Ripper, when I first started looking into making an airsoft PR (about 6 years ago) I was a strong advocate of ensuring that the GL section of a PR remain a functional secondary weapon. I maintained that belief up until about 2 to 3 years ago when we all as a community started to actively look into the options and discuss the possibilities of a firing vs. non-firing GL. There are a lot of factors involved, some of which I outlined above. Aside from the difficulty of inserting a Maruzen M870 gas shotgun into a real steel Spas 12 (the M870 being too wide), here are some of the other issues we needed to consider:Would having a firing M870 really help much? :
Yeah, it's kind of a cool thing to have... a secondary weapon... but the Maruzen M870 is not very powerful at all.
Also, this particular airsoft shotgun uses plastic BB shotgun shells. Whilst some of the other airsoft shotguns would allow the user to fire +/- 10 times, you'd only be able to fire the M870 3 times (this we determined by estimating the potential shell-tube capacity. It would only hold 3 shells). Furthermore, you have to ask yourself whether or not you'd want to worry about loosing these re-usable shotgun shells in the middle of a fire fight. As aggravating as it might be trying to find these shells on the floor in an urban environment, imagine trying to recover them in the forest/woods/jungle.I'm not worried about loosing shells... I'm rich... I can afford it...
Consider this, a maruzen M870 weighs about 1820grams/4 lbs. During a skirmish you will
notice the difference 4 lbs make. Heck, ask Rook, his AEG PR doesn't use a Maruzen M870 and it's heavy enough as it is. Carrying a PR with a M870 is comparable to an airsoft M60 or a M249. How about not using it in a skirmish... it's nice to know that it's there:
If the PR is intended to be purely for wall hanging and not skimishing at all, then yeah, you don't have to worry about loosing shells as much. But if you still want to be able to fire
the GL you have a couple more things to consider. The GL is gas operated via a cylinder that, in the pistol grip version, resides in the pistol grip, and in the full shoulder stock version resides in the shoulder stock. Once the M870 is placed in the PR, where do you place this gas cylinder/reservoir? There is very
little room in the rest of the gun. The PR shroud looks like it should have a wealth of space but that space is taken up with shroud supports and hardware that attaches the shroud to the thompson and GL. I seem to recall that MIM achieved this by placing the gas canister above the GL just below the front of the shroud. Personally, I think this approach is somewhat flawed. That space is integral to allowing the GL to be securely mounted onto the bottom of the thompson's receiver/barrel.
Also consider this, the TM Thompson M1A1 runs on a battery. The MIM PR requires the user to carry the battery externally. There just isn't adequate room in the shroud to accomodate a full size battery... even a small battery probably won't fit. The user is then forced to use a battery pouch and attach said pouch onto the PR somewhere... most likely onto the retractable stock... rendering the retractable stock... non-retractable
. Not to mention the unattractive aesthetic this creates. Most other airsoft PRs, place the battery within the GL, which has adequate space for a battery, but renders the GL non-firing.Well that sucks... can I at least have the GL rackable?
You can still have the GL rackable... there are a few options:
* Do what GEM did and just slide the grip onto the Spas 12 cage, drill a hex bolt into the side of the GL at a point that defines how far back the grip should go. When the grip is pulled back it will only travel up to the bolt. Simple eh? Problems with this: the Spas 12 grip is made of plastic/composite. With enough racking back and forth, the grip will eventually wear away, resulting in a loose grip which will slide about all the time.
* GWII did a fantastic job of keeping the Maruzen M870 receiver in the GL, but removed the barrel and shell-tube. The Spas 12 grip was then connected to the Maruzen M870's rackable system, and each pump of the grip racked the M870. This also cycled a single shell if one was loaded into the breach. By removing the components forward of the receiver adequate space was made for a large battery.
* GNG had a similar approach but much cheaper and functionally different. They modeled the M870 receiver into the all plastic GL. The ejection port was left open, and a tube with an opening in its side was attached to the GL pump grip. When the grip was unpumped
, the GL ejection port showed a section of the tube without
the hole in its side. When the grip is pulled back, the tube inside the GL slides back exposing the hole in the tube, and through the hole you can see the grenade. I liked GWII's approach which is perhaps the most aesthetically accurate attempt at a functional PR. However, in terms of skirmishing, I would prefer GNG's approach which is cheaper (no Maruzen M870 to buy), lighter (no Maruzen M870 to carry), and aesthetically decent enough for even my tastes.How about putting a different shotgun in there?
Other models of shotgun have their ejection and loading ports located in positions that differ from that of the M870. They also have issues with overall width of their shotgun receivers. The Ithaca M37 (by KTW), might
be thin enough, but it uses a bottom ejection system (The same window at the bottom of the receiver is used to load the magazine and to eject the spent cartridges). This is of course aesthetically inaccurate. The M3 Super 90 shotgun is definitely too wide. The Mossberg M500 has it's gas cylinder within the receiver, but is too costly, and you would have to give up the battery space if you want the GL to fire. Probably to wide as well.
Maruzen has developed a new spring operated shotgun that is based on the M870. This new shotgun is dubbed "CA870". However, it does not use shells. Instead it uses a clip that slides into the loading port and hangs down about 1" below the receiver. This is aesthetically inaccurate. We're also unsure as to how much this new shotgun can be modified at this current time. Ripper asked if it's possible to install other types of weapons in their instead. The answer would vary depending on the airsoft/AEG weapon involved. Many things must be accounted for such as how you would supply the BBs to the receiver, and the source of power for such a secondary weapon.
"The M41-A. When you absolutely, positively have to kill every mofo in the room. Accept no substitutes."