View Full Version : bolt action from scratch?.. looking for advice

April 24, 2012, 02:16 PM
hey everyone.. for a project of mine.. i thought about machining a bolt action from scratch... ive seen it done numerous times before.. anyway, im looking to go with possibly a mauser, 1903, or enfield type action.. one of the old military actions rather than the new ones... heck, if i was confident a krag-jorgensen action could be strong enough, quick enough on the reload, and be able to handle modern .308, id consider that route since the krags were very quick and smooth...

my end goal is a .308 caliber scout type rifle, so id like something that can quickly reload, but without the use of a detachable magazine... also, it would have to be a rifle with available blueprints (of course)...

so.. of the rifles i mentioned, which ones would make the best project, have the best end result, and matches the criteria?...

James K
April 24, 2012, 05:01 PM
If you like the Krag action, you might copy the Norwegian Krag, which has dual locking lugs, since the bolt rib bears. The problem is that the lugs are asymmetric, which is not conducive to the best accuracy. Other than that the Model 98 Mauser is hard to beat, but the Remington 700 action would be easiest to make, being basically a piece of tubular steel.

Let us know what you pick and how you are getting along.


April 24, 2012, 05:13 PM
well the mauser 98 is all fine and dandy... but i cant seem to find blueprints for it anywhere... i believe ive found some remington 700 prints but hard to say if theyre backwards engineered or factory... as for the krag, would the norwegian model be as smooth and fast as the american rifle?.. and how accurate, and durable would that be?

April 24, 2012, 05:13 PM
I remember on another forum a fellow who made a rifle M98 type .He used 4340 steel though 4140 will work fine .He took top honors in his country in a competition with it !!! It can be done.

April 24, 2012, 05:24 PM
If you choose to make a Mauser or Remington style action, you will have to broach the bolt ways, somewhat troublesome unless you have a broaching machine handy. Most people who are not set up with a broaching machine choose a "fat bolt" design (a la Weatherby Mark V or S&W I-bolt).

April 24, 2012, 05:52 PM
as for broaching or not.. that would have to depend.. im going more for a fast/smooth action than accuracy.. in fact, im only targeting 1MOA, anything better than that... fantastic, but as long as it achieves atleast 1 MOA ill be happy... since itll have a short barrel, no scope i wont be doing any 600+ shooting... im going to shoot mostly for durability, reliability, and speed

April 24, 2012, 06:17 PM
hmm.. im trying to find more information on broaching the action, what it does, why people do it, and the pros and cons of doing that vs what you call a fat bolt style.. but not finding much with those search terms

April 24, 2012, 11:35 PM
As to broaching:

When you have to cut slots (where the locking lugs on the bolt slide up and down the action for example) you use a broaching machine. Its like a course file, the width of the teeth the size of the slots you want to cut.

The same method you use to cut key way slots in a cylinder.

You make light cuts, and the broacher is moved deeper into the slot by a means of shims. Keep adding shims until the broacher cuts the slot the depth you want.

Take the bolt out of any rifle action and you can easily see the different slots and such you have to cut inside the bolt.

It's time consuming to say the least.

You could do the same process if you have a shaper. Which is a reciprocating arm with a lathe cutter that does the cutting. Not many machine shops use shapers any more.

You start this project you'll see why most manufactors have gone to investment casting.

Jim Watson
April 25, 2012, 12:12 AM
I doubt a mass production broach operates that way.
I have seen pictures of factory broaches several feet long with many cutters, each a little larger than the one before. One pass through a starter hole cuts to final shape and dimension. Pedersoli rifles that way. So did Smith & Wesson in the good old days. Single cutter rifling was too slow and buttoning an asymmetric forging does not give uniform groove depth. Of course they did a lot of lapping when done to get rid of the broach marks.

Mr Garand not only designed autoloading rifles to be shot, he designed them to be manufactured, based on his background at Browne and Sharpe. The Hot New Thing in 1930s manufacturing was the multiple step broach as an improvement over lathes, mills, and shapers. So he designed his rifle to make maximum use of broaching, minimum single point cutters.

April 25, 2012, 04:52 AM
I used to run a big old 1952 American Broach machine.I have a great appreciation for the broach.It is a fine,efficient way to produce parts.
However,I think the actions mentioned were first forged.There is a limitation with a broach.The gullet of each tooth must have enough room to carry the chip for the entire length of cut.If you run out of room for the chip,the broach will break.Might be you could get something like a woodruff cutter in to pre-machine some of the mortice in the open part of the receiver to shorten up the cut.

A broach to do that job might be 3 ft long,and round to pilot a round hole through.It would cut both races at the same time,and have a shape like the bolt with locking lugs.If you could solve the chip clearance problem,on a broach machine,you would raise the ram(about 8 in dia hydraulic),load your part in a fixture on the table,feed the pilot end of the broach through the part,and lock it into a chuck on the ram,turn on the coolant,and lower the ram.In seconds,the cut is done.

With the fat bolt designs,its not a problem,the length of cut is short.The AR type receiver extension is a perfect broach part,no problem.

kraigwy is right,the old single point shaper might be successful,as the chip can escape the cut.The rigidity of the bar holding the bit may be an issue,as you are working in a roughly .700 dia hole.

Nesika Bay says no problem,stands it up and wire edm s it.Great way to build,you can use pre hardened steel,no warp.If you had enough z travel,a sinker edm would be fine.

A steel you might consider if you can scrounge some,17-4 PH.It is a precipitant hardening stainless.Its not bad to machine if you have a good rigid machine.What is cool about it(get real info on heat treating to spec) but you bake it at 900 f or so and it gets up into 40 something rockwell "C",its good,strong stuff.No warp at 900.No quench.

I got involved in a Reminton Hepburn cast kit project,I made up fixtures to hold and guide common keyway broaches to finish cut the mortices through the receiver.Worked great!

There are crossover type actions,bolt actions that borrow some of the tech from the AR,might be relatively practical to make

James K
April 25, 2012, 11:04 AM
Please don't misunderstand, but I wonder if Jason is really set up to make a rifle action from scratch if he is not familiar with standard machining techniques. The equipment to do that kind of work is not cheap and to spend tens of thousands of dollars on the machines and tooling to make one rifle might be fun and a challenge, but hardly cost effective.


April 25, 2012, 11:34 AM
Please don't misunderstand, but I wonder if Jason is really set up to make a rifle action from scratch if he is not familiar with standard machining techniques.

I'll agree with that, and not just the broaching topic.

It would be best just to find an action, true it up, and go from there. I've put together a lot of rifles, made some dern nice target rifles but I wouldn't attempt building an action.

April 25, 2012, 11:52 AM
i know what broaching is, and how its done, my question what what benefits does this have vs not broaching? to determine which would be the best solution for the purpose of the rifle

April 25, 2012, 12:38 PM
hmm.. found some blueprints for the mauser action... had an idea of using steel rod with a square groove cut in it to fit the broach... and have different pieces, with the groove cut to different depths to broach the receiver...

on the other end of the steel rod i could drill and tap it to fit lugs thatll ride in the raceway on one side to help align the broach as it cuts the raceways in the other side... and i guess this steel rod tool for holding the broach would be something to keep, as a tool to simplify broaching other receivers should i decide to make more for myself (i doubt i will though)... but seems for the front-locking actions broaching would be the way to go... and i shouldnt make my raceways TOO tight.. otherwise a little dirt or debris could cause the bolt to "stick" or be rough to operate...

as for these mauser blueprints, i need to recreate these in 3D, and shorten the receiver and the bolt for a "short action" in .308.. since ive decided on .308 winchester for this project there would be no point in building a full-length action as it would just be unused weight

April 25, 2012, 12:40 PM
it seems though that i would prefer a small ring mauser... large rings are stronger, better for magnum calibers, and other larger recoiling calibers, but the rifle im looking into is a .308, so i dont need the extra weight or security, so i think i would rather have a small ring mauser to save the weight, its already a bit shorter of an action... so i think for my goals, i would benefit more with a small ring vs a large

April 25, 2012, 01:46 PM
thought this machining from scratch could be quite the pain in the rear... so anyone familiar with these parker-hale M98 receiver castings? these should have the raceways there... needing to be cleaned up, filed to proper specifications, threads cut, etc.. seems like this might be an easier start than machining from scratch, what do you think?

April 26, 2012, 07:46 AM
While the 308 is not a magnum caliber it is a high pressure round, and typically not recommended for small ring Mausers.

April 26, 2012, 11:56 AM
yeah.. thats true... whats the generally recommended pressure limit for the small ring mauser? anyone know?

April 26, 2012, 12:14 PM
I don't know if anyone mentioned it earlier, but have you considered wire edm for the bolt raceways? Much more precise than broaching. Or you could just eliminate the bolt raceways altogether and consider a fat bolt design like T/C and Weatherby use on some of their rifles. I have some CAD files where I designed some actions. I think they are larger than what you're looking to create though.

James K
April 26, 2012, 06:51 PM
Fat bolt designs are usually multi-lug, which would IMHO involve even more complex breech work than necessary for the Mauser 98 action. Even if the bolt locks into the barrel or barrel extension, I assume you (Jason) will want to produce a shootable product, not just an action, so if your bolt locks into the barrel, you will have to design and make the barrel breech as well.

The small ring Mausers were made for cartridges in the 40-45k psi range. They have been used for rounds exceeding that, but usually are not recommended for rounds in the 60k range like the .308. Of course, that is assuming an old action with early 1890's metallurgy, so it would not apply to a new action made from modern steel alloy. Still, the 98 action has features, such as the way it handles gas escape, that the early actions don't have, and an exact copy wouldn't either.

I am not very familiar with EDM, though I know generally how it works. But it seems to me to be a fairly expensive setup.


Jim Watson
April 27, 2012, 08:56 AM
I would think a Kar98a - a '98 design but with small ring - would be suitable if made out of modern steel like 4140. Also, Frank DeHaas pointed out that the Husqvarna actions advertised as modernized Mausers were modernized '96s, not a '98 pattern.

April 27, 2012, 01:21 PM
yeah.. i was listening to someone else mention the small ring 98s as well.. that does seem like the best choice for an action to save weight while still safely being able to manage the pressure of .308, so i really like that idea for an action...

i heard its possible, though much, much more time consuming to use a jig with progressively finer files to file the raceways into the action... has anyone seen someone do this before?... it would take quite a while though

anyway though.. its strange someone mentioned EDM machining... i was actually debating whether or not i should get into that as a replacement to mechanical machining for metal parts... ive been thinking about setting up a small three or four axis machine

April 27, 2012, 01:56 PM
i heard its possible, though much, much more time consuming to use a jig with progressively finer files to file the raceways into the action... has anyone seen someone do this before?... it would take quite a while though:eek:

You’re still young. Give it a try ...:D

Kidding, kidding ... well, mostly.
Seriously though, specialty tools are time savers, or "get into places easier" thingies. Check out some of the improvised munitions our military has come across over the years. Some of it is truly amazing ... what someone can do with hand tools and a LOT of time.

April 27, 2012, 02:22 PM
my question what what benefits does this have vs not broaching?

If you want the raceways you need to cut them.

They are cut by broaching since there is not actually any other practical way to cut long grooves on the inside of a cylinder the length of the cylinder.

you might be able to figure out a way to EDM them, but that s likely to be just as hard to do on a hobby budget as broaching.

And the 'cut and advance' method described earlier is what a shaper does.

They are rarely used outside of small hobby use.

A cut rifling machine is similar in concept.

April 27, 2012, 08:45 PM
i guess what i was really trying to ask about broaching vs "fat bolt".. is almost every bolt action ive seen the internals for so far have been broached.. so when i think of a bolt action receiver, i automatically imagine broached raceways... so im looking for a description, or photos of what exactly the "fat bolt" style is?

April 27, 2012, 08:56 PM
i get the impression that "fat bolt" just means the lugs on the bolt do not extend beyond the radius of the body of the bolt, meaning the locking lugs in the receiver would have to stick out from the inside wall of the receiver, rather than being flush, and raceways cut the entire length of the receiver...

it seems this would be just as durable, just as reliable, but there would be less material in the receiver, and therefor a lighter receiver? is this true? or am i missing something?

April 27, 2012, 10:11 PM
Since you’re looking for speed/reliability this article about rifles for dangerous game might interest you. It’s a kinda general in scope, but makes mention of several actions, and some of their pros/cons.


April 28, 2012, 11:27 AM
BTW, the wisecrack about you being young. It wasn’t meant as an insult... more along the lines of you have more time than most here.
As you get older, saving time becomes more important if you’re trying to get stuff accomplished, ya know. ;) And the more time you save on work, the more you have to waste on fun stuff:D.

I’ve actually used the "file method" more-or-less. Prototyping a race car part ... it required a channel running down a bored hole in a block of aluminum. I drilled a hole where the channel would be, bored the hole, and then squared it up with files and a jig. It took forever and was a real PITA, and that was 4" long and in T6, but it got done with the tools I had at hand... wouldn’t even think about doing it in steel. That’s what real machinists and money are for.;)
I’m just a hobbyist.

April 28, 2012, 01:41 PM
as long as i had a flat file the right size.. some jig so it would only move perfectly back and forth, and the project itself was pretty secure, i might be able to use some sort of recipcrocating device to do most the work

April 28, 2012, 01:59 PM
all that being said.. a small broach for the size i need isnt that expensive... not expensive enough to go through all that trouble... i should just a get a metal rod to fit the inside of the receiver, cut a channel for the broach to fit in, and use a shop press to push it through.. just isnt worth the extra time and effort to try to use files when this is still a sub-$100 setup not including the shop press which i already have

April 29, 2012, 01:25 PM
On the fat bolt, you're basically right. Weatherby utilizes this design on either their Mark IV or Mark V, can't remember which one, maybe both. The T/C Venture also has a fat bolt and I've seen a couple of 50 BMG actions that use this. Just google the image for the T/C Venture and you'll see it beside a Remington bolt. Machining the recess for the locking lugs could be tricky I guess but shouldn't be a horrible undertaking.

April 29, 2012, 06:54 PM
Go for it.I would not buy anything real expensive,though.I'm thinking you are hungry to learn and gain some experience,and you have the confidence to try.
So it is the destination vs journey thing.There is value in learning to put a good .700 or so dia hole through 6 in of steel.If you are going to use a mandrel to drive a keyway broach through,you will get to mill the mandrel.

Now,truly not to be negative,but I have enough respect to tell you where some quicksand is:With a broach such as a keyway broach,typically you would be broaching through a pulley or gear or something.Say an inch,maybe two in thickness.That will determine how much material is in the chip,and how many cutter teeth are engaged in your workpiece.Behind each cutting edge is a gullet.That is all the chip clearance you have.The chip is captive through the cut.If you are broaching a length of 5 or 6 inches,an issue is going to be the gullet will not have the room to accomodate the chip.You cannot back up and clear the chips.This same lesson about chips filling up the cutter will be important later when you are chambering.It does not work out with a chamber reamer,either,if you do not clear the chips along the way.

Another concern with a long cut using a keyway broach,with a shorter cut,only so many teeth are engaged,3 or 4,maybe 5.Each adds its own cutter pressure you will overcome with the press.With a 6 in cut,you may be pulling 10 chips.There is a limit to how much force your broach will take.

I think the length of cut and broaching limitations helped inspire the multi-lug fat bolt design,and later the receiver extension design of the Stoner AR.

I suggest you study the Weatherby fat bolt,and look close at the AR design.Study the Savage 110 and the Rem 700,See how a bolt can be fabricated by pinning a bolt head on a piece of tubing.Look at the Tubbs rifle.Then there are a number of benchrest actions that may give you some good ideas.

Some more good practice,if you would like to gain experience,find a Yugo M-48 Mauser action surplus,Then thread and chamber a .308 barrel for it.Put it together,go to the range and I suspect you will find it does not feed real well.You will gain some knowledge and experience and understanding of mag box stacking,feed rails,followers,etc.It will be a great education.,and it will be valuable as you machine and shape your own rails.

For practice,you could build a .22 or even a 32 H+R bolt gun .I think a .303 brit bbl would be about the right bore dia.

Frank De Haas has some single shot rifle action designs for the home machinist.

I hope you make chips and build something!!Don't get discouraged if you take a few detours or find a dead end.Rilke wrote something about striving to be "Defeated by greater and greater things"

Or,you could buy a Savage or Remington action and build a 308 that would shoot real well.

Keep us posted as you learn,I'm open to having you teach me something.