Thursday, December 22, 2011

Fitting Echols Scope Mounts: Part 2

Scope Mount Blanks Along With Other Echols&Co. Parts

The next step in the process is to select a set of mount blanks in either 1" or 30mm.  We have our blanks made by Central Valley Machine of Logan, Utah www.cvm-inc.com.  The blanks are made oversize in height and length and undersized in bore diameter to allow flexibility when fitting different scopes.

The front blank is machined to proper height and then is set up in the mill for boring.  The scope bore is bored to actual scope diameter plus .001-.002".  In the same set up, the ring radius (which was established when surface grinding) is bored into the base of the mount thus insuring that both the bore and the radius are in alignment with each other.
Boring The Ring Radius

The mount is then removed from the vise, deburred and set up for splitting the ring halves.
Ring Half Split

Next, the centerline of the mount is found and the screw holes and counterbores are machined.
Mount With Holes and Counterbores

The upper and lower mount halves are stamped with an F or R to denote front or rear and which scope the mounts were designed for (ex. Schmidt Bender=SB).

The rear mount is then machined concentric with the front.  The receiver is held between centers via mandrel and a holding fixture on the inspection plate.  A precision ground 1" bar is placed into the mounts and height and alignment are checked with a dial indicator.
Rear Mount .016" Higher Than Front

Rear Mount 0
Front Mount 0

Lapping is now a formality done mainly to remove machine marks.

Fitting mounts using this procedure ensures that the optic is held stress free and in alignment with the bore.  In most instances, the scope only has to be adjusted an inch or two from its optical center to zero the rifle when firing for the first time.

Excess material is now machined away from the mounts and cosmetic cuts are made (sides are angled and corners are given radiuses).  All surfaces are then hand polished to a 320 grit finish.

Finished Set of 30mm Mounts






Fitting Echols Scope Mounts

No rifle, no matter how inherently accurate it is, can shoot to its potential with a sighting system that is compromised.  The sighting system on a scoped rifle naturally consists of the optic and the scope mounts.   We have no control over the quality of the optic other than to choose a make and model which has proven reliable in the past.  However, we do have control over the scope mounts.  Our goal in our shop is to create scope mounts which are rugged, will hold the scope securely under recoil, and are as parallel to bore line as possible.

The process starts with the receiver.  Most factory receiver's front ring and rear bridge are not concentric to the centerline of the bore of the action (we will term this boreline) whether due to loose tolerance at the factory, warping under heat treatment, or overzealous polishing.   Surface grinding the radii of the front ring and rear bridge concentric to boreline corrects this problem.  Extreme care must be taken not to obliterate the serial number.

Freshly Surface Ground Front Receiver Ring

Once the front ring and rear bridge are ground true to boreline, the scope mounting holes are next.  It is not uncommon for the front two holes to be out of alignment with the rear holes.   The receiver is mounted on a fixture in the milling machine vise,  precision ground bushings are inserted into the bolt bore,  a precision ground rod is inserted into the bushings, the vise is offset till the rod is parallel to the mill bed, and then the centerline of the action is determined with an edge finder.

Once boreline has been established, the screw holes are checked for alignment.  Most misalignment, unless particularly gross, can be corrected by cutting the holes true with an endmill and retapping to 8-40 size.  Moving to the 8-40 size over the standard 6-48 also gives the added benefit of a stronger screw.  Because most magnum conversions result in a 3.600" loading port, we lose one of the original factory holes. Two more holes are added to the rear bridge in addition to the remaining hole.  We now have 5 screws holding down our mounts.
Screw Hole Tapped To 8-40

Now that the receiver issues have been addressed, a build sheet is drawn up with all pertinent dimensions.


  We like to mount our scopes as low as possible for faster sight alignment while allowing the shooter to maintain a proper cheek weld with the stock.  This also helps to eliminate felt recoil to the face with heavy kickers as the rifle has less of a running start.  The wide variety of ocular and objective bell dimensions, tube lengths, and eye reliefs between different makes and models of scopes combined with differing barrel contours and bolt handle positions results in each set of mounts being a unique configuration.

Monday, December 12, 2011

Dave Norin

At the past SCI show in Reno, we had the pleasure of meeting with fellow gunmaker Dave Norin.  Dave is a serious craftsman whose work ranks with best in the trade.  Dave was interested in providing a synthetic stocked rifle to his clientele and had sought us out to look at our Legend stock.   We are proud to have Dave using our Legend stocks on his synthetic builds.

www.davenoringunmaker.com

http://www.davenoringunmaker.com/2011/10/news-release-the-synthetic-option/

2011 Colorado Desert Bighorn


DArcy,
  I thought you might be interested in seeing a picture of a Desert Big Horn sheep I shot on opening day in Colorado. I had spent many days scouting my area and had seen this ram before. I, my son and a very good friend from Wyoming walked in before daylight and found the sheep not far from where we had seen him the day before. We got to within approximately 600 yards right at first light and were able to cut the distance to 356 yards. I was shooting the 300 Weatherby Legend you had built for me and I got on my belly and sent a 180 Barnes TSX in his direction. I want you to know that this was probably the most important hunt in my life and I have a bunch of really good rifles in my safe, but I chose the very best rifle I own for this hunt. I own the 25-06 Classic you built for me and it is a wonderful rifle, but this was crunch time and I wanted the best in my hands. This is the same rifle I used in Alaska 10 years ago to take my Dall ram at 488 yards. It is a fantastic rifle and all I can do is say thank you, Brian, and Matt for your commitment to building the very best.

Thanks,

Tom

Awesome Oregon Blacktail




In early July of 2009 my hunting partner (Andy) and I returned from a successful hunting trip in South Africa.  Within a week or so he called to tell me he had located a tremendous blacktail buck while scouting in southern Oregon. He actually had pics taken through a spotting scope at 1000+ yards and sent them to me. The deer was clearly a big one but I wasn't convinced he was as big as Andy insisted he was.  I was able to make it down to southern Oregon pre-season to do some scouting with Andy.  Miraculously we found the buck in the same canyon within a few hours of backpacking into our camp miles from the truck.  It didn't take long to confirm what Andy had known all along.  The buck was exceptional and was so wide that I didn't even want to guess the measurements.

We hunted that canyon about 12 days of the 35 day season in 2009, Andy putting in much more of those days than I.  Short story is we never laid eyes on him during the 2009 season.  Andy was able to locate him after the hunting season on one occasion and reaffirm he was in fact a giant.  More importantly he had made it through the hunting season.

Andy was unable to locate him during the summer of 2010.  In late October of 2010 I was hunting solo in the canyon we had seen the giant some 16 months before.  It was a little after 10:00 AM and I had seen no deer since being set up prior to daylight.   I was wearing out the lenses of my binoculars desperately looking for a deer.  While glassing the same country for the 19th time I located a buck I knew was a shooter and immediately tried to kill him.  Just as quickly as he appeared, he vanished before I could locate him in my scope.  After about 10 minutes of rather frantic glassing I finally had a clear frontal shot at about 250 yards.  A well placed 168gr TTSX from my 300 H&H Legend sent him somersaulting off a cliff. At this point all I knew was that he was a really good buck.  15 minutes later I cautiously picked my way down the cliff and eased into a nook where I found the buck piled up the brush.  He was clearly the wide buck from the year before - a heavy 4 X 5 with an outside spread of 29 5/8.  One interesting thing about this buck was that he was so wide his horns clearly got in the way of his grazing and he had “broomed” off the tips on each of his main beams.
The big ones are always fun.

Thanks D'Arcy,

Terry

Monday, December 5, 2011

Checkering a .505 Gibbs Classic Rifle

Here is D'Arcy making the final cutter passes on the fore end checkering of a .505 Gibbs Classic Rifle.

The end is in sight...

Testing Feeding of Flat Nose Bullets in .458 Lott Legend Rifle

Here we have a short video of us testing the feeding of a .458 Lott Legend rifle using a mixture of flat nosed 500 gr. Barnes Banded Solids and the Trophy Bonded Sledgehammer solids.  We have found that these two bullets, with their wide flat meplats, are the ultimate test bullets for checking feeding in a dangerous game rifle.  In other words, if the rifle will feed a flat nosed solid when the bolt is worked as if your life depends on it, it will feed anything.

Obviously this is an extreme example as most mortals can't operate the bolt from the shoulder at this speed while actually firing and hitting the target.  However, we have found that most any bullet profile will feed ok when operated slowly, assuming the basics such as extractor tension, feed ramp shape and angle, and rail dimension are correct.  It is at extreme speed of operation that a rifle will most often choke, usually due to the bullet nose deflecting at an extreme angle and burying itself into the extractor cut of the cone breech. The flat nose solid exacerbates this situation.  Careful attention to the feed ramp shape and proper release timing will solve the problem.

*  Warning:  No animals were harmed in the filming of this video, only dummy rounds.

Thursday, December 1, 2011

Proper Floorplate Release Latch Geometry and Heavy Recoil




.458 Lott Legend Rifle Part 2

Our peep sighted Legend rifle in .458 Lott offers the utmost in durability, portability, and lethality while still maintaining superior handling characteristics.  Weighing in at 9.5 lbs., this rifle uses our magazine box and follower system which allows for a 4 round capacity in the magazine, a feature usually limited to a cumbersome drop box design.  The magazine box is fabricated from heat treated 416 stainless steel which will not deform under heavy recoil.

D'Arcy Echols & Co. Magazine Box and Tooling

 The sighting system consists of a rear aperture sight (adjustable for windage) that is manufactured in house combined with a NEGC elevation adjustable front sight.  The rear sight aperture can be threaded to accept a variety of different aperture diameters or opened up to a large "ghost ring" for quicker sight alignment.

D'Arcy Echols & Co. Rear Aperture Sight

This system, when utilized by a skilled rifleman, allows useable accuracy which will rival any scope within 150 yards.  More importantly, it is more durable than any scope made today. 

The bottom metal standard on this rifle was designed in house and is machined from heat treated 4140 steel for the ultimate in elegance and strength.
D'Arcy Echols & Co. Trigger Guard and Floorplate