Building A Custom Mauser, Part Three

In parts one and two of this series we have shown how to prepare a Mauser action rebarreling and finishing. The action has been extensively reworked, drilled and tapped for scope mounting and checked for safety. It’s now time to add our most critical component—the barrel. Before starting to work on the finished action I give it a bath in very hot water and dish detergent. Using an old toothbrush I scrub the action thoroughly inside and out, especially the barrel thread, lug areas and bolt raceways.

When finished, I dry it off using paper towels and compressed air. There is no worries about rust as I apply a little fi lm of oil after it’s dry. This gives a clean slate, so to speak, to begin assembly. I started writing these articles in a list form because I felt it would be easier to assimilate all this information with a logical approach. Bearing in mind what we want to do next and how we want to do it is good practice so we do not inadvertently omit anything.

In the beginning I promised to use hand tools whenever possible for this project. Brownells and Midway USA comes to our rescue with short-chambered barrels to fit the 98 Mauser. It wasn’t too long ago that these types of barrels were not available. With a short-chambered barrel we only need to use a finish reamer, available from Dave Manson Precision Reamers (mansonreamers.com), to hand chamber our rifle barrel without the use of a lathe. Barrels are shipped in hard cardboard packing cases and must be sawed open.

I slap mine on a band saw and open one end. When you get the barrel in your hands the first thing to do is wrap the threads with masking tape to protect them. Check to make sure you have the correct chambering for your application. The barrels are usually stamped at the end of the chamber, however, the last one I opened didn’t have any markings at all on the barrel itself! The cardboard tube was marked but that doesn’t guarantee what’s in it. Use an old case or your headspace gauge to make sure.

I chose the .35 Whelen for this barrel installation. I believe that the The author was able to purchase these components on special from Midway USA for less than one hundred dollars. beginner should use a .30-06-length cartridge for the first several rifles. Why? Because the 8mm Mauser head diameter is 0.473 inches, the same as a .30-06 and cartridges based on it. The length of a Mauser case is given as 2.244 inches. The .30-06 is 2.494, a difference of 0.05 inches.

With the magazine box I obtained from Numrich Gun Parts Corporation there was no problem using the longer length cartridge. If you use the original 98 magazine box you may have to grind a little off the edge to make it long enough to feed these cartridges properly. It is best to fi le off 0.040 inches from the rear and 0.020 from the front to give an approximate total length of 3.370 inches if you need to. Specs for the .35 Whelen OAL (overall length) are 3.340 inches.

This will cover almost any cartridge suitable for this action. Yes, you can chamber the big magnums and .500 Jeffery and all sorts of cartridges in this action, but the bolt face and rails must be extensively modifi ed by someone who knows exactly

It should be a nominal 0.620" and match the receiver’s depth to the barrel shelf. The barrel shoulder should rest lightly on the receiver face. If there is a problem here, a gunsmith with a lathe must be consulted. By "chasing" the threads and using anti-seize paste on both the barrel threads and receiver the author has not had any problems installing his barrels. what they are doing to make it right. For now, let’s keep it simple.

The threaded portion of our barrel from the chamber to the barrel shoulder is a nominal 0.620 inches. Measure your shank and measure the action with a depth caliper. These measurements must coincide or a trip to, our buddy, a gunsmith who owns a lathe, is in order. If there is a problem a little metal taken off the threads or the barrel shoulder will fix things in a hurry. This is not an expensive job and can only be accomplished on the lathe.

The chamber end needs to rest lightly on the shelf made for it inside the action and the barrel shoulder needs to rest lightly against the end of the action or this extra space can cause feeding problems and even problems with safety. This is where "blue printing" the action comes into play. Facing the action and truing the barrel shoulder for a perfect fitis what it entails. So far, all the short-chambered barrels I’ve tried have fit very well and no further modification was needed.

Will accuracy be affected by being a hair out of true? Maybe, but for our hunting purposes you will never notice the difference. I like to try the barrel in the action to see if it will fit without binding or galling. You may not necessarily be able to tighten it all the way into the action with just hand strength but you should be able to go a ways without too much pressure being put on the barrel. Here is where a 98 Mauser action tap comes into play.

It is a tool available from Brownells and if you are making more than one rifle I heartily recommend having one on hand. Even if the barrel seems to go clean, I always tap the threads just to "chase" them and have never had a problem with initial fitting of the barrel. How long do you want your barrel to be? Many experts recommend 22 inches as being ideal for standard, not magnum, cartridges.

I have never been a stickler and I prefer a 24-inch barrel, which is the length that most of these short-chambered numbers come in, however, many of us will want anew crown at the least and a few inches whacked off at most. Brownells offers a hand-crowning kit that has been approved by a lot of the people that have used it. I am not one of them. It probably works but I haven’t tried it. I have never been able to shorten a barrel with a hacksaw that remotely resembles a 90 degree cut.

If I want my barrel chopped off and recrowned I always go to the lathe. It just seems to me to do a more precise job. Most gunsmiths don’t charge anymore than around fifty bucks or so to do this and I think it’s well worth it. Also you can get any kind of crown that you want from eleven degrees, hunter, or recessed.

At this point take a stone (I use a semi-pointed coarse stone made to be chucked in a drill that I obtained from a local machinist’s supply house) and by hand, go around the edges of the chamber breaking the 90 degree angle that is common there. Barrels area lot softer than you may think. Don’t over do it and try to make a knife edge, but simply bevel the chamber face so a case will not hang up on a sharp

This step is best done before the barrel is installed on the receiver. This allows working through the receiver with the barrel attached to the rifle. corner when feeding—very easy. It’s not difficult to forget this step and you can do this after the barrel is fitted to the action, but, trust me, save yourself some aggravation and do it now. Clean the chamber after this step to get rid of the small amount of metal dust it may produce.

Here, I would say that an air compressor is a wonderful piece of equipment to have in any shop but the same thing can be accomplished on small jobs like this with a common can of compressed air available in any camera store. Clamp the barrel in your barrel vise, coat the threads with anti-seizing paste (available from Brownells) and start the action onto the threads. For this operation the barrel does not have to be held with the hydraulic press as a strong vise will do.

Attach your action wrench and turn the action onto the barrel with hand pressure until it stops. Usually it is not difficult to do. Actually, the action should go very easily with the wrench attached since we have "chased" the threads with the action tap and are using antiseize paste. I drop the wrench at the last moment leaving it in the air until I know it only has a little more than a quarter turn or so to go. The weight of the wrench will snug the barrel down perfectly.

This is all the torque you need to seat the barrel. Go ahead and check. You won’t be able to turn it out with hand pressure alone. If you’ve made sure your barrel shank fits in the beginning, you’re done as far as barrel attachment is concerned. If we were headspacing this barrel using a lathe, the action would not be attached at this time and a lathe would take over. Hand chambering is a little different and Ifi nd it easy to do. 35 Whelen used to chamber the barrel.

The author recommends chambering standard .30-06-length cartridges for your first couple of custom rifles. After you gain experience, magnum chamberings can be attempted. Check to make sure you have the correct chambering in anew barrel by using a cartridge case or a Go gauge. The Manson finish reamer is attached to along-shanked T-wrench to enable working through the action. The barrel, locked in its barrel vise, is clamped in a solid bench vise (usually at 90 degrees) and the reamer loaded with cutting oil.

I use Liquid Wrench for this application, applying it several turns at a time to start. You will feel it digging in. DO NOT REVERSE YOUR REAMER! Reversing a reamer can dull and damage it. Continue turning in a clockwise direction and pull the reamer out of the barrel to clean off the chips. Use Go and No Go gauges to check your

Tools to handle this job can be purchased from Enco and B-Square. progress. The extractor does not have to be removed if the gauge is tucked into it like a cartridge case, but I usually take it off. This means the gauge will either fall out when the action is upended or have to be pushed out of the chamber – gently—with a cleaning rod. These gauges are not tools to be rammed into the chamber with the bolt. Only gentle pressure should be used to check headspace.

I know some recommend turning the reamer a full four turns before checking, but much better safe than sorry on this operation and it doesn’t take long to do the check. Different barrels from different manufacturers need a different number of turns on the reamer. It seems that some "short chambers" are very short and others area little long needing more turns of the reamer. Use your headspace gauge as a guide, paying particular attention to how far it protrudes from the barrel when you start the process.

Also, watch where the chips are located on your reamer after you take it from the action. When most of the chips are near the shoulder portion of the reamer you are very close to finishing. Blow out chips with your air gun before measuring. The smallest obstruction can give a skewed reading. Remember, headspace should be within 0.006 inches or slightly less. This weight gives a rock-solid platform for shooting in the field. Acetone will remove any oils and leave the barrel completely dry.

It is best used outside to protect from dangerous fumes. Use gloves and remember acetone is extremely flammable. Oxpho-Blue, available from Brownells, will leave a nice finish if used according to instructions. I prefer a little less, but for a hunting rifle minimum headspace is not a good idea since ammunition must feed effortlessly and smoothly every time. Keep going slowly until the bolt will just close on the Go gauge. At this point try your No Go gauge.

The bolt should not go home and should hang up around halfway closed. If it’s not at least halfway ream slightly more until it is.

Nice going! You’ve just chambered your first rifle. Now is the time to place a witness mark on the barrel and receiver with a pointed punch. If you ever want to remove your barrel this mark will allow you to replace it exactly and maintain your original headspace. This is also the time to stamp what cartridge this barrel is chambered for. Note this is a Federal requirement for gun builders. B- Square makes a handy little jig to hold stamps in line over the barrel.

Inexpensive stamp sets can be purchased from outfits such as Enco. If you don’t want to invest in these tools a gunsmith will probably charge around twenty-fi ve dollars for this job. Contrary to some of the artists who will never allow their custom rifles to be fi red, I take mine to the range in the white. If I don’t shoot it, I don’t own it. This is the reason I saved the original stock.

The barrel channel might not fit the new barrel and may need to be hogged out a little, but this stock can be used to test fi re any other Mauser rifles we are working on. Insert the barreled action in the old stock, point it downrange and attach it to your rest with bungee cords. Cover with a sturdy piece of canvas and with along string tied to the trigger give it a yank. Use factory ammo for this test.

It’s probably not necessary to go through this process if you’re sure you’ve measured your headspace properly, but better safe than sorry. Also, I don’t recommend a public range for this kind of test unless you want to be labeled "That Nut with a Mauser" and have a heart-toheart talk with the range master. The finish of your rifle is now completely in your hands. Rust bluing, hot bluing, Parkerizing, and painton finishes are all an option.

For this project I used a cold-bluing method from Brownells called Oxpho-Blue. This product leaves a more black than blue finish, but Ifi nd it attractive and easy to use in a home shop. Our action is already polished to 320 grit. I use a shoeshine method to polish the barrel. Back your abrasive paper with duct tape and cut it into useable strips for this process.

Go up and down the barrel sort of catty-cornered as you polish, starting with 220 grit and working to 320 trying to take out all the previous sanding marks. I don’t polish any further than this because the Oxpho-Blue seems to hold better without a mirror finish. Using the directions that come with the bluing kit and repeat the process until you are satisfi ed with the outcome. One option is to leave the action in the white.

I can only recommend this if the action was in cosmetically good shape to begin with and highly polished to 400, or even 600 grit. The German actions are made of a steel alloy supposedly containing some amount of copper resistant to rust. Not being a metallurgist, I took this route on a model 96 Mauser years ago and have not had rusting problems as long as I take care of it with light oiling. As a bonus, the highly-polished action and black barrel makes for an interesting look.

The last step in finishing your rifle is deciding what kind of stock it will wear. I love wood stocks and like to shape and apply any number of oils and such to bring out the wonderful grain and beauty. I guess every gunsmith has their own pet way to finish a wood stock and I freely admit to have stolen all the old master’s methods and put all of them together to make them my own. I’m still learning.

My checkering skills are rudimentary but I still like to pick up a rifle with sharp checkering and a smooth wood finish. That being said, a good synthetic stock is much easier to handle for the first-time enthusiast. Most of them require very little fitting (stock fitting has been covered elsewhere in countless articles and books) and they have all the advantages of stability, ruggedness and, sometimes, lighter weight that makes them dear to the heart of hunters throughout the land. For this project I got lucky.

Midway USA had a special deal offering a free Fajan synthetic stock included with the purchase of a short-chambered Adams & Bennett barrel. This gave both barrel and stock for less than one hundred dollars. Not bad! I had used one of these stocks before. It came ready-to-go with sling swivels and a hard-rubber recoil pad attached, weighing in at 28 ounces. The stock I used for this project weighs 38 ounces on my little home scale, quite a difference.

Still, you I couldn’t beat the price and I think these stocks are strong enough to run over with a pickup truck and still be usable. My only gripe is the weight and the fact that bedding compound, such as Acraglas, will not stick to them. Personally, I like a hunting rifle for most applications, like deer and such, to weigh eight pounds ready-togo with scope attached. Our Mausers will be heavier than that no matter if regardless if a wood or most synthetic stocks are chosen.

Stocks weighing less than two pounds are far and few between and I question the stability of some of them. Since we are the masters of this project there is nothing wrong with making up a wood stock and synthetic for the same rifle if we want to. As long as you can obtain whatever accuracy standard you’re comfortable with, why not? Ladies and Gentleman, we’re done. Mount your optic and get sighted in for this season. Good luck and thank you for reading.

I understand that many of you are seasoned professionals and many of you are newcomers to this world we call gunsmithing. Please take what you like from these articles and use your skills to build on this information. If someone has a better way to do things I’d like to hear about it, hopefully as a great article published here in American Gunsmith. Remember, in the beginning I said I would skin my own cats! Source: Dave Manson Reamers Grand Blanc, MI 48439 mansonreamers.com G