A compact version of the ubiquitous Remington Model 700, the Model Seven is an excellent candidate for a lightweight hunting rifle (to read more about the Model Seven action, click here). In this post, I’ll be taking a used Model Seven synthetic chambered in 223 Remington and converting it into a lightweight custom hunting rifle in 257 Ackley Improved (40 degree shoulder). More detailed information about chambering rifles for improved cartridges, can be found here.
For this project, I ordered the following from Brownells:
- Shilen #2 stainless steel barrel
- High-speed steel turning kit
- High-speed steel 35 degree profile turning kit
- Manson Rem 700 false bolt center
- Manson 257 Improved reamer
- Holland’s recoil lug
- Manson receiver accurizing kit
- Manson receiver ring facing tool
- India stones
- Badger M16 style extractor
All lathe work is conducted on a Grizzly gunsmith’s lathe.
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Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.
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This is the donor gun. A very used Model Seven synthetic in 223 Remington I purchased off an auction website for $450. I’ll be using the action, bolt, bottom metal, and trigger from the donor rifle for this project. I strip the rifle and get ready to remove the barrel. With the optics off, I soak the action threads in Kroil penetrating oil to help facilitate its removal.
The action is secured in a Brownells action wrench and the barrel is secured in a Brownells barrel vise. This particular action wrench wraps around the action to prevent it from bending under stress, an important feature when removing factory barrels from actions. The barrel was on so tight I needed to use a “cheater pipe” on the wrench handle to get it to unscrew.
Action off, I can get to work on the bolt. The bolt on this action has a 223 bolt face. The 257 Ackley Improved cartridge I plan on chambering this rifle in uses a 308 bolt face. I could either buy an aftermarket replacement bolt, or machine out a new bolt face for the current bolt. I decided to machine this bolt face to a 308 bolt face.
The bolt is secured in a La Bounty bolt holding fixture in a four jaw chuck on the lathe. The end of the bolt is then dialed in concentric on the lathe.
I use a high-speed steel indexable boring bar to open up the bolt face to the proper diameter. I also make a light pass on the bolt face to make sure it it true.
The bolt face will now accept 308 sized cartridges.
While the bolt is mounted in the lathe, I true the front and rear faces of the bolt lugs as well as the bolt nose with a high-speed steel insert tool.
This is what the bolt nose looks like when it comes off the lathe. Note the aggressive machining marks from the factory.
When the bolt face diameter was opened up, the small rim that retains the factory Remington extractor was removed. To replace the extractor, I will be installing the Badger M16 style extractor. This requires the bolt to be set up in the mill. A Manon false bolt center is screwed into the rear of the bolt. The false center is held in a square collet block and a pair of v-blocks is used to secure the bolt in the milling machine vise.
A 1/4 four flute, solid carbide end mill is used to make the initial cuts for the extractor.
The finish M16 extractor cut has space for the extractor, as well as the extractor spring.
The bolt is rotated 90 degrees. The square collet block makes turning the bolt easy.
A 1/8 four flute center cutting end mill is used to spot the location for the extractor pin.
An undersized hole is drilled through the bolt. Next, a chucking reamer is used to make the hole the proper size.
A quick test fit shows everything was machined correctly.
Time to work on blueprinting the action.
I like using the Manson Receiver Accurizing system to true, or blueprint my actions. Since the Model Seven is so similar to the 700, I can use the same kit to true this action.
The action is held in an action wrench. The two tapered bushings included in the Manson kit are inserted into the action, and the receiver reamer is used to recut the minor diameter of the threads and cut the front surfaces of the receiver lugs.
The reamer is followed by the Manson receiver tap. The tap is coated in oil and turned slowly until it cuts the entire length of receiver threads.
The tap is left in the receiver to true to front of the receiver ring. This operation can either be performed on the lathe, with the tap mounted between centers, or using a special Manson facing tool (shown above). The tool is turned by hand and makes short work of truing the front of the receiver.
A view of the trued surfaces after the truing process is complete.
On this rifle, I am using the factory recoil lug. I checked the lug to make sure its surfaces were square, so I didn’t see a need to replace it. The lug is placed on the end of the action and a depth micrometer is used to measure the receiver to determine the headspace, barrel tenon and bolt nose recess dimensions for the barrel.
The last inch of the barrel is removed from the blank per manufacturers instructions. This blank is a Shilen #2 contour in stainless steel.
A dial indicator is used to dial in the barrel concentric to the bore. The muzzle of the rifle is secured on the outboard side of the lathe in a spider, it is dialed in as well.
A high-speed steel indexable cutting tool is used to cut the tenon to the correct length and diameter. I use a spindle speed of 400 RPM. I make a groove on the tenon where the threads and recoil lug meet. The end of the tenon is also chamfered.
The recoil lug fits snugly on the tenon. Note the location of the stop groove relative to the lug.
The tenon is coated in Dykem. A 60 degree high-speed steel insert tool is secured in the lathe.
The finished threads.
Now is a good time to check and make sure everything fits the way it should.
The Badger M16 type extractor requires a large bolt nose recess than a normal Remington extractor, .785″. I make this cut with a high-speed steel insert boring bar.
Another test fit to make sure everything fits together.
The barrel is ready to be chambered. I am using a Manson live pilot reamer for this application. A PTG reamer stop secured to the reamer shank allows depth of cut to be adjusted in .001″ increments.
This is what the reaming set up looks like. The lubricated reamer is inserted into the chamber and held with a set of pliers. The reamer is advanced into the barrel using a dead center in the lathe’s tailstock. I use a spindle speed of 70 RPM and take my time, stopping often to clean and lubricate the reamer.
I make my initial headspace measurements with a go gauge and depth micrometer. Note: the Manson go and no-go gauges used in this project are specifically designed for use with improved cartridges. To read more about chambering for improved cartridges, click here.
When I get close to the finished depth of cut, I screw the action and bolt onto the barrel with the go gauge in place. I use a feeler gauge to measure the distance between the recoil lug and action to determine how much more I need to cut the chamber.
When the chamber is the right depth you can close the bolt on the go gauge…
Prior to removing the barrel from the lathe, the edge of the chamber and bolt nose recess have a radius cut to ensure proper feeding (not shown).
The completed barrel tenon.
The tool leaves a nice finished crown.
The barrel is secured in a barrel spinner. A belt grinder is used to polish the barrel smooth.
The tenon is coated in anti seize prior to final assembly. A recoil lug alignment tool is used to make sure the recoil lug is oriented correctly.
The barrel is held in a barrel vise. An action wrench attached the the end of a torque wrench is used to tighter the action to the barrel.
The barreled action is test fit in the Bell and Carlson stock. The barrel does not fit in the front edge of the forearm.
Sanding the barrel channel with some 80 grit sandpaper wrapped around a dowel allows the barreled action the appropriate clearance.
You’ll notice I didn’t bed the barreled action into this stock. Normally I do, however, I wanted to see how well the rifle shoots without being bedded in place.
The original action screws were a mess. I decided to clean them up.
A little work with a small file and abrasive cloth and the screw is ready to be finished.
The parts are placed in the blast cabinet.
Aluminum oxide is used to prepare the surfaces for Cerakote.
The parts are degreased again prior to the application of Cerakote.
On the advice of my friend, a tack cloth (used in automotive work) is used to wipe the surfaces and remove any remaining aluminum oxide media.
The parts are painted with an HVLP spray gun and cured in a parts oven (not shown).
When everything is reassembled, I am quite happy with the results. I replaced the factory 223 magazine with one I took off a Model 700 BDL in 308. Finished barrel length is 22″.
The rifle is topped with a Nightforce rail, Nightforce rings and a Nightforce SHV 3-10×42 scope with MOAR reticle. My cranky old friend saw this and wasn’t happy. He doesn’t like modern scopes and mounting systems on hunting rifles, I guess he’d prefer a compact traditional scope with a set of turn in mounts. Well, this isn’t his rifle. I think the added functionality of a quality scope like this Nightforce offers significant benefits despite the slight increase in weight.
I loaded up some 120 grain Seirra GameKings (1650) on Remington brass over Varget and headed to the range to fire form some brass.
A standard 257 Roberts cartridge (left) compared to a fire formed 257 Ackley Improved (right). Note the sharp shoulder and straighter body taper.
Shooting the 257 Roberts was an absolute pleasure. Recoil is mild despite the light weight of the rifle.
The Nightforce SHV 3-10×42 is an outstanding piece of gear. The optical clarity is great, MOAR reticle is functional, and elevation and windage adjustments are generous. Without a zero or boresighter, I was able to touch the edge of a 2″ target at 100 yards within 3 rounds.
Accuracy was exceptional for such a light rifle, especially when considering I was fire forming brass. 3-shot groups (keep in mind this is a very thin barrel) were approximately 1 MOA. This was the best group, .652″ at 100 yards (above).
This rifle is definitely a keeper. Finished weight is 8.2 pounds, including the optic and mount. Using a smaller optic, such as a compact 3-9 and turn in style bases would further decrease weight, however, I prefer the functionality the Nightforce 3-10×42 SHV offers.
I’ll post more information when I complete load development on the fire formed brass.
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