doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com .410 reloading question

Has anyone here ever fireformed 9.3 X 74R brass into 3" .410 shells? If so, specifically, did the rim thickness cause an issue with chambering in a .410? Also, how much increase in case capacity would be expected over current 3" plastic .410 hulls?

I've found a little information about this on the 'net, but not much, mostly just that it can be done.

Stan,
If no one has done it, I expect they will, now that you have asked the question. The rim question should be simple enough to answer (someone try it) and if an issue, simple enough to address (a simple lath job). I use 444 Marlin cases to make 2 1/2" 410 cases , but the 444 case is simi-rimmed rather than rimmed. As far as case capacity is concerned, someone will have to fireform some cases and measure them, fireforming will increase the diameter but will make them even shorter (they are not quite 3")
Mike.

You may have looked at this, but MagTech makes 2-1/2" cases that they claim are for 2-3/4" chcambers. Not sure what that means but I have had some and they seem to be serviceable. As with all the brass shells, they have a larger internal volume than a standard hull and require larger wads.

I have for a while purchased Magtech shells from thegunworks.com. They always seemed to have the best stock and best prices for them.
Their name is, I believe, The Muzzleloader Emporium. The gentleman who started and ran it passed away a couple of years ago but his wife and staff are continuing the business.
I just checked and they have MagTech 410 in stock for $48/box. That is higher than the other gauges but so is everything else .410.

Making 3" from a rifle cartridge is do-able, but for proof of concept it would be easier to buy a box and some wads and try them. They carry a lot of wads, and if they don't have them TOTW has everything from .410 to .450 in stock. (Circle Fly) The recommendation for this hull is .430 for the internal wads and .45o for overshot. With cut wads, the higher internal volume and no an overshot wad right at the mouth, you should easily get a 3" load in the shorter shell. If they work out, a longer rifle conversion could be made, but you can try it without much work. One interesting comment on the Magtech 410 is that, if memory serves, there is no 2 thickness base on them. Due to small diameter, I am remembering that the base is all one level at full thickness. This is a big deal because it negates the objection most people have about the wad encroaching on the flashhole and should be stronger due to the thicker head. I will look to see if I have any of these left to check this.

I just checked and found 2 boxes I have for some "experiments" I have been planning. The measurements I took show an OD at the mouth of .460, an ID based on this and case wall thickness of .446, an OAL of 2.336 and an inside depth of 2.225. The last two numbers would indicate a head thickness of .111, which should indicate a relatively robust head design. I will say that from my experience forming 577 Snider cases, the Magtech cases are rather hard and need to be annealed to reform to any extent. That is probably a plus if you simply glue in wads, since they tend to resist expansion with mild loads and don't change much with cycling.

One other relevent point is that they are made to accept large pistol primers. The primer pockets can be a little tight and should be prepped anyway, so I always use a large rifle pocket reamer instead of a pistol version. If you do this, you can use either large rifle or pistol primers. I tend to always go with the large rifle because I use them with smokeless powder and the ignition may be a little better.

Have you looked at or talked to the people at Rocky Mount. They list 3” .410 shells. I’d check their internal volume as a starting point. See what their largest shot payload they recommend. I know you are looking for that 3/4 to 7/8 ounce .410 payload. In the end I’d rather have a higher velocity 5/8 or 11/16 ounce, tighter pattern load, than a heavier, slower load. Trade off in all things.

Rocky Mountain is the only place I am aware of that has .410 brass longer than 3". I tend to buy all the brass I intend to use from RCC because it seems to me to be the best out there, and they make it for some really odd gauges. Oddly, they don't make it in 3".

The reason I mentioned MagTech is that it is far and away the cheapest of all the brass hulls, and in .410 it has just as robust head as the other makers, so I would have no qualms about using it in a shotgun. For that reason I would recommend trying the Magtech to experiment with wads etc.

Of course the simple thing would be to take a few 9.3x74R shells, anneal the front half of the cartridge, prime them and charge with a normal 410 load topped with a case full of cream of wheat and shoot them.
The slightly smaller cartridge rim shouldn't be a problem; the potential one is that the rim is a little thinner too, and if the chamber is too deep or the firing pin worn there could be weak ignition or misfires. Simply prime a cartridge case and fire it off empty. If there is no problem with a few of these firing and extracting, then anneal, fireform and have fun. I have never measured a 3" 410 case so don't know if they are actually 3" or not, but the .06" difference with the brass should be made up by the internal volume. You can gain something by using a glued in overshot wad, but that can be done with a 3" 410 too. Several people have the 9.3 cartridges in stock right now for a little over $1/round.

Stan, I have always loaded 2 1/2" shells with a much larger shot load than 1/2 ounce. I have my specs posted in my load book, specs that exceed NSSA maximums by quite a bit. I use old style AA hulls and sometimes green ribbed Remingtons that have been fired at least two times to increase capacity. I use wads that intrude the least in the shell. I like the orange PC or Remington wads. The point is that I could do the same with 3" shells now that I have a MEC 600 Jr set up to load them. The idea that comes to mind is to use a robust .410 gun and cut out the chamber to 3 1/4" or longer as long as the wall thickness at the forcing cone is sufficient. I have some Briley tubes that may have long forcing cones suitable to bore out to a longer chamber dimension. My point is "Don't stop at 3" chambers. Go for the gold." There must be someone who has a 3 1/4" or 3 1/2" case that fits in a .410 chamber. Don't believe the Old Wive's Tale that long shot columns won't pattern well. You have to try it to know the truth. What is your recommendation for a strong, inexpensive gun to test our theories? How about a Savage-Fox double? Your friend, Bill Murphy

303 British cases make very cood .410 cases, minimal work, except the primer

I am pleasantly surprised at all the replies to my question. I will attempt to address them all in order.

I have now read, and been informed by p.m., that the cases I mentioned will have to have the case rims thinned by about .005". A "simple lathe job" is not simple if you don't have a lathe. I hope to avoid that, but may not be able to.

These are the cheapest cases I have found, and as I understand it come with the front half of the case already annealed and ready for fireforming. https://www.grafs.com/retail/catalog/product/productId/76364

I really don't think I want, or need, all brass cases longer than 3". Though no one has come up with an actual comparison of case capacity between current plastic 3" cases and these 9.3 X 74R brass cases I cannot help but believe it will be at least 5% increased case capacity, maybe more. That will do what I want to do (though I may someday get greedy and go for the gold, as my friend Bill suggests).

And, as Bill mentions once again, I have absolutely proven that very long shot columns can pattern extremely well. And, before someone points out the obvious that patterns are two dimensional and don't take into consideration the longer shot string, I use them on doves and they are deadly. Straightaway shots don't prove much actually, in regards to shot string length, but crossers do.

Thanks to all for the excellent replies and information.

The simple thing is buy a bag of cases and stick one in the gun.

Not wanting to start a squabble, but I looked at a couple of sources and both listed the dimensions of the 410 as larger than the 9.3 at every important dimension. The 410 is shown as .470 base, .535 rim. .060 rim thickness and 3 inch length. The 9.3x74R is shown as .469 base, .525 rim, .055 rim thickness and 2.94 inch length. The rifle rim is about .01 smaller than the 410 and .005 thinner. The base is .001 less. There should be no case work left except forming. I also found a quote of 82.3 grains of water for the 9.3 capacity but this is meaningless unless you know the fill point quoted. Add to that the fact that the case volume will go up a lot after forming and get a little longer to near the 3" mark.

I am making a rough guess that the 410 cas has an ID close to .410. Measuring a wad should give this number(I don't have any).

The 9.3 is .469 base and probably has around .015 walls for most of it's length. Net ID would be roughly .440. Also close to what I measured on the Magtech. 9.3 is very slightly shorter, but basewad in 410 likely cancels this out. From this, the volume difference should be right at 15% more than the 410, according to my rough calcs. If you really want to stretch it, use punched wads and an overshot wad glued in and you can really get more capacity. The overshot you will use will give you quite a boost. Given the fact that the 410 is star crimped and the brass case can be fully loaded, I suspect the difference will be closer to 25%. Or, as we say, a 28 gauge load. (Most 28 gauges weigh less than the same 410).

The big unknown is the pressure. That's a small bore and the guns run at pressures above most shotguns. Start raising shot charges by big jumps and trying to keep velocity reasonable could put you into rifle pressures.