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Spacehog

DIY Adjustable Comb Stock (How to Thread)

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I just finished up a project for another forum member, that was as much an experiment as trying to help another member out. For those of you with Saiga .308 Ver. 21's with factory furniture, you know going scoped requires a "chin" weld versus a "cheek" weld.

 

Below is an idea that started in my head and I wanted to see if it would be as simple as I thought it would be. I started off with some VEPR furniture which can be modified to fit the Ver. 21 with little effort. The idea was to modify this stock to have an integrated adjustable comb. This could be done with any solid butt stock with any rifle. This is going to be pic heavy and will likely be broken down into several posts.

 

First..Here are the finished pics:

 

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Required materials / tools: band saw, drill press, (or jigsaw and drill with very steady hands), Dremel, 1/4" SS rod, painters tape, and epoxy.

 

Start by transposing any inletting inside the buttstock to the out side so the cheek rest cut out will not interfere with any inletting:

 

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Mark out the location, shape, and length of the cheek rest. Also mark out the location of the posts perpendicular with the straight edge mark from the inletting crossing both the stock portion and the cheek rest portion. This will help you line them up when drilling for the posts.

 

post-37530-0-92588700-1422580054_thumb.jpg

 

The VEPR stocks are extremely difficult to "level" when making cuts or placing in a vice due to the fact there are very few flat surfaces. I used a wood jig to screw into the factory buttstock screw holes to give me a perfectly leveled work piece when cutting out the cheek riser portion on the bandsaw. Next post will cover drilling the holes for the adjustable hardware and rods.

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Mark and measure the center point for the post location using the previously marked lines across both the stock and the cheek rest as a reference. I used a 1/4" drill bit to drill out the post holes making sure to stay parallel with the marks and perpendicular with the horizontal line along the length of the stock. I then used 1" long, 3/8"x1/4" bronze bushings to give a tight fluid fit of the posts into the stock. This required using a 3/8" drill bit to bore out the 1/4" holes to a depth of 1". I added epoxy to the post holes, inserted the bushings, waited for curing and then re drilled using the bushing as a drill bit guide with a 1/4" bit to true up the travel of the posts through the bushings:

 

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I inserted the 1/4" rods into the newly drilled stock and measured 1/2" up from the face. These were cut to length at this mark. I inserted them into the drill press, and used a Dremel cut off wheel to groove the posts where they would insert into the cheek rest portion. The purpose of this was to give the epoxy connecting the two some to grab hold of:

 

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Place a dab of white craft paint on top of each post, and carefully place the cut out portion of the cheek rest on top of the posts making sure to properly align the cheek rest with the rest of the stock. This will transpose the location of the posts to the cheek rest for the purpose of drilling the holes:

 

post-37530-0-56931100-1422586543_thumb.jpg

 

I used a Dremel carving bit to enlarge and undercut the holes in the cheek rest to give some room for final adjustment when lining up and to give the epoxy more tooth to grab hold of. Use painters tape to cover both the stock surface and the cheek rest to make sure the epoxy used to attach the top posts to the cheek riser does not fuse the cheek riser to the stock while curing:

 

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Fill the holes with epoxy, turn the stock upside down with the posts inserted, insert into the cheek rest, and line up the cheek rest precisely with the stock. Use painters tape to keep the rest aligned with the stock while the epoxy cures. (The stock will remain upside down and level during the cure process:

 

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Once cured the cheek riser and posts can be removed from the stock as one piece. At this point you will have a functional adjustable comb.

 

The next post will cover cross drilling for two 10/24 screws to lock the comb at whatever height you desire.

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Once the cheek rest and posts are cured, remove the unit from the stock. Using the same original post lines, mark two spots for the cross screws that will tighten against the posts when inserted. I reattached the leveling jig to the butt stock while drilling these holes on the drill press to make sure they were perpendicular with the posts:

 

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I used brass inserts threaded 10-24 in the predrilled holes:

 

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These were epoxied and screwed into the stock. Once cured 3/4" 10-24 screws were inserted. These contact the posts to the cheek riser, holding it at the desired height with only finger tightening:

 

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Once you are done with this, you will have a fully functioning adjustable comb:

 

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Overall it was not that difficult, and I had about 4 hours total into the project. The wood stripped and stained very nicely, and hopefully it will look great and perform well for its new owner.

 

Finished, stripped, and stained:

post-37530-0-48090300-1422589285_thumb.jpg

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Very nice.

 

Another similar way to make the vertical adjustment is to have a tube which is internally threaded to act as a nut for a cap screw from the top of the riser. It is cut at an angle and bottoms out against a tube which is cut at the same angle over the bolt When the cap screw is tightened this will cause the two tubes to offset and friction lock inside the stock tubes.

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The stock set went to Chile Relleno for his Saiga .308 Ver 21. He is currently working on the fitting process but his computer is down. He sent me some pics and asked that I post them up for him. Here is the stock on his rifle. Still some fitting required, but looking good so far...

 

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All the people who call the slant backs ugly must be looking at something different, because that sure looks better to me.

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I agree. I actually prefer the slant back VEPRs to the square backs. I think they are better constructed as well. I appreciate all of the AK type rifles and want to own one of each. That includes ones with thumbhole stocks such as the MAK 90's, slant back VEPR's and in Chile's case, the Saiga .308 Ver 21.

 

I also think that the standard VEPR slant back thumbhole stock produces one of the best feeling, most ergonomic, and balanced rifles in the AK family. They just feel natural and solid when shouldering. JMO.

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But what if we the weight of extra metal that actually weakens the stock?

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But what if we the weight of extra metal that actually weakens the stock?

You are going to have to clarify that last question for me GF...not sure exactly what you are asking. If you are referring to the comb hardware, it did not add appreciable weight to the stock, additionally all metal to wood transitions were epoxied to make sure that no air gaps remained that could weaken the stock under recoil.

 

If you are referring to Chile's rifle, the Saiga 308 Version 21 is a slant cut receiver already. (Just a slightly different angle) So the stock is unchanged at its insertion point into the rear trunnion.

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I was joking about the widespread preference for square back. That bit of extra metal weakens a thumbhole stock and adds weight.

 

Obviously most people want the square back because they want to ditch the thumbhole stock.

 

Personally, I think the Vepr furniture is rather attractive. Since I am right handed, I would be inclined to leave it as-is. Perhaps I would do a cheek riser similar to what you have done. I've looked at doing something like that for my saiga shotgun, since the AK74 stock is a small footprint which could use both a little higher cheek weld, and a little lower toe. 

 

Did you make the thumbscrews shown in the last pictures, or were they a normal catalog part? They certainly look better than the socket head cap screws.

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I agree, the 10-24 socket head cap screws were simple place holders, but the only option I had locally. I recommended that Chile pick up some of the larger thumbscrews online. I am not sure where he got them. I found loads of them when doing a search on Amazon however.

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I would have expected those to be harder to find. It's the sort of thing I know is in a catalog like mcmaster carr or surplus center somewhere, but good luck finding what they called it or the category.

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They were knurled thumb screws, and yes, I got them at Amazon.

 

Spacehog, text me your PH again, I accidentally deleted it.

I've more pics, if you could be so kind as to post them for me.

(new comp on order)

 

Forearm mod done, just need to epoxy new hardware in permanently.

Giving up on perfection of fitting stock, too much would have to change.

I'd have to redo the angle of the tang, fill and redrill holes for tang screws, I'm afraid the screws would strip out.

Time to BLO the wood, reassemble and then go sight it in again.

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UPDATE:

 

Chile sent some additional pics this morning. He came up with a pretty clever method of attaching the forearm:

 

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He is still having issues with the stock to receiver fitting:

 

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I will allow him to update it from here. Should have the new computer soon. Look forward to some nice pics when it is all back together and up and running.

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The angle of the tang cut out needs to shallowed then? i.e the rear of the cut out closest to the butt needs to be deeper? If it were, would it allow you to pivot the stock upward to close the gap at the top of the slant cut receiver?

 

The existing holes are easy to fill..dip toothpicks in gorilla glue or epoxy and jam then in the holes until you can can't fit anymore. Let em set up, and cut flush. A new hole can be drilled right next to it and it will hold.

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The front hardware of the forearm had to come back. So I lengthened the hole to where it'd lock up tight. Cut a piece of aluminum to fill the hole, will paint it black.
The rear tang just barely came to the hole in the bottom of the receiver.
I inlet the forearm to fit the piece I fashioned.

Two holes drilled and countersunk, when I finish the screws will torque level, nice & clean.

The third hole I tapped, I cut the screw for the perfect length.

I'll epoxy this in with clear JB WEld, two screws & epoxy, it'll be rock solid.

The stock is a PITA.
The angles of the PG & tang make for a seesaw. Snug the PG level to the receiver and the tang slides forward and up.
Level the tang in the stock and the PG leans back away from the receiver bottom.
Too much would have to be altered to make it mate up perfectly.
Tang cut angle adjusted and lengthened.
Tangs holes filled & redrilled.
The top of the stock would rise well above the tang, would need to be fixed to allow TWS hardware to function properly.
Front of PG cut to slide forward 1/8".

Screw it, it will work just fine with a couple of gaps. I can make some spacers out of Delrin.

Time to finish wood with BLO.

Edited by ChileRelleno
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Look forward to seeing it. Sorry the stock fitting was such a PITA. the Robinson Arms thread made it look pretty straight forward and simple. But experience has also shown me that not all VEPR furniture will switch out with other VEPRs either. I wanted to swap the furniture on my .308 with furniture that was on my 5.45, and they weren't even close.

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Spacehog,

the stock is no biggie, I learned a lot from it. Just too many differences stacked up to make it an easy job. And it will work just fine as is.

 

I'll say this again though...

"Thank you very much!"

Without even having shot it yet, I know this is going to be sweet.

 

I look forward to fishing with ya.

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Three dripping wet coats of BLO hand rubbed into this wood, and it is a thing of beauty.

 

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What I don't understand is why you got that savage, when you have this. I can't think of a time when I would prefer a bolt gun over this.

 

 

Admittedly, that is largely because I don't have any illusions about my ability past 300 meters or so. Perhaps you are wanting to do super precision stuff?

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What I don't understand is why you got that savage, when you have this. I can't think of a time when I would prefer a bolt gun over this.

 

 

Admittedly, that is largely because I don't have any illusions about my ability past 300 meters or so. Perhaps you are wanting to do super precision stuff?

The Saiga weighs too much to haul through woods/swamp.

And yes, when it comes to deer, I want pin point accuracy.

 

Why do I have three .308s?

Saiga, Savage & M1A

Why not?

Edited by ChileRelleno
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Mcmaster Carr calls the screws "knurled head thumb screws".. They have many options and head sizes.

 

http://www.mcmaster.com/#thumb-screws/

 

 

I have a Vepr stock set aside for doing exactly this mod.. I was going to use a shaped section of rubber for the check rest, but I like the look of the wood so I may do that instead.

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I have a VEPR Super on the way that is going to get the same treatment. Chile didn't know it at the time, but he was the "guinea pig" so to speak. :) Going to try to make this one adjustable for LOP as well. I will have to see how the rifle feels once it arrives.

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I figured you were doing a little R&D in making this, thats great, cause I'm thrilled to get the results of your labors.

I hope your new Super is a real tight shooter & look forward to seeing it with both mods.

You do nice work.

 

I've seen the Super & Hunter, and I still want a Hunter in 54r very badly.

The fluted barrel and integrated comp are sharp as hell.

If the Veprs had been available back then, I would've gotten one of them instead of the Ver.21.

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