Recoil reducing stock

[hkr]

I'm making a recoil reducing stock for my 870, and was hoping for some input on the stroke length of the shock absorber. It looks like the Knoxx stocks have ~1" of travel, but the butt and grip are fixed together. With mine, the grip will recoil with the receiver. I'm worried about the hand holding the grip now absorbing a lot of the recoil energy if the stroke is too long. I can make it slightly adjustable for fine tuning, but want to get it as close as possible.

For reference, it will be a similar layout to this fixed stock I made, though slightly wider tubing and probably ~2" longer LOP, as this felt too short. Also made of higher quality tube, this one bent after firing some 1.75oz loads!

 

[justinchow]

I believe a company called Endine makes the shock absorber for Mesa Tactical if you're interested. I think their dimensions are based on the buffer tube dimensions for AR stocks, which are also included in their kits

 

[hkr]

Cool, thanks. I didn't realize there was an off the shelf product, looks like I'm reinventing the wheel again

Edit: I sent a few inquiries to dealers on availability/price but judging by the difference between the Mesa kits with and without the recoil buffer, it's probably ~$160. So for that price I will probably carry on making my own!

 

[J.P.]

I think the short stroke is the way it is for a reason.

I have seen the factory ones malfunction where they don't reset after each shot. Kind of get jammed in the compressed position then you kinda have to wiggle and pound on it to get it to pop back out. Just something to consider. There is probably a bit more to getting it right than it would appear. If you want to improve on it might want to look for a double nested variable force spring. Or maybe something like creating a piston that has to compress the air in the tube and squeeze it out a small hole. Simply making a fixed stock with tubing but adding some mercury buffers under it might be an even better option

 

[870P]

Neat little setup there!

I always recommend that folks using pistol grip full stocks, pull backwards from the front of the grip firmly into the shoulder, instead of trying to push the grip forward and giving the recoiling gun a running start into your hand and wrist.

 

[Juster]

A cheaper option would be :
"http://www.edwardsrecoilreducer.com/#!buy/c7o3
"http://emptormaven.com/wp-content/uploads/2009/07/EdwardsRecoilReducerInstalledWithSprayfoam.jpg

I think Brownells has it.

I would love to see pics of your DIY build of course .

 

[hical.ca]

We have kicklite stocks, they work well! HERE.

 

[hkr]

I think the short stroke is the way it is for a reason.

I have seen the factory ones malfunction where they don't reset after each shot. Kind of get jammed in the compressed position then you kinda have to wiggle and pound on it to get it to pop back out. Just something to consider. There is probably a bit more to getting it right than it would appear. If you want to improve on it might want to look for a double nested variable force spring. Or maybe something like creating a piston that has to compress the air in the tube and squeeze it out a small hole. Simply making a fixed stock with tubing but adding some mercury buffers under it might be an even better option

Great minds think alike!

Using a pneumatic cylinder I can play with the spring rate easily, instead of trying to find the perfect metal spring.

Neat little setup there!

I always recommend that folks using pistol grip full stocks, pull backwards from the front of the grip firmly into the shoulder, instead of trying to push the grip forward and giving the recoiling gun a running start into your hand and wrist.

Thanks. That's a good tip, I'll give it a try next time I'm out.

A cheaper option would be :
"http://www.edwardsrecoilreducer.com/#!buy/c7o3
"http://emptormaven.com/wp-content/uploads/2009/07/EdwardsRecoilReducerInstalledWithSprayfoam.jpg

I think Brownells has it.

I would love to see pics of your DIY build of course .

I did a lot of googling and reading about those ones that use inertia, and decided that using a spring to directly absorb the recoil would be more effective. Although I'll be the first to admit that decision was far from scientific

We have kicklite stocks, they work well! HERE.

Thanks, that's almost what I'm looking for, but from the picture it looks like the stock is angled relative to the gun. I would prefer one that is parallel to the bore. How have you found the reliability on those? I would be leery of all the recoil force acting on a single adjustment pin? Although I guess there are lots of people with non-recoil reducing adjustable stocks that would see even higher peak force on the pin, so if it was an issue they wouldn't be so widely used.

Edit: On the kicklite website it says the stroke is 3/4" so that is helpful as a starting point if I make my own.

 

[Juster]

Other designs:

Although I'm have Sterling SMG flashbacks .
edit @hkr:

And the Edwards patent: "http://www.docstoc.com/docs/31605151/Firearm-Recoil-Reducer---Patent-4279091

 

[hkr]

Neat, I'd seen the picture, but not read the patent yet. What do you mean about Sterling?

 

[J.P.]

Great minds think alike!


Using a pneumatic cylinder I can play with the spring rate easily, instead of trying to find the perfect metal spring.



Thanks. That's a good tip, I'll give it a try next time I'm out.



I did a lot of googling and reading about those ones that use inertia, and decided that using a spring to directly absorb the recoil would be more effective. Although I'll be the first to admit that decision was far from scientific

I had thought of using a gas strut too, but they use rubber seals which are going to get cooked by multiple fast actuations. I'm thinking of the kind found in vehicle rear hatches - maybe you found a better one? I was thinking more like a piston in a gas operated semi auto. Like an AK/SKS piston. Just a tight fitting chromed bolt in a bore with a return spring and a small hole to push the air out of. It would have to compress a spring and move the plunger compressing air at the same time. The spring should be on the outside of the inner cylinder and between the stock tube; then the spring cannot bind in any way.

 

[hkr]

I did look at those rear hatch struts, but I couldn't find any short enough - a 30" LOP seemed a bit long. Instead I picked up a regular pneumatic cylinder which I was going to pressurize with air on one side to act as a spring. I hadn't thought about multiple fast actuations being a problem for the seals, but that is something to keep an eye on I guess. I took it apart and it's well greased so I think it should be ok, but I'll keep an eye on it. The downside to this is that there isn't anything controlling the actuation rate or return rate like there is in a strut/shock and your idea. Not sure what effect this will have when firing. If it's a problem I suppose I could try to restrict the air port on the opposite side of the cylinder or add a valve like you'd find in a strut that allows high flow one direction and low flow the other to control return rate.