BAT action truing?

NesikaChad said:
When inspecting an action I first use a thread gauge to check the pitch diameter of the receiver ring. This can also help to show if there's any taper in the threads. It's a simple GO/NO GO setup. Then a mandrel is inserted that is mounted between a bench centers….
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Measuring individual elements on a new action, for example, scope base screw holes, action screws, etc. aid in bolting the add-ons in place like scope bases and trigger guards and such but do not address the issue of performance of the gun after final assembly of the champion quality benchrest rifle .

Here’s are some of the important considerations of will the assembly be accurate enough to compete at the National and Super Shoot level. These round things we call a rifle action are just that, round. They consist of cylinders upon cylinders.

If these cylinders of functionality do not all reside on parallel axis to each other then the vibrations set up by firing of the round, they will not repeat the same vibration pattern each shot.

For example, if the cylindrical hole the firing pin is guided by does not remain parallel to the cylinder of the chamber (or cone in this case) then the firing pin tip may not strike the center of the primer anvil. This is a very common happening that can kill accuracy.

If the action face, which is cylindrical, does not allow the barrel tenon solidly fit to where the barrel is pointing straight away then the barrel vibrations will not be consistent shot-to-shot which can kill accuracy and drive the shooter up the wall because they will notknow the barrel they had chambered by “one of the best” will not shoot to its maximum potential.

An on we would go matching the parallel of cylinder axis (bolt body) to cylinder axis (bolt hole in the action). Then we would need to measure for cylindricity. (Yes that it a word).
http://www.emachineshop.com/machine-shop/Cylindricity/page606.html
(The1980’s effort of GD&T (Geometric Dimensioning and Tolerance) taught us that there are other controllables that effect function.)

I could co on through the entire process of what a First Class tool maker or machinist would look for but I think you get the idea. That person would develop and document an entire inspection PROCESS that would assure what we now call “meeting fitness for use criteria”.
 
So Jerry, I know this all looks really meaningful to the non-machinist crowd, especially the part where you capitalize First Class tool maker, (I probably would have said "First Class Toolmaker" were I prone to that sort of approbative verbiage, but that's just me. :) I grew up in the environment) but are you really trying to convince me or anyone else that you typically spend $3-400.00 checking and tweaking actions like BAT to make them "World Class" or "champion quality?"

A simple 'yes' or 'no' will do.

al

BTW, love 'cylinders within cylinders' visualizations. Very Talmudic.
 
Sorry but post like this scare the hell out of me. I have found a couple little issues with a few different custom actions. None were major problems, most were function or fit finish issues that needed to be straightened out. On the same token I do not do an exhaustive inspection process of every $1000+ action that comes in the shop. If I charged every customer $300 to check his xyz action I would be run over on the net chatter about how I "took" some ones money for a "inspection scam." Every one gets the once over and if somthing looks amiss it is then scrutinized. Some issues that may arise with the firecontrol system may not be noticable until the rifle is in service and had rounds down range. Sometimes it's easier to find a problem once we know there is one.

May-be it's best just to use the sav target action. You know the face is out .002-.005" and the bolt face is tapered.
Cut the reciever face, bolt face, lug abutments and lap it in. John Dunbar has shot 1000 f-class with that same action. During a wind clinic at Lodi, the participants were to shoot a couple sighters to get centered up and then rattle off 5 as fast as they could. That savage with one hell of a driver put 5 in the x ring with 1.5" of verticle at 1000 yards. A half dozen members hear witnessed it. But then again John uses the OCD method of handloading.
 
alinwa said:
are you really trying to convince me or anyone else that you typically spend $3-400.00 checking and tweaking actions like BAT to make them "World Class" or "champion quality?"

A simple 'yes' or 'no' will do.

al

BTW, love 'cylinders within cylinders' visualizations. Very Talmudic.
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No, al, I'm not trying to convince you since you apparently do not have an inkling of knowledge of Engineering Mechanics and Solid Geometry.

I didn't capitalize "al" since it is not a name or proper noun...or anything....but that's just me!!! And a simple yes or no may be beyond your comprehension.
 
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I start checking stuff whan I see evidence that all is not as it should be.

For instance, if I thread a barrel, and when I seat, by hand, the barrel into an action, there is evidence that the face of the action is not making even contact with the barrel, I get very suspicious. Since I know I just machined and faced the barrel tenon on the same set-up, on a lathe that will turn within "tenths", then the only culprit can be either the action threads, or the action face.

If I chamber a round, fire it, and notice that there is only contact with 1/2 tp 2/3's of the bolt face, I get very suspicious. Especially when every case does it, no matter what. This is an indication that the bolt face is indeed out of square.

Things like lug contact are easy to see, fire controle maladies are much more difficult to decypher. We pretty well know from experience that anything under 20 pounds of firing spring is a source of eratic ignition. Shooters, and action builders, really like that 16-17 pound range because they can brag how smooth and easy the action opens.

The weight of the firing pin seems to be a big issue with Bats. Several Gunsmiths who build Rifles for consistant winners insist that the firing pin is too light, and use Tungsten to solve the problem.

Several posters do make a good point in that when testing something, you need to insure that your testing procedures do not induce error. Being in the Machine Shop Business, I guess you will just have to take my word that we have to inspect and test things on a regular basis, and understand that for any inspection procedure to be valid, it must not become part of the problem.

The next time you fire your Benchrest Rifle, look at the primer. Is the firing pin strike dead smack in the middle. If it isn't, (and many are not), something is not truly straight and square. .............jackie
 
jackie schmidt said:
I start checking stuff whan I see evidence that all is not as it should be.

For instance, if I thread a barrel, and when I seat, by hand, the barrel into an action, there is evidence that the face of the action is not making even contact with the barrel, I get very suspicious. Since I know I just machined and faced the barrel tenon on the same set-up, on a lathe that will turn within "tenths", then the only culprit can be either the action threads, or the action face.

If I chamber a round, fire it, and notice that there is only contact with 1/2 tp 2/3's of the bolt face, I get very suspicious. Especially when every case does it, no matter what. This is an indication that the bolt face is indeed out of square.

Things like lug contact are easy to see, fire controle maladies are much more difficult to decypher. We pretty well know from experience that anything under 20 pounds of firing spring is a source of eratic ignition. Shooters, and action builders, really like that 16-17 pound range because they can brag how smooth and easy the action opens.

The weight of the firing pin seems to be a big issue with Bats. Several Gunsmiths who build Rifles for consistant winners insist that the firing pin is too light, and use Tungsten to solve the problem.

Several posters do make a good point in that when testing something, you need to insure that your testing procedures do not induce error. Being in the Machine Shop Business, I guess you will just have to take my word that we have to inspect and test things on a regular basis, and understand that for any inspection procedure to be valid, it must not become part of the problem.

The next time you fire your Benchrest Rifle, look at the primer. Is the firing pin strike dead smack in the middle. If it isn't, (and many are not), something is not truly straight and square. .............jackie
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Jackie, have you found any of these types of errors on custom actions?
Tks.
 
4Mesh said:
That's interesting you mention checking the bottom metal holes, but not the receiver face to thread alignment, nor that the threads are concentric to the receiver bore. I'm not sure if you would be assuming these to be correct or if you would consider them insignificant in accuracy terms. Or maybe more difficult to fix than it is worth. I'm not sure. Checking those bottom holes would seem important to me on something like a Remmy where it is so flimsy you can bend it measurably with your fingers. But not on something like most of todays customs where there is a lot of heft to the entire receiver.

Given the title of the thread is "Bat action truing", I was assuming that most folks talking about actions needing fixed meant just that. Major alignment issues (though I do not mean great big errors, just major items like I mention). I would expect a barrel when screwed in to contact the face pretty much all at once. Within about nothing. Not to contact the receiver face on one side first. I'd like the bolt face to be pretty much in the center of the barrel recess. Inline is a plus too!

I'm thinking Bat's bottom holes are gonna pretty much be within most peoples limits of measurement. I can't imagine a receiver spinning on the mandrel during those operations and having several out of alignment. I know I don't check them. As for lug engagement, I allow the break in lube supplied in a BAT to do its thing and have never seen lapping compound to be needed. Perhaps others are finding that but I have my doubts. Even if someone does want to lap them in, I don't consider that "truing".

Above it was mentioned about paying for the inspection and just considering it a cost of shooting well or whatever. I'm paraphrasing. Personally, I think of it the same as I do with extended warranties, except the cost of an extended warranty is usually less than 10% of the cost I paid for an item, usually closer to 5%. Where here, the cost of inspection is closer to 30-40% of the item cost, and I don't think the odds are good of having 1 out of 3 bat's need this sort of work. With that in mind, I would take my chances.
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What part of this did you miss?

The action is rotated with an indicator to check for runout on the face of the action. Here's where the lathe would be handy if the bearings are tight. Mounting it in a CAT's head and indicating off a mandrel will be helpful to show any runout/taper in the receiver ring threads. In my case I use my VMC and indicate along the inside of the thread using the Z axis of the machine. My setup doesn't allow the part to move. I'd like to think a CNC mill with box ways moves pretty square to the table. I hope it does anyway!
 
JerrySharrett said:
Measuring individual elements on a new action, for example, scope base screw holes, action screws, etc. aid in bolting the add-ons in place like scope bases and trigger guards and such but do not address the issue of performance of the gun after final assembly of the champion quality benchrest rifle
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JerrySharrett said:


Well Jerry that would be where you and I would disagree. If, for instance, I have an action with 3 guard screws as crooked as a fence post just how "tension free" is that receiver really going to be when it gets suckered down into the bedding? I mean if your sitting in a lazy boy all cozy and one grandchild pulls on an arm while the other yanks at your leg just how cozy/comfy are you?

Of course glue ins bedding jobs mitigate the problem, but I have my own opinion on that. It's not that they shoot better, it just eliminates the variable that the bedding could be goofy.

If I'm still mistaken/silly for doing this then fine, I'll eat the shoe. Tell me though why are guys like Jim Borden and Glen Harris thread milling the guard screw/scope mount holes instead of just drilling/tapping? A rigid tapping cycle is exponentially faster than interpolating a hole. Seems from a production standpoint they are quite foolish for doing it this way.

-unless they too have come to the conclusion that thread milling a bore offers far more insurance against a tap wandering off location. Not to mention the benefits of being able to use cutter compensation to adjust for tool wear, pitch diameter, etc. As any tool room grade machinist certainly knows a tap is inclined to take the path of least resistance. If the drill wanders, the tap wanders.

Far less likely to happen with interpolated bores and milled threads.


I stand firmly behind checking to ensure that action screws run square to the bore center/receiver bottom/sides. Whether its a champion quality bench gun or not is irrelevant and largely dependent upon the person shooting it.

Doesn't sound that hard. . .
http://en.wikipedia.org/wiki/Solid_geometry
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Chad....

The screw alignment on my stuff generally gets checked incidentally. I epoxy all my scope bases and screws and only tighten down gently and I make tight fitting inletting/bedding screws for the bottom for use in 2-3 operations. I've found this, BAT screw holes SUCK!!! They're obviously tapped, poorly and generally need to be chased/bottomed. Nesika/Borden and new Borden screw holes on the other hand are good enough to index off of!

IMO the new Borden actions set a whole new benchmark of overall linearity. BUT, I've recently worked with 4 Stillers and they're also well beyond my capacity to "check" other than the obvious. I feel that Jackie's statements above about just keeping your eyes open and chasing down boogers is spot on...... This is real to me. It's also the difference between "gaging" and "measuring." Gaging and back-checking are 'real.' Measuring is something else entirely.

This rubbish about clamping a brandy-new action into your mo'chines and "measuring it up" seems like a pipe dream.

To Me.

But then that's just one perspective. From a guy who can't even capitalize his own name let alone think in three dimensions!

LOL

And BTW....... if I EVER run across a custom action where the barrel shoulder doesn't STOP on contact I'll be hard pressed to ever order another. And I wouldn't straighten it, I'd send it back! And I don't send stuff back, gener'ly, but the actions I buy are those built from absolutely the fewest setups possible (duhh, that's why I buy them!) and if something like thread alignment is buggered??? Bad enough to SEE??? It's going BACK!

al
 
NesikaChad said:
What part of this did you miss?

The action is rotated with an indicator to check for runout on the face of the action. Here's where the lathe would be handy if the bearings are tight. Mounting it in a CAT's head and indicating off a mandrel will be helpful to show any runout/taper in the receiver ring threads. In my case I use my VMC and indicate along the inside of the thread using the Z axis of the machine. My setup doesn't allow the part to move. I'd like to think a CNC mill with box ways moves pretty square to the table. I hope it does anyway!
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Well, I guess I missed THAT part! Lol, sry. Ok, I stand corrected. whoops.

Actually I did read that, but I guess cause it wasn't detailed (didn't need to be I know) I musta skimmed over ... Or lost it as I read the rest.

Al, Bat's holes don't line up? Seriously? Ok...
 
No worries buddy. (seriously) :)

I'm not saying BAT holes don't line up. I'm saying it's a component of the inspection process that I try to pay attention to. I've personally never had any issue with a BAT machine product/service.

I say again, I'VE NEVER HAD AN ISSUE WITH BAT MACHINE PRODUCTS and/or SERVICE.

That cannot be said for others. I even worked for one once. . .

C
 
BAT'S HOLES LINE UP FINE!!!!! It's just that they're tapped, and after working with Stillers/Bordens/Nesikas I find this to be a pita. Also the screws and action metal are very similar (hardness??) they tend to be sticky.

I HAVE had this be an issue. I recently was holding a brand new BAT in my hand while I ran the screws in to show how the mag assy bolted on and the center screw stuck, galled in place. Just silly. It was because the threads weren't bottomed and some little burrs I'm guessing. I got the screw out (wrecked it) and chased the hole and all was fine. I didn't replace the screw because I don't use it. No I hadn't lubed the screws..... dumb on my part.

Holes machined during the initial setup rock

al
 
Gall a 1/4-28... Hmmm...

Actually, I think all the holes are done in one setup Al. All but the one through the middle.

So what do these folks do with the scope mount screws? They don't thread mill them too do they? I gotta tell ya an 8-40 thread mill sounds like a pricey piece. Not exactly on the "in stock" list.

Actually, I don't think thread milling would have made the hole less likely to gall. But, some stainless lube would.
 
4Mesh said:
Gall a 1/4-28... Hmmm...

Actually, I think all the holes are done in one setup Al. All but the one through the middle.

So what do these folks do with the scope mount screws? They don't thread mill them too do they? I gotta tell ya an 8-40 thread mill sounds like a pricey piece. Not exactly on the "in stock" list.

Actually, I don't think thread milling would have made the hole less likely to gall. But, some stainless lube would.
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The center hole isn't a 1/4-28 it's more like a 6-40 or 5-44

Yes the threads on a Borden are machined. The threads run clear to the bottom. They're held small too. Late one night I was fitting one up with different screws because I didn't have the stock ones and I searched high and low trying various screws. The holes are undersized 8-32 and when you start the screw it stops. They WILL NOT run in with finger pressure..... So I finally just bit the bullet, resigned myself to the fact that I may be retapping to size 10 and ran 'em in with a driver.

Next day Called Jim and he chuckled.

I'll agree that drilling/tapping the screws in one setup per side is probably how BAT's are done. But on at least two of them they neglected to switch out taps and bottom the blind holes....

al
 
sailhertoo said:
This is what you said.
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Yup, I did :)

I don't like having to chase out screwholes freehand with a tap. When the factory screw binds and galls in the factory hole before it hits the bottom and I have to make another screw.....

Yeahh, I did overreact though :) :)

It happened in front of somebody when I was showing off a BAT.

I repeat, I WAS showing off a BAT..... ;) ..... they don't suck THAT bad eh!

LOL

al
 
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