Let me preface this post by saying YES I am aware of the risks of using non-published data, and "hot-rodding" recipes on my own. I feel that I'd almost certainly get crucified and get the book thrown at me on Shotgun World or some of the other sites. However, I feel that this site would at least appreciate seeing some "other" data. My buddy and I have been obsessed with .410 the past year, and not competitively like trap or hunting. We just like to **** around, analyze ****, and try to push limits. Both of us have been in the automotive/race engine industry for the past 20yrs or so... which I guess makes pushing the limits of stuff as second nature to us. Anyway, it goes without saying that the load data in this post is to be used at your own risk. You all know the signs, and what to look for when working a load up. Tread carefully.. enjoy the data provided and don't give me TOO much grief for "wildcatting" or "hot rodding" LOL! I'll try to answer any questions that come up. I have multiple pictures and videos of our range trips and can/will upload them if someone can lead me to a good hosting site aside from imgur. Ok here goes...
(By the way.. this all started when I read a post maybe a year ago on here as using a .40" ball as a slug, and working up some loads from there. Not all these loads are slug loads. I'll make the notes best I can. Also, chronograph number posted is an average of however many we shot which was between 6 and 12 shells of each load. All loads were sent from a bare bones, no name Turkish single shot break action 18" barrel.)
The following loads were Fiocchi 2.5" hull, BX410 wad, one Hornady .395" lead ball(80gr) and a cork spacer on top finished with a roll crimp. The spacer was so we could maintain the proper stack height to keep the finished shell at 2.5"
22.0 Alliant 410: 1524fps average. Manageable yet stout recoil. Decently accurate.
18.0 VihtaVuori N110: 1347fps average. Medium recoil. Decently accurate, prob needs more work.
22.0 Lil Gun: 1740fps average. Very loud. Accurate. Big flash.
30.0 Lil Gun: 2127fps average. Even louder. Like a flashbang grenade. Just as accurate. Barrel gets hot.
21.0 AA 1680: 1475fps. Loudest of them all. Would honestly make for a good 4th of July blank possibly. Accuracy ok.
16.8 Longshot: 2296fps. Far and away the winner. Sounds more like a rifle. Very accurate. Will be loading 100 of these soon.
The following loads were same Fiocchi hull/BX410 wad, Fury Bullets 212gr(1/2oz).410 slug, no spacer, finished w/ roll crimp:
21.0gr H110: 1467fps, 22.0gr H110: 1570fps, 23.0gr H110: 1663fps. All were stout recoiling, and good accuracy.
26.5gr IMR-4198: 1427fps. Excellent accuracy, makes some smoke, dirties barrel faster than others. Recoil medium.
16.0gr N110: 1230fps. Mild recoil, and could definitely be worked up more. Not bad for what it is.
18.0gr 300-MP: 1225fps. Similar performance to N110 load but add a lot of muzzle flash.
14.0gr Enforcer: 1083fps. Loud and not very accurate. Low velocity. Prob not ideal. Scrapped this one.
Oh and just for good measure, and since I'm already sharing info.. here's my favorite .410 buckshot load that rocks the house:
22.5gr W296 with BX410 wad and 3 balls of Hornady 000B(.350") finished with roll crimp: 1536fps.
Hope you enjoy reading this post. I know I enjoyed all that testing! And that Longshot load is 100% a keeper! And if you're scared, it works fine loaded back unlike H110/296. We loaded it in steps down to I think 10.5gr and it was still behaving great, just less velocity. Regarding flattened primers or overpressure, there was no "primer flow" at all in this range session. Of course they're all going to be on the flat side with hot loads like this, but nothing to bug out over. If I had to pick the flattest primers of the bunch it would be the AA 1680 and IMR-4198 primers. But I didn't see anything in dire need of being dialed back a notch.
Again: use at your own risk. Cheers!!