Aliens "Hero"(ish) Pulse rifle build: w/APS CAM870 shotgun 'guts' (DONE!!!)

[bigbisont]

I actually considered not even bothering to document the build as so many other excellent Pulse build threads are all over this forum.
However, I didn't see any where the relatively new APS CAM870 Airsoft Shotgun (shell cycling, CO2 powered) was used. Figured maybe someone might find some info here.


The parts list (still growing).


-HCG shrouds
-Scratch-Built Stock and Vent
-Real SPAS cage and slide/forend
-SD Studios front GL block
-Airsoft Thompson (don't like the plastic "lower" at ALL, but it will do for now)
-Custom barrel
-Scratch built aluminum mag base
and finally...
-APS CAM870 shotgun. AWESOME piece of hardware and doesn't need to be deactivated!


The APS 870 is very very much like a real Remington 870. It even comes apart very similarly to a real 870 (there are some differences in how to get from A to B, but the overall parts are damn near dead on.






I probably wont get around to serious chopping on this thing until after the holidays as I am way behind building my Brother's Xmas present (A Jayne Cobb pistol), but I am really looking forward to digging in for real on this bad boy and will post the progress here if I accomplish anything worth while

 

[gunnerk19]

Re: Another "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

I've seen what the CAM 870 goes for :eek

Safe to say this build is gonna be of the Spendy persuasion...

 

[bigbisont]

Re: Another "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Yeah, it wasn't as bad as it could have been. I got it on a cyber week sale 25% off and reduced shipping. Still cost more than the real shotgun in my closet...:facepalm
But hell, its all the realism without any of the deactivation and paperwork.

Suffice to say, this build is easily the most expensive project I have ever undertaken. Between that, the real SPAS cage and the HGC parts, its definitely a project I can never let the wifey know they exact costs on! Its my grail though. Has to happen.

I've seen what the CAM 870 goes for :eek

Safe to say this build is gonna be of the Spendy persuasion...

 

[bigbisont]

Re: Another "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

OK, I made a lot of progress. I'll try not to be as long-winded as I was when posting this to the AL. If anyone has any questions, please do ask.

Grinding down and cutting handle (pretty positive the real ones were cut down, so why over-complicate it when the handle already fits?)


Cutting down the grip and cage (Measure a dozen times, cut once, then hand file)


(As per the excellent tutorial online)



Now to chop the APS shotgun!



And now time to panic, possibly. DONT CUT IT THAT WAY!
I cut the 'spring' that provides tension to hammer. (It is nested in the front of the trigger guard). I didn't cut it bad, and so far it seems like it will hold, but suffice to say, don't cut that deep if you are doing your own.



Now is the time to note, most of the builds documented with photos either use resin copies the 870 shotgun, or actual Deactivated ones. In those case, the entire trigger guard can be removed clear up the receiver (flush, even). When you want to maintain a firing function (be it real [illegal, btw], or this CAM870 shotgun, much of the trigger guard MUST REMAIN IN TACT. Further you must do more cutting of the SPAS cage to make room. It is unavoidable if you want to maintain firing ability and make it fit in the cage.



Another note: I have no idea if other brand of airsoft shotguns use a "hammer", so I have no idea if they have a spring. Cut slowly until you know and try to find exploded diagrams BEFORE you cut on your own.


But it fits now. The 'cut spring' part is actually directly over the front pillar in the magazine area of the shroud so it has bottom support. I am thinking it wont be an issue. (Still best to avoid it if you can, of course)

 

[bigbisont]

Re: Another "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

To make the HCG shrouds fit, some fairly heavy cutting is also involved.

I used dremel tools, a drill press with milling bits, a contraption to turn angle grinders into metal chop saws, and numerous hand files. It is a PITA but it can be done.

Obviously the "nubs/studs" on the rear (which go into the resin HCG Thompson) need to go. The only 2 I truly needed to remove completely were the rear 2 on the bottom rail (both halves of course).

The other studs were not in the way of my parts (but if you use the "block" Tommin adapter you def need to get rid of the top front ones too), or they are going to be useful (I'll explain shortly).

Other than that, its a series of cutting, grinding, trimming and general 'widening' of the bottom rails to cut enough room to slide over the Thompson

Making sure the grenade launcher fits in the shrouds is a bit more work.

This side = easy

Other side a pain in the butt and more cage cutting

Now everything closes up snug though.

 

[bigbisont]

Re: Another "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

The area where the pistol grip/stock screw in to the CAM870 protruded a little far. I needed to be modified.

As for actually mounting the cage to the Thompson, I am trying to keep it simple and using existing holes.

I plan to extend the barrel, so I will use the existing Thompson barrel assly. There is already one hole for the foregrip in it. I just tapped it at a larger/courser thread.
For the rear support I used a longer bolt matching the existing threads for the 2nd hole used to secure the barrel.

I used simple nuts as the spacers

Pretty darn sturdy. Decent clearance on the inside, although it does push the shotgun a little lower than I like. I guess that is normal. Or is it? Anyone done this that has a better idea for super flat bolts that don't push the 870 lower inside the cage?

Once I blacken out that front spacer, I think the gap wont be as noticeable. I also might grind down the spacer nuts just a tiny bit.

So that is where I am at so far. Thanks for looking.

 

[spoudastis]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

It's gonna be awesome when complete. About to start my own as well.

 

[L0B0]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Awesome tutorial!!
Thanks

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Thanks! That reminds me I haven't updated this in a while. Work is going much more slowly now than in the beginning but stuff is getting done. I have high hopes for this weekend. Hopefully some big updates will be ready Monday.

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Alright, finally got more "learning experiences" to document.

The biggest realization was the shotgun sits too low in the cage. I realized this is because no matter how small the screws are attaching the 'cage' to the thompson, the heads of those screws will push the shotgun lower. "How did everyone else deal with this?" I wondered. Well now I realized yet again that most builds dont need to maintain firing function of the shotgun! The bolts cant support just the 'cage', they need to go THROUGH THE RECEIVER to push the receiver as high as it can get!

Ugh, more drilling.


Luckily, the "stop" that keeps extractor bolt assembly in place actually had a recessed area exactly where I need it to be! I drilled that out and the bolt head inside the reciever now acts as the 'stop', so no harm done!!! This worked out pretty well actually. Now the receiver is secured with the bolt to the Thompson and the cage is just sandwiched in there. The rear bolt on the cage I referenced above actually is still getting use too, so the cage has 2 mounting points still, but the receiver just has the 1 bolt going through it.




The HCG mag base is common resin, so I got to chopping and grinding a block of aluminum to try and fab up some new ones. Not yet figured out how I will attach them, but the basic shape is coming along


The magazine itself is progressing as well. Since the base will be permanently attached, I had to 'delete' the "winder" on the metal airsoft mag. So I gutted it.
I took a plastic mag that is fed with a traditional spring feed and grinded it down so the entire thing fit into the metal mag housing (essentially acting as new spring-fed 'guts' to replace the winding mechanism guts)



I have high hopes that this will work.


Now on to the stock. I thought the HCG stock was a bit flimsy so I made one myself out of 14g steel. I will be making a new barrel vent as well.

Old fasioned drill and dremel to get slots. Just a tiny bit of welding to zip it all up.

Now to attach it I just widened the existing holes on the Thompson where the rear sight attaches and used some 1/4-20 nuts and bolts



I realized the front set of bolts would not fly, however, as they not only blocked the cocking handle from going back, but also they prevented the airsoft lower from re-attaching as the bolts were in the way of the gear box/etc. So I just ran with the rear two bolts.


This wasnt bad actually, as HCG shrouds do fit quite snug. In fact, I had to remove some material for those bolts to fit. Its on the very tight and isnt going anywhere.



I have not yet decided if I will try to make a 'locking' mechanism to hold the stock in different positions. I plan to run it "closed" 99% of the time, so it isn't a priority at this stage. I will leave it as-is for now and maybe revisit later.

For now, my focus is 100% on getting the 870 slide attached to the SPAS grip and getting that shell cycling functional again.

After that I address the front barrel and barrel vent (which I will be scratch building)

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Again, trying to not be as long winded as I tend to be. Got quite a bit done.

Made my spacer to connect the 870 slide arm to the "grenade launcher" grip. First up was cutting out the rectangle washer for the grip.


Now I shaped the spacer from 3/16" steel.


When I finally got it where I wanted it and welded up, I tapped and threaded it for a 6-32 threaded 5/8" flat head hex bolt.


Tightens up pretty nice. I now have a 'racking' grenade launcher. When I put the extractor bolt/pin assembly back in it should cycle 'grenades' (or airsoft shells if I needed them)!


Unfortunately I decided I had to replace the barrel. Extending the barrel per screen accuracy was not going to work as the airsoft Thompson features an aluminum barrel (so costly/difficult to weld) and there is no room to try to thread anything while maintaining airsoft function (the brass inner barrel takes up ALL the available space). It was just too complicated so I decided to just do my own new barrel.




This way is nice and snug. I think it will be quite strong.

Only drawback to this way is the hole/mount where I planned to attach the grenade launcher lost its front support. That bottom rail became more a 'tab' that flexes than a sturdy block. I used some spare brass strapping and riveted it in place to restore the stability. I think it is strong enough to support the grenade launcher now. Guess we will see...



Also did some more drilling, grinding, dremeling and hammering on my vents.



I can see the light at the end of the tunnel! I am nearly there. Fastening it all up and sorting out the mag base are the last "big" ones. Little ones include battery placement for the LED and paint.

 

[gyoung2993]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Oh my , how in the world did I ever , miss this thread....I love these builds....sorry I didn't know you were building this...I would have responded long ago...LOL...Congrats , on a fantastic build sir !!!...WOW great job !!!

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Oh my , how in the world did I ever , miss this thread....I love these builds....sorry I didn't know you were building this...I would have responded long ago...LOL...Congrats , on a fantastic build sir !!!...WOW great job !!!

Thanks! Great to hear from the RPFs resident pulse-man! It will be center piece of my collection for sure.

So last night I finally properly bolted up the grenade launcher for the first time.



It feels damn solid and 'racks' perfectly!

Once I went that far, I just had to slap the rest of the parts on for a "dry fit" test.




So still to do:
- Weld the barrel ring and sling loop to the front triangle on the vent
- Figure out how to attach my scratch built aluminum mag bases (last "big headache" here I think)
- re-tap threads for bolts on shrouds (for those not aware, the HCG pulse bolts are glued in place in oversized holes, not actually threaded.)
- Paint SPAS cage
-"Blue" steel parts

I'm so close I can taste it...

 

[gyoung2993]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

That is highly impressive , as far as you have taken this , on your own , BRAVO sir !!! These are tough builds , Congrats !

 

[Noeland]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Thanks for sharing this build. Glad you decided to document it. I never get sick of seeing pulse rifle builds this ambitious.

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Thanks fellas.

More progress. I couldn't do the screen accurate 'barrel extension', but I did decide to simulate the look by adding the 'notches' to the reducer (to enable firing of blanks) from the hero rifles. I think it will look solid.



Also I finished up the welding and bluing. I think it was Stapleton13 that first planted the idea of 'bluing' the parts in my head when I saw what he did on his build several years ago and man I am glad I finally pulled it off myself. An amature 'blue' job for sure, but looks so good in person. Parts are a little darker in hand than they appear in the pics.






By contrast the common spraypainted black of the SPAS and GL block look pretty tame. I will take some steel wool to them pretty heavy and tone that intense 'black' down a bit.




All that is left is to sort out my mag-base disaster and button it all up with a better solution than gluing the bolts in place (like the default HCG did)

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

Neither the HCG holes (oversized) nor stock bolts (M3 metric, tiny things with tough glue residue all over them) were really of much use, so I filled in the holes with steel stick and then re-drilled and tapped them to fit a larger 8-32 bolt. I slightly relocated the rear mag plate as well. The stock one seemed to high for me and by relocating it I could drill and tap solid aluminum instead of 'steel-stick'. Its rock solid right now.




Still not worked out the mag base or battery placement for counter, but did get everything buttoned up pretty nice.



With any luck this weekend I will work out the kinks and be 100% done this weekend.

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: w/APS CAM870 shotgun 'guts' (DONE

Hammered out the mag base (or drilled out, specifically). Also epoxied into place.




Also wired up the basic (default) HCG counter. I moved the batteries into the area under the front carry-handle pillar. I had to dremel out the studs that I previously had ignored in order to make room. The fit is VERY tight to get it closed, but it does indeed close.


I did cut a little groove there so the wires could extend up into that area up top without rubbing the SPAS cage.

Eventually I will install a "majenko" board that counts down, but honestly I am feeling pretty good about the project and am ready to 'rest'. It is in the "some day" list of things to do.

 

[bigbisont]

Re: Another Aliens "Hero"(ish) Pulse rifle build: With APS CAM870 shotgun GL guts

And to cap it all off....FINAL PICS! Thanks for tracking the progress with me and hopefully someone finds the info useful when they build their own.

 

[gyoung2993]

Re: Another Aliens "Hero"(ish) Pulse rifle build: w/APS CAM870 shotgun 'guts' (DONE

Glad to hear that you completed...job well done...the close tolerance level with wiring and electronics and magazine are all a pain in the neck, especially having the shroud halves real close together as you solder the wiring , is what frustrated me the most....LOL...there is no room to play with that's for sure !!!