.410/.303 loading

kjohn

kjohn

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I have several good blown out .303 cases and a batch of .410 cast LEE TL 210 gr. WW bullets. LYMAN 4th edition cast bullet book says 11 gr. Unique for 200 gr. cast bullet in a normal .303 British cartridge. Am I reasonable to think that a 10 gr. charge of Unique in these cases is good to send a 210 gr. cast bullet downrange?

These would be fired in a Lee Enfield No.1 Mk III, original conversion 2 1/8". The barrel measures .409 or a wee tad more at the muzzle and is smooth bore.

Thanks in advance for any helpful thoughts and/or experience.
 
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Interesting question.

I have no experience with what you want to try (I use 303 brass for 410 shotshells, not reduced straight-wall rifle loads) but I think you're still in the ballpark so to speak. I would look around for more powder & charge examples though.

The bore diameter and bullet diameter should be relatively compatible and likely not cause pressure issues, and the action and brass should be able to handle what you propose but unless you load that bullet backwards I don't think it will stabilize very well.
 
kjohn said:
I have several good blown out .303 cases and a batch of .410 cast LEE TL 210 gr. WW bullets. LYMAN 4th edition cast bullet book says 11 gr. Unique for 200 gr. cast bullet in a normal .303 British cartridge. Am I reasonable to think that a 10 gr. charge of Unique in these cases is good to send a 210 gr. cast bullet downrange?

These would be fired in a Lee Enfield No.1 Mk III, original conversion 2 1/8". The barrel measures .409 or a wee tad more at the muzzle and is smooth bore.

Thanks in advance for any helpful thoughts and/or experience.
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You've got it backwards - that Unique load for the 303 Brit can be used as a very bottom end load. The 303 Brit opened to 41 Cal has a very much higher expansion ratio than 303 Brit, and hence pressure does not build nearly as high as it does when necked to .303.

The closest I could find is the 444 Marlin:

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The 444 Marlin has a larger bore size and slightly more case capacity, so I'd go no higher than 15.0 grs of Unique.
 

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Ahh. The 444 is what I am using in my 3" LE. I should have thought of that. I have lots of 700X. Thanks for bring that to my attention. Your post is the very reason I asked for any experience/thoughts.

Marci cho!
 
Newer versions of the Lyman Cast Bullet Handbook have 444 Marlin loads for slower powders, but you asked specifically about loads with Unique.

I keep both Version Three (for fast pistol powders) and Version Four (for slow pistol and fast rifle powders) on hand.

You need to stick to using these listed Starting Loads as Max Loads when used in the .303-410.

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No choke on either of my old lamp stand LE conversions, as far as I can tell. I don't think I'd want to be firing .410 cast bullets out of a full choke barrel.
 
BTW, Lyman #3 Cast Bullet Handbook is available in .pdf in more than one place. Also, it is available on the Internet Archive @ ht tps://archive.org/details/LymanCastBulletHandbook3rdEdition1980Ocr

Just close the gap between the t's. Internet Archive offers a great search feature. It took me right to page 230 for 444 Marlin.
 
Well, I took some of my famous .410/303 loads to the range today. Two batches. One batch had W-W brass, 7.2 gr. of Universal Clays, 2 flattened .395 balls sized to .410 + wads, 5 loaded. Other batch was Federal brass, 10 gr. 700X, same otherwise, 4 shots. I also blew out one Federal brass w/10 gr. 700X + 185 LEE gc ww.

All rounds fired at 50 ft. stayed on an 8 1/2 x 11 target. I didn't keep the targets, but it seems the hotter ones (10 gr. 700X) stayed a bit closer together. The Federal that I blew out did fine. Now I have five of each, W-W and Federal, to play with.

I also have 19 brass marked 1944. DI (or D1) Z already blown out, basically ready to use. Some of them have small splits at the mouth.

I even jury rigged two PP milsurp Berdan cases with Boxer primers and 700X and blew them out. They blew out fine, but the fire hole I drilled isn't entered and are tricky to get the primers knocked out of. They will be for a later project.

Next trial will be with .410 Tumble Lube cast bullets.
 
Latest episode in reloading for the .410/303 brass. Primed, powdered, and put a 210 gr. LEE TL cast bullet in. Hmm. They are a bit loose. Fiddled and searched for the right die that was tight enough to crimp the case to hold the bullet. Finally came up with a Lyman 30-30 die, FL I think it was. The cartridge just barely started into the die and I could feel it jump two or three ribs on the TL bullet. Nice and tight now!

The fired cases don't need resizing, so the chamber is obviously big enough if the case won't fit tight on the .410 TL bullet. One thing I will do at the next loading is pack a cardboard wad down on the powder to keep it at the primer end. I have fired lots of rifle rounds with 10 or more 700X etc, with no wad. 700X burns easily, though.
 
kjohn said:
I have several good blown out .303 cases and a batch of .410 cast LEE TL 210 gr. WW bullets. LYMAN 4th edition cast bullet book says 11 gr. Unique for 200 gr. cast bullet in a normal .303 British cartridge. Am I reasonable to think that a 10 gr. charge of Unique in these cases is good to send a 210 gr. cast bullet downrange?

These would be fired in a Lee Enfield No.1 Mk III, original conversion 2 1/8". The barrel measures .409 or a wee tad more at the muzzle and is smooth bore.

Thanks in advance for any helpful thoughts and/or experience.
Click to expand...


4.2 grains of Unique pushes a 160gr cast bullet in a 38 special with no problems. I would find someone who has done this before attempting it on your own. Handgun powder is very fast burning compared to rifle loads. In many cases handgun loads are only filled 1/3 full with powder which gives them room for error to dangerously overcharge the cartridge, where rifle powder is usually full close to the top making in impossible to double charge a dangerous load.
 
10 grs of Unique I use in 30-30 ,300 Savage and 308 Winchester with 150 to 180 gr bullets. In the 44 Rem mag it’s a target load with 250 -250 gr bullet. The 410 being a larger bore you should be good to go and could likely go with more powder. Using a lighter bullet than the 44 with a longer case so pressure should be under its pressure.
 
As I suggested earlier, you can use 10.0 grs of Unique as a Starting Load and work up to 15.0 grs, which is a conservative Max Load.
 
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Latest performance: Blew 7 NNY cases out. 5 came out nice, 2 didn't survive the trip.

NNY a x.jpg
 

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