Truing or squaring an action

[BrokenHorn]

I'm just trying to learn more about what takes place when truing an action. I've done a few searches but I can't find anything that explains what takes place? Can some one help me understand this process?

 

[Shawn Carlock]

Kirby wrote a very detailed piece with good supporting photographs if you cannot find it, I will dig some up.

 

[Boss Hoss]

Here ya go---Enjoy.

http://www.bryantcustom.com/articles/true.htm Action BP

 

[Bart B]

The 'smith who has trued all my Win. 70 actions does the following:

1. Screw a mandrel longer than the receiver into the barrel tenon threads then put it between lathe centers so the receiver face can be trued perpendicular to the thread axis.

2. Lap the bolt lugs to their receiver mating surfaces so both make full contact.

3. Screw an adapter into the barrel tenon threads to hold an end mill that's hand turned to square up the bolt face with the barrel tenon threads.

That's all; nothin' else.

I don't know of anybody who has trued up any box magazine (and perhaps any other) action that ends up in a rifle using cartridges larger than a .260 Rem. that shoots more accurate than what he does. There may be a few that will be equal.

 

[Fiftydriver]

Bart B,

Not hammering on your smith but that is not the correct way to truely blueprint a receiver. Only way to do it correctly is to dial in the receiver along the bolt way axial center at two different points using precision fit bushing and a precision ground mandrel. This removes any conical variation in the receiver as it spins in the lathe.

The threads then must be recut, single point recut, to the same axial alignment as the receivers bolt way to insure that the barrel axial alignment is perfectly aligned with the receiver.

Then the bolt locking lug recesses are cut perfectly square to this axial alignment as well. And finally the receiver is also cut perfectly square.

As for the bolt, its basically the same process with the dialing in of the bolt and cutting the bolt lug contacts and using some bolt fixtures the bolt nose and face as well.

If you go off the receiver threads as you are discribing, it is nearly impossible to get a receiver perfectly true. Some of the relating baring surfaces may be square but others will not be using the factory threads as a starting point to the accurizing process.

What you have discribed is not the best way to correctly accurize a receiver, in fact it is a poor method of doing this in my opinion. I know this because when I started I used the same method and now use the Gre Tan method of accurizing and the two do not compare.

With smaller calibers the system you mentioned can at times produce very good shooting rifles, as the size of the chamberings increase you will see more and more problems with accuracy using this system. This is what led me to look for a better way and the Gre Tan accurizing method is the best I have seen out there being used today.

Again, not a hammer to your smith but he should look into buying the tooling and fixtures to accurize receivers correctly, he will not be sorry for the upgrade, neither will his customers.

Good Shooting!!

Kirby Allen(50)

 

[Bart B]

50driver, I expected you to post something saying my 'smith's method isn't really correct for blueprinting an action. I agree with you that the method you explained will sure make one trued up very well indeed. My 'smith has told me many times over the years that he gets told that at least once a month. But nobody's built a rifle on any box magazine action reworked any way that's shot any more accurate. So, he says, why go to all that extra work at his time and the customer's expense when it isn't gonna help.

It is important that the receiver's barrel thread section be fairly well in line with the bolt axis. There was a pre '64 Model 70 action floating around the highpower match rifle 'smiths in the early '70s that nobody could get to shoot with any barrel. My 'smith finally was sent it from its most recent owner to fit a barrel to and its serial number rang a bell. He called another 'smith and asked him about receiver number xxxxxx and the other 'smith said he'd tried two barrels in it and it wouldn't shoot. So my smith put it on his facing mandrel, chucked it in a lathe and spun it at low speed. The back end had near a quarter inch of runout. He didn't barrel it but instead returned it to its owner explaining it was a bad receiver for a competition rifle but fine for hunting.

 

[Fiftydriver]

If your rifles shoot and your happy with them then by all means go for it!!

I can assure you though, using the latest accurizing techniques will create more consistant rifles on average.

Good Shooting!!

Kirby Allen(50)

 

[Shawn Carlock]

Bart B,

You can choose what level of work you want done. I get customers that don't want to pay or feel they need a full blown truing job. For the most part I will build them whatever they want, but I also give them my opinion that is what they pay me for. It is my opinion that there is the occasional killer deal but mostly you get what you pay for. What you pay for in a reamed, mandral indexed, trued, squared and bushed action / bolt job is consistancy and guarantee. There is a reason that 99% of the top end long range / competition smiths offer this level of job. When your reputation counts on a 1/2 moa gaurantee and an expectation of 1/4 moa you do what is necessary. Ultimately I explain my position and let the customer make an informed choise. That being said I agree that there is really only one proper way to square and true an action.

 

[EddieHarren]

I have been shooting IBS benchrest matches for 18 years. I shot a Rem 700 SA in the Hunter and Varmint Hunter classes until 2005. I built this rifle and never touched the action threads. Squared the face, squared the bolt face, lapped the lugs, period. In the years that I used this rifle I set 4 IBS records and, was Shooter of the year once. I build rifles for a living and, I too will do whatever the customer wants done to the action.

 

[pablo]

I have been shooting IBS benchrest matches for 18 years. I shot a Rem 700 SA in the Hunter and Varmint Hunter classes until 2005. I built this rifle and never touched the action threads. Squared the face, squared the bolt face, lapped the lugs, period. In the years that I used this rifle I set 4 IBS records and, was Shooter of the year once. I build rifles for a living and, I too will do whatever the customer wants done to the action.

I've had similar experiences with 700's and 40X's.

I recently bought a lathe and tooling to true actions and chamber barrels. My wife bought me the Gre Tan truing video for Christmas last year and I've watched it twice. It's an exceptional sleep aide but I did make it through twice. Greg is a great machinist and I wouldn't say his is the wrong method but the bang for the buck is not there. Using the PT&G gen 2 tooling, in my opinion, gets you about 95% of the practical correction available in a reasonable amount of time. If a guy needs or wants better he should buy a custom action. The problem with all the corrections is it's hard to make a crooked hole straight, it's much easier to make a straight hole and finish ream it. The point is 700's aren't straight and making it perfect is a stretch.

 

[Remington 243]

I'm just trying to learn more about what takes place when truing an action. I've done a few searches but I can't find anything that explains what takes place? Can some one help me understand this process?

"High Speed Shooting Systems' Hsss, has video that show every step, phase, of trueing up the action, bolt, barrel, impact lug, everything on his lathe. Amazing video.