How important is blueprinting an action

[tomsd]

There are apposing views on this process and the results are sometimes hard to prove so it boils down to what a person thinks and wants to believe. I blueprint every action to assure myself that the accuracy potential is available and not impaired with sloppy machining.

I have seen poor dimension on many different parts that when combined canceled out each other and shot well. So just the fact that they shoot well doesn't mean all the parts were dimension-ally close.

I just finished a rifle for a friend and according to my notes, The donor action had dimension problems, but it shot fairly good.

The action face needed .004 thousandths to square up.
The lug abutments were the worst with One lug not even touching and the other was only 20% in contact. There was a .0085 difference in the contact surfaces and I had to remove .010 thousandths to get them even and perpendicular to the bore center line.

The bolt lugs were close and only needed .002 the true them on the contact side and the front was within .0005
so I did not remove anything from the front of the bolt lugs (Non functional)

The factory recoil lug only had a .001 thousandth difference from best to worst so it was ground to flat .000 difference.

The bolt face needed .0035 to square up and the barrel shoulder did not have any differences.

Total material removal to true all parts of assembly was 0.020,5 with the greatest difference in the lug abutments
and in general the rest of the differences were not unusually off and may have been the reason that the rifle shot OK for a hunting rifle.

This is by far not the worst action that I have seen, And without exception I have found "ALL" actions including customs will need something corrected because they are machined the same way as the factory actions and only their quality control catches more that the factory does. But all actions should definitely benefit in my opinion from this truing process.

And this usually makes the firearm more forgiving to different loads and not be so picky about the ammo.

J E CUSTOM

Wow - a much better appreciation of "truing" an action? Can you pls"guesstimate" what the "average" cost for this would be?

 

[J E Custom]

Wow - a much better appreciation of "truing" an action? Can you pls"guesstimate" what the "average" cost for this would be?

It is labor intensive because of the set up time, so smiths have different rates depending on the work load and if it is part of a complete job. I would guess that most are in the neighborhood of $175.00 to $225.00 plus or minus.

J E CUSTOM

 

[DSheetz]

In this time and age a lot of the machine shops in the U.S. have one person running more then one CNC machine at a time . They set up and proof each machine start it and go to the next machine to do the same and check them as they can . My daughter runs three at the same time thus the tooling may not get changed out as needed and the tolerances are with in spec but vary . I still believe in craftsman ship being the key to precision products . The dollar is what these shops are after but the parts they turn out are to spec just not as close as some of us want and that is why we pay good people ( who know what they are doing ) with small shops to make them to our specs and J E can stay as busy as he wants making them meet our expectations

 

[Will Gray]

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.

 

[tomsd]

Agree with that also - but when you have it all else set-up - the action needs to be sweet as well to really shoot !!.

 

[tomsd]

Agree with that also - but when you have it all else set-up - the action needs to be sweet as well to really shoot !!.

So I may just buy a 700 ADL Remington - in 6.5 Creed - get the action trued - and shoot 1/2" ? That or a Tikka 3x

 

[GunHawk]

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?

 

[tomsd]

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?

My non-engineer two cents: The better the bullet seating - snugly - perfectly aligned - - in the throat of the barrel - - the better to send it's on its way - smoothly spinning, etc - with no expanding powder gases escaping by it, etc..

 

[GunHawk]

My non-engineer two cents: The better the bullet seating - snugly - perfectly aligned - - in the throat of the barrel - - the better to send it's on its way - smoothly spinning, etc - with no expanding powder gases escaping by it, etc..

Worth more than 2 cents, at least $0.02000001 . But wouldn't the conical shape of the throat achieve that? Ok maybe not perfectly, but at least a long-ish barrel would align and stabilize the bullet before muzzle exit?

 

[DSheetz]

Gun hawk you want every thing as well lined up to each other as you can so that you aren't putting side loading stress's on things before the bullet leaves the case and enters the barrel true to the center line of the bore . It's less expressed then making a bank shot in pool shooting but works the same way if your bullet strikes with more force on one side of the barrel then it becomes unstable , for every action there is an equal and opposite reaction

 

[tomsd]

Gun hawk you want every thing as well lined up to each other as you can so that you aren't putting side loading stress's on things before the bullet leaves the case and enters the barrel true to the center line of the bore . It's less expressed then making a bank shot in pool shooting but works the same way if your bullet strikes with more force on one side of the barrel then it becomes unstable , for every action there is an equal and opposite reaction

**** straight !!

 

[tomsd]

Worth more than 2 cents, at least $0.02000001 . But wouldn't the conical shape of the throat achieve that? Ok maybe not perfectly, but at least a long-ish barrel would align and stabilize the bullet before muzzle exit?

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

 

[antelopedundee]

I'm wondering why the $150,000 machines used to make custom actions aren't as precise as the $15,000 machines used to true them.

It's likely that they're only as good as the starting stock and the person running them.

 

[GunHawk]

Gun hawk you want every thing as well lined up to each other as you can so that you aren't putting side loading stress's on things before the bullet leaves the case and enters the barrel true to the center line of the bore . It's less expressed then making a bank shot in pool shooting but works the same way if your bullet strikes with more force on one side of the barrel then it becomes unstable , for every action there is an equal and opposite reaction

Thanks, that makes sense (to me).