Tag Archives: How to

Excerpt from “Gunsmithing Student Handbook Series”

At the time of this writing there are three books in the Gunsmithing Student Handbook Series.  In early 2018 “Chambering Rifles for Accuracy” was released.  In its first week on Amazon.com it was #1 in two categories.  Gordy Gritters, famed benchrest gunsmith & Fred Zeglin well known wildcat and hunting rifle maker joined forces to create this comprehensive title.  It covers the subject of installing and chambering barrels from simple rechamber jobs, to hunting rifles and the last half of the book is all about benchrest quality gunsmithing.

The excerpt here gives you an idea of how careful the authors are to cover details often overlooked in such books.  Enjoy:

Tolerance Stacking; 
                Everything You Need to Know About Pilots?

Chamber reamers come with two styles of pilots, solid or removable bushing (the later sometimes called a floating pilot).  One is evil and one is practically perfection.  But which is which?  I can tell you that in renting tools to gunsmiths I have found the industry is split on this question about 50/50.  In other words, about half demand solid pilot reamers exclusively and the other half will not touch those nasty solid pilots with a ten foot pole.

It is clear that there is a trend toward the removable pilot reamers.  This is because barrel makers are not all holding to the same production standards.  Some have the idea that a tighter bore is better, while other makers hold close to the “standard” bore dimensions.  Example, .308 bores are .300” on the bore and .308” on the groove.  Custom barrel makers have tightened the bore to say .298”  This will required a smaller pilot as the standard pilots are normally .299” with tolerances of + 0 to – .0005”. removable pilot reamer 

Removable pilot reamer.

The reason for the tighter bore?  In short, it is believed that it produces better accuracy.  This is only true as compared to a loose bore that is oversized, i.e. a groove on a 30 caliber of .309 or .310 will produce lower pressures and potentially be less accurate because the bullet is not fully engaged until pressure bumps the bullet up to match the bore.

For a pilot to work correctly it should be .001” smaller than the actual bore dimension.  In other words, it needs to be a close slip fit.  If a pilot is too tight it will bind and likely break the reamer, and possibly damage the bore.  If a pilot is too loose it will promote chatter.  It is possible to run the pilot on a removable pilot reamer closer to the bore diameter (.0005” under bore diameter is ideal), but it must still slip easily in and out to avoid damage to the barrel or the tools.

A little history at this point might be interesting:  Red Elliot was and still is legendary with old timer gunsmiths as the absolute best reamer maker of the last century.  Near as I can tell he was the first to offer removable pilots on his reamers.  Why did he do this?  Well, he found that there were enough different barrel makers in his day that the dimensions of the bore diameter (where the pilot rides) varied a fair amount. 

So, this problem of bore dimensions changing a little is nothing new.  What about SAAMI standards you say?  I will address that in just a moment, for now lets talk about how Red Elliot handled bushing pilots.

I have seen several of Red’s reamers with bushing type pilots, what we sometimes call floating pilots today.  Red held very tight tolerances on his bushings so that it required a little pressure to slide them onto the reamer, held in place by a screw mounted in the end of the reamer the bushing would not turn once the screw was tightened.  This is contrary to the bushing pilots we see commonly used today, where the bushing is a slip fit with about .0005” tolerance internally.  This tolerance is added for manufacturing ease. Tolerance stacking is not usually mentioned in conjunction with floating pilot reamers, but we are going to take a closer look at it here.

Another source of tolerance issues is the fact that the pilot receiver on the reamer must be concentric (round), and in line with the reamer.  If either of these conditions is not correct there will be problems with the reamer cutting oversized or out of alignment with the bore.  Admittedly, this is not much of an issue with today’s cnc machines.  So long as the operator does not make an error, and no chips get caught in the set-up.  One other possible source of trouble would be a warped reamer (not common).

Now for SAAMI, their standards are voluntary, so obviously any barrel maker can decide whether or not to hold solid to the standards.  Industry standard is plus or minus a half thousandth (+ or – 0.0005”) on the bore diameter.  The bore diameter is the smallest diameter of the barrel, also referred to by shooters as “across the lands”.  The same tolerance applies to the groove of the barrel.  I will leave the discussion of groove depth as we are talking about bore diameter as it relates to chambering tools, groove depth does not affect these dimensions.

Admittedly barrels considered “match” grade or “air gaged” are supposed to be held to a tolerance of .0003” or less total variance, end to end of the barrel.  This does not indicate the actual bore diameter, we are left to assume that it is the standard diameter for caliber.  In the case of a 30 calibers we would be talking about a .300” bore.  What if the maker decides to simply use a gage that works with the bore diameter they are making, say .2995” and it air gages as above.  You have a match grade barrel but the bore is at the minimum size according to industry standards. 

Are you starting to see how bores can vary and still be within standards?

Of course there are those makers who operate outside the standards and make perfectly good barrels.  The point being; different size pilots will be needed to chamber these barrels as was recognized back in the 1950’s and 60’s by Red Elliot.  It’s pretty obvious by now that removable pilots are necessary tools in dealing with variations in bore dimensions.  It should be clear by now that variations in bore diameter of plus or minus .001” or even more, is not that unusual, even though such dimensions do not follow the voluntary standards set by SAAMI.

Solid pilot reamers offer certain advantages over the floating pilot.  First and most obvious there is no built in tolerance between the bushing and the reamer, because the there is no bushing.fixed pilot

 

 Solid Pilot Reamer

Since most barrel makers today are making barrels by the button rifled method dimensions tend to remain pretty steady for a given maker as buttons last a long time if properly cared for.  So if you deal with the same barrel maker all the time chances are a solid pilot reamer will fit the same from barrel to barrel. 

There are other factors that play into the bore and groove dimensions, but that is for a discussion for another book.

One limitation of a solid pilot reamer is that it cannot be changed to deal with variations in bore diameters.  Of course you can have the pilot ground down if necessary to fit a tight bore, but then you would probably need a second or even a third reamer to deal with various diameter bores. 

Everything in life is a trade-off.  Because of the expense of multiple reamers for the same caliber removable pilots are a cost effective answer to the problem.  $10 for a bushing beats $100 or more for another reamer.  There are shops that stock bushings in 0.0002” steps for the popular calibers.  This allows them to match the bushing to the bore every time.

pilot bushingsPilot bushings can be a big investment.

To make the use of removable pilots efficient and accurate, the gunsmith should invest in a set of pin gauges.  These are precision ground pins that can be used to gauge the bore and insure that the correct bushing is selected.  Using pin gauges allows the gunsmith to know what bore diameter the barrel maker is really supplying.

Now keep in mind the pilot has to slip into the bore, so in mechanical terms the pilot has to be about 0.0004” smaller than the bore to slip in without any interference. In most shops the pilot is figured at 0.001” smaller than the bore and rightly so.  Too tight a fit can gall and or leave marks in the bore or stress the reamer and break it during the reaming process.

What happens if the pilot is too loose?

Ninety-Nine times out of a hundred when a reamer chatters (vibrates) in use, it is because the pilot to bore fit is too loose. 

The lack of support when the pilot is too small allows the reamer to move around in the bore, as the tool tries to bite into the steel it grabs hard and because even tool steel is flexible you get chatter as the tool loads and releases tension.  This is the reason that some gunsmith’s insist on having a set of pilots that cover the possible variations in .0002” (That’s 2/10,000 of an inch.) increments.  Keeping the pilot as close to bore dimensions as possible will help eliminate chatter and promote a more precise chamber. 

If you have a pilot that is a perfect match for the bore but is too loose on the inside where it rides on the reamer then the advantage of a close fitting pilot is negated.  To pull the whole concept together…  If you have a .0002” tolerance on your bushing to barrel fit and the same on the pilot to reamer fit, you end up with .0004” total slop on the pilot. 

I can tell you that most people do not grasp this or understand why these tolerances  matter.  I base that statement on 30 years of talking to gunsmithing customers, and the people who call to rent tools.  The comments that shooters and gunsmiths make during our conversations indicate their level of understanding in a hurry.

In general if the total pilot run-out is under .001” then all will work fine and there should be no worries.  This rule holds true for solid pilot or removable pilot reamers.  Long ago I lost track of how many rechamber and barrel jobs I have done.  I can tell you that

Chambering Rilfes for Accuracy, cover

 it is possible to get an accurate job from either type of reamer.  In fact, if pressed for a choice I would say that solid pilot reamers are more accurate on average.  Especially for inexperienced gunsmiths.

I do not make this statement lightly, as I own hundreds of reamers of both types.  This goes back to the understanding of how the tools relate to the barrel.  To reiterate, the one caveat would be that for best accuracy the pilot of the reamer must meet the tolerances of less than .001” run out verses the bore, for all this to hold true.

There is another major factor in how well a reamer cuts and how accurate the gun will be…  The gunsmith must do a good job on the set up for machining.  If the threads are not true to the bore, or the chamber is crooked or oversized, or the throat of the chamber ends up off center, accuracy will be elusive to say the least.

Use of a floating reamer holder is a great way to insure an accurate chamber.  This tool allows the reamer to follow the hole in the barrel without any side pressure that might be caused by minor misalignment of the tail stock to the bore of the lathe.

Whether you plan to build accurate hunting rifles or top quality competitive benchrest and long range guns this handbook has detail descriptions and plenty of clear photos to make the subject easy to understand.  The other titles in the series deal with headspace, the vital counterpart to chambering, check them out here.  More titles are planned for the series.  These are college level training manuals that a gunsmith at any level of experience will value.

Another post of interest on this subject.

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Filed under accuracy, Books, Gunsmithing, How To, Rifles, Shooting, tools

Flathead Valley Community College offers AAS in Firearms.

Learn Skills

Projects that Challenge

Heading into our fifth year, this program started out as a two-semester certificate program created to provide a solid foundation in theory, design and function of firearms. In 2017 the program grew to include a second two-semester certificate. The second certificate will interest folks who are more interested in traditional gunsmithing and custom gun work. The Big new for 2018 is that the Board of Regents authorized a two year degree that combines all the classes into an Associate of Applied Sience (AAS).

Course topics will include firearms safety, manual mill and lathe operation, bench metal techniques, firearms repair, machine tools for gunsmiths and precision rifle building. Stock making, checkering, bluing and other finish techniques are taught along with custom modifications of all kinds of firearms.  Many of the classes have little or no prerequisites, so they are open to anyone who would like to learn and expand their experience with guns, contact the school for more information.

Students who successfully complete the program will be prepared for entry-level positions in the firearms industry and will have a better understanding and knowledge base for owning a gunsmith business. The program contains both lecture and significant hands-on training designed to instill an understanding of the design and function of today’s firearms.

“FVCC has the only Firearms Technologies Certificate Program of its kind in the country,” said FVCC Firearms Technologies Coordinator Fred Zeglin. “Students are challenged to develop skills that are not part of any other program. We are very proud to now offer a two year AAS degree that will jump start a student’s career in firearms.  By partnering with manufacturers in our area we have assembled a program that addresses the needs of the employers.”

Applicants must be at least 18 years old and able to legally own and possess firearms. A background check is required for all students who are accepted into the program.

The program was developed to build upon a foundational machining background, which is provided through the college’s Tier I Machining Certificate Program. Tier 1 Machining . Firearms Technologies Program applicants with industry or previous learning experience may opt to bypass the Tier 1 Machining Certificate Program by requesting testing and/or instructor consent.

Prospective students must apply both to the Firearms Technologies Program and for admission to FVCC. Firearms Technologies Program applications are available online at www.fvcc.edu/firearms or in the Admissions Office in Blake Hall on the FVCC Kalispell campus. For more information, contact Will Richards at 756-4862 or wrichards@fvcc.edu.

Download the application to attend classes

NPR story about the program

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Filed under accuracy, Firearms, Gunsmithing, How To, Pistol, Rifles, Rimfire, Shooting, Shotgun, Sights/Scopes, Stocks, tools

Chambering Rifles for Accuracy

Have you ever wanted to be a gunsmith?

Or, do you just want to know what a gunsmith does to make your rifles more accurate?

This book is idea for both the guy making a living in gunsmithing and the hobbyist who wants to know how.  It’s no B.S. approach is to tell you all the considerations that go into accuracy in a rifle.  It’s not just the barrel, or how its installed.  Things like trigger jobs and the quality of the ammunition certainly play into the equation.

When I went to gunsmithing school we were taught a rudimentary understanding of how to install a barrel.  A simple list of the facts would be:

  • Face the barrel breach square to the muzzle
  • Put the barrel in a four jaw chuck
  • Install a spider on the outboard side of the lathe head
  • use the chuck and spider to dial in the barrel on the bore.
  • Thread the barrel
  • Chamber the barrel
  • turn it around and dial it in again
  • Crown
  • Polish and blue

Very little was taught about headspace, tollerances, throats, crowns or various ways to hold the reamer for better results.  My first year working in a  gun shop in Coeur d’Alene, ID I learned more about this subject than I did in two years of school.  Luckily I worked for a guy who had years of experience and had learned a lot of useful tricks.  Once my mind was opened up the concept of constantly looking for a better way, the flood gates opened up.  I have tried just about every tool and method I could think of or that I was made aware of.  Some things work better than others and often it’s a matter of personal taste as to which method works best in your shop.  With that said, facts are facts.   Some methods and tools really improve the quality of the work performed, sometimes they are no better but the speed the process aiding the working gunsmith in making a decent living.

My Buddy Gordy Gritters and I were discussing this subject and quickly came to the conclusion that we had a book in the making.  Our combined experience is over 75 years working in the gun industry.  This book is #3 in the “Gunsmithing Student Handbook Series”.

I took on the task of describing methods, tools, and all the variables that go into accuracy, no matter who is doing the work.  Gordy took on the task of writing about the methods used for benchrest quality barrel work.  You see there is a substantial difference in the cost of a hunting rifle over a bench rest gun.  The reason for this is simple, time and effort spent on detail after detail when you build bench rest guns.  In short, it cost money to squeeze every bit of accuracy from a gun.

It ended up that we split the book into two parts.  Part I is about hunting rifles and how to get sub-MOA results and not have to sell the farm to pay for it.  Part II is no holds barred, spend all the time and money that it takes to punch holes in the paper that are so close together that it’s tough to tell more than one shot was fired…

Whether you are a gunsmithing customer who wants to understand what is involved, a hobby gunsmith needing to learn or a professional who wants to hone skills that will make you money; This book is for you.

ISBN-13: 978-0983159858

 

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How To: Inlet Your Barrel Correctly

A barrel should be inlet up to the center line of the bore, or in other words, half it’s diameter should be below the wood line.  All too many new gunsmiths and hobby gunsmiths just inlet until they can get the screws into the action and call it good.

There is a simple way to make sure your barrel channel is deep enough so that the bore line will be aligned to the top of the stock.  Take a square and place the outside 90 degree corner of the squared into the barrel channel.  If the square touches on all three sides then the barrel channel is a half circle.  GEDSC DIGITAL CAMERA

If the point at the bottom of the barrel channel touches and keeps the sides from contacting the top of the stock then your too shallow.  Conversely, if the point of the square does not touch but both sides are in contact with the top of the stock then your past 50 percent depth.

Fred Zeglin is working on a series of booklets, “Gunsmithing Student Handbook Series”.  This little how-to tip is just one peek into the upcoming books.  What gunsmithing tips would interest you?

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Filed under Books, Gunsmithing, How To, Stocks, tools

Renting Reamers Can Be a Life Saver

I have heard many gunsmiths say they would never rent a reamer.  How foolish…  Buying a reamer you will probably only use once is a waste of money.  But, more important even than that is the fact that sometimes time is the most important concern.  Renting a reamer is a fast way to get the tool you need and not poor resources into a stagnant tool.

The reason most gunscranks give for not renting is they figure the tools have to be poor quality.  All you have to do is think about business, profit comes from repeat customers, so no rental place will knowingly send you a bad tool.  Next time you have a client breathing down you neck because you have had a job on the shelf too long, consider saving time by renting the tools.  I always pass this cost along to the client, some shops even mark it up a little.  Probably depends on your client base when it comes to the pricing.

fitting a rifle barrel

Reamer snobs make less money and their rifles don’t necessarily shoot any better than anybody else’s.  Here’s to saving time and making money!

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Lapping Scope Rings for improved contact

Wheeler Engineering Professional Scope Install Kit

Pictured here is the Wheeler Engineering, Professional Scope Mounting Kit. The kits are available in more than one configuration.  You can get kits for 1″ scope tubes, 30mm scope bodies, or like shown here the professional kit contains both 1″ and 30mm tools.

Adjustable torque wrench, inch pounds for scope mounting.

Most of the parts in the Wheeler kits can be purchase separately, like this torque wrench.

The torque wrench included in the kit is adjustable and easy to use.  You just treat it like a fat screw driver.  Torque the scope bases to the desired setting.  Leupold suggests: base screws 14 in/lbs, ring screws, 15-17 in/lbs, and 45 in/lbs on the windage screw.   Like most things in gunsmithing there are many opinions.  Personally I have been mounting scopes for over 25 years and I like 20 to 25 in/lbs on the ring screws and about 20 in/lbs on the base screws.  Now that is with a whole host of exceptions.  First the diameter of the screw, second the number of treads engaged.   It should be obvious that if you have less threads engaged that you have less strength, so then Leupold’s suggestions make more sense to me.  However if I have five or six threads engaged, I have much more strength to draw on.  It should be noted that if you over torque a screw you can shear if off.  In the case of scope rings if you torque too tight you can and probably will dent the tube of your scope.

Now that you have the scope bases installed look back at the first picture above, the center tools are installed in the scope rings so that you can see if the rings are properly aligned.  Not only windage but also elevation matter when installing your rings.  The rear base of the system shown here had to be shimmed to align the rings.  Its not necessary to fully tighten the scope rings with the center tools, just snug so that the tools will not slip.  Once the rings are closely aligned it is time to install the lapping rod.

ready to use the Wheeler Engineering scope ring lapping rod.

Place the rod in the rings and leave the ring loose enough so that you can slide the rod back and forth fairly easily, but the rings should not move around or rattle.  The kit includes lapping compound, smear a small amount of the compound on the rod and begin moving the rod fore and aft.  You just need enough compound so that the lapping rod is coated well, the compound is actually going to cut metal away from the rings.

Wheeler Engineering 220 grit lapping compound for scope rings.The compoud that Wheeler includes in the kit is 220 grit, so it is pretty aggressive.  Scope rings are usually made from soft material because they are just a clamp to hold the scope in place and are under very little stress.  Consequently it only took me a minute or two to get the desired results.  Scope rings must be able to clamp down on the scope tube to hold it in place.  If we were to lap too much we would ruin the rings ability to clamp the scope, so more is not better.  When you look at the pictures of the inside of the rings below keep in mind that we just wanted to increase the contact area and improve alignment so that the scope is not put in a bind by the rings and mounts.  The uneven amount of blueing removed in the  pictures here show how the slight misalignment of the rings is repaired by the lapping process.Lapping rings is best used to increase alignment and contact.

The bottom ring on the left of the action (front)  is lapped more on one edge, the rear ring is also lapped a bit more on the rear edge,  this is because the rings were slightly misaligned in elevation.  Now the scope will rest in the bottom of the rings without any tenancy to twist or tip.

I will finish the mounting of the scope soon, check back.

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Filed under accuracy, Firearms, Gunsmithing, How To, hunting, Rifles, Sights/Scopes, tools