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February 28, 2016

Posted in


Dan Petersen Rifle

I was contacted by a client who wanted to give his bear guide a custom rifle as a tip for the successful bear hunt where he harvested a beautiful 10 ft 6 in fall brown bear.

As the rifle would only be used when things turned bad the cartridge selected was the .416 Remington to be built on magnum pre-64 Winchester Model 70 action. The action's claw extractor and three-position safety make it an ideal choice for a big game guide's backup rifle in Alaska where pursuing a poorly shot bear into thick cover can be quite dangerous and stressful.  Shots in these situations can range from a few feet to a few yards making a scope with quick detachable rings ideal for the optical system.

I designed the barrel with an integral 1/4 rib that would accommodate a mid-rib rear open sight and front sight blade on an integral oval front ramp.  The top surface of the quarter rib and the top of the front ramp are located .100 higher than the scope bases on the reciver. A front sight hood was omitted as they tend to collect leaves and small twigs in heavy cover rendering iron sights useless.

An integral sling swivel stud was located 9" back from the muzzle. I incorperated a low oval base to compliment the oval oval theme used to transition the quarter rib and front sight bases into the mid-rib.  Although 9" may seem a bit forward for the sling mount, positioned like this keeps the muzzle lower than the hunter's head when slung making it much easier going in heavy cover.

The final design feature of the barrel is an integral recoil lug located 4" forward of the receiver face.

My first and foremost objective for the barrel design was to give the final barrel an eye pleasing complement of the heights and dimensions of the accessories relative to overall dimensions of the barrel.  In the end I believe the lines must compliment and not dominate elements of the stock and action.

Programing and design work were done using Mastercam, the machining work being done on my CNC HAAS mill.  This allows the complex nature of multiple arcs and ovals to be gracefully merged into the basic solid surfaces of a raw barrel. The design programing on a quality barrel typically takes from 5-7 days and the CNC machine work taking another 5 days.

The CNC work is followed by hours of hand polishing with diemaker's stones and the final finish is brought in with Scotch Brite pads. The Scotch Brite finish gives the metal a beautiful matte finish that quickly exposes the slightest blemishes.

The final polishing must be done carefully and slowly in order to preserve all lines and sharp corners and reach the subtle areas where

Prior to taking the barrel to the milling machine the barrel is chambered and indexed on the receiver to establish the top flat of the rib which makes it possible for the arcs at the rear of the quarter rib to flow cleanly and precisely into the receiver face.  I contoured the scope bases for the radius on the front and rear receiver bridges and left the final fitting to the gunmaker that would also stock the rifle.  Mathew Roberts of MNR Custom Rifles was that gunmaker and he established the final height of the scope bases and machined the dovetails to accommodate a set of my quick detachable rings.

The stock blank was a very nice piece of Turkish walnut with clean lines through the grip and action areas.  In addition to the stock work, Mathew welded on a Mcfarland two pannel bolt handle and regulated the sights on a fast turnaround. His work is impeccable and cannot be fully appreciated until you hold one of his stocks on your hands. The finished project pointed like a fine custom fitted shotgun with the shooter's eye naturally finding the sights simply by mounting the rifle. The outcome could not have been more perfect for a dangerous game rifle where close and quick shots are ocasionally required. I was honored to present this rifle to its new owner but regretted having to do so.

August 04, 2015

Posted in custom rifle, miniature Martini, ovate barrel


Ovate Rifle Barrel From Full Round Blanks

This article about preparation of rifle barrel blanks to create an ovate rifle barrel for a Martini rifle project first appeared in the Spring 2015 edition of “Gunmaker-Journal of Custom Gunmaking” magazine.  The American Custom Gunmakers Guild is a non-profit organization dedicated to preserving the art of fine custom gunmaking.  Associate membership is available to anyone and professional membership is available to associate members that have achieved peer recognition for achieving the organization’s standards of finest gunmaking.

By Dennis Daigger
This is Part 1 of a 2-part article about the barrels for a multi-barrel Model 6 BSA takedown Martini rifle project. In Part 1 I describe what was required to get the barrel blanks ready for CNC profiling and in Part 2 the profiling process.

What began as a straight forward project just involving me to build a .17 HMR rifle on a BSA Model 6 Martini action took a turn to the complex when I met Morris Melani last year. I went to his Big Lake shop to buy a set of his quick detachable CZ style rings for a Satterlee actioned .404 Jeffery rifle that I was completing and in passing told him about the Martini project. I had the action and wood and a Lothar Walther profiled barrel was on order. I expected to have the project done in a few months.

Morris has been interested in creating ovate barrels with his HAAS CNC for some time and he offered to collaborate in the project by creating such a barrel for me from a full round blank if I got one. This would be the catalyst for his development of the Mastercam CAD/CAM solids, design and development of the CNC fixtures and the actual creation of an ovate barrel by CNC.

The action I have is a takedown and a multi-barrel rifle eventually evolved in our conversations. I acquired four barrel blanks, and an additional breach block (calibers include rimfire and centerfire) and then it turned into Morris’ show.

This article will chronicle the steps preparatory to the CNC milling. Full aspects of the project are chronicled at Morris’ web blog, http://www.alaskaarmsllc.com/blogs/news/94039105-ovate-barrels-part-1, for those interested in the entire project.

In addition to the .17 HMR I chose other chamberings of personal interest. Ballistic characteristics of these cartridges are quite different and I wanted a tailored sight configuration for each barrel. The Mastercam CAD/CAM produced solids would have slight variations to accommodate the following configurations:

Cartridge

Primary Sight

Secondary Sight

.17 HMR 6X Unertl Small Game Scope None
.22 LR BSA Peep sight, front globe Scope bases
5.6X50R 10X Fecker Scope Flip up front, standing rear
.25-20 WCF Standing rear, Beach front Scope bases

My specifications were simply: 26” final barrel length; integral target bases; longitudinal front dovetail that would accommodate Recknagel blades; and; an integral bottom lug for attaching the forearm.

With the exception of the inordinately well finished Lothar Walther 17 caliber 1.250” diameter blank, the other blanks were very rough and needed a lot of work.

Two of the barrels had not been rough turned on the exterior and these not only had significant rust on them but the bores were noticeably off center in the full round blanks as was the third one which had been rough turned. All had bores that were remarkably straight so work on them proceeded.

Morris set the barrels up on the lathe on centers and carefully trued a section on each end of the blank to be concentric with the bore. Very precise tolerances were maintained for this operation. As each barrel was held between centers very light skim cuts were performed on it until the outside was trued to the axis of the bore.

Using the trued section on the breach end of each barrel as a reference point the overall length was brought to 26”.

Morris describes the process for standardizing the barrel length:

“After the shortest barrel had been faced and had centers cut on both ends, I stood it on end on the surface plate. The other three barrels were faced on one end and I stood each, one by one, next to the first and used a depth mic to determine the amount to shorten each to achieve a standard length. This resulted in all barrels being within .005” of the standard length.”

Each barrel was crowned at the breach and the muzzle. Again, Morris’ description:

“Total run out with the barrels chucked in the 4 jaw was .0002”. The ends of each blank were faced and a 60 degree center was cut in the end using a boring tool feeding the tool from the bore out to draw burrs out of the barrel. The barrels were next placed between centers with the tailstock pressure only and a 2” section was turned concentric with the bore. After this step it was possible to chuck one end of the barrel in the 4 jaw and indicate both ends of the barrel. A steady rest was then used to support the barrel and the entire outside was turned concentric with the bore.”

muzzle_4barrelsMuzzles of trued barrels

The action barrel tenon was cut on each barrel and this tenon was threaded using a 55 degree tool. The Martini uses 55 degree Whitworth threads. The leading edge of the tool was rounded manually to produce the appropriate Whitworth thread profile.

Morris’ description:

“A 55 degree threading tool was ground on the surface grinder with a half thread width feed side that allowed the thread to be machined to the shoulder eliminating the relief cut and allowing threads to be turned to the shoulder adding strength to this critical area.”

Morris previously made a tool fixture for cutting the threading tools using the surface grinder. This is a very precise fixture that gives extraordinarily consistent tools. Because this one is set up for cutting a 60 degree angle a sine plate was needed to reduce the angle to the required 55 degrees.

thread_tool_cutting_fixtureGrinding fixture for thread cutting tools

Each barrel was then threaded to give a consistent snug turn-in to the action face. With this takedown system using four barrels it is important to have precise tolerances from barrel to barrel.

Finally, each barrel was chambered using a floating reamer holder in the tail stock. Morris’ description:

“The chambers were cut to a feel on the go gauge +.001 shim stock. The chamber reamers were removed as soon as the dry chips emerged from flutes. The reamer was then withdrawn, cleaned and thoroughly oiled. Several dry patches were run through the bore. The reamer and copious amounts of oil were reinserted and the entire process restarted.”

Each barrel was screwed into the receiver with its appropriate breach block installed and firing tests were conducted to ensure primer ignition. Because the head diameters of the .22 LR and the .17 HMR are slightly different I had some concern about whether the rimfire block firing pin location set up for the .22 LR would detonate both the .22 LR and the .17 HMR cartridges. Both the rimfire and centerfire tests resulted in detonation and the conclusion is that no adjustment to the location of the rimfire firing pin is needed.

centerfire_block_test_firing

rimfire_block_test_firingCenter fire and rim fire test results 

Before the barrels can have ovate profiles cut for this project the take down system groove through the lower part of the barrel threads needs to be cut on each barrel.

The BSA Martini takedown system consists of a tapered screw that passes through the action from left to right perpendicularly to the axis of the bore. The taper of the pin mates with the cut on the underside of the barrel threads and as the pin is screwed into the action the first thing that happens as the screw taper engages this barrel cut is that the barrel is rotated into the top dead center position until the screw surface and the barrel surface are fully mated. As the screw is fully tightened the barrel is pressed firmly upwards into the upper parts of the action threads ‘locking’ the barrel to the action. There is nothing particularly sophisticated about this system but having studied some of the other British takedown systems it is as svelte and reliable as anything I’ve seen.

The problems associated with implementing this system on a four barrel project were evident. First, how to use a common pin for all of the barrels. Multiple barrel-specific parts present a problem because if something is lost, the efficacy of the system is diminished. Two breach blocks and four extractors would be needed already and I did not want any more duplication of parts. I wanted to use a lever on the takedown pin that would index straight down when torqued in for each barrel. A lever would afford the luxury of not having to have a screw bit readily available for barrel change outs. Morris thought that EDM gave the best opportunity to control this part of the project precisely through four iterations.

The takedown screw was secured in the vise of an optical comparator and the taper of the pin was established as 4 degrees.

optical_comparator_taper_pinTakedown pin on optical comparator

I had rough turned takedown screw blanks out of O-1 tool steel and Morris brought two to near final dimensions on the lathe and threaded each. The taper would be ground with the surface grinder after the profiles had been cut.

crosspin_threadingTakedown Pin Blank

Graphite rods 5/16” in diameter were then secured in a Harig jig and dialed in. This set up was moved to a sine plate setup to give the appropriate 4 degree taper. Using the surface grinder, four EDM electrodes were cut that precisely duplicated the profile of the takedown screw.

edm_takedown_pin_electrode Grinding EDM Electrode at 4 Degrees

To reduce the EDM time needed to cut the groove in the bottom of the barrel threads the barrels were placed on two V blocks and loosely secured. This setup was moved to the mill, the action was screwed to the barrel with the slightest snug up. The setup was then dialed in using the side of the action. The sides of the action had previously been precisely surface ground to the thickness of plus or minus .002”. Once dialed in and secured in the fixture a 3/16” end mill was centered in the takedown screw hole, the action was removed and a rough groove was cut through the threads.

A second mill cut was done while the barrel was secured in this setup. A 3/4” x 1 1/2” section of the barrel about 4” forward of the action was milled. This flat on the left side is 90 degrees left of top dead center for the barrel and will be used for verifying the dial-in in the CNC barrel set up and later in dialing in the barrel in the CNC fixture.

barrel_setup_millDialing in EDM setup

A reliable method of controlling the depth of the EDM cut needed to be established and this was done by screwing the original takedown screw tightly into the action. The action was then set up on the surface grinder and the head of the screw was ground flat. The original BSA barrel from the action was then screwed in, the takedown pin was screwed in and brought up tight and then backed out ½ turn. The width of the action from the right side to the top of the screw head on the left was measured and this would become the desired depth for the EDM cut.

The barrel still secured in the V block fixture was then moved to the EDM where the tapered electrode was installed. The side of the action was dialed in and the mill-cut flat on the barrel (can be seen in this photo) was used for a cross check verification.

barrel_initial_setup_edmDialing In Barrel at EDM Mill

The setup was then secured, rechecked and then the takedown pin hole was positioned under the electrode. The electrode was lowered so that it could be brought into contact with the threaded portion of the barrel and by alternately touching off in the X and then the Y axis the center position was established for the center of the pin.

barrel_edm_dialin_

The action was unscrewed from the barrel and the EDM process was sequentially completed for all four barrels.

Checks were made periodically to gauge depth progress by raising the electrode, screwing the action into the barrel, screwing the takedown pin in and finally measuring the width from the top of the pin head to the opposite side of the action. The final result looks very good and is quite repeatable to ensure tight tolerances from barrel to barrel. Light hand stoning removed the hard surface material deposited during EDM machining.

barrel_takedown_edm

Part 2 will describe the CNC milling fixture, the setup and the results from running the Mastercam program.

September 20, 2014

Posted in


Alaska Arms LLC quick detachable scope rings on custom rifle

Another application of Alaska Arms LLC quick detachable scope rings on custom rifle.

Morris,

“I don’t know if you can use these or not, but I just finished a rifle on a Granite Mountain Arms action and used one of the ring sets you sent me.”

“The rings have been working great and I really appreciate how helpful you’ve been.”

Regards,
Matthew Roberts
MNR Custom LLC

Rings 7

Rings 6
Rings 3

Rings 4

September 19, 2014

Posted in


Custom installation of Alaska Arms LLC scope rings

American Custom Gunmakers Guild member James Tucker used Alaska Arms LLC gunsmith bases and the CZ quick detachable scope rings on this custom Mauser rifle.  These rings are ideally suited to this application as they are sleek and highly reliable for returning to zero when the scope is removed and and reattached.

AKqdAK Base TopsAK Side

September 19, 2014

Posted in


Alaska Arms LLC scope rings in Africa

Alaska Arms LLC quick detachable scope rings are ideally suited for hunting dangerous game in Africa where changing conditions may require removal or attachment of a scope.  These rings return reliably to zero every time.

Additionally, assurance that the scope will maintain its zero allows it to be removed and hand carried as the Jeff Bryson proved.

“The detachable rings for the CZ .416 Rigby worked great. I am the guy from North Dakota, we talked once on the phone before the trip, gun was sighted in and scope removed so I could take in my carry-on. Got to Limpopo region of South Africa, put scope on to check zero, and Right on! Great product. Anyone can contact me about your system. Thank you.”  Jeff Bryson.

DSCF0021

Ovate Barrels Part 4

Part 4 The Takedown System

Before the ovate barrels can have profiles cut for this project the takedown system needs to be cut on each barrel.

The BSA Martini takedown system consists of a tapered screw that passes through the action from left to right perpendicular to the axis of the bore.  The taper of the pin mates with a cut on the underside of the barrel threads and as the pin is screwed into the action the first thing that happens as the screw is engaging this barrel cut is that the barrel is rotated into the top dead center position until the screw surface and the barrel surface are fully mated.  As the screw is then fully tightened the barrel is pressed firmly upwards into the upper parts of the action treads ‘locking” the barrel to the action.  There is nothing particularly sophisticated about this system but having studied some of the other British takedown systems it is svelte and reliable.

The problems associated with implementing this system on a four-barreled project were evident.

First, how to use a common pin for all of the barrels.  Multiple barrel-specific parts present a problem because if lost, the efficacy of the system is diminished.  Two breach blocks and two extractors would be needed already and I did not want any more duplication of parts.  I wanted to use a lever on the takedown pin that would index straight down when torqued in for each barrel.  A lever would afford the luxury of not having to have a screw bit readily available for barrel change outs.  Morris thought that EDM gave the best opportunity to control this part of the project.

The takedown screw was secured in the vise of an optical comparator and the taper of the pin was established as 4 degrees.

optical_comparator_taper_pin

I had rough turned four takedown blanks out of O-1 tool steel and Morris brought each to near final dimensions on the lathe and threaded each.

crosspin_threading

Graphite rods 5/16” in diameter were then secured in a Harig fixture and dialed in.  This set up was moved to a sine plate set to give the appropriate 4 degree taper.  Using a surface grinder, four EDM electrodes were cut that duplicated the profile of the takedown screw.

edm_takedown_pin_electrode

To reduce the EDM time needed to cut the groove in the bottom of the barrel threads the barrels were placed on two V blocks and loosely secured.  This setup was moved to the mill, the action was screwed to the barrel with the slightest snug up.  This setup was then dialed in using the side of the action.  The sides of the action had previously been precisely surface ground to a thickness of plus or minus .002”.  Once dialed in and secured in the fixture a 3/16” end mill was centered in the takedown screw hole, the action was removed and a rough cut of the groove was cut through the threads.

barrel_setup_mill

A second mill cut was done while the barrel was secured in this setup.  A 3/4”X1 1/2” section of the barrel about 4” forward of the action was milled.  This flat on the left side is 90° left of top dead center for the barrel and will be used for the CNC set up.

A reliable method of controlling the depth of the EDM cut needed to be established and this was done by screwing the takedown pin tightly into the action.  The action was then set up on the surface grinder and the head of the takedown pin was flat.  The original BSA barrel that came with the action was then screwed in, the takedown pin was screwed in and brought up tight and then backed out 1/2 turn.  The width of the action from the right side to the top of the screw head on the left was measured and this would become the desired depth for the EDM cut.

The barrel still secured in the v block fixture was then moved to the EDM where the tapered electrode was already installed.  The side of the action was dialed in and the mill-cut flat on the barrel (can be seen in this photo) was used for a cross check verification.

barrel_initial_setup_edm

The setup was then secured, rechecked and then the takedown pin hole was positioned under the electrode.  The electrode was lowered so that it could be brought into contact with the threaded portion and alternately touching off in the x axis and y axis the center position was established for the center of the pin.

barrel_edm_dialin_

The action was unscrewed from the barrel and the EDM process was started.

barrel_edm_dialin

Checks were made periodically to gauge depth progress by raising the electrode, screwing the action onto the barrel, screwing the takedown pin in and finally measuring the width.  The final result looks very good and is quite repeatable to ensure tight tolerances from barrel to barrel.  Light hand stoning will be used for the final fit.

barrel_takedown_edm

The CNC setup will be covered next starting with design of the fixtures.

Ovate Barrels Part 3

Preparing the Action

Since the miniature Martini breach block’s face is not perpendicular to the axis of striker travel conversion of a rimfire block to centerfire uses two dial in references.

The dial in with a snug fitting gauge pin in the block striker bore will be used for three operations: 1) the EDM setup to remove the striker nut retaining screw that was broken off in the hole; 2) tapping the original firing pin hole; and; 3) drilling the new firing pin hole.  This is what the setup looks like.

block_dialin_striker

The rimfire breach block that is being converted to centerfire was secured in a tool maker’s vise and was dialed in on a surface plate as shown above.  The setup was moved to the mill and a 4-40 tap was used to thread the existing rimfire firing pin hole to the full depth of the hole.  A 4-40 bead blasted screw was then screwed into this hole leaving the screw proud of the breach face.  The circumference of the protruding screw was TIG welded to the breach face.

breach_block_weld

The block was then set up again in the tool maker’s vise and the block face dialed in.  The setup was then taken to the surface grinder.  The protruding part of the screw as well as the bead of weld surrounding it were brought level with the face.

breach_block_ground_face

Preparatory to locating the the new firing pin the existing firing pin was ground from the striker nearly to the striker flange. Again the block was dialed in on the surface plate with the gauge pin in the striker bore and with the vise turned onto its side the new firing pin hole could now be drilled.  The new firing pin location is off center of the axis of the striker but this setup would ensure that the new firing pin would be parallel to the striker axis and would not bind as it travels longitudinally back and forth.  The center of the barrel axis had been previously established with the block installed in the action and this center was marked on the breach face. The setup was moved to the mill and with the striker installed in the block under full tension of the striker spring a 1/16” hole was drilled through the breach face and into the striker flange.  This spotted hole on the striker flange would then be center of the new firing pin location.

A section of 1/16″ O-1 drill rod was soldered into the striker and after the parts of the breach block unit were reassembled the firing pin was shortened and then rounded to give a pin protrusion of .055”.

striker_modified

The last work that needed to be done on this block was removal of the striker nut retain screw.  The block came to me with this screw broken off and I drilled the screw out as best as I could.  It is something like a 5-56 screw and after drilling the screw with a still smaller twist drill there were thread remnants that I thought I could remove with the tap.  I broke the tap off and Morris used the EDM to remove the tap.  The threads were then carefully cleaned up and the new screw fitted.

EDM_breach_block

Preparing the Barrels

By now we had four ovate barrels that needed fitted to the action.  The preparation consisted of work that I am simply not capable of doing even with the excellent machines made available to me.  This was Morris’ show and I gratefully moved aside.

The first problem was that the exterior of each barrel was rough.  Two of the barrels had not been rough turned on the exterior and these not only had significant rust on the exteriors but the bores were noticeably off center in the full round blanks.  The other two barrels also had bores that were off center but not to the degree of the other two.  All had bores that were remarkable straight so work on them proceeded.

Morris set the barrels up on the lathe on centers and carefully trued a section on each end of the barrel to be concentric with the bore.  Very precise tolerances were maintained for this operation.  As each barrel was held between centers very light skim cuts were performed on each barrel until the outsides were trued to the axis of the bore.

lathe_truing_barrel

Using the trued section on the breach end of each barrel as a reference point the overall length of the barrel set was established at 26” and each was precisely brought to this length.

Morris’ description of process:  “After the shortest barrel had been faced on and had centers cut on both ends I stood it on end on the surface plate. The rest of the barrels were faced on one end and had center cut I stood them next to the finished barrel and used a depth mic to determine the amount to shorten the remaining barrels. This resulted all barrels being within .005 of the same length.”

Each barrel was crowned at the breach and the muzzle.

Morris’ description of process: “Total run out with the barrels chucked in the 4 jaw chuck was .0002/ the ends of the blank were faced and a 60 degree center was cut in the end using a boring tool feeding the tool from the bore out to draw burrs out that result from turning. The barrels were next placed between centers with tailstock pressure only and a 2 inch section was turned concentric with the bore. after this step it was possible chuck one end of the barrel in the 4 jaw chuck and indicate both ends of the barrel. The center was then used to support the barrel and the entire outside was turned concentric with the bore.”

muzzle_4barrels

The action barrel tenon was cut on each barrel and this tenon was threaded using a 55° tool.  The leading edge of this tool was rounded manually to produce the appropriate Whitworth thread cut in the action.

Morris’ description of process: “A 55° threading tool was ground on the surface grinder that allowed the thread to be machined to the shoulder eliminating the relief cut and allowing the threads to be turned to the shoulder adding strength to this critical area.”

Morris made a tool fixture for cutting threading tools using the surface grinder.  This is a very precise fixture that gives extraordinary tools.  Because this one is set up for cutting a 60 degree angle a sine plate needed to be used to reduce it to the required 55°.

thread_tool_cutting_fixture

Each barrel was then threaded to give a consistent snug turn-in to the action face.  With this takedown system using four barrels it is important to have precise tolerances from barrel to barrel.

threading_barrel

Finally, each barrel was then chambered using a floating reamer holder in the tail stock.

Morris’ description of process: “The chambers were cut to a feel on the go gauge + .001 shim stock. The chamber reamers were removed as soon a the chips were showing in the flutes dry. The reamer was then removed, cleaned and thoroughly oiled. several dry patches were run through the bore.  The reamer and copious amounts of oil were reinserted and the entire process restarted.”

breach_4barrel

Each barrel was screwed into the receiver with its appropriate breach block installed and firing tests were conducted to ensure primer ignition.  Because the head diameters of the .22 LR and the .17 HMR are slightly different I had some concern about whether the rimfire block firing location set up for the .22 LR would detonate both the .22 LR and the .17 HMR cartridges.  Both tests resulted in detonation and the conclusion is that no adjustment to the location of the rimfire firing pin is needed.

centerfire_block_test_firing

rimfire_block_test_firing

Using the EDM to cut the takedown screw groove on each barrel’s thread bottom will be covered next.

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