NEWS FROM THE TUNNEL, Barrel Indexing

AVanGorder said:
Gene,

Do you have some pictures? I have a wild and vivid imagination, want to make sure I'm on the same track.

Adrian
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Adrian, I'm sorry but I do not have any pictures at this time. Boyd Allen did his best to teach me how to take and transmit digital photos but he gave up in frustration. I guess I'm just not smart enough.

Later,

Gene Beggs
 
Gene,
If you can get it to me as an attachment to an email, I will post anything that you like, and if you need help attaching it to an email, call, and I will walk you through it. There goes that excuse:D
Boyd
 
GENE Thank You!

As a learning gun builder I have known that indexing barrels does make a difference and have done a few rim-fires the hard way, and sometimes you wonder if the chamber and throat are the same as the last position then you mess up and have to go all the way around again:(
I have not offered this as a service because of the time it takes, it's impossible to make a nickel.
I've been watching the guy's with the fancy fixtures that allow a barreled action to be fired in any position with envy, but simply cannot afford one at this time. Once you found the best position you marked the barrel then carefully re-indexed and rechambered it, allowing a possibility for something to change.

With your method it will change the sport forever and for the better!
Threads like these are why I spend more time here than anywhere else!

Thanks again, Kim
 
Gene-Jerry

What with you guys being buddy's, has there been any discussion about making an action with a larger receiver ring to facilitate a larger thread diameter for a bushing? Or is this something Jerry wishes I hadn't mentioned? The Moore I think about it, it maby would sell. Besides, it would be something Jerry could do in his spare time.
Passing thought or passing gas?
Steve Moore
 
mostly gas

The body would have to get larger and that would be heavy and too big. For the few it would sell it is not worth it. For a PPC you could probably go all the way down to 7/8 threads on inside with no problem. If you want to index this will work fine. I have an 1/8 inch difference on the python action and make adaptors, they are fine. 7/8 would leave 3/16 on most actions. I think a bigger action thread is solving a problem that doesnt exist
 
stiller said:
The body would have to get larger and that would be heavy and too big. For the few it would sell it is not worth it. For a PPC you could probably go all the way down to 7/8 threads on inside with no problem. If you want to index this will work fine. I have an 1/8 inch difference on the python action and make adaptors, they are fine. 7/8 would leave 3/16 on most actions. I think a bigger action thread is solving a problem that doesnt exist
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Jerry, glad to hear you say that because .875 tenon diameter is what I specified for the first batch of bushings which are in production as we speak.

Later,

Gene Beggs
 
Stephen B Moore said:
What with you guys being buddy's, has there been any discussion about making an action with a larger receiver ring to facilitate a larger thread diameter for a bushing? Or is this something Jerry wishes I hadn't mentioned? The Moore I think about it, it maby would sell. Besides, it would be something Jerry could do in his spare time.
Passing thought or passing gas?
Steve Moore
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One problem which comes to mind is that as you make the major tenon larger you must answer with increasingly fat barrels to maintain an abutment shoulder against which to tighten the barrel.

I recently acquired a large tenon BAT and the 1.125 hole coupled with a 1.250 "standard diameter" barrel is already perty iffy. I'm using an inch four-fifty barrel shank just because I want a solid abutting surface.

And that's all I got to say about that, don't know no moore..... ;)

al
 
Al- Gene- -

I think a recoil lug like Remington's [only ground parallel] would solve that issue.
Gene, are you going to furnish recoil lugs with 7/8" ID holes with your kits?

Steve Moore
 
Lynn said:
Al
If you go to www.pac-nor.com and click on "ready to ship" barrel ID # 268 this is the correct set-up for your action.I think free floating it would require good pillars and good quality bolts.
Lynn
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Ohh yeahhhh, GOOD call Lynn ........ That would look suhwEEET!

Why don't I just drill and tap the bottom of the barrel??? It'd take a coupla' quarter/28's no problem.... self-contained barrel block.

al
 
Forget the recoil lugs..............

..........that is what the back of the action is for.

Besides, putting a recoil lug between the action and barrel is about the poorest design idea to ever be adapted, complete waste and complication.

Nothing creates a cantilevered off-boreline recoil impulse like a recoil lug hanging down between barrel and action.

Mill a slot in the action if you have to, but get away from those sandwiched recoil lugs.

Why is it that the most accurate MOA guns in the world never have barrel/action recoil lugs, but are glue ins or glued and screwed?.........Don
 
Gene
Which actions are your bushings going to fit and when will joe ordinary be able to get one without a wait?
Lynn


Lynn,

The first batch of bushings should be available next week. They were designed specifically for the Viper and Cobra drop ports as those are the only actions I have at this time.

Next week I will try a Stolle Panda as that is the standard of the industry. I'll report my findings here on the forum.

Later,

Gene Beggs
 
Lynn said:
Al
I was seriously thinking about buying that barrel and having it chambered in 6BR.I got a reply from Dave Tooley saying those monster barrels get bad nicknames when you roll one across your finger or wrench your bacl lifting it into the lathe so I decided against it.
Maybe I can get The Pumpkin to chamber it up?
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That's funny! Go for it...... I've been having a time to find someone to build me a hunnerd-pounder. Guys say "they're a pain to set up", "they're a pain to take down", (I had one guy tell me that it was like changing a lathe chuck every time they set up the barrel! :D )

So anyway, that's why I was laughing ......

But I don't want a gun that heavy in 6BR.......... 300wsm maybe......

LOL


al
 
Lynn said:
Al
If the gun doesn't move at least 3/4 of an inch they don't seem to shoot all that well.I already have a 65 pound 6BR and it is a real shooter.
When it comes to setting up a heavygun Gary Alvey is hard to beat and his craftmanship is the best in the industry.You need a very large mill to make the entire gun parallel and perpendicular and he has all the equipment.
Lynn
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Lynn, that is my side of this barrel index discussion, gun assembly alignment. Lets assume the pivot point of a ill bedded/chambered assembly is 24" back from the muzzle. i.e. The recoiling gun will pivot 24" from the muzzle in its recoil path. From that 24" pivot point, if the barrel muzzle moves just 0.005" sideways, the POI change at the target at 100 yards is 3/4", and at 600 yards it is 4.5" and at 1000 yards the POI has shifted 7.5" if my 6AM math is correct.

Now, we know if every shot there was a 0.005" lateral movement, the bullets would all still go through the same hole. But, we know from shooting an ill assembled gun that it does not recoil the same with each shot whereas a properly assembled gun does recoil along its central axis.

My argument is that the muzzle bore exit point must be exactly straight in front of the chamber/action/stock assembly.
 
JerrySharrett said:
Lynn, that is my side of this barrel index discussion, gun assembly alignment. Lets assume the pivot point of a ill bedded/chambered assembly is 24" back from the muzzle. i.e. The recoiling gun will pivot 24" from the muzzle in its recoil path. From that 24" pivot point, if the barrel muzzle moves just 0.005" sideways, the POI change at the target at 100 yards is 3/4", and at 600 yards it is 4.5" and at 1000 yards the POI has shifted 7.5" if my 6AM math is correct.

Now, we know if every shot there was a 0.005" lateral movement, the bullets would all still go through the same hole. But, we know from shooting an ill assembled gun that it does not recoil the same with each shot whereas a properly assembled gun does recoil along its central axis.

My argument is that the muzzle bore exit point must be exactly straight in front of the chamber/action/stock assembly.
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Jerry,


I think that many of us are in agreement with you regarding WHAT we're trying to accomplish...... that being "balancing the entire rifle on the head of a pin." The "pin" being the centerline of the bullet or the centerline of the recoil impulse or SOMETHING that allows for consistent recoil.

My contention is that all of the measuring in the world cannot accomplish this, I mean it's like setting a motor and "carb" to exactly where you think it needs to be........ until you fire that badboy up and tune it on the dyno all the pre-measuring is just ballpark. Sametime, screwing on another barrel and getting it to hit within an inch is by-golly luck for sure! But by the same token getting one to be more than 3-4" off no matter how you line it up to chamber is rare.

I've got no meaningful opinion as to whether your method of trying to measure the rifle up so that the muzzle hole is lined up exactly with the centerline of the bolt makes for more or less side forces BUT..... think about this. If you were to set up and chamber three barrels: one of them is "straight", one of them has .005 of curvature and one has .010 of curvature but in all cases the muzzle of the bore is exactly in front of the firing pin. Are they all going to recoil the same? Most rifle bores seem to describe a kind of helix, it'd be pretty hard to predict anything from them.


And another thing.

When Beggs does a thing in the tunnel AND IT WORKS!!! It's pretty hard to argue with :) we can all 'scuss and rescuss the why's and wherefores BUT...... ya' cain't argue with results!


still fun to argue though ;)

Thanks Jerry,

LOL


al
 
Just thinking along here.

From my experience with long distance shooting of various types, there's a common thread that comes up - barrels that shoot closer to the wind.

Maybe this explains that phenomenon. Close shooting barrels are the ones that got indexed perfectly by pure chance.
 
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