Saturday, March 7, 2015

WIP - Hammer - Pump Retal Build

I think it's about time I added a superstock pump gun to the armory. Just because.

The first thing many will ask, is Rampage or EAT. I wanted to steer well clear of both. The former is a sweet gun with a solid history going back to 2008, but sideloaders are not great. The latter is in short supply, I can't afford one now, and when I don't want a pump gun with $60+ worth of desire, I wouldn't keep one if I did own it - plus the thing is the most flimsy feeling and inefficient of the Elite CS guns as well as the most lacking of durability in hard use.

What I did have was a Retaliator, a solid and consistently sweet-shooting piece, which was begging to have a pump grip.

What was certain early on was that I was not going to just put an inner barrel on there and go. With something that isn't an auto, I can't afford any negative impact on koosh accuracy, nor do I want to lose any of the circa 105FPS that this thing has - so it was going to be a BFU barrel. I did not want to buy kits, use stock Retal handguards underneath the pump grip, use an accessory rail as a grip guide, have those janky angled links putting extra forces on things. Nor did I want a slide, since a flat top setup was mandatory.

I started with the barrel. I chose 3/4" SDR21 PVC pipe and was planning to build a bulkhead to mount it solid, but then I tried ramming a piece into the stock twist-lock muzzle. It only took grinding a flat on there to clear an internal protrusion and some Devcon and I had a perfect barrel install on the stock chamber.

Next the grip guide. I considered a coaxial pump grip but settled on a second tube below the barrel for the grip to run on. This is 3/4" Schedule 40 and is bonded to the barrel. The trunnion is one piece because none of the barrel stuff is clamshell and is Devconned on the right receiver half and screwed to the left through some PVC blocks with an 8-32 socket flat head.

The base of the pump grip is 1" Schedule 40 PVC sectioned and slightly expanded hot. The resulting grip runs smoothly on the rail with not too much clearance.

This is an 8-32 tee nut. Normally these are hammered into wood and used to accept a threaded fastener. However...

...This is a trimmed tee nut which will be used as a threaded insert in this build.

And here is one being torched. Why?

Because this.

I carefully set the inserts flush while hot, Devconned them in, and trimmed the outboard end. Now I have steel 8-32 threads in the bolt carrier, rather than pin holes that were too large already for me to tap or mess with for attachment means confidently.

Currently these and the 8-32 grip studs are the wonkiest thing about this gun and testing is pending. For now it is all working great, but revisions may happen to hardware in this area.

This is the pump grip after adding 2 more thermoformed layers and marking out for attachment flats.
And here is where a lot of pulverized PVC used to be. Freehand, grinder.

And even more pulverized PVC came from carving grip grooves.

This grip is a solid, heavy part.

Mocked up

Linkage fabricated. I was going to use aluminum, went for PVC sheet instead. Does the job, solid. The grip end is Devconned and the screw is there for insurance, which is why there aren't 2 screws.

Current state. Missing the (important) top accessory rail and the barrel shroud, the flash hider is still a blank, and there are some holes to patch in the receiver. So far, it doesn't look the greatest with those issues remaining, but it already feels great, points nicely, shoots just as this Retal always did, and is the most effortless and nice pump-action I have ever used.

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