Print Page | Close Window

What do you think action blueprinting is?

Printed From: The BaitShop
Category: The Library
Forum Name: The BSB Archives
Forum Description: The cream of the BSB crop! When a topic of discussion becomes a true resource, it ends up here so that any sportsman can quickly look up the most useful information on any subject!
Printed Date: 02 December 2023 at 08:11
Software Version: Web Wiz Forums 11.10 -

Topic: What do you think action blueprinting is?
Posted By: Fiftydriver
Subject: What do you think action blueprinting is?
Date Posted: 12 April 2004 at 16:14

To all,

Just talked with a couple basement gunsmiths in my area that wanted to come up to the shop and see what my set up was like.  We got on a conversation about building extreme accuracy rifles and one fella informed me that his rifles shoot in the 1's and 2's with boring consistancy.  I was interested to see how he set up his actions for such rifles.

He said "blue printing" actions was just a waste of time and that all you have to do is square the reciever face if it is more then a thou or two out of square and everything will shoot fine.

The other fella did not even do that much.  They asked me what I did to my actions prior to barrel fitting?  This is how I discribed my "blue printing" proceedures.

This for setting up a Rem M700 receiver that is to be rebarreled.

1. I first recut the receiver threads 0.010" over sized to ensure that they are perfect with the center-line of the receiver.

2. I use a precision ground mandrel that threads onto the freshly cut receiver threads and mount this mandrel into my 6 jaw chuck on the lathe.  I then dial indicate this mandrel to .0002" or less run out.  When zeroed, the live center is used to support the rear of the mandrel which passes through the receiver.

With everything zeroed, I take light facing cuts on the receiver until it is cleaned up and perfectly square to the center axis.

3.  I then take the mandrel out of the chuck and insert the receiver into the cuck with the mandrel nose out toward the tailstock.  This is then zeroed to the same .0002" or less.

4.  Once zeroed, the mandrel is removed and I use a specially ground boring tool to clean up the locking lug recesses.  Which are now cut perfectly square to the center line of the receiver.

5.  Next I take the stripped bolt body and install another precision ground mounting stud into the rear of the bolt.  This stub is then placed in the chuck and zeroed again to .0002".  With the stub and bolt zeroed, I bring in the live center to ride in the firing pin hole of the bolt, GENTLY.  Just enough to positively drive the live center.

6.  I then true up the face of the bolt and then the diameter of the bolt nose down to the leading face of the bolt locking lugs.  These are very light cuts, only removing enough to make everything perfect on center with the firing pin.

7.  I then recut and square the locking surfaces of the bolt lugs.

8.  Finally, I true up the full diameter of the recoil lugs and chamfer all edges to assure smooth bolt movement as well as solid contact with the locking surfaces.

9.  The locking lugs are then lapped for a 100% fit which after cutting only takes a few minutes when done correctly.  After this the action is basically done.

On to the barrel fitting which is a big part of my action blue printing process.

10.  Once the barrel shank is cut and fitted for an oversized recoil lug and the threads are cut to a class 3 thread fit  to the receiver, I then then start on the chambering process. 

11.  I then measure the diameter of the bolt nose and depending on the intent of the rifle, cut the counterbore to match.  For a hunting rifle, I will allow for 0.010" clearance in depth and 0.005" clearance in diameter.  For a bench style rifle, competition or varmint, I allow only 0.005" clearance in depth and 0.002" to 0.003" clearance in diameter for the bolt nose.  It should be noted that it does not take much to fill this area so the rifle needs to be kept clean.

Once this is cut, I chamber the barrel using a floating reamer holder.  My reamers are fitted with live pilot bushings and I match these bushings to the nearest 0.0002" to the bore for a perfect chamber which is then finished to a 800 grit  polish.

12.  Once this is done and the barrel is finished in the manor the custoemr wants, I then cut a modified 11 degree crown.  The modified part is my own special touch so I will keep that to my self.

After I told that to these two fellas, they just set there and stared at me.  I was not sure if they were sleeping or stunned.  The one of them said I was wasting alot of time with all those fancy steps and said I was just charging more then I should for things that made little difference.

I invited them out to my range with a rifle I had just completed for a customer which I had yet to group test after the barrel break in.  This rifle was a sporter hunting rifle using a Rem M700 action prepped in the steps listed above.  The barrel was a stainless light sporter #4 contour Lilja 3 groove .257", 1-10" twist that finished at 27 1/4" and chambered for the 257 STW.

The entire rifle with the pillar bedded thumbhole laminated stock and 4.5-14 Burris weighted in right at 8 lbs.  I asked the one fella that was telling me I wasted customers money what he though this rifle would group at driving a coated 100 gr Ballistic Tip at 3900 fps.  He said that with the light barrel it would shoot in the inch range  if the barrel was cool.

I invited him to fire three rounds off but at my 300 yard target instead of the 100 yard target he was looking at.  He looked a little shocked and then asked where to hold for that range.

I told him he had no reason to worry about trajectory for at least a couple hundred more yards, he would easily land on the one foot target with alot of room to spare.

He pulled off three rounds and was impressed by the rifles feel and shooting quailties.  Quite a compliment from such a qualified smith for sure.  We walked up to the target(thats how I get my workouts) and saw a perfect 1" triangle. 

I said well, you were right, it shot an inch group, he did not say much.  We walked back and the second fella and I each shot three shot groups which were .755" for him and .702" for my three.

We all agreed it was a top notch sporter rifle.

This just got me thinking, what is it that we pay for from some of these basement gunsmiths that say they are blue printing actions but are instead turning out factory quality performance.  It is no wonder everyone is so gunshy to have a rifle made because its hard to tell what you will get and unfortunately you do not always get what you pay for.  The one fella stated that he charged within $100 of what I did for a rebarrel job and after hearing his method, I would jsut as soon buy a factory rifle.

I know there are other steps that can be done to accurize actions even more but these are the basics I will do on every rifle that I rebarreled unless the customer flat says no thanks.

How do you blue print and set up rifles or handguns for extreme accuracy?

Thanks for the comments and thoughts!

Good SHooting!!!


Posted By: Timberghozt
Date Posted: 12 April 2004 at 16:25
Fifty,good post.My neighbor up the road is a smith.I have seen some of the Mauser 98 large rings he has rebarreled  and seen what they do on paper.I plan to let him build my new rifle.I want to observe and see what he does with it while its being built.It sounds like you`ve got it going on with those groups.Gene

Posted By: dakotasin
Date Posted: 13 April 2004 at 01:57


ahh... yeah...

i'm no gunsmith, and i don't even pretend to be, so i do none of that stuff. i might take it to a 'smith, but i sure don't have the skills or tools to do that stuff myself!

i appreciate the information in your post, though. precision stuff fascinates me.

Hunting is not a matter of life or death; it is much more important than that.

Posted By: Moose6
Date Posted: 13 April 2004 at 02:01
Cool stuf.  I've learned a lot this week with this post and Kingpin's 1700th post.

Y'all shoot straight!!!

Moose - Knoxville, TN

Posted By: TasunkaWitko
Date Posted: 13 April 2004 at 04:00

great post! i know nothing about gunsmithing, but it seems to me that your procedures are sound. kingpin might weigh in on this one?

TasunkaWitko - Chinook, Montana

Helfen, Wehren, Heilen
Die Wahrheit wird euch frei machen

Posted By: Fiftydriver
Date Posted: 13 April 2004 at 08:18

Well, it just seems to me that there are alot of people that go out and purchase a second hand lathe and call themselves gunsmiths.

Please do not take the thinking that I think I know everything there is to know about building accurate firearms, I know better, I have been at it for a relatively short time but I did study the proceedures of one of the best smiths in the country I feel, Mr. Holland.

I have tried his techniques and they are easy to understand and flat out work.  One of my first rifles I ever built was on a Mauser 98 clone action which I barreled with a cheap Adams & Bennent barrel.  Being the first rifle I put together I did not want to start out on a top dollar barrel, I was nervous enough as it was.

I took my time which I admit I am slow and the riflke is a 1/2 moa rifle out to at least 500 yards.  The only problem is that the bore is a bit rough but this is to be expected from a lower priced barrel.  If I keep it cleaned every 25 rounds or so, it will run with most other custom rifles.

I guess my feelings are that those of use that take the time and invest the large amount of money for the best tools and machines for the job often get undercut by basement smiths that just lowball everyone just to get a job or the recognition. 

I know several that will just have guys come over and do their work as they watch.  In fact I just fixed a Ruger M77 in 338 WM that had the barrel ported by one of these so called smiths.

The internal crown was so bad that the rifle would not stay on paper at 50 yards.  In fact, a quick view with the bore scope revealed that nearly 1/2" of the rifling on the right side of the bore was washed out because the "smith" used a poorly fitted pilot instead of saving up to get a set of replaceable live pilot reamers.

The owner of this rifle had faught it for years because this smith said he should port the rifle right from the start so the owner thought it was the rifle and not the poor quality work.

He in fact even sent the Burris scope back saying it was faulty and Burris sent a brand new scope not questions asked.  Still the new scope did not shoot any better.

The rifle set from 1999 until the spring of 2003 when I ran into the guy and he had heard I was gunsmithing and asked about what could be done with this rifle.

He brough it up to the shop and as soon as I saw the work of this hack, I knew the problem was not the rifle.  I stripped the rifle and through the barreled action in my big spindle bored lathe and lopped off the port and another 3/4" of barrel.

I then fitted the correct diameter pilot to the crowning tool and recrowned the rifle.  Took less then 30 minutes total including cold blueing the muzzle and we headed to the range.  His first three shots went well under an inch and the owner was more then pleased and quickly payed his bill which was a fraction of what the other smith had charged him to ruin his rifles accuracy.

The worst thing is that the guy was amazed how easy the 338 Win Mag was to shoot and not at all painful. 

This is my point, the combination of poor recommendations along with the very poor quality of machining left this guy with a useless rifle and a poor view of gunsmiths.

I have talked with Kingpin a little and know him to be a top notch smith and someone I can learn much from.  But for every Kingpin, I would guess there are 100 so called smiths that make alot of shooters very gun shy toward having custom rifles made.  Those that do and have them made correctly seldom have any complaints at all.

So if your going to have gunsmithing work done, do your research and find a good qualified smith.  A good one will be honest with what they can do and what they have done in the past, a bad one will learn on your rifle which is not the way to do things in my mind.

Good SHooting!!!


Posted By: Orion
Date Posted: 13 April 2004 at 09:05

     In a small nutshell, blueprinting is determining a point of reference to establish a "zero". From there it is squaring surfaces to match the baseline measurement. I can do machine/tool die work. It has been a requirement of a few of my past jobs. I have only ever recrowned barrels, profiled same, opened bolt faces, recut forcing cones and a few other very basic items on a firearm. I am in no way in the same league or the same caliber of tool/die work as Kingpin or Fiftydriver. Most of my work now is with wood.

     Thank you for the post Fifty. Between you and King we all should be able to continue our technical schooling. It is  invaluable information!! The detail is superb. You and King should both be thanked and congratulated for sharing your knowledge.

"No man's opinion is any better than his background, his experience, and his general common sense." -- Jack O'Conner

Posted By: macca
Date Posted: 13 April 2004 at 10:25

"I only drive them,I don't know what makes 'em run."Oddball  from Kelly's Heroes.

I have neither the tools or expertise to do what 50 and King do.I do appreciate the info.One of my best mates is a barrel maker/gunsmith and he does all my work.

It must be very satisfying to make your own rifle from scratch and see it perform well.Star


don't let the bastards grind you down.

Posted By: Hudge
Date Posted: 06 December 2004 at 04:06

I am in no way a gunsmith nor do I ever claim to be one, but I do help some of my friends out on items like scope mounting and boresighting. For them, that is where it ends, but I do adjust my own triggers, and few other minor things, in hopes of getting a little bit tighter group. I've lost count of how many times I had to mount and bore sight scopes for my neighbor this past month! The best thing about it, is I don't charge unlike many places in town, where one of my hunting partners takes every thing to. I keep telling him I can mount his scope, make sure it's properly alligned and bore sighted free of cost, but he always refuses. That's fine, because I always laugh when his cheap crap fails in the field!


Posted By: Kingpin
Date Posted: 07 December 2004 at 11:53
It's a good post, but it's not brain surgery. All one has to do is have the equipment and the desire. I do it as a matter of building a custom rifle. I always make the customer take the rifle and shoot it before he pays me. In VERY few cases, I got static for the cost. I can't abide in barreling a rifle without a total action job. We have all heard the saying, repitition builds experience. I can think of one BSB member that has owned one of my guns. The sad thing is, it was one of the best ever. Dam I wish I would have kept it!!!!!! Anyway, the latest one seems to be just as good, good Lord willing and the creek don't rise......................Kingpin

There are times when a normal man must, spit in his hands, hoist the black flag, and begin slitting throats.

Posted By: Fiftydriver
Date Posted: 07 December 2004 at 13:23

Since I posted this initial post I have learned even more as I have dove into the relm of building extreme accuracy rifles.

THe most dramatic thing I have learned is that while the proceedure I listed above certainly will tune up some actions and make nearly all rifles shoot in the 1/2 to 3/4 moa range, there is a  much better method of accurizing which is the one I use now.

Before when I would print an action I woudl thread in a mandrel into the action and use this mandrel to dial in the receiver in the lathe, all you are doing is dialing in a single point on the axis of the mandrel.

What does this do for you as far as accuracy, not much.

You see, it is generally the receiver threads that I have coem to learn that is the largest problem as far as accuracy and consistancy goes.

Here is my new method and as far as I know this is the most modern accurizing method being used today.

Step one:  Dialing in the receiver in the lathe.

Unlike before, where the receiver was chucked up in the lathe chuck, now I use an accurizing fixture that is basically a 6" long cylinder of aluminum with a wall or roughly 1" in thickness.  This cylinder has four bolts in around the front of the cylinder and four around the rear of the cylinder.  On the rear there are two sets of holes, one for long actions and one for short actions. 

These eight bolts(4 front, 4 back) are used to hold the receiver in the cylinder which is then mounted in my four jaw chuck.  The fixture is dialed in so that there is no noticable wobble in the fixture as it spins.  There is no need to get it perfect as the action will be fine tuned later.

After the receiver is secured in the fixture and the fixture is centered in the lathe chuck, specially sized bushings are placed in the receiver.  One in the rear of the receiver and one in the front.  These bushings vary in diameter by 0.0005" so that the bolt way diameter can be matched perfectly.

When the proper bushings are fitted and in place, a precision mandrel is then slide into these cyinder shaped bushings.  This mandrel extends 6" in front of the receiver.

Now comes the dialing in part.

With the old common method, dialing in a receiver took about 5 minutes, this new method can at times take up to 1/2 hour but generally 15 minutes or so.

First step is to take two 0.001" dial indicators and position one just ahead of the face of the receiver on teh mandrel at 12:00.  The other is placed at the end of the mandrel, 6" farther out and again set up at the 12:00 position.

The receiver is then turned in the lathe chuck by hand and the dial indicators will be dancing all over hell!

To dial the receiver in, the four mounting bolts on the front and rear of the truing fixture are used as four jaw adjustable chucks.

The front bolts are adjusted first.  These correct the run out for the dial indicator right at the receiver face.  When this is running in the 0.005" range you move back to the rear 4 bolts which adjusts the dial indicator out at the end of the mandrel, 6" from the face of the receiver.

This is also dialed in to roughly 0.005".  There is no point getting it perfectly trued yet as adjusting either set of bolts will effect the run out of the ones you do not adjust.

Then you go back to the front four bolts and adjust them down to 0.001" and then go back to the rear four and do the same thing which just put more run out into the indicator you jsut adjusted but as you do this back and fourth several time, the run out on both dials begins to shrink as the receiver comes into alignment with the axis of the bolt way.

Once both 0.001" dial indicators are reading less then 0.001" and I dial them down to less then 0.0005", you remove the 0.001" indicators and replace them with 0.0001" dial indicators.  This is really fine tuning here.

The same proceedure is followed until these fine reading indicators are basically not moving.  They both should be basically static as the receiver is turned in the lathe.  We are dealing with run outs in the millionths which is less then the human eye can really accurately detect even with these fine measuring tools.

Once you have both of the dial indicators perfectly dialed in, your action is perfectly true to the axis of the bolt way in the receiver.

Just to show myself the difference this makes compared to dialing in off the receiver threads, I fitted the threaded mandrel to a perfectly zeroed receiver and took measurements with a 0.001" indicator right at the receiver face on the mandrel again at 12:00 and then 4" out which is as far as the threaded mandrel would allow.

This action was perfectly zeroed to the axis of the bolt but the readings on the threaded mandrel told a very interesting and disturbing tale. 

The indicator at the receiver face was showing a total thread run out of 0.008" and out at 4" there was 0.028" of run out.  This just shows how out of axis the receiver threads are cut in relation to the axis of the bolt way.

Once the receiver is dialed in perfectly in the fixture, the threads are then single point cut to a 0.010" larger diameter or whatever it takes to clean up the threads so that they are now perfectly square the the bolt way axis.

After the threads are perfectly trued, the bolt lug locking recesses are recut perfectly square to teh bolt way axis as well and then finally the receiver face is trued up.


The difference this method makes is this.  In the old method, and frankly, the one 80% of the gunsmiths out there are using, the bolt lug recesses, threads and receiver face may well be in alighnment with each other but they are not on teh same axis as the bolt way axis and thus the bolt face and locking lug surfaces will also be canted to teh axis of the bore.

With this new method, everything is in perfect alignment and to prove this a simple measurement is taken.

With the bolt and receiver trued you insert the bolt in the receiver and close it down in the locked position.  This is a stripped bolt and receiver. 

A measurement is then taken from the bolt face  to the receiver face with a depth mic with the receiver pointed toward the ceiling.  Four measurements are taken, at 12:00, 3:00, 6:00 and then at 9:00.

With the old method, you would generally gave around 0.001" variation in the measurements.

With the new technique, the difference is not measurable with these tools so it is well under 0.0001".  

To take things a bit further, the bolt way can be reamed with a precision  reamer which is also piloted with the bushings mentioned above.  After the receiver is reamed, the bolt is fitted with sleeves that produce an extreme quality fit between the bolt and the receiver.

In a conventionally accurized rifle, even if everything is perfectly square, when the rifle is cocked, the striker assemply is forced vertically and thus the bolt is as well.  At least as high as there is slack between the bolt body and top of the receiver.  On Rem 700 actions this is generally in the 0.005" to 0.008" range.  What this does is lifts the top recoil lug off its baring surface. 

So even though the bolt lugs and lockign recesses are pefectly lapped for 100% contact, when the rifle is cocked, the top lug is liften off its baring surface.

When the rifle is fired, the bolt drops from its raised position and creates a vibration pattern which is not consistant from firing to firing and fliers will result to some degree.

With a properly sleeved bolt, there is no room for the bolt to move and so the botl lugs stay perfectly solid agains their locking recesses and consistancy and accuracy are greatly improved.

Here is an example of the first rifle I built using this method.  This is a three shot group at 200 yards from one of my Barrel Bedded V-Block rifles chambered in the 22-6mm AI shooting the 80 gr Berger.


This is my personal best three shot group at 200 yards.  Hell its my best three shot group at even 100 yards.

This is the true measure of the diffence this accurizing method can produce.

I must say I though I knew quite abit about blue-printing actions when I posted the original post not that long ago.  Since then I have learned that I was doing what 80% of the smiths out there are doing, offering a product that is supposed to be blue-printed but in reality they are not even close.

Kingpin is right, it is not rocket science but it is spendy to get tooled up to do this correctly and also like he said, you need the desire to do it.  It can be frustrating bending over your lathe for 30 minutes to get a receiver absolutely perfect.  Many will say you don't need to dial an action in this tight. 

Everytime I hear this I just think of that little .094" three shot group and tell myself it is well worth the time.  It adds a little to my accurizing costs but again when my customers are averaging 1/4" groups out to 200 yards and 1" groups at 500 yards, they forget about a few extra buck.

Well just thought I would update my post and publically tell you all that I had ALOT to learn.  Still do but I know alot more now then I did a few months ago and the rifles are really showing the results on paper and in the field.

Here is a pic of the rifle that shot that group:

All of my rifles from that rifle on will be built using this method obviously, including my Extreme Sporters in the Allen Magnums.

Good Shooting!!  You should all be ready for bed after that boring reading!

Kirby Allen(50)

Posted By: Fiftydriver
Date Posted: 08 December 2004 at 07:41


Thanks for the help posting the pics for me.

Kirby Allen(50)

Print Page | Close Window

Forum Software by Web Wiz Forums® version 11.10 -
Copyright ©2001-2017 Web Wiz Ltd. -