Payload substiiution 12g and Lee 1oz slug, further experiments

[sthwestvictoria]

Following on from this thread:
http://castboolits.gunloads.com/showthread.php?261975-Payload-substitution-12ga-bore-diameter-Foster-type-34gm-slug-fun-first-result&highlight=substitution
I understand the concerns about substitution and that I am voiding my warranty. However I am not a silly fellow and believe I am operating from some safe first principles and evidence, as set out in that first thread. I would like re-load my own empty hulls however there seems to be a real dearth of wads currently. Powder (a bit) and primers are not actually the problem but wads really are. So I am not as restricted as Yman but am standing on his shoulders.

With the home brew slug mold, I now have a Lee 1oz slug mold as well.
I opened the fold of some Winchester Bushman 32gram #4 shot, removed the 32grams of #4shot and popped in the Lee slug and re-folded the petals with a Lee Load-All Junior. Pretty simple work other than starting the fold to open.
I shot them at 25metres only, Right barrel:
139147
and left:
139148

Lessons:
Should use 28gram target loads, they will have a bit more powder and bit more velocity (maybe Winchester AA Super Sporting 12G 7.5 28gm 1350fps listed)
I need some nitro cards under the slugs. I only found one wad but it was right down next to the target and had a deep key impression in the base of the cup.
Need a rear sight of some type to improve the repeatability of elevation holds and a taller front sight than just a brass bead.

[longbow]

I don't get too excited about wad substitutions as long as both are similar ~ cushion leg for cushion leg. If you were to replace a cushion leg wad with a solid wad column I would expect to see higher pressure due to effectively less volume at ignition since there is no cushion leg to give.

I think that is somewhat illustrated in BPI's shot hull loading data. The short hulls do not have cushion leg wads and seem to generate more pressure with less of same powder and regular hull loads with cushion leg wads.

Also, my very subjective opinion is this seems more pronounced using fast burning powders... again based on comparing different loads and hulls.

What can make a big difference in pressure is hull and/or primer substitution. Be very careful there.

All opinion and all subjective. Unless a guy has pressure testing equipment it is an educated guess so don't stray far off published load data.

Longbow

[glenr1]

Don't know if you have seen this. http://www.ballisticproducts.com/load14_04_25.htm It has a number of loads for assorted powders, and wads, along with their info and great pictures on their site should give a real good idea of the types of wads that can be used.

[sthwestvictoria]

I must have confused people with the first post . Wad substitution is not the concern - I cannot buy any wads to load in my part of Australia currently. Therefore I am buying complete 12gauge loads and pulling them down, discarding the shot and loading a Lee 1oz slug.

I presume the wad situation is due to reduced 12gauge reloading in Australia and the general shooting consumable drought. Others are having similar difficulties, see this thread on Australian forum Feb 2015: http://shootingaustralia.net/forum/reloading/12203-winchester-12-g-wad-shortage

[Cerberus62]

I need some nitro cards under the slugs. I only found one wad but it was right down next to the target and had a deep key impression in the base of the cup.
Need a rear sight of some type to improve the repeatability of elevation holds and a taller front sight than just a brass bead.I understood your post completely and sympathize with your situation, we have wads but spotty powder.

The "drive key" impression on the wad means the system is working as designed. Lee meant for that to be a means of transferring the twist of rifled barrels to the undersized slug. In a smoothbore a 20ga hard nitro card under the slug might help accuracy, if you have them available it would be worth a try.

For shooting over an open bead those groups don't look too bad, considering how you are having to cobble these together.

[longbow]

I would be one that misunderstood.

If all you are doing is replacing same payload, have at 'er. Slugs generate less pressure than shot so equivalent weight loads are just fine. You are not doing anything silly.

I am not so sure about using the Lee slugs without a nitro card wad under them. While Lee may have intended the "drive key" to transfer torque from rifling to slug, I believe it depends on the wad as the whether is is suitable. I had some that looked pretty bad after firing. Also, if the Lyman sabot slug works without a drive key and has less bearing surface than a Lee then I have to think the key is more or less irrelevant for torque transmission. It does keep the wad from blowing inot the hollow cavity though and seems pretty good at that job. Just my opinion though.

If you are shooting smoothbore then the key is not transmitting anything and is just keeping the wad in place.

you might want to give round balls a try. A 0.678" round ball (Lyman standard mould) is a prefect fit for many regular shotcups. A 0.662" ball is also good but a little undersize in many so I patch them up a bit and they shoot very well. Round balls are quick and easy to cast and easy to load.

Longbow

Longbow