1889]

@ Ajay

I'm the one that drew up that design when the OP asked me via. PM what I would do if I were wanting a 10ga. hollow base full bore diameter foster slug like he desires. I by no means wish to be combative and I'm not being defensive or anything like that. Just would like to give a few "Why" answers why I didn't include some of the design features you did in your recommended design.

#1 ~ I have found that the "platform for the roll crimp to rest on" is not a necessity provided the slug is large enough diameter to fully fill the hull (not undersized diameter for the gauge size) and there isn't a bunch of slack around the outside diameter of the slug inside the hull and the angle of the slug nose where the roll crimp sits isn't sharper then just a touch more then 45-degrees or so. I've gone up to 50-degrees on the slug nose angle and haven't had the slug have issues with not opening the roll crimp smoothly and reliably (looking at the mouths of fired hulls, watching the chamber pressure traces, and the muzzle velocity deviation spread). Now I did have one slug that had about a 70 degree nose angle and on that one I did have problems with the slug on ignition trying to over-run the roll crimp rather then unroll it so if you have that pointy of a nose angle you do need a lip like you suggest. It doesn't have to be totally flat though just a shallower more blunt angle.

If one desires it (not a matter of need but rather a desire) you can certainly have a lip edge like that for the roll crimp to sit against, and it certainly isn't a bad idea so long as you give it a little bit of taper (like 5-degrees minimum). If you make it totally flat you can have mold release issues and it can make the slug try to stick in the mold, an issue I found out with one of my previous custom mold cuts where I had the mold maker cut the lip totally flat and I ended up eventually having to use lapping compound to un-square that lip in order to get decent mold release because I got tired if the slugs sticking. With a slug that is cast from hard alloy and not soft lead using such a lip is also a good idea in order to make a "cutting edge" on the outside diameter of the slug so it leaves a permanent wound channel the full diameter of the slug rather then just wedging the flesh to the side and the wound closes back up partially after the slug passes through. With soft lead slugs that isn't as much as an issue because the nose of the slug flattens out pretty quickly on impact to cut a full diameter wound like a full wadcutter would so with a soft lead slug you can make the slug nose a little more aerodynamic and it flattens out on impact to cut a big hole.

#2 ~ If you look at what you drew you will notice that at the very bottom of your lube groove the groove is deep enough to compromise the thickness of the skirt and create a weak point (a mistake I've made on earlier designs as well). You need to back the depth of the bottom relief groove (or lube groove if you prefer) off so that its depth is about the same as what you gained in thickness due to the taper on the hollow base so the thickness of the skirt wall stays the same and you don't create a thin weak point with the groove.

Not to mention that for choke safe reasons the bottom of the slug is where the relief grooves don't need to be as deep as they need to be up front on the head where the solid nose doesn't squeeze down as easily as the hollow base does (which is also what requires thinner driving bands up front and allows for wider driving bands in the back for the same reason).

#3 ~ I haven't had very reliable results with full bore diameter slugs that only have two driving bands one front and rear with a large long relief groove between them, especially when cast from soft lead. I've got a only a couple slugs to work with only two driving bands. Much better results with three or more driving bands, especially with soft lead. I'm not sure why this is true, I suspect it has something to do with the initial jump from the hull through the forcing cone into the main bore but I have no proof of that and its only a strong suspicion in my mind at this point. Adding that middle third band really doesn't add much weight either, its a small fraction of the total (eliminating the middle drive band on my three band slug design would only save about 20 grains of weight when cast in pure lead).

#4 ~ You might be right about a slightly smaller hollow base diameter but the skirt as I drew it on that design is thicker then any other successful design I've done so far with two exceptions that don't really count because they didn't have a hollow base for smooth bore stability reasons so with a 0.53-0.54 diameter hollow base the skirt is over all thicker then several successful deigns I've already done. Making the hollow base a little smaller down to 0.50 like you suggest might be a good idea but I've got a couple 12ga. hollow base slugs that have a 0.73" outside diameter with that exact diameter hollow base that work fine so going even thicker is probably unnecessary but I could be wrong. Thing is though that a hollow base pin can always be turned down a little smaller in a lathe and its a 10-minute quick job or even just chucked into a drill press with some sandpaper and then smoothed over with a cotton rag impregnated with fine lapping compound if you've got the skill. A whole lot harder to make pin bigger rather then smaller.

You also don't need that much taper on the hollow base pin for good release and it adds nothing for strength. The greatest stress level on a compression load supporting hollow round tubing column (what the hollow base of a slug under acceleration stresses can be modeled as in strength of materials structural engineering analysis) is at the very bottom of the column so purely for strength considerations alone the skirt of a hollow base slug should be thicker at the bottom then at the top (just like the supporting walls of the great roman era architectural wonders that are still standing today have walls that are thicker at the bottom then at the top progressively tapered to exactly match the load stresses. Unfortunately, that won't work with hollow base plug on a mold because you wouldn't be able to get the pin back out. But there is no reason to add extra weight where it is not needed for strength and is on the wrong side of the balance point for stability, when your trying to make a slug stable through drag stabilization with the nose heavy and the tail light, you don't want to add weight to the tail unnecessarily, so you use just barely enough taper on the pin as necessary to get it to release which is about 3-to-5 degrees of taper in my experience with a hot lead casting mold. With a cold swagging die you can get away with even less taper.

Just saying "Why". I respect most of your development work with sabot load so I thought I'd share with you the reasons behind the details of what I do with full bore slug designs.

[turbo1889]

Oh, yah, Ajay is also right about making a solid base with several good hard nitro cards under the slug.

[turbo1889]

@ Ajay

Also, as to your lower weight and faster velocity argument, that's a very good reason to not make the hollow base smaller diameter or put more taper on it then absolutely necessary for strength reasons.

In raw numbers:

A hollow base that is 0.535" diameter at the bottom and is 0.500" deep with 3-to-5 degrees of taper on its sides and a slight rounding on the edges of its tip displaces about 275 grains weight of pure lead.

On the other hand a hollow base that is 0.500" diameter at the bottom at the same 0.500" depth with more taper angle (lets say about 10-degrees that's about how what you drew looks) it only displaces about 190 grains weight of pure lead even without any rounding of the corners on the tip.

That is a whole extra 85 grains of weight added to or reduced from the slugs weight just by a very small difference in the diameter and taper angle of the hollow base. For me its mainly a question of stability, that's 85 grains on the wrong side of the balance line for stability from a smooth bore. But for someone using a lighter and faster philosophy. I'm sure its enough weight to make a difference in that as well.

[turbo1889]

@ OP (bikerbeans)

Long story short, I have no problems with the alternate nose shape suggested by Ajay so long as you put a little taper (5-degrees minimum) on that flat 0.040" lip edge he suggests to get good mold release. But the drive-band/relief-groove body he suggests I would say is problematic and his hollow base profile suggestion adds more weight then I believe is necessary to the tail of the slug which is the last place you want to add weight for stability of a drag stabilized nose heavy smooth bore slug design (if your going to add weight you want it on the nose end of the slug, and you only add as much weight to the tail end as is necessary for structural and accuracy reasons).

His nose shape would be less aerodynamic but would "hit a little harder" especially when cast of hard lead where there isn't deformation and nose shape makes much more difference in terminal performance and for many people that indeed would be a trade worth making and is a trade you may wish to make yourself. I just don't think he has yet learned some of the lessons I have learned (mainly the hard way) about designing a full bore diameter slug below the nose with the drive-band/relief-grooves profile and the hollow base profile.