Building a custom 260 Remington precision rifle

The 260 Remington has gained quite a following in recent years. Adopted by SAAMI in 1999, this flat shooting 6.5mm cartridge housed in a necked down .308 Winchester case and affords the shooter, especially the reloader, a wide range of quality bullets and barrels. With higher ballistic coefficient bullets, the round shooters flatter, with less wind drift then the .308 Winchester.

We are building a custom rifle to compete in tactical rifle matches as well as mid range (600 yards) and 1,000 yard F- Class competition. Since the rifle is not a .223 or a .308, we would not be limited by the 18.0 pound weight limit from T/R rifles, however, we plan on shooting tactical matches with it, so the weight needs to be reasonable. We selected a standard Palma contoured barrel to keep the weight down. The contour is similar to the Remington Varmint, with a little more meat on the chamber end.

We will be using a custom stainless steel action made by Blackheart International(BHI), supplied by Brownells.

The Blackheart International action has the following specifications:

CNC machined from 416R stainless steel and hardened to 41 Rockwell
bolt bore raceway is wire EDM’ed with the rails to ensure exact tolerances are held
rails have an anti-bind rail for smooth operation when cycling across ejection port cut out
bolt is spiral fluted and clearance through bolt bore is held to .004 -.006
bolt handle is straight with a black knurled tactical knob and black bolt shroud
action has a standard Remington 700 magazine cut out
includes one-piece 20 MOA Picatinny rail with four 8-40 mounting screws and two 1/8 dowel pins to ensure rigid mounting
recoil lug is surface ground and pinned
front and rear of action is the same diameter to provide for greater rigidity
M-16 style extractor
bolt stop is on non firing side above stock line

Blackheart International custom short action with supplied recoil lug. The action is ready to go right out of the box. This is a huge time saver.

We ordered the following supplies from Brownells to complete this project:

All lathe work is conducted on a Grizzly 4003G lathe with a Bald Eagle spider attached to the faceplate.

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The standard Palma profile (top) is similar to a Remington varmint contour (bottom). The shank on the Palma is longer.

The barrel is mounted through the headstock and secured on each end with a spider (four brass tipped screws)

There are quite a few ways to align, thread and chamber barrels. Normally, we “dial in” the chamber end of the barrel (see our chambering article for a detailed description of this process). On this project, we decided to “dial in” the muzzle and chamber end of the rifle.

A PTG Grizzly rod with appropriate sized bushing is inserted into the chamber end of the barrel. The screws on the spider are used in conjunction with a dial indicator to center the barrel. Initial adjustments are made with a .001″ indicator.

The muzzle end of the barrel is aligned using the Grizzly rod. After tweaking each end, and utilizing a .0001″ indicator to minimize run out, the barrel is ready to machine.

The tenon is turned to the appropriate dimensions. The shoulder is undercut to allow the recoil lug to sit firmly against it, a thread relief cut is made and the end is chamfered in preparation for the threading operation. — The tenon is turned to the appropriate dimensions and coated in Dykem layout fluid. The shoulder is undercut to allow the recoil lug to sit firmly against it, a thread relief cut is made and the end is chamfered in preparation for the threading operation.

Our high-speed steel threading tool is aligned with a center gauge.

We use a thread gauge to verify the pitch of the threads. In this case, 16 threads per inch. — After a light pass, we use a thread gauge to verify the pitch of the threads. In this case, 16 threads per inch.

The bolt nose recess is cut with a piloted counter bore secured in a floating reamer holder.

The action, lug and bolt are test fit to check our work so far.

We use a floating reamer holder to chamber our barrels and have had good success. The depth of cut is controlled with a PTG Lambeth-Kiff adjustable reamer stop. The stop allows precise, .001″ adjustments in the depth of cut. Utilizing the stop, we have regularly been able to control headspace to within .001″ or better.

We run our lathe on its slowest speed, 70 rpm, and use plenty of Viper’s Venom cutting oil. The reamer is advanced .025″ at a time, the lathe is stopped, the reamer retracted, cleaned, coated in oil and reinserted into the chamber. This process takes a while, but produces nice chambers.

Our reamer is secured in a floating reamer holder. The holder is equipped with a PTG reamer stop. Initial adjustment of the stop is made with a headspace gauge. The stop is set to cut shallowed then the gauge.

When the reamer has cut to the stop, the action, lug and bolt are screwed onto the barrel with a "go" gauge in place. A feeler gauge is used to determine how much deeper the chamber needs to be cut. We set out reamer stop to half of this dimension, cut, and remeasure until the bolt closes on the "go" gauge, — When the reamer has cut to the stop, the action, lug and bolt are screwed onto the barrel with a “go” gauge in place. A feeler gauge is used to determine how much deeper the chamber needs to be cut. We set out reamer stop to half of this dimension, cut, and remeasure until the bolt closes on the “go” gauge.

When the headspace is correct, the bolt with close on the "go" gauge.... — When the headspace is correct, the bolt with close on the “go” gauge….

and stay open on the "no go" gauge. — and stay open on the “no go” gauge.

Prior to removing the barrel from the lathe, a gentle radius is cut on the edge of the bolt nose recess and chamber. This aids in feeding and prevents brass from being scratched.

The barrel is removed from the lathe and reinserted with the muzzle facing the tail stock. We use the same process of “dialing in” each end that we did for the chambering.

The barrel is now reversed in the lathe, with the muzzle facing the tailstock. The barrel is cut to length, in this case 27", and squared. A .420" piloted crown tool is secured in the floating reamer holder and the crown is cut. — The barrel is now reversed in the lathe, with the muzzle facing the tailstock. The barrel is cut to length, in this case 27″, and squared. A .420″ piloted crown tool is secured in the floating reamer holder and the crown is cut.

The piloted crown tools produce excellent, and burr free, results. — The piloted crown tools produce excellent and burr free, results.

We polish our barrel to 400 grit. The barrel with be blasted with Aluminum oxide prior to finishing with Cerakote. — We polish our barrel to 400 grit. The barrel will be blasted with Aluminum oxide prior to finishing with Cerakote.

Painters tape is used to align the stamps so appropriate chamber markings can be made on the barrel.

We selected the McMillan A3 stock for rifle. The stock we had was provided with a inlet for standard bottom metal, we shipped it back to McMillan to have it changed to a Surgeon bottom metal inlet. In our experience, it is faster, easier and cheaper to have the stock maker adjust the inlet. While wait times vary, in this case around 8 weeks, we find it is worth the wait.

The Palma barrel has a similar profile to a factory Remington Varmint taper. The shank requires some minor inletting. A barrel bedding tool makes quick work of this.

The front and sides of the recoil lug are coated in tape to provide adequate spacing from the bedding compound. We wrap the side of the lug with electrical tape and trim with a razor. For the front we use 10 mil bedding tape from Brownells.

The action and bottom metal are sprayed with release agent. Clay is used to fill any voids.

We make a clay "snake" and place it in front of the recoil lug slot to prevent seepage of the epoxy. The Marine Tex epoxy is mixed and applied to the areas of the stock. — We make a clay “snake” and place it in front of the recoil lug slot to prevent seepage of the epoxy. Epoxy surfaces are abraded with sandpaper to remove paint and provide a clean surface for it to adhere to, The Marine Tex epoxy is mixed and applied to the areas of the stock. A small amount of Marine Tex is place inside the pillar holes.

The two aluminum bedding pillars are coated with epoxy and inserted into the stock from underneath. The action is slowly placed into the epoxy and The action screws are gently tightened. Excess epoxy is cleaned away with cotton swabs- lot of them. — The two aluminum bedding pillars are coated with epoxy and inserted into the stock from underneath. The action is slowly placed into the epoxy and the action screws are gently tightened. Excess epoxy is cleaned away with cotton swabs- lots of them.

The inside edges of the bedding are cleaned up on the milling machine.

The stock and metal are off to paint. The stock will be coated in Duracoat, and the metal, Cerakote (check out our articles on finishing). Once finished, the rifle is reassembled and looks great!

Our 260 Remington built on a Blackheart International action, ready to go!

Side view of the 260 Remington built on a Blackheart International action.

Even though this rifle has a 27″ barrel, the relatively light Palma contour makes for a fast handling and relatively light rifle.

We headed to the range. Our first group at 100 yards measured .591". Our three handloads utilizing 140 SMK and IMR 4350 measured .591, .725, .888, .661 and .605. The average size was .694. We are confident with increased load development work, this can be improved. — We headed to the range. Our first group at 100 yards measured .591″. Our three handloads utilizing 140 SMK and IMR 4350 measured .591, .725, .888, .661 and .605. The average size was .694. We are confident with increased load development work, this can be improved.

We were limited by a poor selection of powder on hand due to the current shortage. We are confident this rifle will prove to be a solid sub half MOA performer.

We will be providing updates on the rifle and the cartridge in the future.