Thread: .30BR Rem 788 Chassis build

.30BR Rem 788 Chassis build


I put this rifle together some time ago but never did a build thread for it. Lock down has given me a tiny bit of time to do so now so here goes…

Over the past 20 years I have built and owned quite a few .30 BR’s, it has always been one of my favourite cartridges.
For those that are unfamiliar with the cartridge it is basically a 6mm or 7mm bench rest case necked up to .308 cal. More great info about it here:

https://www.6mmbr.com/30br.html

The 30BR is a very versatile calibre that suits many roles. It can be loaded with any 30cal projectile from the 80gr to the huge 240gr.
Currently, the 30BR is used almost exclusively for Benchrest competition. However, it has great potential for other applications given its inherent accuracy and superior efficiency. The 30BR in its long barrelled slow twist (1-17” or 1-18”) bench rest role can drive a 118gr bullet faster than the 6BR case can drive a 105gr bullet. In fact, the 30BR can push a 125gr bullet faster than a Rem 260 can drive a 123gr Scenar, despite using 10 grains less powder. Using suitable hunting projectiles, the 30BR is a viable deer-hunting round, with ballistics superior to the venerable 7.62x39 and 30-30

The .30 BR delivers 30% more energy than the .300 Blackout with supersonics & has the potential to push sub-MOA accuracy and stopping power well beyond the 300 yard mark that the .300 BLK is limited too but carries the same subsonic capabilities of the BLK. Years ago the late JD Jones actually chambered this cartridge in 1-8” fast twist Shilen barrels to shoot the 240gr SMK and labelled it the .302 Whisper.

One of my most memorable and favourite rifles Ive ever built and owned was a lightweight Remington LTR accurised M700 action in a McMillan hunters edge carbon fibre stock and fitted with a match 15" Shillen 1-8 barrel in .30BR.
Incredible accuracy from that rifle and it took a lot of game.

Interesting so it uses the 308 case head?

Originally Posted by 300CALMAN

Interesting so it uses the 308 case head?

Yes, .473".

I will add to this build thread today and through the next few days between entertaining kids etc.. it will be a lengthy one with a lot of information and pics for like minded machinist and Rem 788 fans.

So onto the build.

The donor rifle was a 1967 shot out cut down iconic Remington 788. the barrel was rough but the rest of the rifle was quite tidy.







The Remington 788 is a bolt-action, centerfire rifle that was made by Remington Arms from 1967 to 1983. It was marketed as an inexpensive yet accurate hunting rifle to compete with other gun companies' less expensive rifles alongside their more expensive Model 700
They have quite a cult following and are well known as a quality old school build with accuracy that much to Remington's embarrassment rivalled their more expensive model 700 at the time.

While not a perfect action with a few short comings such as the bolt handle is low temperature brazed to the side of the bolt body which had the tendency to break off with rough use, a heavy non adjustable trigger and over all a bulkiness that made it feel like a heavy target action.
However the 788 made up for these weaknesses with its robust design, sturdy lock up and slickness that utilises a single-column detachable steel magazine holding 3 or 4 rounds depending on calibre, that fed any cartridge without complaints.

The Remington 788 has two main distinguishing design features. The first is the bolt. The multi-piece bolt featured nine rear locking lugs in three rows of three, as opposed to the front locking lugs found on the vast majority of bolt actions designed since the late 19th Century. The 788's bolt lugs are located in front of the bolt handle and lock into the rear of the receiver. In addition, the lock time was unusually fast. The lack of lug raceways in the receiver allow for a much smoother action. Due to this design, the bolt handle lifts only 60 degrees on opening giving more clearance for scopes compared to the 90 degrees required for the Model 700 and other two-lug rifles. The bolt travel is also reduced because of the rear lugs.



The second distinguishing feature is the receiver. It has a smaller ejection port than similar bolt-action rifles, and no bolt lug raceways. The single stack magazine design yields a smaller feed opening in the bottom of the receiver compared to rifles using a double stack magazine well. When machining of these smaller ports is complete there is more steel remaining in the receiver between the ejection port and adjacent feed port, and significantly more steel overall where all receivers have the least strength. These characteristics combined to make the Remington 788 receiver more rigid and stronger than most, if not all, competing designs, including the Remington 700 which shares the same outside receiver diameter. A rifle's accuracy tends to increase slightly as the rigidity of the receiver increases, as this slightly reduces barrel deflection during firing. Thus the Remington 788 has the structural foundation to be a very accurate rifle.

The 788 was offered in 3 action lengths, “super short action”; .44 Rem mag “short action”; .222Rem .223rem, .22-250rem, and.30-30win and finally the “medium action”, .243win, 6mm rem 7mm-08 rem and .308win. the long action cartridges such as .30-06 Spr and 270 Win were reserved for their M700 range.
Left hand models were offered in 6mm Rem. and .308 Win.
A .22 rimfire model was also produced known as the 580, 581, or 582 depending on its method of feed. A target version of the .22 caliber 58x series, the 540X, was used by the US military as a training rifle.
The floor plate and trigger guard are steel stampings (not plastic!) and blued to match the barreled action, which received the standard Remington polish and bluing. The finish on the barreled action is clearly superior to the essentially un-polished matte bluing seen on most modern economy rifles.
The majority of Model 788s were outfitted with plain, birch hardwood stocks stained to resemble walnut. The comb is not fluted and there is no checkering. There is also no pistol grip cap and the butt plate is black plastic. This stock is anything but lovely, although it is more appealing than the cheap, noisy, plastic stocks found on most modern economy rifles.

Overall, the Remington Model 788 was a well made, accurate economy rifle. I consider it to be better designed and more attractive than most budget bolt action rifles on the market today.

I have lost count of how many 788’s I have owned over the years but all have been excellent shooters and great wildcat platforms. In fact I took my first deer back in the day with a .338 Whisper I built on a .22-250 Rem 788.
The .222 and .223 short actions made great .300 whispers (aka .300BLK) too as not many other rifles at the time fed these front heavy short cartridges.

I'd have one if it came up at the right price. Ex family friend had a carbine in 243. Bloody tack driver

I was also handed a Krieger 1-13" twist .308 win 30" Palma match barrel to use on the donor action.

I stripped the rifle down removing the barrel and the trigger (which was in for some serious mods later) I measured up all the major action dimensions to see if I had the required materials on hand.



When I made my last CZ 527 Grendel chassis I actually cut 3 blocks of alloy to length and had turned and threaded them in the 4 jaw chuck to except a buffer tube at the same time to save on machine setup time.








In hind site it was a little over zealous of me to pre-cut them all to CZ 527 length because it was a little too short to fit the 788 action. However I devised a plan to fix that that later that still saved on 4 jaw set up time on a new piece of billet and machining time.














The next stage was mocking up and marking out. It was obvious at this stage that the billet was about 30mm too short to capture the recoil lug at the front and leave enough room to mount the pistol grip. The trigger was also going to be an issue as it the blade is long way back and wasnt long enough to protrude from the chassis. I was tossing up whether to continue here or go back to the drawing board and design a new shape that would work that would have to be machined out of a much larger alloy billet.
Here it is laid out with the CZ 527 Grendel build.

Next up was to rebarrel it.
The 788 tenon thread is a fairly small 1"x20tpi so there was plenty of meat left in the palma profiled knox once the .308 chamber was trimmed off.
Once centred in the lathe I profiled it for the new tenon thread and also a thread on the knox for the barrel nut that will secure the fore end.













The barrel was trimmed to a more compact 18" for a flush fitting over barrel suppressor.

Then it was on to chambering it in the mighty .30BR.
For my past builds I used a 7mm Rem BR reamer and finished it with a .308 neck and throat reamer which always ended up with quite a long freebore. This has not been an issue in the past because I used fast twist 1-8" barrels and the super long 240gr bullets as subsonics and longer mags to cope with the longer COAL. I also used to run the shorter factory Remington Peters 7mm BR brass which is unfortunately no longer made.



The alternative is using Lapua 6mm BR brass and necking it up. this doesn't come without its issues though.
Necking up the thicker 6mm brass leaves quite a large brass doughnut at the neck and shoulder junction of the Lapua brass, this has to be neck turned off to avoid dangerous pressures from no neck clearance.






The Lapua brass is also longer than the 7mmBR RP brass was so I ordered the correct reamer with a short freebore.











An exciting new bullet has also been released since I last has a .30br in the cabinet, the Sierra 125gr tipped match king which was specifically designed for the use in .300 BLK and was hopefully going to be the bullet exclusively used in this build.



Finally it was chambered threaded for the suppressor and crowned.

mean. I have 22br. how do you like the optimum mill? would you buy the same again?

Originally Posted by bully

mean. I have 22br. how do you like the optimum mill? would you buy the same again?

A 22br would be cool! How do you find it vs a .223?

Sent from my SM-N960F using Tapatalk

Originally Posted by bully

mean. I have 22br. how do you like the optimum mill? would you buy the same again?

I have the reamer for the .22BR too but have never built one. I hovered over it for a while while considering a .224 barrel on my desert tech but ended up going with a .22x47 Lapua AI instead.
The mill is nothing special but its compact and does all I ask of it. I bought the one that bolts onto my lathe bed, if I did it again Id get the stand alone one. Its never given me any problems.

Originally Posted by dnsn

A 22br would be cool! How do you find it vs a .223?

Sent from my SM-N960F using Tapatalk

it smokes a 223. 1:8 twist, 80gr does about 3200. well I used to run 80's in a 223, which was good, but it made me think about driving them even faster, and so 22br.
just have to neck down 6mmbr brass, and good to go. easy.

if you run the numbers the heavy .22 going 100fps faster than a heavy 6mm is even in bc. but I think I'm about 200 faster, it was a while ago I ran the numbers and new projectiles are out now, something like that.

Originally Posted by Wingman

I have the reamer for the .22BR too but have never built one. I hovered over it for a while while considering a .224 barrel on my desert tech but ended up going with a .22x47 Lapua AI instead.
The mill is nothing special but its compact and does all I ask of it. I bought the one that bolts onto my lathe bed, if I did it again Id get the stand alone one. Its never given me any problems.

cool. I have there baby lathe, no problems. I almost did 22x47, when I was struggling to find a 22br reamer.

Back into the mill to inlet it for the action, a series of drills and end mills to start with cut out the mag and trigger slots and rear action screw position









Then a series of ball nose mills to cut the actions inlet radius and smaller end mills to cut the safety catch relief.





With the action now sitting down in the inlet as low as possible as to not interfere with the bolt stroke, the lack trigger blade protrusion and rearward position was very clear. This was always going to be the case, as I mentioned before, I had pre-cut these billets for CZ 527 actions so there was no real drawn up design for this action, I was just creating as I went along.. Evolving art so to speak.





I had several plans to amend this, I had considered machining a higher recessed section between the mag and the pistol grip but because I was using a flat topped AK47 grip it just wouldn’t look or feel right. The trigger was also so far back it was almost touching the front of the grip. The grip cant be moved back due to the buffer tube cut out.
The most simple and best option was to modify the trigger blade.

This is the trigger out of something else used to illustrate how far the 788 trigger had to shift forward and down.





So I removed the trigger from the cluster and cut of the blade. I forged a new one out of some round bar I had on hand and ground/ filed it into the required shape. I then tig welded it to the old trigger stump and finished the final shaping.
Finally it was re case hardened polished and blued.









The end result puts the trigger right were it should be to feel right with the AK47 grip.