This one here has been on the project table for about 10 years. I always knew what I wanted, but it's taken a while to get there. Other projects took precedence and I was never really in a rush, anyway. The rifle has never been a pile of parts so it's always been shootable.
This started out as a Plain Jane, Savage 308; even though, I knew I needed a 223 bolt face. I got it in a trade, at a great price, so I wasn't in a position to be picky. Thanks to the miracle of the internet and the Castboolits forum, there was a guy living 3 miles away who wanted to do a bolt and barrel swap. That was easy.
I got a 1:8 30cal barrel blank, which I measured at 8.5:1 (is that odd?), chambered it for 7.26x39 and threaded the muzzle and tennon. I, also, opened the bolt face for the new cartridge and installed a modified extractor.
Rifle in factory stock.
The next step was a new stock and a drop magazine. After quite a bit of research, I settled on a Choate Tactical with PT&G bottom metal and MTD molded magazines. The Choate stock seems nicely made, albeit the grip is quite large. I will have to do some sanding on the right side . The LOP is about 13", where the Savage is at 14". This will be remedied when I get into modifying the stock.
So, the first sorts was to see if we needed any inletting, for the bottom metal. The good news is that the PT&G bottom metal will fit the Choate cutout. However, the bottom metal's uppermost portion has too much metal. It will not rest far enough into the stock's magazine inlet. This is due to Choate's aluminum "core" embeded in the stock. If one was so inclined, they could do some milling to the stocks magwell area. Im just not sure how much of the aluminum is there and wouldn't want to weaken the stock.
Here is the PT&G bottom metal, before being molested.
This is how much material I had to remove.
No big deal, just some aluminum
The bottom metal drops right in and lines up nicely. Unfortunately, the front action screw is about 8 threads into the lug area. I have a choice: cut 8 threads off the screw (about.3") or make a spacer for the bottom metal's screw cavity. I make a spacer. Its .375"OD x .32"L with a .25" clearance hole.
Everything bolts up nicely now. Mag slides in and comes out with little effort, not drop free (although time and use may change this).
Yes, the mag reads .223. I did some filing on the lips and the .308x39 works like a charm.
The only issue I see is that the barrel is not centered in the stock's channel. It is favoring the right side by .125". I loosened everything up, but it all fits perfectly, misaligned. I planning to remove about 5" of the stock's forend and fit an integral silencer so, for me, this will not be an issue.
It looks like I'll be able to get a 1.375", over barrel, tube to fit inside the barrel channel. This should work nicely.
As you can see in the below picture, my plan was to shorten the forend of the stock (approx 5") and create an adjustable butt. The blue parts, on the buttstock, are the prototype pieces as I have made some revisions that will be reflected in the next print.
Fully extended, the LOP will be about 14", about 1/2" more than the Savage factory.
Retracting the stock will decrease OAL by about 3.75", for the prototype. The next build will be more like 3.5".
The bipod shown is 9"H, the final build will have a 6" version.
Final build pieces for buttstock fitted. Spare scope thrown on for some pics.
Extended
Collapsed
I'm contemplating rebuilding the adjustable assembly out of Aluminum. For now, though, the 3D printed parts perform almost flawlessly.
So, this gets us to where we currently lie. The form has been approved, for some time now, and I've gone through several revisions. At First, the plan was to use a K baffle similar to the ones in my 45 Mauser. Then, I revised to mimic the stepped style in my AR22 build. Finally, I settled on a 60* cone with some extra features and a radius clip.
This was the first design
With these baffles
Then, these baffles
I settled on this design
With these baffles
The plans I was using, when I first started cutting everything, had 10 baffles with a spacing of 9/16". I made an 11th hour decision, actually 2, to change the baffle configuration and add indexing/alignment tabs. This last revision brought the baffle count to 14. The blast baffle and the next 3 will be spaced at 9/16". The next 4 will be @ 1/2". The final 6 will have a spacing of 3/8".
I lied. I made 3 final revisions. The last baffle was to have no skirt. I changed this to have a skirt, that slipped into the end cap, and turned into the wedge for a wipe, if ever I wanted one. So, 14 baffles and a wipe
Yes, this will be a true integral. The barrel will be ported, just after the throat. Being that the outer tube is .058, 6061, I've allotted for an internal blast shield, made from 310SS, around the ported area.
My original subsonic loads, from the 17" barrel, only filled the case approx 70%. I would use some polyfill to make up the rest. I plan to change to a different powder, one which will fill the case to ~96% and yield ~1350fps. I'll be shooting a baseline of 5 rounds, then, cutting the first 3 ports. I'll repeat this until I hit around 1000fps. We'll see how it goes.
Barrel nut: Sorry for the craptastic photography. Which, is a shame because it came out beautiful.
Baffles, patiently waiting for the mill
Muzzle brake portion, pre-welding.
The brake is cut for a 5/8" hex so a socket can be slipped into the tube for removal. If you're wondering why I Didn't make the blast spacer in 1pc, it's because I had some tiny drops and I'm not one to waste material. My welder is great at making short things longer
I will continue to update the OP as I progress. Just don't expect to see it with finish or get a video, as I rarely come through with either
-------------------------------------------------------------------UPDATE 4/6/2019---------------------------------------------------------------------
Face milling is complete
I haven't, yet, purchased a rotary table, but I'm making do with the Luan dividing plates
Those are brass stops, for holding place on a framing square. Simply index the angles, set the stops, and you can easily cut arced slots.
This is the mandrel I made, to hold the baffles.
-------------------------------------------------------------------UPDATE 4/7/2019---------------------------------------------------------------------
Out of this batch, just need to cut the index tabs for the blast baffle spacer. I'll do this after the barrel headspace is set. Made another change. Was planning to leave the blast baffle alone, but gave it a symmetrical, radius clip. This will be indexed 90* from the rest of the baffles.
Should be cutting the endcap and, possibly, the outer tube, tonight.
-------------------------------------------------------------------UPDATE 4/13/2019---------------------------------------------------------------------
OK. The suppressor parts are complete.
Tonight, I'm going to start on the Barrel Nut wrench and see about putting 2 pins in the handle for an End Cap spanner.
-------------------------------------------------------------------UPDATE 4/25/2019---------------------------------------------------------------------
Alright. I'm, now, just waiting on some time to shoot and chrono. I think I may have a powder to where I won't need to port the barrel for a velocity drop. In which case, I'll port near the muzzle and make use of the over barrel chamber.
While I'm waiting, I made an insertion/extraction tool for the baffles. It has a hook/lip, a spring, and lines up w/ the baffle's index tabs.
Put the baffle on the disc. Push the extractor through the clip. Rotate. Insert baffle into tube. Align index tabs. Push tool and rotate extractor to align with clip. Remove tool. Yes, the tube is clean, for now, but it works great. We'll see how things go once I'm done w/ a shooting session.
-------------------------------------------------------------------UPDATE 5/5/2019---------------------------------------------------------------------
Got out to shoot today, as planned. I started with Quikload's 100% case fill.
Win 7.62x39 case
CCI 200 LR primer
7.7gn Trailboss powder
190gn HPBT projectiles
COAL 2.265"
I tried these with both an old batch of primers and a new box. Also, I did 3 separate strings w/ no crimp, a light crimp, a mild crimp. There was little difference between the 2 primer boxes even though date of Mfr is 30+yrs apart. The no crimp rounds gave the most velocity and a consistent SD.
I need to get out and do larger strings, but here's some unsuppressed firings. These are from a very steady rest. All flyers were marked with outside the norm velocities.
55*F, 800' ASL, 0 wind, Light Rain, 52m Target Distance
At this point, I was quite happy and decided to put the suppressor on. Now, I wasn't happy with where the initial headspace was and redid it after the first 2 rounds (from the start of the day, unsuppressed). This rotated the baffle clip from how I originally wanted it. The common baffles should have been North or South orientation. They're, now, at the East/West. Suppressed groups were shot with all common baffle clips at the shooter's 3 o'clock. You can see what a dramatic POI shift there was, once the suppressor was added (the 7.7gn group). This shouldn't matter as the group size didn't seem to be too affected and this will be shot 100% suppressed. For the 7.8gn, suppressed, group, I dialed the scope to a new zero.
I plan to trim the muzzle brake a bit as to reorientate the clips to the intended North/South index. Also, I think I might deepen the common baffle's clip cut. Same cutter dia, just a bit deeper. Suppression seemed pretty good. I was shooting from inside and towards a wall of windows. I should have stepped outside, for a shot or 2, but time ran short and I had to clean-up.
Now, for a vote. As there's no need to port near the barrel's chamber, should I port near the muzzle (before the threads)? I have a large over-barrel, reflex volume that isn't being used. I also have the option of cutting slits into the rear portion of the blast chamber. Thus, allowing the initial blast into the reflex portion, instead of porting the barrel. I'm leaning towards porting the barrel.
-------------------------------------------------------------------UPDATE 5/11/2019---------------------------------------------------------------------
Finally made a video. I have a Ruger MKII w/ an AAC Pilot in there for a comparison. Also, I put my dedicated AR22 SBR in there.
Here you go, John
I pushed the loading up to 8grn of Trailboss and think this would be about max case fill. Still subs.
I still plan on reindexing the mount, to orientate the clips back to North/South. I'll shoot again, for a POI baseline, and, then, plan to port near the muzzle.
-------------------------------------------------------------------UPDATE 5/18/2019---------------------------------------------------------------------
Well, that POI shift was non-existent. Turns out, the suppressor tube was rubbing against the stock's barrel channel. Once rectified, I fired 3-2rnd groups, in the following config:
No tube or internals
Tube installed
Tube & internals
Here's all 6 rounds, with the same POA
I'm not 100% certain on the order fired, but this is pretty much a zero POI situation.
Next step is porting near the muzzle.
-------------------------------------------------------------------UPDATE 5/24/2019---------------------------------------------------------------------
I completed the muzzle porting. (6) 3/32 holes arrayed around, (5) arrays spaced 0.20, starting 1.00 from muzzle.
I only popped off 5 shots, but there's an extreme difference in sound reduction. I'll have to get a new video up.
