Reloading 410 slugs, 163gr (~3/8oz) swagged foster slugs
Some heavy weight 410 slugs
WARNING: The information described on this page is for amusement only! Actually doing any of the following is dangerous to life and limb. The data on this page has NOT been tested in an instrumented test barrel and thus I have no real idea how much pressure the loads are producing. These loads could damage or destroy your firearm and possible even damage or kill yourself.

YOU HAVE BEEN WARNED!
Working up a load for some Heavy Weight 410 slugs

The setup(click to enlarge)

The slug: Left: ~163gr Foster Slug
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Left: 163gr Foster slug Right: Remington Slugger (~92gr)
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Conditions, Goals and Methods

Conditions: Warm mid 70's, moderate humidity, and a nice breeze. All the testing was done at 25 yards from a shooting bag on a bench. The chronograph was setup 10 ft in front of the muzzle. All the slugs were fired through a Steven 38B with a 3-inch chamber 22.5 inch barrel cylinder bore.

Goal: work up safe powder charges for these new heavy weight 410 slugs and hopefully get good accuracy out of them.

Method: There were two different methods of constructing the loads. One method utilized Alliant Herco powder and the second method utilized Hodgdon H110.

The slugs are a 163gr swagged lead slug with 6 straight ribs and a thick ring near the base. They have a very blunt conical nose with a very small meta-plate. The hollow base is small compared to other 410 slugs and has a square bottomed.

Load Construction


Load construction for Herco Load
Note the above picture does not show the powder charge or shot buffer.
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Load construction for H110 Load
Note the above picture does not show the powder charge or shot buffer.
(click to enlarge)

Slug Construction

For the loads utilizing Alliant Herco were constructed very similar to other loads I have built utilizing this powder. Since my internal ballistic software has this powder in its database and I had already used the software and powder to work up other slugs loads I repeated the process with this heavier slugs.
  • Cheddite 2.5 inch primed Hulls
  • Powder charge was pored in.
  • Half of a Stump wad was used as a gas seal
  • 1 - 3/8" felt wad was uses as a cushion
  • 2 - 1/8" over-powder card wads was placed on that
  • The hollow base of the slug was then filled with Ballistic Products shot buffer and then hull inverted and placed over the slug
  • Finished with a roll crimp
The loads utilizing Hodgdon H110 were constructed in a similar manner with some subtle changes. This powder is not in my software's database but I found some data using Winchester W296 powder and 3/8oz shot loads. From my research H110 and W296 are either the same powder or extraordinarily close to the same. I extrapolated the data I had to create the loads I used with the H110 powder.
  • Fiocchi 2.5 inch primed Hulls
  • Powder charge was pored in.
  • Half of a Stump wad was used as a gas seal
  • 1 - 1/2" waxed fiber wad was uses as a cushion
  • 1 - 1/8" over-powder card wads was placed on that
  • A pinch of shot buffer was dropped in, just enough to cover the surface of the over-powder wad
  • The hollow base of the slug was filled with hot melt glue and placed in the hull (glue was cold when put in shell)
  • Finished with a roll crimp
163gr Foster Slug Using Alliant Herco Powder

9.4gr Herco, 5-shot group at 25 yards, Group Size: 8.5 inch (click to enlarge)

10.4gr Herco, 5-shot group at 25 yards, Group Size: 10.0 inch (click to enlarge)

11.4gr Herco, 5-shot group at 25 yards, Group Size: 19.4 inch (click to enlarge)
Load and Velocity data

Load 1:
Charge: 9.4 gr Herco
Velocity Data:
Low Velocity: 1162fps
Hight Velocity: 1226fps
Average Velocity: 1187fps
Extreme Spreed: 63.26
Std. Deviation: 26.75

Group Size: 8.5 inch

Load 2:
Charge: 10.4 gr Herco
Velocity Data:
Low Velocity: 1263fps
Hight Velocity: 1335fps
Average Velocity: 1283fps
Extreme Spreed: 72.16
Std. Deviation: 29.63

Group Size: 10.0 inch

Load 3:
Charge: 11.4 gr Herco
Velocity Data:
Low Velocity: 1371fps
Hight Velocity: 1411fps
Average Velocity: 1391fps (I fat-fingered the chrono and only got data for two shots instead of five.
Extreme Spreed: -
Std. Deviation: -

Group Size: 19.4 inch

This load did not work very well at all. The velocity was lower than I had predicted with my software by at least 100fps on each load. The accuracy was very poor. I am not too surprised about the velocity I knew this powder was a bit fast for a slug this heavy. In keeping the pressure under control it was going to cost some velocity. The accuracy sort of puzzled me at first though. The slug is a tight fit in the bore and that usually leads to acceptable if not good accuracy in all my previous experiences. The shot buffer in the hollow base kept the wadding from sticking in the hollow base. After a closer look at the targets I think the problem may be a stability problem. The slug is 1.7 diameters long and this is about the maximum length to diameter ration for a drag stabilized foster style slugs. This theory is supported if you look closely at some of the holes, they show signs that the slugs did not go straight through the cardboard backer. If the slug was wobbling or flying with a cant then that would explain the very large group sizes. This marginal stability is going to present a challenge in making these heavy slugs work.



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Two examples of holes that look like the slug was yawing as it passed through. Its very possible this was caused by the wadding but I found a lot of the card wads, felt and gas seals on the ground in front of the target. The grease marks also make you think its lead not wadding.
163gr Foster Slug Using Hodgdon H110 Powder

18gr Herco, 5-shot group at 25 yards, Group Size: 14.0 inch (click to enlarge)

20gr Herco, 5-shot group at 25 yards, Group Size: 15.2 inch (click to enlarge)

22gr Herco, 5-shot group at 25 yards, Group Size: 12.9 inch (click to enlarge)
Load and Velocity data

Load 1:
Charge: 18.0 gr H110
Velocity Data:
Low Velocity: 1331fps
Hight Velocity: 1373fps
Average Velocity: 1355fps
Extreme Spreed: 41.09
Std. Deviation: 18.11

Group Size: 14.0 inch

Load 2:
Charge: 20.0 gr H110
Velocity Data:
Low Velocity: 1475fps
Hight Velocity: 1500fps
Average Velocity: 1486fps
Extreme Spreed: 24.82
Std. Deviation: 10.04

Group Size: 15.2 inch

Load 3:
Charge: 22.0 gr H110
Velocity Data:
Low Velocity: 1576fps
Hight Velocity: 1598fps
Average Velocity: 1590fps
Extreme Spreed: 21.65
Std. Deviation: 8.77

Group Size: 12.9 inch

This load did not shoot very well either. I was fairly happy with the velocity. It was much closer to what I had extrapolated from the little bit of data I found but the accuracy was still very poor. These slugs also shot evidence of wobbling with some elongated holes through the card board target backer.
Conclusions: Herco is definitely not the powder to use with these heavy slugs. The H110 on the other hand has some potential. The 22 gr of H110 would have resulted in a 163gr slug going 1590fps which would have been 915ft-lbs of muzzle energy. That would be more than enough to make me happy for whitetail this winter assuming I can get them to hit where I am aiming. I did have another issue and that was a pretty nasty leading problem. I had to use the old 0000-steel-wool on the bore brush and my cordless drill to get the lead out of the first half of the barrel. This slugs might be a touch too much over bore diameter and I might have to swag them down to close to 0.410 inch. As for the accuracy I think I have a plan that will stabilize the slugs and help the accuracy a lot. I will make UHMW-polyethylene bases for the slug as I did for some of the lighter slugs I have worked up loads for. Watch for a second test hopefully soon with those bases added. I am really hoping to have a load worked up that is accurate enough for deer season this year.


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