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February 17th, 2021

How to Blueprint a Rem 700 Action — Rifleshooter.com Reveals

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizingYou may have heard the phrase “blueprinting an action”, but do you know what that really means? Do you know what operations are done to an action during the blueprinting process? To help you understand, gunsmith Bill Marr of RifleShooter.com has created a helpful article showing a Rem 700 blueprinting job start to finish. This article spotlights how the procedures can be done with manual tools. Bill, who runs 782 Custom Gunworks Ltd., can also perform many of these operations with modern automated machinery. In fact, Bill has written a follow-up article on Truing a Rem 700 receiver with a Lathe.

READ Full Action Blueprinting Article HERE with 30+ Photos »

Bill explains: “Blue-printing, or truing a rifle action, ensures the receiver face, threads, lugs, bolt lugs, and bolt face are square to the center line of the receiver.” In Bill’s informative article, Bill shows how he blueprints a Remington 700 short action receiver with .308 Win bolt face. He covers the following procedures step by step:

Action Disassembly
Ream Minor Diameter of Receiver Threads
Square the Receiver Lugs
Square the Face of the Receiver
Lap the Bolt Lugs
Square the Bolt Face

Bill employed a variety of tools from Brownells to complete the blueprinting job, including: Remington 700 Armorer’s Kit; Manson Receiver Accurizing Kit; Bolt Lapping Kit; Bolt Face Truing Tool; Manson Receiver Ring Facing Cutter; Multi-Vise with Jaw Pads; Silicone Carbide Abrasive; and Do-Drill Cutting Oil.

Highlights from the Rifleshooter.com article:

1. Chasing the Threads

We use the bushings to guide the receiver tap. This chases the threads and ensures they are square.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

2. Truing the Receiver Face

Using the receiver facing tool, the front of the receiver is trued. The tool is placed over the tap and turned by hand. We used Do Drill to lubricate it.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

3. Lapping the Lugs

The bolt lapping tool screws into the front of the action and applies rearward pressure on the bolt face. A little bit of lapping compound is placed on the front of the receiver lugs. The bolt handle is then raised and lowered repeatedly. Note — it is critical that we do not get any lapping compound on any other surfaces.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

4. Truing the Bolt Face

On this bolt, the central part of the bolt face was low. After the truing operation, this Rem 700 bolt face is now completely square to the action.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

READ Blueprinting Rem 700 Action with Lathe Article HERE »

IMPORTANT: Rifleshooter.com states: “This article highlights our project and is presented for information purposes only. This provides an overview of the process and should not be attempted without the guidance and supervision of an experienced gunsmith“.

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August 27th, 2019

Cutting .338 LM Barrel from 30″ to 17″ — Velocity Loss Revealed!

.338 Lapua Magnum LM barrel length vs velocity cut down test chrono rifleshooter.com

With Randy Wise’s recent record-setting ELR performance with a .338 Lapua Magnum Savage rifle, we thought our readers might be interested in a .338 LM velocity test conducted by our friend Bill Marr, Editor of Rifleshooter.com.

READ FULL .338 Lapua Magnum Barrel Cut-down Velocity TEST »

782 custom gunworks ltdA couple seasons back, Bill did a fascinating barrel cut-down test on a .338 Lapua Magnum rifle. Bill, a skilled gunsmith who runs 782 Custom Gunworks, cut down the barrel from 30″ to 17″ in one-inch increments. During the cut-down process, Marr measured velocities at each barrel length, shooting four rounds after each cut. As you’d expect, there was a huge change in velocity from long to short. Speeds were measured at the muzzle with a Magnetospeed barrel-mounted chronograph.

If you’re looking for max velocity with the .338 LM, go long. With 250-grain Sierra MK bullets, the peak velocity Bill measured was 2942 FPS at the full, 30-inch length. This decreased pretty steadily down to 2547 GPS at the shortest 17″ length. That’s an average decrease of 30.4 FPS per inch from 30″ to 17″.

.338 Lapua Magnum LM barrel length vs velocity cut down test chrono rifleshooter.com

Bill also tested 300-grain Sierra MatchKings. This is interesting because Randy Wise ran 300-grain bullets (Berger Hybrids) in a 26″ factory barrel for his ELR record. Peak velocity was 2833 FPS at 30″, 2799 FPS at 26″, and 2492 FPS at the shortest 17″ length. Interestingly, velocity at 29″ was higher than at 30″ for the 300-grainers. Bill notes: “The 300 SMK load showed a slight increase from 30 to 29″. I’ve recorded this in other tests and it seems to be more common with a heavier load. I suspect it is primarily due to the small sample sizes being used along with the relative proximity of muzzle velocities in adjacent lengths.”

At each new (shorter) barrel length, velocity was measured with a MagnetoSpeed chronograph using two different loads, 250gr SMKs with H4831sc and 300gr SMKs with Retumbo. Four shots were fired at each length with each load, a total of 112 rounds.

Load #1: 250gr Sierra MK, Lapua brass, CCI #250 primer, H4831SC, OAL 3.720″.
Load #2: 300gr Sierra MK, Lapua brass, Win WLRM primer, Retumbo, OAL 3.720″.

.338 LM Barrel Cut-Down Test Results Summary

.338 Lapua Magnum LM barrel length vs velocity cut down test chrono rifleshooter.com

.338 Lapua Magnum with 250gr Sierra MatchKings
After shortening the barrel from 30″ to 17″, total velocity reduction for the 250-grainers was 395 FPS, an average loss of 30.4 FPS per 1″ cut. The amount of velocity loss per inch rose as the barrel got shorter, with the biggest speed reduction, a loss of 55 FPS, coming with the cut from 18″ to 17″.

Start Velocity: 2942 FPS | End Velocity: 2547 FPS | Average Loss Per Inch: 30.4 FPS

(more…)

Permalink Bullets, Brass, Ammo, Gunsmithing, Tech Tip 3 Comments »
August 17th, 2019

Truing a Rem 700 Action — RifleShooter.com Shows the Process

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizingYou may have heard the phrase “blueprinting an action”, but do you know what that really means? Do you know what operations are done to an action during the blueprinting process? To help you understand, gunsmith Bill Marr of RifleShooter.com has created a helpful article showing a Rem 700 blueprinting job start to finish. This article spotlights how the procedures can be done with manual tools. Bill, who runs 782 Custom Gunworks Ltd., can also perform many of these operations with modern automated machinery. In fact, Bill has written a follow-up article on Truing a Rem 700 receiver with a Lathe.

READ Full Action Blueprinting Article HERE with 30+ Photos »

READ Blueprinting Rem 700 Action with Lathe Article HERE »

Bill explains: “Blue-printing, or truing a rifle action, ensures the receiver face, threads, lugs, bolt lugs, and bolt face are square to the center line of the receiver.” In Bill’s informative article, Bill shows how he blueprints a Remington 700 short action receiver with .308 Win bolt face. He covers the following procedures step by step:

Action Disassembly
Ream Minor Diameter of Receiver Threads
Square the Receiver Lugs
Square the Face of the Receiver
Lap the Bolt Lugs
Square the Bolt Face

Bill employed a variety of tools from Brownells to complete the blueprinting job, including: Remington 700 Armorer’s Kit; Manson Receiver Accurizing Kit; Bolt Lapping Kit; Bolt Face Truing Tool; Manson Receiver Ring Facing Cutter; Multi-Vise with Jaw Pads; Silicone Carbide Abrasive; and Do-Drill Cutting Oil.

Highlights from the Rifleshooter.com article:

1. Chasing the Threads

We use the bushings to guide the receiver tap. This chases the threads and ensures they are square.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

2. Truing the Receiver Face

Using the receiver facing tool, the front of the receiver is trued. The tool is placed over the tap and turned by hand. We used Do Drill to lubricate it.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

3. Lapping the Lugs

The bolt lapping tool screws into the front of the action and applies rearward pressure on the bolt face. A little bit of lapping compound is placed on the front of the receiver lugs. The bolt handle is then raised and lowered repeatedly. Note — it is critical that we do not get any lapping compound on any other surfaces.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

4. Truing the Bolt Face

On this bolt, the central part of the bolt face was low. After the truing operation, this Rem 700 bolt face is now completely square to the action.

Bill Marr Rifleshooter.com truing Remington Rem 700 action accurizing

IMPORTANT: Rifleshooter.com states: “This article highlights our project and is presented for information purposes only. This provides an overview of the process and should not be attempted without the guidance and supervision of an experienced gunsmith“.

Permalink - Articles, Gunsmithing, Tech Tip 2 Comments »
May 7th, 2019

6mm Creedmoor — How Many FPS Will a Shorter Barrel Cost You?

6mm 6.5 Creedmoor rifleshooter.com Bill Barr barrel length cut-down velocity test chronograph Magnetospeed chrono

Our friend Bill Marr of Rifleshooter.com has done it again — conducted a fascinating 6mm Creedmoor barrel cut-down test that reveals how velocity changes with barrel length. This time Bill started with a 24″ Proof Research stainless steel barrel on a Howa action. Bill says this was a well-used barrel, with over 1800 rounds through it. So, the velocities might be a bit different than a new barrel of similar length. Bill cut the barrel down in one-inch increments. Here are some results from the test:

24″ Velocity: 2893 FPS | 20″ Velocity: 2755 FPS | 16.1″ Velocity: 2598 FPS

CLICK HERE for FULL TEST REPORT on RifleShooter.com »

6mm 6.5 Creedmoor rifleshooter.com Bill Barr barrel length cut-down velocity test chronograph Magnetospeed chrono

6mm 6.5 Creedmoor rifleshooter.com Bill Barr barrel length cut-down velocity test chronograph Magnetospeed chronoFor this latest test, Rifleshooter cut the barrel in one-inch increments from 24″ to 16.1″ (just over legal minimum). Velocities were measured with a MagnetoSpeed V3 chronograph mounted on arm attached to the stock. This allowed the chrono to be adjusted inwards as the barrel was cut shorter, inch by inch.

For the 6mm Creedmoor cartridge, Bill loaded Hornady 108gr ELD Match bullets over 41.5 grains of Hodgdon H4350 with CCI 200 primers in new Starline brass.

The results were interesting to say the least. Bill reports: “Muzzle velocities ranged from 2,893 ft/sec at 24″ to 2,598 ft/sec at 16″ for a decrease in muzzle velocity of 295 ft/sec. Muzzle velocity changes per inch of barrel length ranged from 6 ft/sec per inch between 20 and 19 inches to 63 ft/sec per inch between 19 and 18 inches. Average velocity change per inch of barrel length was 37.9 ft/sec.”

Bill concludes: “An average drop of 37.9 ft/sec/inch of barrel is fairly significant and is what would be expected with a fast moving 6mm cartridge like the 6mm Creedmoor. While I’m used to seeing 6mm Creedmoors with slightly longer barrel lengths than 24″, when coupled with a sound suppressor the additional length can make moving the rifle quickly more difficult.

I’d suggest staying with longer barrel lengths wherever possible with this cartridge. At shorter lengths, it does give up more performance than its big brother the 6.5 Creedmoor.”

More 6mm Creedmoor Velocity Data from 2017 Cut-Down Test

If you’re curious about 6mm Creedmoor velocities at longer barrel lengths, back in 2017 Rifleshooter completed a 6mm Creedmoor barrel cut-down test from 31 inches all the way down to 17 inches. The test included four bullet types from 95 grains to 110 grains. With the 110gr Sierra MK, velocity at 31″ was an impressive 3110 fps. Surprisingly the velocity didn’t decrease that much for the first few inches. Even at 26″ (a five-inch reduction), measured velocity with the 110s was 3073 fps, a loss of 7.4 fps per inch on average. With a barrel shortened all the way to 20″ however, velocity had dropped down to 2949 fps, a significant (161 fps) loss. CLICK HERE for complete results from that 31″-17″ Barrel Cut-Down Test.

6mm 6.5 Creedmoor rifleshooter.com Bill Barr barrel length cut-down velocity test chronograph Magnetospeed chrono

CLICK HERE for 31″ to 17″ 6mm Creedmoor Barrel Test Report »

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