Billet Chassis Projects

ApexOrdnance

Well-Known Member
Hi all,
When the March lockdown hit and it became apparent that I was going to the range any time soon I did what most men do when faced with excess family time and hid in the workshop. A bit of background, I've been in engineering for the best part of 25yrs and prior to moving to the darkside of shirts and ties, spent the majority of those years as a machinist. This was in the days when we read dials and not g-code. I had an engineering business for a few years and kept the most of the machinery when I finished. I've never been a wood and blue person, more matt black and multicam. I had a Rem 700 in a composite stock that I was never 100% happy with. The stock flexed at the fore end and would touch the barrel under its own weight when shot from a bipod. I considered epoxy filling the stock to give it more strength but didn't fancy all the mess and refinishing involved. I also wanted a box mag conversion but was far to tight to invest in new bottom 'metal'. Since the Rem 700 inletting is relatively simple geometry I decided to machine a billet chassis and a box mag conversion whilst I was at it. I set out line boring some square billet to the action diameter.
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Next, following a set of Rem700 action drawings I started inletting. First off was the recoil lug pocket and action screw holes. These are the most important datums. Everthing else can be located from the action screw holes.The hole for the mag conversion. I left plenty of clearance first time round with this as I was still unsure of how I was going to uild it.
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Once the main features are in the block is flipped to recess for the trigger guard and mag well.
Next was the angled cut at the back to clear the safety and some relief on the sides to drop some weight and add some shape to it.
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I had to add a support at the front to mount a fore end. Not something I had initially considered.
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The fit was good, I marked the closed bolt position and moved on to the hand guard. Heavy walled tube was the solution.
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Next was the mag well and trigger guard. I borrowed a friends legacy plastic mag conversion to copy.
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I didn't get any photo's of building the adjustable cheek and butt pads but after some fettling and a good dose of krylon I had what I thought was a pretty nice rig.
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This chassis was sold the day I returned to the club after putting about 40 rounds through it. I was happy with how it turned out but it wasn't perfect. There were too many fixings, I didn't like the tiny mag well or the front mag release. The next chassis was going to be better.
I decided that now I was comfortable with the relationship between the bolt and the magazine I could do my own thing. I opted for a much deeper mag well with a rear release catch, it allowed the magazine to sit flush and prevented accidental release if up againsr barricades.
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Second chassis in the bag, out with the krylon and ready for assembly.
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I managed to get 20 rounds through this before I once again sold it to another member.
I'm now well into the third chassis and have now perfected the magwells and have moved to side button release.
Muzzle brake was the next thing to come off the lathe.
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It didn't make me the most populat person on the firing point but certainly did the job.
Next up is my A-Bolt. I've never liked the skinny stalker barrel so I decided to carbon wrap it. Took the diameter from 17mm to 24.5. I've re-machined a more manly contour, added a muzzel brake and am about to start on a mag conversion and chassis. Let me know if you find it interesting and I'll post the journey.
 
Over the years I've done a fair bit composite work both applying and machining. I've wrapped plenty of rotors in carbon fibre and machined them so I figured a barrel would be similar. The trick I found is to use a low viscosity resin, this will soak into the carbon tape easily, and keep the barrel rotating as it drys. This stops the wrap sagging and non-concentric. If you are planing on machining the profile after wrapping it tightly in clingfilm works brilliantly and helps force any air out of the wrap.
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The muzzel threads are protected by the aluminium bar that doubles as a centre the hold the barrel in the lathe. It's a good idea to keep the dust down as much as you can in the area and keep the temperature constant. Ideally above 24c. You want to leave it rotating for at least 8 hrs and the temp constant for 24. After 72hrs it can be machined. Machining carbon fibre requires at minimum a carbide tool ideally with good sharp positive geometry. I find inserts designed for aluminium finishing work well.
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A quick muzzel brake and it's looking like a good heavy barrel. Diameter was increased fro. 17mm to 24.5 at muzzel. Weight increase was approx 175g, mainly the epoxy.
 
Absolutely outstanding. A pleasure to see the quality of your workmanship. Please share more projects as you do them.
Kindest regards,
Carl
 
Interesting.
I am just about to get the rifle back from Neil McKillop after a rebarrel, so how long would you need it for please ?
I'm not really looking to make them to order. Its only a hobby so time is limited. If I do build a chassis that I don't have a rifle for then I'm more than happy to sell it. I'll keep this thread updated with the chassis's being built and let people know if they're available. With Wales goig back into lockdown I could be spending alot of time on the machines.
 
Thanks for the info.
To be honest I am gonna need the rifle to hand now, right through until the lambing is finished next spring, so would be looking to travel with it to you next summer and discuss if possible please ?
 
Now that is a fine looking stock feller well done for a long range setup let alone other , its very much like mine all be it mine is a factory unit . STR 300wm . Also is the AR/M4 tube buttstock also of your making and if so what is its recoil max is it if tested .
 
Now that is a fine looking stock feller well done for a long range setup let alone other , its very much like mine all be it mine is a factory unit . STR 300wm . Also is the AR/M4 tube buttstock also of your making and if so what is its recoil max is it if tested .
Good question, not something I'd considered. The buttstock is constructed from 6061 heavy wall tube, wall thickness is 5mm. The tube itself is 40000 - 45000psi yield so no buckling issue. The fixings securing the butt stock to the tube would be the weak link. 4 CSK M6 at minimum 7.8kN shear which is about 790kgf, I'd have to do some more math to estimate in ftlbs but I'd say you'd probably lose your shoulder before the stock gave in. Cyclic loading in an aluminium threaded hole is another matter though. I would guess a good few thousand rounds before the holes start to stretch. Would probably out live the barrel. I'll do some work on this and give a conclusive answer.
 
Thanks for the reply and your prob spot on . There is a reason for the Question :norty: as I really like the shape of it , also is there a point that if needed a bag rider or a mono pod / pic rail could be fitted . Also again is it the same OD as a M4 tube, But not the milspec type .
thanks again it a cracking stock .
:tiphat:
 
Thanks for the reply and your prob spot on . There is a reason for the Question :norty: as I really like the shape of it , also is there a point that if needed a bag rider or a mono pod / pic rail could be fitted . Also again is it the same OD as a M4 tube, But not the milspec type .
thanks again it a cracking stock .
:tiphat:
The chassis that I'm working on at the moment has a bag rider. I'm a big fan of rear bags.
 
The above chassis is now with it's new home and performing as it should. Unfortunately I didn't get any pictures, no photography at our range. Since then I've built another Rem 700 chassis for myself and included the rear adjustable bag rider. I'll get some pics up on here. At the moment the A-bolt chassis is nearing completion but I've been distracted with a take on the Eric Cortina style barrel tuner and an annealing machine.20201108_133359.webp
 

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