Making the Most of the “Little Gun”
I have lots of experience with the .410.
While I carry one for woods walking and to shoot garden varmints, my 12-ga. Winchester Model 12 riot gun is the "go to" gun for things which go bump in the night. So, If you intend to own ONLY ONE shotgun, get a 12-ga. pump. Reduced recoil law enforcement loads are viable if females and youngsters must use the same gun. Their recoil compares to a 20-ga. load.
The .410 slugs are accurate in some guns, but you can determine that only by testing. I found them mostly ineffective on game larger than foxes, at ranges beyond about 30 yards.
Grouping of shotgun slugs from a plain, bead-sighted single-barrel shotgun at best is 1 inch spread per ten yards of range. AND your gun may not hit where it looks, so you must test and practice. You could spend $25 in ammo just to find out that it doesn't work for you...
A .410 slug weighs about 80 grains. While initial velocity is high, it loses half its striking energy in the first 50 yards, where its energy compares to a .25-20 rifle firing black powder loads. Certainly no bear gun!
Better than .410 slugs for larger varmints or home defense are the 3-inch five-pellet 00 buckshot loads now popular for home defense and widely available. In most .410s they are much better than slugs and are the best choice. They put the same number of pellets on a silhouette target at 25 yards that a cylinder bore 12-ga. riot gun firing 9-pellet 00 buck does at 40.
You can expect 4 out of 5 pellets striking an Army "E" silhouette at 25 yards, which is a killing pattern. At 40 yards the .410 gets at best 3 hits out of 5, which is barely adequate, if one more more pellets happen to hit a vital area.
An accepted standard is that total kinetic energy delivered by buckshot on a hostile target should equal that of a hit from an M1911 .45 pistol firing service ammunition. That is the standard that the Army has used since WW2. If you are lucky, you might land 2 pellets out of 5 at 50 yards your Zombie silhouette, if your particular gun likes the load, still, better shoot him twice!
I spent $250 in ammo test firing various .410 rounds in three guns, a full-choke, high-dollar Beretta, a sawed off cylinder-bore Iver-Johnson and a modified choke H&R youth gun to prove the above to my satisfaction. If your Daddy’s .410 happens to be a stone killer, it may indeed be that you have a great gun and that mine are all POS, because the luck of the blind monkey rules the universe in these things.
Each 00 buckshot pellet fired from a .410 has about the same energy at 25 yards as a .32 ACP pistol slug. Less than 3 pellets hits do not total our magic 350 ft.lbs. of kinetic energy and so cannot be considered effective for defense or hunting deer-sized game. The longest range at which you can expect all 3 pellets hitting when firing the shorter 2-1/2 inch buckshot rounds is about 20 yards from a typical single-barrel shotgun.
If using the Judge revolver no farther than 7 yards in the best case, based on one gun I tested. Velocity really drops off quickly from a .410 handgun. Winchester 5-pellet 00 buck gets 1230 fps from a standard shotgun, and only 800 or so from the short-barrelled Judge revolver and 880 fps from the long-barreled one.
When using a .410 with bird shot for hunting small game, it will work OK IF you stay within its rather severe range limitations. The most important thing to remember is that given its small payload (1/2 oz. in the 2-1/2 inch shell and 11/16 oz. in the 3 inch shell) you have very few pellets in the pattern.
In order for a shotgun pattern to be effective on a game animal the size of a rabbit, or a bird the size of a pheasant or duck, you need to achieve a number of pellets hits equal to the shot size, such as six No. 6 or 8 No. 8 within 20 square inches or a 5 inch circle paper plate, about the size of a rabbit.
Having less than 200 shot in the shell makes obtaining effective patterns difficult beyond about 10 yards because the pattern spreads about 1 inch per yard of target distance. Using shot larger than 7-1/2 in the 3 inch shell or No.8 in the 2 inch shell is ineffective unless you limit ranges to 25 yards from a single-barrel shotgun, or 5 yards with the Judge revolver.
It is important to fire test patterns with your gun and ammo and to PRACTICE with the smaller gun, learning to acquire the target and shoot quickly, so that you have clear knowledge of its capabilities and develop enough shooting skill on your part to somewhat make up for its reduced effectiveness.
The biggest drawback in using a .410 is that developing skill requires buying and shooting up more ammo in testing and practice to obtain that knowledge and maintain that skill. A casual shooter needs to fire 100 shells a year at clay birds to simply maintain basic skills and not decline.
To improve your skill you need to shoot a case of 250 shells a year just in practice. And .410 ammo costs about TWICE as much as the same number of 12-ga. or 20-ga. shells because the factories don't produce or sell as many. If you shop seasonal promotions you can buy case lots of "dove & quail" no. 8 or or "duck & pheasant" no. 6 12-ga. or 20-ga. loads reasonably, but not .410s. My advice is to get either a 12-ga. or 20-ga. gun and stock up on bargain ammo whenever you find it.
You won't find any bargains in .410 ammo. At least, I've never seen any. In some areas it is difficult to find .410 cartridges in shot sizes smaller than No.6. Marketing people try to make up for the .410s lack of killing power by pushing larger shot, which is pure lunacy, particularly large shot such as No.4, which is entirely useless beyond 20 yards unless you happen to have a full choke barrel which "likes it". In those cases a gun may pattern so tightly that you must shoot it like a rifle, which means that you could have used your .22 pistol and saved a dollar!
Shot sizes of No. 6 or larger should only be used in choke bore .410 guns which pattern the particular load well, within the ranges at which you have determined that they are actually "effective." A shot load throwing "effective" patterns means that you can reliably depend upon putting a number of pellets equal to the shot size, such as four No. 4s, five No. 5s, six No.6s, seven No.7-1/2s or eight No. 8 shot on your 5-inch paper plate at your given range. Determining this means firing in a rapidly thrown-up 2 second instinctive snap-shot. Misses with a single buckshot do not count anything!
Given the modest shot capacity of a .410 the maximum useful range at which you can expect effective game patterns with any confidence is only 25 yards under the best circumstances. With cylinder bore guns you may do no better than 20 yards...With a Judge revolver no more than 5-7 yards.. I can kill grouse with my slingshot flipping a stone that far for less money and more silently.
There is NO substitute for patterning your gun. You do not have to dissect shells, count pellets, put up a big piece of paper, count all the pellets, draw circles and figure pellet percentages. But it is necessary to determine where the center of your pattern falls in relation to the sights, and to assess whether patterns are uniform, or if they tend to be thicker towards the center or patchy around the edges.
Take a roll of wide butcher paper, roll it out and hang it along on a wire fence. Then take 5-inch paper plates, your representation of a rabbit, duck or pheasant. Staple these every 4 feet or so along the rolled out butcher paper until you have five or six of them. Now, then take your walking shotgun, load, walk TEN paces away from the fence, turn and fire quickly at the first plate you see. This should be natural-point snap shooting as you would at a flushing bird. Turn around, walk away another 5 paces, repeat, turn and shoot the next one, etc. until you have fired five patterns at 5 paper plates, the closest at ten paces and the farthest about 30 paces away. Try 35 paces if you are a dreamer, of course. Looking these patterns over and repeating the exercise again with each shot size and counting the hits on the plate will give you a crystal clear perception of what your little .410 will (or won't) do.
After doing this exercise you will probably come to one of two conclusions, which I did:
Use the .410 only where the reduced weight and cube of gun and ammo is worth its extra cost. Such as when you have a rifle-shotgun combo for the survival ruck in your boat, private aircraft or as a spare gun at the hunting or fishing camp. It is NOT TO BE your ONLY shotgun to depend on. The .410 is a great as an EXTRA gun, especially for use by a recoil-shy family member.
You will then forget the .410 slug fantasy. Instead buy a hundred rounds of 5 pellet 00 for large varmints or defense use, 250 rounds of 3-inch No. 7-1/2s to hunt small game with and 250 rounds of 2-1/2" No. 8 for clay bird practice. Then have all users also pattern the gun so they can understand where it hits FOR THEM, and everyone PRACTICE with it.
Or
Instead buy a 3" magnum chambered 20-ga. gun with modified choke or, better, equipped with screw-in choke tubes. It can use either 3" magnum or standard 2-3/4 inch shells. Buy 100 rounds each of 20-ga. slugs which ARE effective and 3 inch magnum No. 2 buckshot for defense, and 250 rounds each of 3 inch magnum No.6 and 2-3/4" 1-oz. 7-1/2s for small game and birds. If you will be teaching other family members to shoot and throw clay birds for practice, buy an additional 500 rounds of 7/8 oz. No. 8 "dove and quail loads." My two cents.
A brief how-to-do-it on loading all-brass .410s might be helpful. I've successfully done this, fire-forming .303 British or 9.3x74R brass and most recently using Magtech .410 all-brass shells from Midway. Load data, wads and assembly/crimping technique for all-brass shells are different from using modern plastic shells and wads.
In break-open shotguns, all-brass cases can be fireformed from .303 British brass, which is cheap and plentiful. Charge the case with ten grains of fast-burning pistol or shotshell powder. The powder type isn't important, almost anything you have around will work. Push a cotton ball down onto the powder, fill the case up to the shoulder with Cream of Wheat, then press a Gulf wax plug into the case mouth. Fire-form the case pointing the muzzle straight up. The resulting case is 2.25" in length. Cases should fire-form perfectly without splits on the first pop if they are mouth annealed first. Cases which have been reloaded as rifle rounds several times absolutely must be annealed first!
A quickie on how to anneal rifle brass which works for this application: https://www.youtube.com/watch?v=MVeRDAsrCfM
With Magtech brass use, 15.4 grains of #2400 powder, thrown from the RCBS Little Dandy powder measure, using the rotor #19. Place a Buffalo Arms .44 vegetable fiber 1/16” card over the powder, then two Buffalo Arms .44-45 wool felt cushion wads . LIGHTLY oil the top cushion wad only, applying TWO DROPS of SAE 30 weight motor oil with an eye dropper, squishing the wad between the fingers a few times to work the oil in, then wrapping the wad in a square of toilet paper, squeezing it again between the thumb and forefinger to wick out and absorb the excess oil.
A .45 Schofield case holds half an ounce of lead shot to solder up a dip measure. Fill the case to within 1/8” of the case mouth with No. 7-1/2 oir No.8 shot, insert another 1/16” card and glue in place with Elmers. You can get a little more shot in using the old fashioned card and fiber wad column, but my cylinder-bore gun patterns much better using the Federal No. 410SC (1/2 oz. Skeet) shotcup over the card, pouring the shot into that and closing the shell by crimping (or gluing with Elmer's) a .36 cal. card inside the top of the shotcup, as shown below. If using plastic shotcups in the Magtech brass is is absolutely necessary to place a card over-powder wad first, otherwise powder will leak past the shot cup, which is too small to seal the interior of the case wall, causing “bloopers.”
You can make a more finished-looking crimp by inserting a blank Lyman 450 sizer top punch into the seater die plug of a Lee .308 or .243 Winchester seating die, adjusting the seating stem to position the top card below the die shoulder. Use a .44 cal. card to fit the all-brass shell, or .36 cal. to fit inside the Federal shotcup when using that wad. You want to hold the overshot card slightly below the case mouth, as you bump the case mouth against the die shoulder to form a nicely rounded crimp.
When loading buckshot, insert the card firmly over the powder, as you did before. If using a Federal No.410SC plastic shotcup as a container for 00 buckshot the felt fiber cushion wads are not needed. A reminder again, plastic shotcups MUST NOT be used in all-brass cases without an over-powder card, because omitting the card results in powder leaking past the wad, causing “bloopers.” After firmly seating the Federal No.410SC plastic wad column, drop four 00 buck into the shotcup, then add one cast .390” round ball cast of SOFT lead on top of the stack. Adjust the seater so the top ball is crimped positively in the end of the shell. Alternately you can load only FOUR pellets of 000 buck in the shot cup, or the same number of .390" cast round balls in the brass shell with fiber wad column and no plastic shot cup.
Four .39" cast round balls total 350 grains, about 0.8 of an ounce. Each pellet at 25 yards has 150 ft.-lbs. of energy, approximating a .380 ACP pocket pistol at the same distance. If the .390 balls fall through your gun's choke and they pattern well, the increase in energy is dramatic! I use the same 15.4 grain charge of #2400 in my gun, it is, admittedly a "hot" load. Your mileage may vary, so I suggest reducing the charge to 12 grains initially, using Little Dandy Rotor #15 and working back up cautiously.
The 1951 Ideal Handbook provides data with #2400 powder for .410 shells with conventional wad columns. It suggests thickness of the filler wad(s) should be not less than 1/2 bore diameter and not more than bore diameter. Minimum filler wad thickness in the 410 bore is 0.205 inches.
A .444 Marlin sizer die with Lee No.5 shell holder can be used to resize brass cases if necessary. Prime cases with large pistol primers. The RCBS Little Dandy Rotors #19 or #20 measure appropriate charges of Alliant #2400. Thumb over powder card into case mouth, and slide firmly onto the powder using a dowel. Similarly seat the filler wad(s), or plastic shotcup, if used. Add shot and top card or buckshot. Glue top card or crimp, if a suitable die is available. That’s all there is to it.
I have lots of experience with the .410.
While I carry one for woods walking and to shoot garden varmints, my 12-ga. Winchester Model 12 riot gun is the "go to" gun for things which go bump in the night. So, If you intend to own ONLY ONE shotgun, get a 12-ga. pump. Reduced recoil law enforcement loads are viable if females and youngsters must use the same gun. Their recoil compares to a 20-ga. load.
The .410 slugs are accurate in some guns, but you can determine that only by testing. I found them mostly ineffective on game larger than foxes, at ranges beyond about 30 yards.
Grouping of shotgun slugs from a plain, bead-sighted single-barrel shotgun at best is 1 inch spread per ten yards of range. AND your gun may not hit where it looks, so you must test and practice. You could spend $25 in ammo just to find out that it doesn't work for you...
A .410 slug weighs about 80 grains. While initial velocity is high, it loses half its striking energy in the first 50 yards, where its energy compares to a .25-20 rifle firing black powder loads. Certainly no bear gun!
Better than .410 slugs for larger varmints or home defense are the 3-inch five-pellet 00 buckshot loads now popular for home defense and widely available. In most .410s they are much better than slugs and are the best choice. They put the same number of pellets on a silhouette target at 25 yards that a cylinder bore 12-ga. riot gun firing 9-pellet 00 buck does at 40.
You can expect 4 out of 5 pellets striking an Army "E" silhouette at 25 yards, which is a killing pattern. At 40 yards the .410 gets at best 3 hits out of 5, which is barely adequate, if one more more pellets happen to hit a vital area.
An accepted standard is that total kinetic energy delivered by buckshot on a hostile target should equal that of a hit from an M1911 .45 pistol firing service ammunition. That is the standard that the Army has used since WW2. If you are lucky, you might land 2 pellets out of 5 at 50 yards your Zombie silhouette, if your particular gun likes the load, still, better shoot him twice!
I spent $250 in ammo test firing various .410 rounds in three guns, a full-choke, high-dollar Beretta, a sawed off cylinder-bore Iver-Johnson and a modified choke H&R youth gun to prove the above to my satisfaction. If your Daddy’s .410 happens to be a stone killer, it may indeed be that you have a great gun and that mine are all POS, because the luck of the blind monkey rules the universe in these things.
Each 00 buckshot pellet fired from a .410 has about the same energy at 25 yards as a .32 ACP pistol slug. Less than 3 pellets hits do not total our magic 350 ft.lbs. of kinetic energy and so cannot be considered effective for defense or hunting deer-sized game. The longest range at which you can expect all 3 pellets hitting when firing the shorter 2-1/2 inch buckshot rounds is about 20 yards from a typical single-barrel shotgun.
If using the Judge revolver no farther than 7 yards in the best case, based on one gun I tested. Velocity really drops off quickly from a .410 handgun. Winchester 5-pellet 00 buck gets 1230 fps from a standard shotgun, and only 800 or so from the short-barrelled Judge revolver and 880 fps from the long-barreled one.
When using a .410 with bird shot for hunting small game, it will work OK IF you stay within its rather severe range limitations. The most important thing to remember is that given its small payload (1/2 oz. in the 2-1/2 inch shell and 11/16 oz. in the 3 inch shell) you have very few pellets in the pattern.
In order for a shotgun pattern to be effective on a game animal the size of a rabbit, or a bird the size of a pheasant or duck, you need to achieve a number of pellets hits equal to the shot size, such as six No. 6 or 8 No. 8 within 20 square inches or a 5 inch circle paper plate, about the size of a rabbit.
Having less than 200 shot in the shell makes obtaining effective patterns difficult beyond about 10 yards because the pattern spreads about 1 inch per yard of target distance. Using shot larger than 7-1/2 in the 3 inch shell or No.8 in the 2 inch shell is ineffective unless you limit ranges to 25 yards from a single-barrel shotgun, or 5 yards with the Judge revolver.
It is important to fire test patterns with your gun and ammo and to PRACTICE with the smaller gun, learning to acquire the target and shoot quickly, so that you have clear knowledge of its capabilities and develop enough shooting skill on your part to somewhat make up for its reduced effectiveness.
The biggest drawback in using a .410 is that developing skill requires buying and shooting up more ammo in testing and practice to obtain that knowledge and maintain that skill. A casual shooter needs to fire 100 shells a year at clay birds to simply maintain basic skills and not decline.
To improve your skill you need to shoot a case of 250 shells a year just in practice. And .410 ammo costs about TWICE as much as the same number of 12-ga. or 20-ga. shells because the factories don't produce or sell as many. If you shop seasonal promotions you can buy case lots of "dove & quail" no. 8 or or "duck & pheasant" no. 6 12-ga. or 20-ga. loads reasonably, but not .410s. My advice is to get either a 12-ga. or 20-ga. gun and stock up on bargain ammo whenever you find it.
You won't find any bargains in .410 ammo. At least, I've never seen any. In some areas it is difficult to find .410 cartridges in shot sizes smaller than No.6. Marketing people try to make up for the .410s lack of killing power by pushing larger shot, which is pure lunacy, particularly large shot such as No.4, which is entirely useless beyond 20 yards unless you happen to have a full choke barrel which "likes it". In those cases a gun may pattern so tightly that you must shoot it like a rifle, which means that you could have used your .22 pistol and saved a dollar!
Shot sizes of No. 6 or larger should only be used in choke bore .410 guns which pattern the particular load well, within the ranges at which you have determined that they are actually "effective." A shot load throwing "effective" patterns means that you can reliably depend upon putting a number of pellets equal to the shot size, such as four No. 4s, five No. 5s, six No.6s, seven No.7-1/2s or eight No. 8 shot on your 5-inch paper plate at your given range. Determining this means firing in a rapidly thrown-up 2 second instinctive snap-shot. Misses with a single buckshot do not count anything!
Given the modest shot capacity of a .410 the maximum useful range at which you can expect effective game patterns with any confidence is only 25 yards under the best circumstances. With cylinder bore guns you may do no better than 20 yards...With a Judge revolver no more than 5-7 yards.. I can kill grouse with my slingshot flipping a stone that far for less money and more silently.
There is NO substitute for patterning your gun. You do not have to dissect shells, count pellets, put up a big piece of paper, count all the pellets, draw circles and figure pellet percentages. But it is necessary to determine where the center of your pattern falls in relation to the sights, and to assess whether patterns are uniform, or if they tend to be thicker towards the center or patchy around the edges.
Take a roll of wide butcher paper, roll it out and hang it along on a wire fence. Then take 5-inch paper plates, your representation of a rabbit, duck or pheasant. Staple these every 4 feet or so along the rolled out butcher paper until you have five or six of them. Now, then take your walking shotgun, load, walk TEN paces away from the fence, turn and fire quickly at the first plate you see. This should be natural-point snap shooting as you would at a flushing bird. Turn around, walk away another 5 paces, repeat, turn and shoot the next one, etc. until you have fired five patterns at 5 paper plates, the closest at ten paces and the farthest about 30 paces away. Try 35 paces if you are a dreamer, of course. Looking these patterns over and repeating the exercise again with each shot size and counting the hits on the plate will give you a crystal clear perception of what your little .410 will (or won't) do.
After doing this exercise you will probably come to one of two conclusions, which I did:
Use the .410 only where the reduced weight and cube of gun and ammo is worth its extra cost. Such as when you have a rifle-shotgun combo for the survival ruck in your boat, private aircraft or as a spare gun at the hunting or fishing camp. It is NOT TO BE your ONLY shotgun to depend on. The .410 is a great as an EXTRA gun, especially for use by a recoil-shy family member.
You will then forget the .410 slug fantasy. Instead buy a hundred rounds of 5 pellet 00 for large varmints or defense use, 250 rounds of 3-inch No. 7-1/2s to hunt small game with and 250 rounds of 2-1/2" No. 8 for clay bird practice. Then have all users also pattern the gun so they can understand where it hits FOR THEM, and everyone PRACTICE with it.
Or
Instead buy a 3" magnum chambered 20-ga. gun with modified choke or, better, equipped with screw-in choke tubes. It can use either 3" magnum or standard 2-3/4 inch shells. Buy 100 rounds each of 20-ga. slugs which ARE effective and 3 inch magnum No. 2 buckshot for defense, and 250 rounds each of 3 inch magnum No.6 and 2-3/4" 1-oz. 7-1/2s for small game and birds. If you will be teaching other family members to shoot and throw clay birds for practice, buy an additional 500 rounds of 7/8 oz. No. 8 "dove and quail loads." My two cents.
A brief how-to-do-it on loading all-brass .410s might be helpful. I've successfully done this, fire-forming .303 British or 9.3x74R brass and most recently using Magtech .410 all-brass shells from Midway. Load data, wads and assembly/crimping technique for all-brass shells are different from using modern plastic shells and wads.
In break-open shotguns, all-brass cases can be fireformed from .303 British brass, which is cheap and plentiful. Charge the case with ten grains of fast-burning pistol or shotshell powder. The powder type isn't important, almost anything you have around will work. Push a cotton ball down onto the powder, fill the case up to the shoulder with Cream of Wheat, then press a Gulf wax plug into the case mouth. Fire-form the case pointing the muzzle straight up. The resulting case is 2.25" in length. Cases should fire-form perfectly without splits on the first pop if they are mouth annealed first. Cases which have been reloaded as rifle rounds several times absolutely must be annealed first!
A quickie on how to anneal rifle brass which works for this application: https://www.youtube.com/watch?v=MVeRDAsrCfM
With Magtech brass use, 15.4 grains of #2400 powder, thrown from the RCBS Little Dandy powder measure, using the rotor #19. Place a Buffalo Arms .44 vegetable fiber 1/16” card over the powder, then two Buffalo Arms .44-45 wool felt cushion wads . LIGHTLY oil the top cushion wad only, applying TWO DROPS of SAE 30 weight motor oil with an eye dropper, squishing the wad between the fingers a few times to work the oil in, then wrapping the wad in a square of toilet paper, squeezing it again between the thumb and forefinger to wick out and absorb the excess oil.
A .45 Schofield case holds half an ounce of lead shot to solder up a dip measure. Fill the case to within 1/8” of the case mouth with No. 7-1/2 oir No.8 shot, insert another 1/16” card and glue in place with Elmers. You can get a little more shot in using the old fashioned card and fiber wad column, but my cylinder-bore gun patterns much better using the Federal No. 410SC (1/2 oz. Skeet) shotcup over the card, pouring the shot into that and closing the shell by crimping (or gluing with Elmer's) a .36 cal. card inside the top of the shotcup, as shown below. If using plastic shotcups in the Magtech brass is is absolutely necessary to place a card over-powder wad first, otherwise powder will leak past the shot cup, which is too small to seal the interior of the case wall, causing “bloopers.”
You can make a more finished-looking crimp by inserting a blank Lyman 450 sizer top punch into the seater die plug of a Lee .308 or .243 Winchester seating die, adjusting the seating stem to position the top card below the die shoulder. Use a .44 cal. card to fit the all-brass shell, or .36 cal. to fit inside the Federal shotcup when using that wad. You want to hold the overshot card slightly below the case mouth, as you bump the case mouth against the die shoulder to form a nicely rounded crimp.
When loading buckshot, insert the card firmly over the powder, as you did before. If using a Federal No.410SC plastic shotcup as a container for 00 buckshot the felt fiber cushion wads are not needed. A reminder again, plastic shotcups MUST NOT be used in all-brass cases without an over-powder card, because omitting the card results in powder leaking past the wad, causing “bloopers.” After firmly seating the Federal No.410SC plastic wad column, drop four 00 buck into the shotcup, then add one cast .390” round ball cast of SOFT lead on top of the stack. Adjust the seater so the top ball is crimped positively in the end of the shell. Alternately you can load only FOUR pellets of 000 buck in the shot cup, or the same number of .390" cast round balls in the brass shell with fiber wad column and no plastic shot cup.
Four .39" cast round balls total 350 grains, about 0.8 of an ounce. Each pellet at 25 yards has 150 ft.-lbs. of energy, approximating a .380 ACP pocket pistol at the same distance. If the .390 balls fall through your gun's choke and they pattern well, the increase in energy is dramatic! I use the same 15.4 grain charge of #2400 in my gun, it is, admittedly a "hot" load. Your mileage may vary, so I suggest reducing the charge to 12 grains initially, using Little Dandy Rotor #15 and working back up cautiously.
The 1951 Ideal Handbook provides data with #2400 powder for .410 shells with conventional wad columns. It suggests thickness of the filler wad(s) should be not less than 1/2 bore diameter and not more than bore diameter. Minimum filler wad thickness in the 410 bore is 0.205 inches.
A .444 Marlin sizer die with Lee No.5 shell holder can be used to resize brass cases if necessary. Prime cases with large pistol primers. The RCBS Little Dandy Rotors #19 or #20 measure appropriate charges of Alliant #2400. Thumb over powder card into case mouth, and slide firmly onto the powder using a dowel. Similarly seat the filler wad(s), or plastic shotcup, if used. Add shot and top card or buckshot. Glue top card or crimp, if a suitable die is available. That’s all there is to it.