re-inventing the wheel 788 6.5CM build

[cody c]

This thread is to show off some of my handi work, and perhaps a pinch of some out of the box thinking, though really Im sure everything has been done by others somewhere else before.

After getting my hands on a steyr model M full stock, I kind of got infatuated with rear bolt lug rifles, I like the short bolt stroke, 60 degree throw, and as they do not have lugs at the front there is less barrel between the magazine and back of the bolt at that end, essentially the chamber relative to the mag may be shorter than other arms, or they make better use of the barrel length without having grooves and channels for the locking bolt lugs.


Having an action that is fairly short puts things in place for a shorter OAL. I decided to condense things by creating a new trigger piece that puts the finger about 30mm forward of factory but still behind the magazine, essentially being able to shorten a rifle 30mm without loosing barrel length or LOP. I also decided to aim for a lighter weight build and integrate a bipod, at the same time the lines of this build were/are to be streamlined in the interest of easily sliding it in and out of a scabbard like the eberlestock pack I have without getting hung up. Basically a light/compact shooter that performs at a distance with a full length barrel.

Time for some pictures to get started. We start with a LH 788 in 308, carbon six barrel (through mystic precision) chambered to 6.5CM. Ron smiths son put the barrel on it, I took the belt sander to the factory stock:

 

[cody c]

The next thing was to get building a stock for it..

Ultra Light weight balsa wood, about as light as styrofoam and I started to give it a shape:




I realized I wanted to reinforce it, so started building an aluminum skeletonIMG_1345[1] by cody c, on Flickr

IMG_1343[1] by cody c, on Flickr


One thing I wanted to try was mounting QD flush mount points on the sides, the front and both sides of the rear stock... Ill explain later. The aluminum trigger guard was scratched up with CAD and I had a few cut at the local waterjet shop in Calgary...

Edit: The QD (quick disconnect) flush mount point for slings; I put them all over, when one gets a hold of a hammer everything looks like a nail they say!
The purpose of them is that I have them in multiple places to be used for just a conventional sling, The one on top of the butt stock at back is there so I can run two slings and carry it like a backpack, thats why there is QD's at the sides of the forestock as well, I can carry it flat, against my back with the bolt knob facing out, and then at the top on the sides of the rifle one sling attached above the other, I just need two slings with QD's. I suppose one could simply make a back strap thing to carry but this way if I want my hands free to climb or hike all I need is a second simple spare sling and when you look at the weight of a second nylon sling for a backpack carry setup its not too bad (at least in my head)

IMG_1346 by cody c, on Flickr

IMG_1353[1] by cody c, on Flickr

 

[cody c]

The legs were from a cheap bipod I had that came with the AICS knock off airsoft stock from another project. I wanted this to be light, but with the new pipe being actually even heavier than the factory barrel, despite the lightweight balsa stock I was pushing over 7 pounds without the carbon fiber laid on it or paint or any other details...

In my favor, that was 7 pounds with a bipod on it, and a couple places I could trim weight. I was learning by making some mistakes at this point..

I did keep track of weights as best as possible for others to have an idea for their own projects.

788 factory stock 39 ounces
factory 308 barrel with action 65.7 ounces (factory barrel 39.2 ounces)
carbon six barrel with bare action 84.48 ounces (58.8 ounces)

I realized that a target or sendero profile barrel was heavy. It was my mistake and I should have ordered a different contour...

Other data for ounce pinchers
balsa core 6.3 ounces
front (bipod mount) piece of aluminum 2.86 ounces
main skeleton with bedding block 8.1 ounces
UTG bipod 10.26 ounces (was modded to about 7 ounces or less)
Finished stock with bipod and paint weighs 38 ounces


So, I went to throw carbon fiber on it, first time for everything... It went on, two layers but as for all new things on the first try, not as well as expected

IMG_0227 by cody c, on Flickr

The carbon wouldn't stick to the stock, it would lift off, the resin was super sticky and I was losing my cool without any experienced guidance or wisdom at hand, needed to make a call on keeping it on, used the latex gloves pulled over it to keep the fiber against the balsa in place. I hoped I could use something like acetone or mineral spirits to melt the gloves off, not so...

IMG_0229 by cody c
, on Flickr

I managed to sand most of it off, it was still really hard to sand off without taking carbon fiber with it. I was planning on a camo paint anyways, functionally it seemed strong, but cosmetically a fail..

IMG_0319 by cody c, on Flickr

 

[cody c]

It did come together well enough at the end, but I needed to get my head out of sanding and filling resin many many times to smooth it out. Back to the weight.

Scope rings.. Cheap chinese made 6 bolt caps. There are some more expensive versions of these sold by bigger names but I like the sturdiness of these and they were a good candidate for a project. Replaced the factory screws with larger titanium, I had to file down the sides to square so they would fit between the rails of the EGW picatinny rail. Replaced the nuts with wing nuts, de-horde (sanded the edges) of the rings and lightened them up around an ounce or so if I remember correctly. Probably spent $20-30 on them all in.

IMG_0361 by cody c, on Flickr
IMG_0363 by cody c, on Flickr


At this point I also drilled a fourth hole for the rail. The 788 action comes with three #8 screw holes whereas a remington 700 usually comes with four #6 screws. ordered a tap and pilot and extra screws from EGW
Im sure it would have worked fine with three, but for some reason it seemed inadequate knowing other actions have four screws and I wanted it sturdy. Another thing, as I condensed the OAl by moving the trigger forward slightly, the scope placement also needed to sit forward further. I had to take the angle grinder and then file to the EGW rails lugs at the vary rear to move the scope forward slightly so the mag ring wouldnt interfere.

IMG_1362 by cody c, on Flickr


The other thing I decided I could chop weight off of was the bipod legs. I had integrated them into the front end of the stock to sit flush and remain on. This was important to me as if youve ever tried to leave a bipod on a stock and then slide it into a scabbard you'll realize you need to pull the legs and put them in your pack. What a pain and not ideal for mountain hiking.

First I removed the aluminum and added in some CF tube glued into place to replace the existing aluminum tube, maybe dropped an ounce or half of one but it looks sharper and I made them a pinch longer...

IMG_1394 by cody c, on Flickr


Then these little pins which lock the legs in place.

Steel (0.7 ounces each) 1.4 total

IMG_1351 by cody c, on Flickr

To 7075 aluminum I shaped up ( 0.2 ounces each) 0.4 total ! Dropped one ounce for fairly easy work.. getting closer to the under 7 pounds goal!

IMG_1350 by cody c, on Flickr

Bolt handle chop and mod:

IMG_1371 by cody c, on Flickr

Pretty simple, cut, thread, build something out of aluminum (used a drill press and grinder to shape, no lathe unfortunately) and skeleton the bolt handle slightly. I think it was 1.5-2 ounces here saved.

 

[cody c]

Anyways, it was mostly together, after trying and trying to get the carbon smooth I had reached a point of diminishing returns. I want to hunt it and not look at it all day. Had a friend create some leaf stickers with a vinyl cutter (a machine kind of like a printer for stickers) and used them as a stencil. I finished the CF with a matte clear coat, or rather many layers of it which acts like a filler to sand and smooth things and dull the CF from being too reflective. I threw a few stickers on the CF so that it would show through in the shape of leaves, and then others on top of paint:

A6446422-3648-484C-AD39-41749A0D466D by cody c], on Flickr

67C0E95B-00BB-4961-B688-6CFEBF9A3102 by cody c, on Flickr

ABF4E8A7-9CEC-45C2-AF3D-778D8CDE0039 by cody c, on Flickr


And here is how it sits today:


351AEA7F-FB1C-4EE0-9385-FBC94139F338 by cody c, on Flickr

I had made an aluminum trigger saddle to widen the trigger face, the trigger on it is modified to move placement forward, as is the trigger guard which has a cutout for the magazine to slide through. I misplaced the trigger saddle when painting it and need to build another, as well I plan on building an extended magazine which will block the opening of the trigger guard better. Also waiting on butt pad foam to come in the mail and then I can go see how it groups. You can see the factory and modded trigger in the image below with action dimensions.


dimensions trigger by cody c, on Flickr

Its been a lot of time and a little bit of money, but I have something with super fast bolt action lock time, short OAL (just under 40" without foam and 22" barrel) and decent finished weight for a rifle with a heavy barrel and 4-24 x 50 (30mm tube) strike eagle scope. Ill add more to the thread later as Im now tired of typing.

 

[double gun]

I like reads like this, nice job. I bet it’s the only 788 in existence wearing a CF barrel. I may have missed it, But what did the stock end up weighing?

 

[cody c]

I’ll dig up that weight, right now in terms of weight the thing is about 10 pounds on the nose, so totally missed my goal of a lightweight target rifle but also not really in a way... considering the scope runs about 26 ounces so with rings and rail about 2 pounds, and that weigh includes a bipod it’s closer to equaling a 7.5 pound bare rifle with a heavy barrel and thumbhole stock, so also not bad I guess. In terms of uniqueness being fairly short and still something you want to shoot at mid range comfortably it’s actually a compromise that kind of checks boxes in many categories ie. target, compact, hunting, and almost low weight if it were for a different scope and ring combo. Sorry rooting my own horn here but I had fun putting it together.


Edit: stock weighs 2 pounds 6 ounces (38 ounces) finished/painted. (So with the bipod still an ounce less than factory) In hindsight, or if or when I do it again I would do less aluminum skeleton, styrofoam and a single layer of CF, while maybe doubling it up on the wrist.

The steel thread protector weighs in at just over an ounce and I have a small bubble level on the rail. I think if I drop those (or rather replace the steel muzzle protector with aluminum) I can take it to the high 9 pounds unloaded, the other thing is the bolts that thread into the bipods are steel, if I replace with 7075 or similar I can probably drop another ounce, but Im kinda done with it till the butt stock arrives. Ill shoot it a while till I get used to where holding it level is and then remove the bubble level, i built it to hunt with but am curious to see how I do with keeping things level punching paper for a bit first.

 

[IvoB]

does it shoot?

 

[dan belisle]

Very nice work. - dan

 

[cody c]

does it shoot?

Don’t even know yet.. have a butt pad coming in the mail, when it’s here I’ll get it out and see I spose. Neighbor gave me a box of 140’s that didn’t want to cycle in his tikka for some reason that I plan to try out, I’ll get to load development eventually but will probably just grab a few boxes of factory loaded for this seasons hunting. I will definitely post up what I find out though.


Edit: thanks Dan!

 

[New Camper]

To be forthcoming, I was cringing at the start but by the time I reached the last photos... that turned out well. You could lose a couple more ounces by shedding the muzzlebrake. How comfortable is pulling the trigger around that large radius of stock your trigger finger must wrap? I really like what you did with that bipod arrangement: a hint of scout rifle.

I've considered thinking outside the box entirely with wood no one considers: White Elm - probably because it's stringy grain and tendency to not being straight, is also very light. I have a few planks that have been drying for years in the barn and they are still straight and laminated would introduce the stability required... light and strong, a pure wood stock could be used plain as it is would be of no importance when covered with a camouflage paint scheme. I need to do some experimenting.

 

[cody c]

Hey NewCamper, thanks for the feedback. Ya the grip looks large, it fits my hand well enough, I probably have big mitts though. And yes, a hint of scout rifle with an integrated bipod and trying to keep OAL and weight down for sure, though I definitely am on the heavy side for a scout designation.

I also have a muzzle protector that is 6061 and shaped to match the profile of the barrel... just can’t remember where I put it.

You should give the white elm a try! Definitely have fun with it. This was my first composite build but wont be my last, lots of small mistakes and learnings and will enjoy building another again.
I have a couple pieces of styrofoam that I shaped to match my Boyd’s evolution SS thumbhole that I plan on CF skinning later, just need to find the right action candidate for the task.

In hindsight a factory 788 with the barrel fluted could have put this at around 8.75 pounds as it sits. If I redid the stock without the bipod and less skeleton I think I could drop a pound off easy and get it closer to 1.5 pounds. Will have to try it again sometime, maybe the Norinco JW-105 .223 would be a good candidate.

 

[cody c]

I have some pics in the matador arms thread but thought Id update this as well..

Had it out up north and ran about 2 boxes worth through it playing with the brake. It shot crap. Then I realized there was play between the rail and action and tightened the screws up. It'll do a 3 shot group at 100 yards with about .75" or better. I was shooting on a windy day so Ill leave it as a disclaimer but I think it'll do .5" maybe, im gonna play with some load development too.

Check out this range, far end is 500 yards with a gong.

I also updated the bolts/screws with thumb screw ends on the bipod arms to titanium, I think it was 0.6 ounce saved, (for about $6.14 CAD via aliexpress) I believe the weight was just under 10 pounds without a thread protector on, might get it at the same with the bubble level off and the thin aluminum thread protector. I guess under 10 pounds for a rig with a bipod and 4-24x50 scope with rail is not the worst.

IMG_2215 by cody c, on Flickr

IMG_2220 by cody c, on Flickr

Also made a leather sling at my buddys leather shop for it, out of scrap and leftover shearling from the takedown lever bag. I should have put the flush mount QD a bit higher at the very tip of the stock, the CF barrel is a bit heavy in the sendero profile and more so with a brake extended off the end that the balance is more at the barrel end. You can kind of see the sling on the bench.

 

[ForealBoreal]

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[Rembo]

Man,....I like that.

Throw convention to the wind and just do what you feel will work for you...-

That's a great project very well executed.

We hear of guys "building" a rifle by screwing together parts.....this is way more than that.

Kudos.

 

[Besim]

Looking like a sweet rifle. Very nice.

 

[cody c]

I spot an hdj81 in the background or it’s the Cummins converted 80 series from Calgary off mud if I remember correctly
Nice build dude

Ya thanks guys. Agree on the “rifle build” where people bolt on a stock and scope and bipod. That wasn’t a build, my 9 year old could do that.

Cruiser is a 92 US model with a 91 6BT, NV4500 on 38’s.

 

[ForealBoreal]

........

 

[jparent]

Your stock design is brilliant, reminiscent of the Steyr and those old discontinued aftermarket stocks with the bipod hidden in the forend. The buttstock reminds me of the Sentinel chassis.

Would love to have something like this available for purchase. Super practical. You should patent and build these!

 

[tokguy]

I've a 788 question. You have one so it seems logical enough to ask.
Do you suppose the rear lugs will allow the bolt to compress enough to shorten case life? Or would that be specific to a particular cartridge type like rimmed and tapered one?
If you reload mind you.
Cheers Tok