So I stumbled across a couple videos online showing people taking cheap 1-1/8 oz birdshot 12GA rounds, cutting the "star" part of the crimp out of the hull (leaving the roll part of the crimp), dumping the shot, and then replacing it with a slug made to go in a shot cup. Specifically the lee 1 oz key drive slug.
Is this considered ok? I did a little looking online and it seems to be a somewhat common thing.
So going to the slug, is 1/8 oz lighter of a "projectile". However does it make a difference with it being a slug instead of shot? They seemed to have no issues with them, and they used several different brands of rounds (all birdshot).

So that got me wondering. From what I can tell, the lee 1oz slug is made to go into a standard shot cup and use a regular star crimp.
If you had a specific load using a specific hull, wad, powder, etc.. but is made for 1-1/8 oz of bird shot. Would it be safe to substitute the 1-1/8oz of birdshot with the 1 oz lee key drive slug? Or would this be a big no no?
If it is a no-no, then can you explain the differences of two two. I am wanting to learn here.
My lyman 5th edition manual does not show any data for the lee slugs (7/8 or 1 oz), they only show the forster slug or the lyman sabot slug.

No hands on experience,  but a guy at the gun club tried it.
He had to put over shot cards in first to get the slug up in the wad for a good roll crimp.
Didn’t crono, but the "patterns ", not groups,at 50 yards were horrible.
This was in a smooth bore 870.
The problem issue I noticed was the wads were scattered and mangled in different ways.
We came to the conclusion that the wads won't separate consistently,  there by causing erratic flight.

I have done that. I found federal loads seemed to work best, but I converted others as well. I never grouped them, but I shot a few hundred of them in 3 gun competitions, and they always worked well enough doing that. Not that I recall any of that being particularly precise shots. I seem to remember them typically being plates at 25-50 yards or so.

The tricky part is getting the slug down in the cup without pinning and of the “pedals” under it.

Yea these would not be for hunting or long range shooting, so superior accuracy is not that big of a deal. Just range fun shooting water jugs and whatnot, hence wanting to use cheap shells or a load I already use.
I plan on picking up one of the molds and casting some to try, since the molds are not very expensive.

Probably be better of doing a cut shell or wax slug if its just for fucking around at the range

Hard to say without pressure testing it, but I would surely chrono it at least.  My personal experience is role crimped shells can be quite sensitive to specific loads.  And they are usually lower pressure than star crimped shells.  The combination of change of weight and crimp could create a very unstable load.  I guess it could also put you over pressure too because shotgun shell combos can be sensitive that way.  I'd consider that an emergency only technique.

As far as I know it’s called a cut shell. Rumor has it, was a redneck way of hunting deer with cheap shells during the depression.

With slugs being cheap enough and my shoulder not enjoying shooting them anyway I never took the time to try

They can be very accurate for a shotgun

Cut shells are made by cutting almost all the way thru the hull wall just above the brass.  That cut line will give before the crimp does (in theory) and so most of the hull, the wad/shot cup, and shot become the slug

It is more than okay, I do it.

I also highly recommend the Lee 7/8oz slug, it’s naturally more accurate and use less lead.

Also, for every 3.5 shells you convert, you gain an extra slug.

So, out of a box of 100 converted bird shot loads, you will gain 100 loaded slugs and 28 extra 7/8oz slugs.

(Also to save $$$, reverse the boxes to store your converted rounds)

Cut shells are more dangerous and if needed for life saving are not up to par. Gel tests show shallow penetration.


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Not really planning on converting already loaded shells, as I have a loading press and lots of hulls, plus a load I already use with 1-1/8 oz of #8 birdshot. So my idea was to simply load the rounds with the slug instead of the shot.

I just melted down a bunch of lead today and cast it into a muffin tin to get some good clean lead for casting. I ended up with 35 pounds. Will be ordering the mold soon.

Gotcha. Rule of thumb for shotguns is if you remove 1-1/8oz of lead shot and replace with a 1oz slug, you are good to go. It’s okay to go under weight, not add weight.

Just make sure the slugs you use will fit in the wad and not bulge your hulls to the point they won’t load.

If yiu are using a choke, sacrifice 1 wad from one of the bulls and out in the slug. Run the wad (with slug inside wad) through your choke to make sure it’ll pass. If not, I wouldn’t shoot it.

Since you lose some volume, you might need to add 1-2 cardboard nitro cards, can be easily made with a 5/8” gasket maker punch. Moving the slug up a bit from the wad will help prevent the wad jamming into the slug.

Good luck!

This is how I do it. A couple 20 gauge nitro cards to bring the slug up for a good roll crimp. Cycle my 1100 fine. Less recoil than factory slugs.

The slug I plan on starting out with is the lee key drive 1 ounce. It is made to fit in a normal shot cup. I got it cause the mold was very inexpensive. Just wanted something cheap to start with.
I may end up getting the lyman sabot slug mold later on down the road. The lyman manual I have actually shows loads for it.

Well I was melting down some scrap brass today and casting it into some muffins.
While In was at it, I figured I would try out my new lee 1 ounce key drive mold.
I'll save the long story as there was a little learning, trial, and error, as I had never cast anything before in my life. But I finally got it figured out and cast about 40-50 slugs to play with.
The lead is a mix of who knows what. There is some old birdshot, some wheel weights, some pre cast bullets, and some ingots of unknown alloy I bought online from other people.
Slugs came out between 418 and 420 grains. So just under a ounce. But that is fine as they are just for plinking, not planning on doing any type of hunting with these, just range run.
I load up 5 using the hull, powder, and wad I have been using with 1-1/8 birdshot.
The crimp is too deep in the middle as the slug is shorter than the shot, so it is open a tiny bit. I stuck one in a wad and eyeballed it. It looks like a disc of cardboard would give it the right height, so I have ordered a 5/8in hole punch to make some.
But I shot the 5 I loaded, standing at 25 yards and they all hit POA. I was smacking a 10 inch plate with no issues. Hulls and primers look fine.
Gonna try again once I get the gasket punch to get a better/fully closed crimp and try again. I will then try them at 50 yards off a bench and see what they do. I also have a rifled choke tube to try out.

I played with it some. Cut open the shells, melted down the birdshot and cast slugs to go back in.

I had some newbie casting troubles of course, but I got a few good ones and while I never tested accuracy I was able to hit 12x20 torsos at 80yds with them, but I only had about 10 rounds to play with.

I would just buy a box of slugs.

Converting cheap birdshot ammo is much cheaper.

OP, the 7/8oz is more accurate and save a bit of lead.

If you want to add a little more weight to the slug, you can file down the top of the aluminum key slot. Don’t file too far as you will change the center of gravity.

Thank you for this useful thread. I have done wax slugs in the past, but never converted any birdshot rounds into slugs.

I think I will order a mold, roll crimp tool, and a punch to give this a try. With the limited availability of ammo over the course of the last 2 years along with the significant cost differential between bulk birdshot loads and slugs this process makes a lot of sense to me.

Wish someone could gel test a Lee key drive slug loaded backwards

Send out some emails and see if anyone would do it for you if you sent some rounds and a couple bucks. Or start a thread here and ask as we have a few people that do gel tests.

Why backwards?

I have my own personal range I built right next to my house (on my property). If someone sent me whatever gel, I would load some and shoot it. Don't have a video camera, only regular camera.
Or I can send some of the slugs to someone. I have 82 pounds of processed lead right now with nothing to use it for but slugs, so I can spare a few slugs no problem.

The back of a slug is empty. A big cavity.

If fired into gel/tissue, the tissue would fill into the cavity while causing the slug to be unstable thus causing it to tumble

A tumbling .69” lead slug would probably do some serious damage.

Can it maintain its accuracy? Would be fun to test.

I might try it on some Lee slugs I have.

Save your spare lead. Shooting pistol/rifle cast bullets really lowers the costs.

I always wondered how a round ball as big as will fit would work.

They make molds for round balls.

https://www.ballisticproducts.com/Lyman-12ga-690-Round-Ball-Slug-Mould/productinfo/1245690/

Not sure how well or badly they work.

So far all I have is the lee 1 ounce key drive mold. However I did just order a sabot slug mold from ebay. It is identical to the lyman sabot slug, but it comes with different inserts to change the size of the hollow base and change the overall weight of the slug. Down side is it ships from russia, so it may be a while before I get it.
I figure it would be fun to try the different weights and see how well/poor they shoot and the accuracy of them.

Round balls work great in my rifled barrels.  Best Lee 7/8 load is 20 gr. Of greendot,win hs hull,win209 primer,  fiocchi 27 wad,line up the drive key slot with the ridge inside the wad. They seem to separate more consistently and are more accurate

Tried out some of the slugs yesterday.
I bought a 5/8 hole punch and cut out some cardboard spacers to get the slug up high enough to get a good fold crimp.
I shot at 25 yards, standing, unsupported. Gun was a mossberg maverick 88 with a 28in vent rib barrel, bead sights. Shot 5 rounds of each load

First was my 1-1/8oz birdshot load using win AA hulls, IMR 700x and a WT12 wad (cheaper copy of the WAA12 wad).  It took 2 pieces of cardboard to get a good crimp. Slugs pushed in easy with no issues.
Was able to cover the group with my hand. 1179 average FPS

Next was using the rem sts hulls. Same powder (different weight to match the hull) and wad. 2 pieces of cardboard on these as well, but the slugs were real finicky to get pushed in (pedals of the wads kept wanting to catch the slug). Don't know if the rem hulls are slightly tighter or what, making it more difficult to push the slugs in.
Group was similar to the win hulls, but a little larger. 1137 average fps.

Next was a load I got from hogdon's website. Win AA hull, WAA12R wad, and HS-6 powder.
The WAA12R was was significantly shorter and it took 5 pieces of cardboard to get the slug up high enough for a good crimp. Also it was a nightmare to get the slug in. Every one of them were catching on the pedals bad. The pedals on these wads seem a tad thicker. It was so much of a pain I said screw this I am not using this load anymore.
And you guessed it, It had the best group, 4 touching, but the 5th I pulled. 1195 average fps.

Next I tried a load of HS-6 made for 1-1/4 oz of birdshot using the WAA12/WT12 wad that I got from my lyman manual.
Group was a little larger than the rem hull 700x load.

Last I tried a couple loads of unique using the win hulls and the same WAA12/WT12 wads.
Either the slugs or the gun did not like unique. Groups were both, over twice or larger than all the other groups. 1175 and 1217 average fps on those two loads.

So I need to try and figure out a better way to get the slugs in place using the HS-6 and WAA12R wad. Of course the most pain in the ass to load had to be the best group.

I’ve used felt wads to take up space, other people I know do the same. Now that said, we’re using the 1 oz slug mold as opposed to the 7/8. I recently acquired the 7/8 oz for a special project, but I haven’t tried it yet. Also, I’ve never actually “papered” my loads/conversions for accuracy for accuracy-they were good enough for what I was doing with them. So I can’t make any suggestions that way.

Federal cases seem to be the easiest to “convert” if you’re converting birdshot loads. Once upon a time I knew why that was, but I’ve been playing with that long enough that I don’t remember now.

Last year, I started actually loading complete rounds rather than converting them. I’ve so far only used unique(I have some older powder I’m trying to use up), but I’m starting to think about what else I might use. I’m interested to see what you come up with. What are you shooting them out of to test?

I've been using a old mossberg maverick 88 with a 28 inch vent rib barrel for testing. I have been using it for it's longer barrel to get "normal" velocity readings, as I am pretty sure most commercially loaded 12 ga ammo that has velocities printed on the box, almost always use either a 28 or 30 inch barrel to measure their velocities.
I also have a mossberg 590A1 with a 20 inch barrel I plan on shooting these out of as well.
I have a few other shotguns too that I do not shoot as much.

I have ordered a couple bags of felt 20 ga felt wads (1/8 and 1/4 thick), they should get here this week. I got the 20 ga felt wads as they are the same diameter as the lee slug and fit in the 12 ga shot cup.
I am done with making my own out of cardboard, even with a sharp gasket punch, it is a pain in the ass cutting them out, even with a small mallet.

I have a ton of win AA hulls (600-700) and probably 200+ rem sts hulls. So I plan on using them. The win hulls seem to be working better as of right now.
There might be other hulls that work better, but for now, I will just stick with what I have.

With the low pressure that 12ga runs at I’d be surprised if there were a big velocity difference.