FIREARM OVERLOAD
Dedicated to your SAFETY!
12 ga Shotgun Minishells by Aguila®™
Modification & Testing of Mossburg®™ 500A 12 ga Pump Shotgun
12 ga Shotgun Minishells - Manufacturer Data
The Above information comes from the manufacturer. Please see their site for more information.
Reloading at best is a 1 second lag in firepower. That speed is based on a lot of practice. Reloading, is the time to advance. A person can advance 21 feet in 1 second......42 feet in 2 seconds.
The moral to the story...You should always bring more than 1 gun to a gun fight. The Military brings martial arts, knife, handgun, and a rifle. You see the difference. You can never have enough ammo or backup.
The idea for the modification came from being to cheap to purchase a 10 rd Mossberg pump 590 aka military/police setup for two matches a year.
MY MOSSBURG 500A Modification
aka - Mossberg Mini Plug
CAUTION: WARNING: ADVISO: ACHTUNG: Listen UP!
You assume all risks, known and unknown for this modification. This will void your warranty. This could result in miss feeds. Failure to feed has been reported by others but not by using this modification. I did not have any failure to feed during testing and shooting in matches. Additional testing by independent sources needs to be performed as to FTF.
I compete with my Mossburg 500 in USPSA Shotgun matches. These matches usually have stages with following characteristics:
Points divided by time so you cannot dilly dally. Reloads are the largest time factor. With the modification I can carry more in the tube. Using regular or magnum 12 ga shells the tube magazine holds five shells and one in the chamber, giving a total of 6.
SHOT:
Steel knockdown targets ranging from 8 inch diameter steel plates, to larger 4 foot size knockdown steel. There are stands that hold regular clay pidgins and mini pidgins. These could be as close as 10 feet and as far away as 50 feet.
BUCK:
Cardboard regular USPSA target and / or USPSA 1/3 Target set at 40 to 60 feet. Scored based on pellets x Score on A-D ring
SLUG:
Cardboard regular USPSA target from 20 feet to 100 feet . Scored based on A-D ring
Photo of Regular Rifled Slug compared to Aguila mini slug
MODIFICATION:
A small plastic/ nylon spacer attached to receiver with set screws. The Mossberg-Mini-plug was designed out of nylon. Easy to cut and mold with a dremel tool. Then attached to the Mossberg receiver with two self tapping screws going through 2 undersized holes in the receiver, which in turn taps into the Mossberg-Mini-plug.
With the spacer in place you can still load regular size shells one by one if needed. This is a removable feature. Requires 2 holes drilled through the receiver. Once in place everything performs in real world situations. The matches I have used the mini shells have a total round count of at least 60 rounds. Way more ammo then you will ever use in a home defense situation.
Like any modification, it will void your warranty. I will not be held responsible for your modification.
Dimensions for the Mossberg-Mini-plug.
Picture of Mossberg-Mini-Plug
Pictures in receiver
TESTING ON THE RANGE
CYCLE TEST
First Test was a basic cycle test. I used a foam block with heavy metal foil tape as a prototype.
Cycle test with nylon Mossberg mini plug passed with flying colors with 200 rounds cycled.
RANGE TEST
1- Cycle Test. Holding shotgun down, up, and at different angles.
2- Shoot 10 shots total waiting 15 sec between each shot.
3- Shoot 10 shots total rapid as possible.
4- Shoot 10 shots total rapid as possible, mix shot, slug, then reload 10 and shoot rapid as possible.
5- Shoot 15yds shot for pattern test twice
6- Shoot 25 yds slug for analysis using Modified cylinder and rifled choke
All tests passed. No misfire of any kind. No miss feeds due to Mossberg-Mini-plug
Pictures of 25 yard test of the Slug, below
Pic 1a.
25 Yard Sandbag rest
Mossburg Shotgun 12 ga Pump
Modified Choke
Wolf 12 ga slug Standard size.
Not too bad of a group
3.5 Inches.
Pic 1b.
25 Yard Sandbag rest
Mossburg Shotgun 12 ga Pump
Modified Choke
Aguila Minishell Slug
Seems to open up a bit.
11 inch group.
For personal defense works fine out to 25 yards.
But for the long shots in USPSA there is a margin of error.
Pic 1c.
25 Yard Sandbag rest
Mossburg Shotgun 12 ga Pump
Rifled Choke
Aguila Minishell Slug
Seems to tighten up a bit.
to 9 inch group.
For personal defense works fine out to 25 yards.
But for the long shots in USPSA there is a margin of error.
PERFORMANCE at the MATCHES
I came out to the range to shoot a shotgun match. Everyone took bets from; It won't have enough power to knock down the steel, ha ha ha... Sure they work? it will jam just watch ...etc.
Time to put up or Shut them UP!. In a quick test in front of the Range Officer, crack-a-towa- the Minishell shot did have the power to take down the steel.
The Minishells shot worked great all match. The slugs have no stabilizers , ie. rifle grooves. so once you get out to a distance the slugs tend to spread a good bit compared to regular rifled slugs. I even tried a rifled choke to add some spin. In a match I missed , or had a low D ring score on the targets at 80 feet. I did some tests and took photographs. The difference is obvious.
A regular size shell can be inserted as needed one by one. For example add a regular size rifled slug for the far away shots.
I no longer use the mini shells in matches due to the new rules on power factor. The matches I did shoot showed the modification worked in the heat, dust, repetitive firings, and staged scenarios of those days.
CONCLUSION:
The testing and matches proved the rounds are manufactured well and offer reliability.
There are limitations for the Slugs, which come into play once you get past 60 to 75 feet range.
The difference I found was the diameter of the slug. Regular slugs fit tighter in the barrel. The factory
might be able to improve this. 25 yards is well within a practical home defense parameters.
The ability to load a regular rounds is a plus. Especially for a 100 yard shot.
I personally opt for more ammunition. In this case 40% more for a total of 10 rounds at the same weight as 6 rounds.
The rounds are 30 to 40% less powerful, less recoil, still effective at home defense ranges.
This set up could work for Military or Police.
So take a look at your shotgun, and if it is a pump, you may be able to make the modifications and up your on board firepower by 40%.
The Aguila site has information on other shotgun modifications and an actual Shotgun designed from the ground up for the mini shell.
CORRECTIVE ACTIONS:
More testing as to the (FTF) failure to feed or jams needs to be performed by independent multiple sources. I did not have any FTF, even in rapid pumping mode.
More testing as to the design of the Mossberg-mini-plug, and improvements needs to be performed by independent multiple sources.
Change the two screw system in the prototype to a punch pin.
Manufacturer should investigate the diameter of the slug compared to other manufacturers slugs as to tighten the fit to decrease the spread at 25 yards.
Manufacturer should investigate the addition of rifling on the slug compared to other manufacturers slugs as to to decrease the spread at 25 yards.
Manufacturer should investigate the use of more 1 buck and less 4 buck in the buckshot round. 1 buck is considered the smallest round to use to be effective.
Additional test photos of shot pattern and buckshot pattern to be included in next revision of document.
Appendix:
Shotgun Shell type Comparison | ||||
By USPSA Power Factor | ||||
Min Power Factor to knock down steel is 125 | ||||
SHOTGUN | ||||
Aguila Mini Shot | Reg 3 Dr Shot | |||
FPS speed | 1175 | FPS speed | 1145 | |
Projectile Weight | 277.78 | Projectile Weight | 492.00 | |
Power Factor | 326.39 | 57.94% | Power Factor | 563.34 |
Aguila Mini Slug | Reg slug | |||
FPS speed | 1250 | FPS speed | 1600 | |
Projectile Weight | 385.808 | Projectile Weight | 438 | |
Power Factor | 482.26 | 68.82% | Power Factor | 700.8 |
Aguila Mini Buck | Reg OO Buck | |||
FPS speed | 1200 | FPS speed | 1200 | |
Projectile Weight | 304.2 | Projectile Weight | 484.2 | |
Power Factor | 365.04 | 62.83% | Power Factor | 581.04 |
Buck Shot Pkg | size | wt grains | ||
four 1buck rounds | 0.3 | 40 | ||
seven 4buck rounds | 0.24 | 20.6 | ||
Total Wt grains | 304.2 | |||
RIFLE Round | ||||
7.62x39 123g | 5.56 | |||
FPS speed | 2400 | FPS speed | 3100 | |
Projectile Weight | 123 | Projectile Weight | 55 | |
Power Factor | 295.2 | Power Factor | 170.5 | |
HANDGUN Round | ||||
.45 cal HG | 9mm cal HG | |||
FPS speed | 920 | FPS speed | 1125 | |
Projectile Wt | 230 | Projectile Wt | 124 | |
Power Factor | 211.6 | Power Factor | 139.5 |
Mossberg, 500A, 590 Mossburg®™ O.F. Mossberg & Sons, Inc. - Firearms, Shotguns, Rifles
Aguila®™ Ammunition Aguila Ammunition / Centurion Ordnance, Inc.
Wolf®™ Ammunition WOLF Performance Ammunition
Federal®™ Ammunition Federal Premium ammunition
Firearms Tactical© www.firearmstactical.com/briefs10.htm
The photos are copyright © 2008 All Rights Reserved William E. Fowler, AceEyeEd
Article copyright © William E. Fowler 2008
Firearm Overload www.geocities.com/firearmoverload
©Copyright 1998 - 2009 William E. Fowler "AceEyeEd" , Owings Mills, Maryland Updated on 5/15/2009 |