How important is blueprinting an action

[bigngreen]

I go back to the basics: great barrel, perfect alignment of chamber centerline with centerline of the bore. Snug headspace on the "go" gauge (no unusual indications on fired brass). Rigid stock, with good bedding, floating barrel, all screws properly torqued (action to stock, rail and ring screws). OR you can spend LOTS of cash on the action.

All of that won't shoot any better than the action will allow it. I can put a perfect barrel on a turd action and get repeatable turd results, great barrel and a great action leaves little on the table other than me!!

 

[shortgrass]

A lot of times the order of the machining will change things greatly. I wouldnt finish machine the bore, front face and threads until after the rest of the action is machined. Removing pockets of metal here and there will make things move.

The custom action makers that have been successful aren't quit like todays' gunsmith, who was in another field of work a week ago. They have extensive machining experience t begin with.

 

[Jud96]

The custom action makers that have been successful aren't quit like todays' gunsmith, who was in another field of work a week ago. They have extensive machining experience t begin with.

That's a bold statement to make about gunsmiths. The successful ones didn't start last week either. They've been involved with guns for their whole life or a large part of it. I'm sure there's a few shady ones around, but a good majority of them know what it takes to make a rifle accurate and consistent.

 

[GunHawk]

Well - I am going to round up to 3 cents !

Check is in the mail.

 

[Mram10us]

Gunhawk, the guy that mentored me in the beginning has been shooting lr and building rifles since the 70s. He always asks me, "if truing the action is that important, then why do many off the shelf remington and savage shoot less than 1/2" ?" He has built and shot many rifles that shot in the zeros and ones, so I trust his opinion.

That said, I true everything except the threads because I'm anal and can't help myself. Do your own testing and see.

 

[J E Custom]

I have a theoretical problem with this issue and I'm hoping someone with engineering/technical experience can help me to understand how much truing helps.
As I understand, the purpose of the barrel is:
1. To guide the bullet along the bore axis, and 2. To impart a spin on the bullet.
So, if that is happening how does the alignment of the bolt affect anything? Now, a firing pin directed away from the center of the bore axis could "theoretically " change the direction of the barrel/bore axis alignment, but I seriously doubt that the force and direction of that force would move the barrel appreciably from its original alignment. I expect that barrel quality is responsible for 99.89999999% of the rifle's accuracy/precision (ignoring the trigger quality). Please help this poor FOOL?

I use this word all the time in reference to accuracy. "Consistency" The more accurate everything fits the more consistent/repeatable it will be.

The object of blueprinting/truing it to keep stress and movement to a very minimum and locate the cartridge in exactly the same place in the chamber every time and also control movement during firing. If all parts of an action are aligned with the bore centerline, Thrust is in a straight line opposite the bullet travel minimizing the thrust vectors that could effect accuracy in the rifle. With the bolt aligned with the centerline and with proper head space the cartridge is located in the same place in the chamber and not allowed to move in any other direction that could launch a projectile with yaw or improper alignment.

If we go to great lengths to load perfect (Concentric ammo, it doesn't make sense to allow your equipment to alter this alignment. Doing many concentricity test, the concentricity of the ammo makes a huge difference in the accuracy. Best accuracy is with 0.000 concentric ammo as you add eccentricity by 0.001 accuracy falls off, when it reaches 0.003 accuracy is not acceptable to many.
and by the time you reach 0.006 it is practically unusable. it will still fire but that is about the only thing it does.

So back to the question If the action has more than 0.0005 misalignment in certain areas it will not be as accurate as it could be. Many shooters will not be able or capable of seeing this improvement, but even the best shot cant reach his potential in a poorly assembled rifle.

Slack or improper alignment Is not conducive to consistency, so it should be minimized. One of the quickest ways to spot poor workmanship, is to try a fired case in an action/chamber for ease of closing. Many times it will have to be index't in the same position it was fired in to freely chamber because something was misaligned or allowed to move.

J E CUSTOM

 

[J E Custom]

Gunhawk, the guy that mentored me in the beginning has been shooting lr and building rifles since the 70s. He always asks me, "if truing the action is that important, then why do many off the shelf remington and savage shoot less than 1/2" ?" He has built and shot many rifles that shot in the zeros and ones, so I trust his opinion.

That said, I true everything except the threads because I'm anal and can't help myself. Do your own testing and see.

Good question !

I have seen the same thing but the percentages of good shooting factory is not very good compared to poorly shooting with a few Oks thrown in.

I once re barreled a Savage that shot very good and in the process I trued everything up. The first thing I do in this process is check the parts for accuracy so i know what I need to do. "Shocker" this thing was so bad I began to question if blueprinting was even necessary if this thing would shoot.

As I dimension'ed every part, I was really astounded that it could even shoot a 5'' group at 100 yards, much less a 1/2 MOA group. so I decided to index/orient each component like it was put together. And the question was answered.

The apposing parts fell amazingly in the best position to cancel out the errors and become relatively true to the bore centerline. the recoil lug had a 0.004 thickness difference on one side and the action had a 0.0045 on the opposite side so the total error of this one assembly was 0.0085 but the assembled error was 0.0005. the bolt lugs had the same problem but canceled the error out simply by there location.

Since that time I have found many actions that had less errors dimension ally but they didn't cancel each other out, and a few have had some that did in some areas and did not in other areas.
So to eliminate the chance ether way, I blue print every action to verify it's accuracy. and in a few actions I find very little/few issues.

The fact that a rifle shoots well doesn't mean that it is true, just that the errors were in the right place to effect the accuracy very little.

J E CUSTOM

 

[Rflshootr]

The machine can only do so much and mine has it's limit and can do work within 0.0005 if I do my part. Some of the really expensive CNC machines can/do work within 0.000,01 or better.

So if I can measure in half thousandths and some times depending on the finish 0.000.01 If I can improve it I will, If not so be it.

If the setup doesn't measure within these tolerances you are wasting time trying to improve the action.

The goal is to make the action truer/better than it was.

J E CUSTOM

You're measuring within .00001 (10 millionths or less then 1 helium light band) or a .0001 (one tenth of a thou) ?

 

[Alex Wheeler]

Its all about vibration control. Harmonics/vibration is how a rifle is tuned and getting that vibration consistent is how to make them shoot small. You cant tune a rifle that doesnt have consistent harmonics. So any time you wonder how something can help accuracy, ask how it can either make the vibration more consistent, or reduce the overall amount of vibration. In the case of lug contact thats pretty simple to see how good lug contact will reduce the vertical harmonic vs one lug doing most the work. You really have to look at how a rifle aggs. A rifle with issues will still shoot small groups, mixed with larger ones. So because the rifle shoots an occasional small one doesnt mean a thing. If you want a rifle that shoots well day in and day out, it has to be right. I am sent rifles all the time that will shoot zeros backed up with average or 4 in the zeros and one out. Problem is in the action usually. Sometimes its in the ignition as well.

 

[Andrew Cowling]

Thanks for this thread JE, I find this sort of topic very interesting.

The last sentence in your OP say's a lot for why the process is important, all part of the accurizing process like bedding etc.

If I had my time again gunsmithing would be something Id be greatly interested in doing as a career.

But back in the 80's/90's in Australia it wasn't such a big thing in demand.

Fitting & turning was a career of course but I guess most people who went onto that sort of thing had it as part of their family history or schooling.

Even now its hard to find a decent smith here & even getting basic stuff done can take forever, getting a rifle built can be a 12 month + wait

I agree that a good smith is hard to find. For your info I am one of them based in Tasmania. Unfortunately I end up with a lot of work to fix that a so call gun smith has stuffed up. All custom rifles that I build are built on actions that I blue print. If for nothing else than for piece of mind knowing the boxes have been ticked leaving nothing that could cause accuracy issues.

 

[J E Custom]

You're measuring within .00001 (10 millionths or less then 1 helium light band) or a .0001 (one tenth of a thou) ?

I am measuring within 5 10 thousandths. with the micrometers that I use. they will go to .00000 but I work to .0005 most of the time. Better if I can.

J E CUSTOM

 

[shortgrass]

That's a bold statement to make about gunsmiths. The successful ones didn't start last week either. They've been involved with guns for their whole life or a large part of it. I'm sure there's a few shady ones around, but a good majority of them know what it takes to make a rifle accurate and consistent.

Callin' it the way I see it Jud. 28-30yrs ago I couldn't find a competent 'smith without driving the 95 miles into Mashburn Arms. There were a couple who worked as 'smiths closer, but for a re-barrel they just wanted to ship it off to Shilen or Douglas. Both were very limited as to what they could/would do. That was one of the things that drove me off to school in '91. Within the past 5yrs or so there have been several set-up in my local area. None schooled, none machinists to begin with, every one self trained. They work cheap while they learn, I guess. Very, very limited as to what they can do. Had a guy bring a rifle in asking me to check the head space. Ok, no problem. A guy I had done work for in the past. While I stripped bolt and pulled my gauges he told me of a guy his son hangs with that is building $5000-$6000 rifles. I ask why he didn't have him check the head space, his son is friends with the guy and he's miles closer. He said he had asked and the guy told him he didn't have the tools. Who, that builds $5000-$6000 rifles, doesn't have a set of belted mag head space gauges!? I am sure the same situation is not unique to my local area......

 

[nksmfamjp]

JE, I really appreciate your post on truing. I didn't see a couple things and want to post a couple questions based on that post.

First, the truing you mentioned seems to rely on relatively close fit between the bolt and action bore....Are there any you just call the owner and say, sorry bud, but this one is too sloppy? Related to this, do you lap bolt lugs to the abutment? I ask because I really wonder if this is good or bad after one trues each to the best they can.....

Also, do you guys work on the timing....First do you do anything to the camming surfaces to smooth them up when closing the action? Also, do you "time" the cocking piece to the trigger to reduce cocking piece movement when cycling the cocked action?

 

[J E Custom]

JE, I really appreciate your post on truing. I didn't see a couple things and want to post a couple questions based on that post.

First, the truing you mentioned seems to rely on relatively close fit between the bolt and action bore....Are there any you just call the owner and say, sorry bud, but this one is too sloppy? Related to this, do you lap bolt lugs to the abutment? I ask because I really wonder if this is good or bad after one trues each to the best they can.....

Also, do you guys work on the timing....First do you do anything to the camming surfaces to smooth them up when closing the action? Also, do you "time" the cocking piece to the trigger to reduce cocking piece movement when cycling the cocked action?

There are occasions that the actions or rifle is beyond proper repair and declining the work is the prudent thing to do. But I try to explain why, instead of just saying no. This is one of the reasons I like to check everything before the work starts.

Also occasionally when setting a shoulder back to freshen a chamber and lead you run across a barrel and chamber that was reamed off center and won't clean up with 62 thousandths set back, or one thread. I wont go beyond one thread set back but I have seen rifles that had 2 or 3 thread set back. So I warn the owner if the chamber looks off center and may not clean up.

I recently tried to set back a chamber to true it up and after .0625 set back, the chamber still didn't clean up and going to .094 it didn't clean up so the job was abandoned. I have seen many
rifles that I was ask to fix and had to decline because someone didn't use good judgement and ruined the rifle and created an unsafe condition.

Lapping can improve the contact area, but does nothing for truing. the abutments must be square to the bolt centerline and also the bolt lugs. they must be cut true and then you can lap them for final finish.

Other things like timing, polishing, Jeweling, fluting are done as needed.

J E CUSTOM

J E CUSTOM