21st Century Blunderbuss

<XMP><BODY></xmp>21st Century Blunderbuss

21st Century Blunderbuss

        The idea of the Recoilless Grenade Launcher (RLGL) both replaces and improves on weapons such as the OICW and 40x46mm Grenade Launcher. This article proposes an idea for a complimentary weapon system that will replace weapons such as the 12 gauge shotgun and M203.

        The Combat shotgun is a useful weapon in any situation where ranges are short. One of its lesser known, but very useful applications is that it can be used to blast off the locks and hinges of doors during urban operations.
        While the shotgun is a useful weapon, it is not without its flaws, some of which have been discussed in this article.
        For a moment, let us review the most common combat loads:-

	Pellet dia.	No. of Pellets 2 ¾” 12g Shell	No. of Pellets 3” 12g Shell
OOO buck	0.36”	8	10
OO buck	0.33”	9	15
No. 4 buck	0.24”	27	41

Gelatin testing of Shot loads.

Also in use are flechette loads. A typical load would be 20 flechettes 1½” long and 1/16” in diameter. These figures are for a 2¾” shell. I suspect the 3” has the same capacity but launches them at a higher velocity.

1” flechettes from Sabot Designs

        As a rule of thumb, the spread of a pattern of shot fired from a true cylinder bored shotgun is about 1” for every yard/metre of range. (The formulae used by Forensic examiners is spread in inches - 1 = range in yards). Extreme spread may be as much as an inch per foot, but the majority of pellets obey the 1” per yard guideline. From this it can be seen that a blast from a 12 bore is not the “room sweeper” that is sometimes expected. For the larger shot sizes there can be considerable gaps between the pellets in the pattern.
        Striking power of the 12g shell is also sometimes wanting. For destroying door fittings it is more usual to use specialised slug loads such as the “Hatton round”. Even with these when shooting off locks and hinges it is often necessary to hit each feature at least twice.

        As countless Hollywood movies have shown, a major benefit of the M203 is that it is readily to hand, allowing the user to quickly tap into extra destructive power. In real life the 40mm grenade has a long arming distance of 14-27m which turns it into little more than a baton round in many close combat situations. Canister rounds would help but these are not commonly issued and the M203 is a single shot weapon. A revolver grenade launcher like the South African MGL would be better, although it can be argued that 40mm rounds are a little oversized for the role

        My proposal is to develop a new round of about 25-28mm calibre, and a family of weapons to fire it. For obvious reasons, I've begun to think of this more as a 21^st century blunderbuss than a shotgun.

        The Russians already have a 23mm weapon.

http://www.wapahani.com/samreshot4.html

http://www.baconbomb.com/spetsnazmod/w_shotgun.html

http://www.pmulcahy.com/shotguns/russian_shotguns.htm

Before I expand on this idea, I'd like to acknowledge the shotgun ideas of Dino Snider who set me off on this tract. We differ on a few points, but most of the groundwork for this concept can be found here.

Dino's Wildcat Shotgun round

Dino's idea is for a round based on a shortened form of the 30x113mm Aden case or the Russian 30x 29mm AGL case. Internal payload would be 1” by 1” and he's aiming for an overall round length of 2”. I've my doubts on how relieably such a snubby round would feed, and internal space should be at least 1½” to accommodate the flechettes already in common use. By increasing the calibre slightly we can accommodate 7 OOO shot in each layer, and I'd keep overall length of the round at 2 ¾”. It is possible that this new round could be used by existing designs of 12 bore weapon by altering the dimensions of just a few components such as the magazines and barrels.

As Dino points out, shotshell design has changed little since the 19^th century. For this round I'd investigate using the Hi-Low pressure system already used in 40mm grenades. The case would be semi-rimmed for easy feeding and to save on brass and weight it would be relatively short, with the shot or flechettes held in a plastic or aluminium capsule, as is done for larger calibre canister loads.

120mm Canister round

40x53mm Flechette Canister load

        Blunderbuss rounds would be of similar power to 12g 2¾” rounds, but by merit of their greater diameter fire a larger number of projectiles. If we are firing a larger mass of material at similar velocity, recoil will be higher than firing a conventional 12 bore. Such things are relative, however. The Blunderbuss will probably kick less than a 40mm GL or a OICW, and attention to features such as muzzle brakes and ergonomics will make the weapon more manageable. A load of 21 OOO buck (in three tiers of 7 balls) would weigh around 3½oz, less than the canister and grenade rounds of the 40mm.

        The 12-bore Belted round developed for the CAWS program gives us some idea of the possible performance of the Blunderbuss round. The CAWS round had eight OOO lead balls of 70gr (4.5gm) each at 1,600fps (488m/s) or 20 flechettes of 5.8gr (0.376gm) at 2,952fps (900m/s) and both were effective to at least 150m. There was also a round with eight tungsten pellets each of 48gr (3.1gm) weight at 1,765fps (538m/s) which could penetrate 20mm of pine or 1.5mm mild steel plate at 150m. The Blunderbuss round would have even greater capacity and potential.

        For reference, the M576E2 canister round for the M79/M203 held 27 pellets of OO (0.33” ), while the Flechette rounds held 45 darts. I've not come across any designation for the flechette round so it may have been experimental. Sources such as the Field manual 3-22.31 and this page claim the M576 held

        “ 2,000 pellets, which cast a cone of fire 98 feet (30 m) wide and 98 feet high and travel at 882 feet per second (269 mps)”

        A 40mm round couldn't hold 2,000 pellets of any size that could legitimately be called Buckshot and the degree of spread also seems unrealistic. I suspect this is a misprint, since the Jane's Infantry Weapons 2002-3 entry for the South Korean M576E1 round states it holds 20 pellets of 310gr total weight with a range of 30m and muzzle velocity of 269m/s. The USA entry also describes the M576E1 as containing 20 balls. Possibly somewhere down the line 20 OO has been read as 2,000.
        Appendix D of this USMC manual instructs that

        “When firing M576 cartridge from the M203 launcher, be sure to aim at the foot of the target”

        This is probably because the sights of a M79 or M203 are set up for the firing of low velocity grenades with a very curved trajectory.

        Shown on the right are some dart-like projectiles for an experimental Swiss weapon in the 70s called the Sarmac “Falconet”. This was intended to fire 24mm explosive shells/grenades as “Offensive rounds” and “Defensive rounds” containing multiple projectiles. Data for the Defensive round gives a weight of 70gm and if this refers just to the twelve projectiles this would give each a weight of around 90gr.

        I see the Blunderbuss round being mainly used in two forms of weapon, both of which have already been suggested for 12g shotguns. One is an “assault shotgun”, the other an underbarrel weapon.
        The underbarrel weapon would probably use a tube-mag, although a 5-6 shot cylinder or a harmonica action are also possible. The Assault Blunderbuss would probably be use box-magazines and drums, rather like the Saiga weapons or USAS-12. There might also be a simple double-barreled weapon for mounting under SMGs. This would mainly be used with Less-Lethal, Canister and Short-range concussion/doorknocker rounds.

When I read about the Payload Rifle one idea that occurred to me was that the same projectiles could be mounted in Dino's shotshell case. On further reflection this would probably not work. The 25mm grenades illustrated here appear to be about 7-8” long, and the fuses probably require a rifled barrel, or at least a faster twist than I envision for the Blunderbuss barrels. How useful would a HE round for the Blunderbuss be?

In the Falklands some Argentine units had shotguns with 12 bore “Grenade rounds” , fused to explode at a preset distance from the muzzle. This article suggests that modern fuse designs allow smaller rounds to hold a much greater quantity of explosive. In my previous article on shotguns I suggest :-

“…..a HESH or HE slug with enhanced incendiary effects. This would have an impact fuse but also have a timed self-destruct. This allows the round to air-burst when it reaches the limit of its effective range or if it embeds in soft material such as sandbags.”

Frag-12 Explosive Shotgun Rounds

More on the FRAG-12

        Such a round of 25-28mm calibre would have an even more useful capacity. A single explosive round for the Blunderbuss probably wouldn't equal the effect area of a 40mm grenade. I've seen a fragmentation radius of 2 metres quoted for the 12g FRAG-12 anti-personnel explosive shotshell, which seems credible. An effect area of 2 to 4 metres seems plausable for the Blunderbuss round. A smaller blast radius would allow the round to have a shorter arming distance and make the Blunderbuss more useful for close-range combat. The FRAG-12 family of rounds use a fuse that arms in 3 metres. This would be more useful in MOUT, CQB and indoor engagements than the 14-27m arming distance of the 40x46mm.
        The smaller effect area of the round might be partially offset by the weapon's greater capability for rapid fire and its flatter trajectory. Velocity of the round is likely to be in the region of 900-1,440fps (275-440m/s) rather than the ca250fps (76m/s) of a 40mm grenade which will give the round a flatter trajectory and increase the probability of it being placed closer to the target at medium ranges. The 25-28mm HESH round is likely to behave a lot like a shotgun slug fired from a rifled shotgun, so should be able to be used for point blank fire against a man-sized target out to at least 150 yds. It can be argued that a competent enemy is unlikely to cluster so that there is little likelyhood of either a 25-28mm or a 40mm grenade hitting more than one individual so a larger effect area is unnecessary if accuracy is greater..
        A direct hit from a Blunderbuss HESH round is likely to defeat any body armour. The self-destruct feature would be a welcome improvement over the standard issue 40mm.

        I see the Ripley-Blunderbuss mainly as a weapon for improving close to medium range fire-team firepower. The 25-28mm canister round loaded with buckshot, flechettes or Falconet-style darts would do this at close range.
        The HE or HESH round would be useful against point targets such as doors, light vehicles, armoured personnel etc. A HESH round would have the merit of simplicity and versatility but I'm unsure that the projectile would maintain sufficient velocity to flatten at likely engagement ranges.
        The alternative would be a HEDP round. This might resemble a larger version of the FRAG-12 round and use some of the components developed for it. Since it is not practical to achieve an optimum stand-off distance with these rounds a Misznay�Schardin EFP warhead is probably preferable to using a Munroe-effect Hollow Charge as used on current 40mm M433 HEDP rounds. The round would also be designed to throw out a cylindrical pattern of anti-personnel fragments. A fragmentation radius of about 2-3m wouldn't match the 40x46mm grenade but it would be capable of being used at ranges of less than 27m, making it more useful for MOUT, Jungle fighting etc.
        A non-fragmenting Concussion or Thermobaric round with a Super-Quick fuse might also be issued for door breaching, as described here.
        The Ripley could be loaded with various LLW rounds -CS, CS-ferret, Bean-bag, Multiple-baton, Instant CS cloud, Hatton-type non-explosive doorbuster and Dye/Scent marker.

        For longer range engagements the Blunderbuss is supplemented by systems such as the Rifle/Hand Grenade, RLGL, DGL (including Ring Airfoil Grenades), 3BT, HAGL and Platoon Mortar.

        While researching this article, I came across this entry on a Role-playing game page. It gives some idea of how useful an Assault Blunderbuss might be.

“ Militech “Cowboy” U-55 Grenade Launcher. This is a multi-round, semi-automatic grenade launcher designed specifically for use in urban situations. It fires a variety of specialized and all-purpose rounds from a rotating drum magazine. The grenades are 25mm projectiles similar in appearance to large shotgun shells. The weapon may be fired semi-auto or in three-shot bursts. Any combination of loads may be in the magazine. A common technique is to use three-shot bursts, and load the weapon so that each salvo fires one frag, one concussion and one incendiary round. For riot control, similar combos of flash, gas and shotshell rounds are used. The launcher can be smart-linked, and has an integral optical sight. Light weight and a stubby design make the weapon ideal for the close confines of urban combat.”

http://www.sc2000.net/~babbitt/cyberpunk/compendium/grenlaun.htm

“BACKDATE”
        I though it might be of interest if I included some information on the performance of the original blunderbusses. Information is taken for Harold L.Peterson's excellent “ The Book of the Gun” .
        Tests conducted by the NRA found that most blunderbusses had similar preformance. At 40 feet the pattern was 20 to 36” across. At 60 feet the pattern was 40 to 50” .
        Blunderbusses were loaded with musket or pistol balls or buckshot. A typical load would be 16 balls of buck with 120gr of black powder.

UPDATE
        Most recent news is that the XM29 is to be dropped and will be replaced by a stand alone air-burst grenade launcher of 25mm calibre, the M-25. The intention appears to be to use the same 25mm shells as the XM307 OCSW. A round based on the Krupp universal shell would be a very useful. One can hope that there will also be a canister round, and 21 balls of OO arranged in three layers of 7 is not unreasonable. It may be possible to create an underbarrel “Ripley” , although this may be limited to canister and “dumb explosive” rounds only.
         Intention for the M-25 appears to have a weapon with a box magazine. The Russians have the Izmash JSC MP-1331K, a variety of shotgun that has both a box magazine and a tube mag and the user can switch between the two. It occurs to me that an XM-25 loaded with a box magazine of grenades could also have a reserve tube magazine loaded with several canister rounds. If the grenadier finds himself suddenly in close combat he can select these rounds should he not have time to load a box of canister. Possibly this magazine would automatically be selected should the laser rangefinder detect that the target is too close for grenades. In a CQB operation he might have a box of canister loaded but have a few grenades “in the tube” just in case.
        An alternative to having a dual magazine weapon would be to issue the disposable “Canister barrels” I describe on the MetalStorm page. The technology of the MetalStorm 3GL would be very useful if combined with the sort of projectile proposed for the Blunderbuss.