Build Thread An absolutely ridiculous Mossberg Shockwave build

[bradsteen]

Ok then, someone rig up a linked belt feeding from a 40mm ammo can

In case there was any doubt, I would abso-freaking-lutely buy a belt-fed shotgun if such a thing existed.

 

[sikhed]

In case there was any doubt, I would abso-freaking-lutely buy a belt-fed shotgun if such a thing existed.

If you build it, we will buy it.

 

[JSAV97]

I was looking into shell carriers for my Mossberg Shockwave, and a thought struck me... Why don't they make a shell carrier that runs the top length of the shotgun from receiver to barrel nut and has a rail / sights on top of that? Seems like a lot of unused real estate, and I want to carry more than a handful of spare shells. Obviously height over bore would come into play for the sights, as would sight height compared to cheek weld, and you wouldn't want the shells on top too close to the muzzle - nobody wants to accidentally KSG their hand while grabbing a spare shell. So there were problems to overcome, but it seemed doable.

I kept telling myself it's a dumb idea and it'll look ridiculous, but I just couldn't make it go away. In the end my curiosity got the better of me, so I finally decided to bite the bullet and give it a shot. The results are... Well, you can see for yourself. Kinda reminds me of something you'd see in the movie Alien, or a futuristic FPS game. Weird, but neat.

View attachment 1776831
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Full disclosure, this was a pricey conversion. I was just going for a proof of concept, so I ended up using budget-friendly parts where possible to keep my wallet from screaming too loudly. These are marked "cheap" on the list. If I were building this as a real go-to defensive weapon I would definitely recommend using better quality accessories.

Components Used:

• Mossberg 590 Shockwave
• Mesa Tactical Fallon Rail System
• Ergo Grip Mossberg Shockwave MLok Tri-Rail
• Cheap MLok picatinny rails (4" and 1.5")
• Kriss VFG with integrated finger stop
• US Aluminum receiver extension adapter
• SB Tactical SBM4 with buffer tube
• Ergo AR pistol grip
• Trinity Supply picatinny rail 5-shell carrier (x3)
• Cheap AR A2-style picatinny mounted front sight (mounted backwards intentionally because aesthetics demand it)
• Cheap medium-height optic riser
• Sig Romeo Zero with short riser
• Cheap pressure activated WML
• Cheap mlok pressure switch holder
• Brown Coat Tactical shell holder
• NDZ Tactical Extended Safety Lever

I have the Shockwave set up with the OpSol mini clip adapter for running mini shells (presently #4 buck). This bumps the standard capacity up from 5 shells to 8 (+1 in the chamber). With the build complete it now carries 15 shells across the top, 6 on the left of the receiver, and 12 on the right of the SBM4 for a grand total of 33 spare shells. The Brown Coat Tactical shell holder was designed to be a little wider so it could hold 2 mini shells per slot, facing each other. If running standard shells in this configuration, capacity would drop to 5+1 with 27 spares. So, the goal of more spare shells = mission accomplished.

Findings from this experiment:

• With the added weight and height I was expecting it to feel and handle really awkwardly, but for some reason it's not that bad. Using the VFG was probably a big contributing factor.
• The Kriss VFG was definitely the right call - the finger stop helps prevent the hand from slipping off the grip and going in front of the muzzle. I may go back later and add a strap between the finger stop and the base of the grip just to provide a little extra security for the pump-hand.
• Sighting isn't great, but manageable. Optic window is between 2" and 3" above the buffer tube, which the receiver extension adapter puts the buffer tube basically in line with the top of the shotgun receiver. So it is not terrible, but definitely could be better. Still need to tweak the optic height a bit, but it's close enough for now.
• This thing is a PIG. It weighs 11.4 lbs with tube empty and spare shell holders full, so will be close to 12 lbs fully loaded. Not something I'm willing to trek around for hours with, but should be manageable for short duration encounters i.e. home defense.
• Definitely needs a sling.
• The added weight should help reduce felt recoil when running standard-length defensive loads.
• An extended safety lever is a must-have for this kind of mod - the high-profile buffer tube and top rail make for a narrow space in which to activate the safety, and the stock one doesn't give you much to grip.

In conclusion I think the concept of using space along the top of the receiver and barrel to hold shells does make sense, but a custom-built solution to overcome the challenges of weight and sighting would definitely be ideal. A shell holder of this type that has an integrated rail over the top of it would make a lot more sense than running a rail and putting shell holders on top of it. This would save about 2 lbs of unnecessary weight, and would lower the sight height by at least 1/2", bringing it into a more comfortable cheek weld-to-sight territory.

In the end I like the concept enough that I'm going to keep it as-is and upgrade some of the cheap components. There's a Hollywood / gamer quality to it that my inner nerd appreciates, regardless of how unnecessary it is. I also now want to do a similar build on a Remington 870 because the high-profile buffer tube mod for the 870 doesn't require a weird gap to accommodate the safety lever - instead it runs straight to the receiver top, which would look a lot cleaner. Methinks perhaps that with a HERA CQR stock and this over-the-top shell holder mod might be kinda badass. Hmmmm... more tests are needed.

It is a thing of beauty.

 

[icookies112221]

I was looking into shell carriers for my Mossberg Shockwave, and a thought struck me... Why don't they make a shell carrier that runs the top length of the shotgun from receiver to barrel nut and has a rail / sights on top of that? Seems like a lot of unused real estate, and I want to carry more than a handful of spare shells. Obviously height over bore would come into play for the sights, as would sight height compared to cheek weld, and you wouldn't want the shells on top too close to the muzzle - nobody wants to accidentally KSG their hand while grabbing a spare shell. So there were problems to overcome, but it seemed doable.

I kept telling myself it's a dumb idea and it'll look ridiculous, but I just couldn't make it go away. In the end my curiosity got the better of me, so I finally decided to bite the bullet and give it a shot. The results are... Well, you can see for yourself. Kinda reminds me of something you'd see in the movie Alien, or a futuristic FPS game. Weird, but neat.

View attachment 1776831
View attachment 1776832
View attachment 1776833
View attachment 1776834
View attachment 1776835

Full disclosure, this was a pricey conversion. I was just going for a proof of concept, so I ended up using budget-friendly parts where possible to keep my wallet from screaming too loudly. These are marked "cheap" on the list. If I were building this as a real go-to defensive weapon I would definitely recommend using better quality accessories.

Components Used:

• Mossberg 590 Shockwave
• Mesa Tactical Fallon Rail System
• Ergo Grip Mossberg Shockwave MLok Tri-Rail
• Cheap MLok picatinny rails (4" and 1.5")
• Kriss VFG with integrated finger stop
• US Aluminum receiver extension adapter
• SB Tactical SBM4 with buffer tube
• Ergo AR pistol grip
• Trinity Supply picatinny rail 5-shell carrier (x3)
• Cheap AR A2-style picatinny mounted front sight (mounted backwards intentionally because aesthetics demand it)
• Cheap medium-height optic riser
• Sig Romeo Zero with short riser
• Cheap pressure activated WML
• Cheap mlok pressure switch holder
• Brown Coat Tactical shell holder
• NDZ Tactical Extended Safety Lever

I have the Shockwave set up with the OpSol mini clip adapter for running mini shells (presently #4 buck). This bumps the standard capacity up from 5 shells to 8 (+1 in the chamber). With the build complete it now carries 15 shells across the top, 6 on the left of the receiver, and 12 on the right of the SBM4 for a grand total of 33 spare shells. The Brown Coat Tactical shell holder was designed to be a little wider so it could hold 2 mini shells per slot, facing each other. If running standard shells in this configuration, capacity would drop to 5+1 with 27 spares. So, the goal of more spare shells = mission accomplished.

Findings from this experiment:

• With the added weight and height I was expecting it to feel and handle really awkwardly, but for some reason it's not that bad. Using the VFG was probably a big contributing factor.
• The Kriss VFG was definitely the right call - the finger stop helps prevent the hand from slipping off the grip and going in front of the muzzle. I may go back later and add a strap between the finger stop and the base of the grip just to provide a little extra security for the pump-hand.
• Sighting isn't great, but manageable. Optic window is between 2" and 3" above the buffer tube, which the receiver extension adapter puts the buffer tube basically in line with the top of the shotgun receiver. So it is not terrible, but definitely could be better. Still need to tweak the optic height a bit, but it's close enough for now.
• This thing is a PIG. It weighs 11.4 lbs with tube empty and spare shell holders full, so will be close to 12 lbs fully loaded. Not something I'm willing to trek around for hours with, but should be manageable for short duration encounters i.e. home defense.
• Definitely needs a sling.
• The added weight should help reduce felt recoil when running standard-length defensive loads.
• An extended safety lever is a must-have for this kind of mod - the high-profile buffer tube and top rail make for a narrow space in which to activate the safety, and the stock one doesn't give you much to grip.

In conclusion I think the concept of using space along the top of the receiver and barrel to hold shells does make sense, but a custom-built solution to overcome the challenges of weight and sighting would definitely be ideal. A shell holder of this type that has an integrated rail over the top of it would make a lot more sense than running a rail and putting shell holders on top of it. This would save about 2 lbs of unnecessary weight, and would lower the sight height by at least 1/2", bringing it into a more comfortable cheek weld-to-sight territory.

In the end I like the concept enough that I'm going to keep it as-is and upgrade some of the cheap components. There's a Hollywood / gamer quality to it that my inner nerd appreciates, regardless of how unnecessary it is. I also now want to do a similar build on a Remington 870 because the high-profile buffer tube mod for the 870 doesn't require a weird gap to accommodate the safety lever - instead it runs straight to the receiver top, which would look a lot cleaner. Methinks perhaps that with a HERA CQR stock and this over-the-top shell holder mod might be kinda badass. Hmmmm... more tests are needed.

tbh, it looks very cool, but it is gonna be hella heavy to carry nice built thos.

 

[bradsteen]

tbh, it looks very cool, but it is gonna be hella heavy to carry nice built thos.

Thanks! Yeah, it's way heavier than I'd prefer. Looking into prototyping a more lightweight version as a single integrated piece instead of bolting so much hardware onto a rail - will see how that goes.

 

[Michael566]

I was looking into shell carriers for my Mossberg Shockwave, and a thought struck me... Why don't they make a shell carrier that runs the top length of the shotgun from receiver to barrel nut and has a rail / sights on top of that? Seems like a lot of unused real estate, and I want to carry more than a handful of spare shells. Obviously height over bore would come into play for the sights, as would sight height compared to cheek weld, and you wouldn't want the shells on top too close to the muzzle - nobody wants to accidentally KSG their hand while grabbing a spare shell. So there were problems to overcome, but it seemed doable.

I kept telling myself it's a dumb idea and it'll look ridiculous, but I just couldn't make it go away. In the end my curiosity got the better of me, so I finally decided to bite the bullet and give it a shot. The results are... Well, you can see for yourself. Kinda reminds me of something you'd see in the movie Alien, or a futuristic FPS game. Weird, but neat.

View attachment 1776831
View attachment 1776832
View attachment 1776833
View attachment 1776834
View attachment 1776835

Full disclosure, this was a pricey conversion. I was just going for a proof of concept, so I ended up using budget-friendly parts where possible to keep my wallet from screaming too loudly. These are marked "cheap" on the list. If I were building this as a real go-to defensive weapon I would definitely recommend using better quality accessories.

Components Used:

• Mossberg 590 Shockwave
• Mesa Tactical Fallon Rail System
• Ergo Grip Mossberg Shockwave MLok Tri-Rail
• Cheap MLok picatinny rails (4" and 1.5")
• Kriss VFG with integrated finger stop
• US Aluminum receiver extension adapter
• SB Tactical SBM4 with buffer tube
• Ergo AR pistol grip
• Trinity Supply picatinny rail 5-shell carrier (x3)
• Cheap AR A2-style picatinny mounted front sight (mounted backwards intentionally because aesthetics demand it)
• Cheap medium-height optic riser
• Sig Romeo Zero with short riser
• Cheap pressure activated WML
• Cheap mlok pressure switch holder
• Brown Coat Tactical shell holder
• NDZ Tactical Extended Safety Lever

I have the Shockwave set up with the OpSol mini clip adapter for running mini shells (presently #4 buck). This bumps the standard capacity up from 5 shells to 8 (+1 in the chamber). With the build complete it now carries 15 shells across the top, 6 on the left of the receiver, and 12 on the right of the SBM4 for a grand total of 33 spare shells. The Brown Coat Tactical shell holder was designed to be a little wider so it could hold 2 mini shells per slot, facing each other. If running standard shells in this configuration, capacity would drop to 5+1 with 27 spares. So, the goal of more spare shells = mission accomplished.

Findings from this experiment:

• With the added weight and height I was expecting it to feel and handle really awkwardly, but for some reason it's not that bad. Using the VFG was probably a big contributing factor.
• The Kriss VFG was definitely the right call - the finger stop helps prevent the hand from slipping off the grip and going in front of the muzzle. I may go back later and add a strap between the finger stop and the base of the grip just to provide a little extra security for the pump-hand.
• Sighting isn't great, but manageable. Optic window is between 2" and 3" above the buffer tube, which the receiver extension adapter puts the buffer tube basically in line with the top of the shotgun receiver. So it is not terrible, but definitely could be better. Still need to tweak the optic height a bit, but it's close enough for now.
• This thing is a PIG. It weighs 11.4 lbs with tube empty and spare shell holders full, so will be close to 12 lbs fully loaded. Not something I'm willing to trek around for hours with, but should be manageable for short duration encounters i.e. home defense.
• Definitely needs a sling.
• The added weight should help reduce felt recoil when running standard-length defensive loads.
• An extended safety lever is a must-have for this kind of mod - the high-profile buffer tube and top rail make for a narrow space in which to activate the safety, and the stock one doesn't give you much to grip.

In conclusion I think the concept of using space along the top of the receiver and barrel to hold shells does make sense, but a custom-built solution to overcome the challenges of weight and sighting would definitely be ideal. A shell holder of this type that has an integrated rail over the top of it would make a lot more sense than running a rail and putting shell holders on top of it. This would save about 2 lbs of unnecessary weight, and would lower the sight height by at least 1/2", bringing it into a more comfortable cheek weld-to-sight territory.

In the end I like the concept enough that I'm going to keep it as-is and upgrade some of the cheap components. There's a Hollywood / gamer quality to it that my inner nerd appreciates, regardless of how unnecessary it is. I also now want to do a similar build on a Remington 870 because the high-profile buffer tube mod for the 870 doesn't require a weird gap to accommodate the safety lever - instead it runs straight to the receiver top, which would look a lot cleaner. Methinks perhaps that with a HERA CQR stock and this over-the-top shell holder mod might be kinda badass. Hmmmm... more tests are needed.

What was your final cost on this monster? I love it

 

[bradsteen]

What was your final cost on this monster? I love it

Too much, lol.

• Mossberg 590 Shockwave = ~$500 (already owned)
• Mesa Tactical Fallon Rail System = ~$180
• Ergo Grip Mossberg Shockwave MLok Tri-Rail = $65
• Cheap MLok picatinny rails (4" and 1.5") = $10 (already owned)
• Kriss VFG with integrated finger stop = $30 (already owned)
• US Aluminum receiver extension adapter = $30
• SB Tactical SBM4 with buffer tube = $60 (already owned)
• Ergo AR pistol grip = $20 (already owned)
• Trinity Supply picatinny rail 5-shell carrier (x3) = $100
• Cheap AR A2-style picatinny mounted front sight (mounted backwards intentionally because aesthetics demand it) = $15
• Cheap medium-height optic riser = $10
• Sig Romeo Zero with short riser = $150 (already owned)
• Cheap pressure activated WML = $20
• Cheap mlok pressure switch holder =$10
• Brown Coat Tactical shell holder = $20
• NDZ Tactical Extended Safety Lever = $10

Grand total (not counting shipping, sales tax, etc)
= ~$1,230 if you bought everything new, but I actually only spent around $460 because I already owned the Shockwave, optic, brace, etc.

Other ways to save cost...
- Replacing the top shell holders with plastic ones (reduces weight, lowers height)
- Drop the brown coat shell holder (that was just for fun)
- Change to an Ergo picatinny tri rail instead of mlok.
- Ditch the WML

Doing these things would cut almost $100 off the build cost.

 

[Sxsnuf]

That's just cool. ABSOLUTELY no "wasted real estate".
Thanx for sharing