Interesting stuff guys. I hope to do some load development this summer with a variety of cast slugs. Your experiences certainly give me food for thought.
Interesting stuff guys. I hope to do some load development this summer with a variety of cast slugs. Your experiences certainly give me food for thought.
"Only accurate rifles are interesting."
- Colonel Townsend Whelen
Gosh, drm I sure wish you would put together some components of that load and take a picture of it and them enter it in the castpics contest for this month so we all see what you are using, maybe include in the image a completed round along with the components it was assembled with.
Drm50:
What were group sizes for that load at 100 yards? If under 6" I'd be very interested in details too.
Longbow
Tested the difference between deep/shallow crimp with a heavy slug (1-1/4 ounce) over 34 grains of Blue Dot. At 1450 fps this is a "warm" load probably above 10.000 psi. As with the fast powder test the deep crimp resulted in slightly faster speed and less variation, but not much and percent-vise less than with the fast powder.
I managed to dig one of the slugs out of the berm (the front slug in the picture) and it shows clear signs of having expanded during launch as the flattened ribs indicate - also, the polystyrene wad showed signs of being heavily compressed.
I then tested the same slug at 1150 fps by shooting them into a berm of fine sand to see if expansion was still a problem - at the same time I tried two different types of wads: High Density Polyethylene and Polystyrene. (all loads had a x12x seal under the slug and nothing else) The result can be seen in the rear row in the picture. Both types of wad held up pretty well with the HDPE (left side) being a little more forgiving.
In this picture the difference in pushing the slug 300 fps faster can clearly be seen on the nearest slug.
When looking closely at the slugs it turned out that the "pattern" of the wads had been slightly imprinted in the base of the lead slugs - this could actually be a good thing if the slugs were to be shot from a rifled barrel as the imprint actually locks the slug & wad together.
I have an idea for a different slug based on Uncle Dino's idea of fastening the wad to the slug by using a slug with a spigot instead of a cavity as in my Brenneke clone, but it'll have to wait till later.
Cap'n Morgan
As always Cap'n Morgan, great stuff!
I do like those slugs. Is that the same wad you used for accuracy testing a while ago? I don't recall the "cavities".
As for distortion. I had some Gualandi DGS slugs given to me (I have not seen them available in Canada and certainly not where I live) which I loaded up to a BPI recipe. Accuracy was okay though one keyholed at 50 yards but recovered slugs showed significant wad and slug distortion much like you experienced with the wad imprinting the slug. The Gualandi slugs are hard lead alloy and possibly heat treated , but hard anyway.
Blue Dot is pretty slow powder but I wonder if even slower would reduce wad damage?
Longbow.
The "cavities" has been there all the time. The first design was too weak so I added more support. The reason the wads are not solid is that the plastic shrinks too much which prolongs the solidifying process as the plastic loses contact with the mold. It is possible to add a small amount of "foaming" material to the plastic which will counter the shrinkage, and I may try that if the need for stronger wads comes up.
As for slower powder I'm a bit reluctant... last time I tried Steel in a slug load I ended up with a sack in the barrel.
Cap'n Morgan
I understand the reasoning for the cavities, I just didn't recall seeing them before.
When I bought some BPI AQ slugs to test many years ago they came with what appeared to be an injection moulded long plastic wad with helical ribs (quite deep) and a hole up the middle. I am guessing the hole accomplished the same thing as your cavities.
Recovered slugs showed that the deep helical ribs in the plastic were almost completely flattened off and the wads got shorter and fatter. That was with a recommended load using Unique IIRC. I may still have the recovered slug(s) downstairs somewhere. I'll look.
That wad does take a lot of abuse! No doubt about it. I still think it is the weak link in the home tinkerer's supplies. It is hard to find anything that will take 10,000 PSI and come out smiling. Everything distorts which is okay if the distortion is consistent and controlled or the distorted bit isn't attached to the slug.
I wonder if a felt or cork wad between gas seal and your slug would add just enough cushion effect to protect the attached wad?
Slightly different situation but when I tested my finned slugs I found the 6 fins sliced, diced and shredded nitro card wads and hard card wads. I tried a few things but in the end the solution was to put a couple of polyethylene disks under the slug to protect the wads below. I wonder if the reverse might work for you by spreading load on the wad.
Regardless, you've done a terrific job and beat us all in the slug accuracy game.
I have found that a flex seal or brush wad improves accuracy. It also helps with base distortion. A square even crimp is critical, with some compression. .I recover slugs where the base is square and undamaged. These were fired @1250 fps
Capn, from the looks of those base wads they out to be pretty easy to rivet those on with a short tail out the back of the slug.. Nice bases, fine job on those. D
Last edited by uncle dino; 07-09-2017 at 08:40 PM.
I would think so. Normally I have always added a 1/2" felt wad between the seal and the slug. I'm trying to keep things as simple as possible which is why I skipped the felt wad. The slugs still grouped well, under 4" at 55 yards, but since I was using 2-3/4" plastic shells, trimmed to about 2.44, the slugs will actually be in a short free-flight before entering the bore.I wonder if a felt or cork wad between gas seal and your slug would add just enough cushion effect to protect the attached wad?
Cap'n Morgan
4" at 55 yards is good accuracy in my book!
Been working on a Lyman 525gn Sabot in Rio hull with a Claybuster CB-1114-12 wad with various powders all roll crimped. I like the Rio clears for Slugs. Ordering more components soon to have more options. Trying Longshot, Blue Dot, Hodgdon Clays and WSF. Will report back on accuracy.
Kraken Fan #69
Kraken, the more, the merrier! Slugs are fascinating...
Clear hulls for slugs make sense, especially for safety reasons, that's why I only use roll crimp; With my sloppy way of handling things, sooner or later a slug load will end up in a pocket in a hunting jacket together with a bunch of normal shotshells. Hopefully I will then notice my mistake...
Cap'n Morgan
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |