Precision Barrel Fitting, Part One

I think it appropriate to begin with a bit of biblical theology as I understand it. Here goes: The Old Testament emerged from the words of Hebrew prophets. The New Testament grew from the Disciples of Christ. Together, the two are the basis for all Jewish and Christian religion. That brief summation might be over simplified. To say the least, it is definitely the oddest of ways yet attempted to start off an article on gunsmithing. There-in other Testaments must be added. Colonel William S.

Brophy authored The Springfield 1903 Rifles, considered the bible on Springfields. The same Brophy composed another bible, Marlin Firearms: A History of the Guns and the Company That Made Them. Both belong in your reference library right next to Hatcher’s Notebook. Add to them another unchallenged bible, Mauser Bolt Rifles by Ludwig Olson, The Winchester Book by George Madis, Remington: America’s Oldest Gunmaker by Roy Marcot and you’re beginning to sense a trend here.

So far, I haven’t mentioned The Complete Illustrated Guide to Precision Rifle Barrel Fitting by John Hinnant. Without question, it is recognized as the bible on the subject To order, call John Hinnant or Dave Manson The cost is about $39.00 and worth every cent. It dates back many years but still takes the great mystery out of operating the machine tool used more by gunsmiths than any other.

To order, call South Bend Lathe by the publishers of American Rifleman and Precision Shooting, Shilen Rifles, as well as several dozens of greatly respected precision toolmakers and ‘smiths. It also provided the road map that kept yours truly from fouling up big time way back when I first tackled a rifle barreling job. I have received permission from its author to borrow significantly from his work in preparing and illustrating this article. As entitled above, this will not be a pure, condensed

The company produces lathes designed from the ground up for gunsmithing. They are far more expensive than the one pictured here but, depending on your specific requirements, the 1002 could represent a considerable savings. version of the Hinnant work. That approach, in my opinion, assumed the serious risk of accidentally omitting even one or two of the vital details he provides. Since omission is not to be justified, a better course has been chosen.

In this and all the articles to come on this specific subject I will be cherry picking the book in sections. I believe this will serve handsomely to encourage members in recognizing the total excellence of John Hinnant’s 304 page classic. Within those pages are tables of valuable information that deserve a prominent place on your shop wall. For example, there’s one defining lathe cutting and feed rates for a variety of materials. Two more pages express fraction-decimal-metric and millimeter-to-inch equivalents.

Quotations appearing here and in the Guide area attributed to the well known authorities who made them to emphasize a point being made regarding a specific rifle. These quotations are not to be taken lightly. Remember them verbatim and from which source they originated. Nearly needless to say but being said anyway is barrel replacement, chambering and fitting calls for acquiring a useful knowledge of how to work with a lathe.

True, you need not be a master machinist with years of experience to acquire enough know-how to apply the practices spelled out in the Guide to your advantage. I do advise you not invest in a multipurpose machine tool. Too often, these are incapable of delivering the close tolerances that come almost automatically from a lathe designed for gunsmithing. If the cost of one causes you to pause, don’t purchase it initially.

I was faced with that exact problem, so I laid out the bucks for a small, Austrian-made one to get familiar with lathe operation. I still own it and use it for fabricating small parts for firearms and probably will never part with it. The large gunsmithing lathe I subsequently purchased for my rifle work I sold many years ago.

It was a sad farewell, but the state in which my business was located outlawed hunting with a rifle, leading to such a major decline in my riflesmithing practice the big lathe wasn’t paying for the space it was taking up in my work area. In addition, it had outlived its usefulness as a tax deduction and was replaced with a well built, table mounted milling and drilling machine tool equipped with an X-Y table, the deprecation of which remains an entry on my 1040.

I’ll suppose that you have no desire to or haven’t yet squirreled away sufficient funds to purchase a

small lathe to practice on. You can still bone up on lathe operating. Among those ways is How To Run A Lathe from South Bend Lathe. Many, many other possibilities will appear on your computer monitor after directing your browser to "Machine Tool Operations," or "Lathe Operations." If your nerves remain a wee bit rattled about lathe operations and hands-on is the only way to settle them down, check into any adult classes going on in machine tool operation at a high school or community college.

If nothing turns, ask around at nearby machine shops. Get lucky and you’ll find an owner who might be willing to let you sit in beside one of is lathe operators for some of the hands-on experience you need to calm yourself. The good news concerning making significant investment in a gunsmithing lathe is twofold. First, like my milling/drilling acquisition the investment can be depreciated as years pass. In other words, written off at tax time.

Second, in subsequent articles there will be at least one dedicated to the hand tooling now available for critical barrel fitting work. Getting Started There is no substitute for a good barrel vise. There’s more than one good barrel vise on the market, so you have a choice. If you have any doubt the one chosen could be better, don’t risk the purchase. Hinnant shows you how to make your own from scratch and his design results in a vise proven successful, meaning no failures, for over 20 years.

Check out the components. No assembly bolt smaller than one inch in diameter is used. Exception: If the barrel requires a wider base plate (1) and sliding plate (2) with an assembly bolt positioned at each corner, nothing smaller than ¾-10NC is recommended. Page 17 of the Guide details the procedure for locating and drilling perfectly aligned holes in the base and sliding plates. A boring bar you can fabricate appears on page 20.

Boring comes into play to enlarge holes when drills large enough to do the job aren’t available. Boring also is applied to enlarge holes in the sliding plate to avoid the possibility of the plate binding. Clamp Blocks (10) are drilled and bored to a 1½" minimum diameter holes simultaneously in an independent 4-jaw lathe chuck. Place a 1/8-3/16" thick cardboard spacer between the blocks prior to the drilling. This will eliminate an interrupted cut, known to be hard on tool points.

Follow this drawing to make one or head out to your nearest industrial tool supply store and lay down the dollars. Either way, you’ll be needing one. These hold the split bushings described in the text that protect the barrel finish during removal and reinstallation. The barrel vice’s split bushings (#4) can be turned, drilled and bored from a variety of materials, such as hardwood, high density plastic, brass or lead, though Hinnant’s preference is aluminum.

Round scrap can usually be found at a metal salvage yard, or square or rectangular shapes can be secured in a four jaw lathe chuck and turned. The final hole in the bushings should equal the diameter of the breech plus the thickness of a cardboard backing from a writing tablet. Before the split bushings are used the cardboard is removed, coated with rosin and reinserted between the barrel and the bushings to prevent them from scratching the finish or slipping.

The interiors of straight-walled bushings do not serve tapered breech rifles, such as the Remington 700 and Winchester 70. True, they must be drilled and bored larger than the breech and cardboard insert, as were the straight-walled bushings. Then the breech and any receiver ring present have to be coated thoroughly with epoxy release agent (paste car wax makes a dandy substitute.)

The bushing is then slipped over the breech. Fill the space between the barrel OD and the bushing ID with epoxy. Acraglas or Acraglas Gel laced with aluminum or fiberglass filler is recommended. Once the epoxy has set, gently tap the bushing off. Tap toward the muzzle and provide clearance for the cardboard by wrapping the breech with a couple of turns of masking tape. Cut the bushings in half, dress any rough edges with a 0-cut file, sand them smooth and they’re good to go.

Additional, specialized instructions for preparing clamp blocks for Ruger #1 and #3 rifles appear on page 24. The blocks are drilled and bored as already described but the left side of each has to be machined to provide clearance for the forearm hanger bracket. The bracket is cast to be integral with the receiver. This requires the receiver be unscrewed a little at a time. Note, Ruger barrels, rifle or otherwise are notorious for being screwed in very tightly.

Getting one started out very often makes the use of an extension to the receiver wrench mandatory. Due to this dedicated love affair, extreme attention must be paid to not allow the barrel to slip in the vise. This can require the vise to be loosened and retightened three or four times before the barrel is loose enough to be unscrewed by hand. One more thing: To prevent damage to it or, worse, the receiver, the extractor has to be removed prior to making any attempt at separating the devoted couple.

If you feel uncomfortable about your machine tool skills and tackling the fabrication of this rifle vise, Brownells offers one to erase your concerns. Next step, the action wrench. AG