1 piece scope base improving action rigidity?

11 December 2007, 01:29

Westpac

quote:
Originally posted by wildboar:
Hi, I've heard that a 1 piece scope base can improve rigidity; could it apply to a Rem 700 action? Could it improve accuracy over a 2 piece base? Thanks.

I'm certainly not a mechanical engineer, I will let Chic speak to the science of it, but I do know that solid top receivers flex and stretch less than those that aren't. Granted, a 1 piece base held by 3 small screws might not contribute a whole hell of a lot to a receivers rigidity, but I'm thinking, until convinced otherwise, that it should provide some additional support over a two piece base.

11 December 2007, 02:07

Marc_Stokeld

Chic is a Sewage Engineer (Civil), I am a mechanical engineer.

On paper you cna make the case that it is marginally more rigid. A lot would depend on the action. Something like a solid bottom 40X would likely as not see no rea rigidity increase. On a Mauser with full thumb cut, well, a little more impact, but if you are depending on the scope base to actually make a real difference then you are screwed.

Also, unless all three of the scope base holes are in alignment (they won't be) and the action holes are in alignment (they won't be) then you could add a torsional force to the action. This would be anti-good.

This is one of those little things that gun writers hear and then start spouting off like they know what they are talking about. Yes, it is true that the base makes it more rigid. The rest of the story is that it is a trivial amount, and the shooter is the problem.

Man, some of those true BR actions are rigid in spades! Cuts just large enough for feeding and extracting.

People chase things, trying to buy small groups. THe OVERWHELMING factor in how small the group turns out is what your second flag is doing right when you touch the trigger. Loading and shooting technique are non-trivial and more than theoretical influences on your group size. Changing soemthing little here and soemthing little there will not help. The differences are so small as to be lost in the scatter. But true BR techniques can really help

11 December 2007, 06:00

tnekkcc

quote:
Originally posted by Marc_Stokeld:

This is one of those little things that gun writers hear and then start spouting off like they know what they are talking about. Yes, it is true that the base makes it more rigid. The rest of the story is that it is a trivial amount, and the shooter is the problem.

I look down on gun writer's technical canards.
But Ackley and de Haas are approved by this engineer.

11 December 2007, 06:38

ireload2

quote:
THe OVERWHELMING factor in how small the group turns out is what your second flag is doing right when you touch the trigger.

Another good way is checking the angle of the mirage.

11 December 2007, 06:53

jstevens

I do know for a fact that those one-piece bases are a pain in the ass when you have to reload fast. I'll never have another one on a rifle.

12 December 2007, 04:32

boltman

The weakest part of the scope mounting process is the screws. Two piece bases have four screws holding them, one piece bases have three. To me that means the two piece bases are the stronger setup. I don't buy the argument that that a metal strap across the top of the receiver is going to add any rigidity to an action which is essentially a pipe. Plus, one piece bases are ugly and they obstruct the loading port as mentioned above.

12 December 2007, 10:18

tnekkcc

quote:
Originally posted by boltman:
..one piece bases are ugly and they obstruct the loading port as mentioned above.

But a one piece MIGHT prevent Bubba from lapping a pair of rings when lapping for alignment.
Anything that prevents gunsmith lap dance ring wrecking is a good.

12 December 2007, 19:14

22WRF

Call David Miller and ask him if he has done any testing with his. He makes a custom one piece base with integral rings for every custom rifle he sells. The receiver and the base are custom honed so they fit perfectly, and I believe he uses three screws forward and three back although I am not sure.

I doubt very much that he would go to all of that trouble and I doubt very much that his customers would pay about $1500 for this set up unless there were some mechanical advantage to it. In addition, he fits these so that they do not have an impact on the loading port.

As for doing anything to avoid ring lapping, there is one sure fire way to avoid that, which is to use the Burris Signature Rings with the plastic inserts.

12 December 2007, 20:22

OldGuy

I use mostly one piece bases, but to be able keep the rings in alignment if I use a shim to gain more scope adjustment. As others have said, adding to rigidity of the action is not paramount.

12 December 2007, 21:08

olcrip

It is to my understanding that unless your action is a rear locking type such as the old Rem. 788 then you really don't realize any strength advantage from the one piece bases. Front locking receivers and bolts apply all the stress to the front ring of the action. Unless your action is not bedded properly it won't flex in the middle and any advantage derived from the one piece base is negligible. That's my theory and I can be educated to see things in a different light.

12 December 2007, 21:33

Marc_Stokeld

For one thing, i doubt if David Miller has made and run an FEA model of the M70 with his mount attached. Even if he has, it is only showing any gains that will be there on paper. As stated in my first response, a one piece base WILL add strength and rigidity on paper. As also stated in my first post, it will not show up as any improvement on a field rifle.

There are calcs for this run in the book "Rifle Accuracy Facts." H.R. Vaughn actually gave it the wrong book title. It would be more accurate to read "Rifle Accuracy My Opinions." Now granted, that man knows A LOT more than I do abou tmany things, but that does not mean everything in his book is rock solid.

13 December 2007, 02:24

Woodjack

A precise well engineered&fitted one piece bridge base&ring setup like Dave Millers(which also supports the tube) does allow more rigidity in the mounting system and would certainly offer you less chance of knocking the scope out of alignment or bending the tube, compared to an off the shelf system. BUt I would say that is its major advantage, more so than offering any great improvement in accuracy by way of improving action rigidity.
None the less, what ever actual degree of increased action rigidity the Millers sytem offers, it would certainly be superior to any degree of increased rigidity/stability one would get from an typical off the shelf system.
To get the best of both worlds one should really get one block of steel and machine the action,bridge base and rings all in one integral piece ie; imagine a D.miller rifle where the mount is not joined on, but rather molecularly one with the action.

Heres an action that goes part of the way, integral rings,but no tube supporting web.
I prefer it to the current D.Miller method.

13 December 2007, 03:45

Westpac

Wildboar,

If you are seriously looking to increase the rigidity of the action through the use of a 1 piece scope mount, then this is the baby I would recommend!

Of course the action will require about $200.00 worth of modification so the "lugged" rail will fit.

13 December 2007, 04:49

tnekkcc

Those mount screws are not there in high frequency vibration. [Watch something with a strobe when it is being vibrated perpendicular to the screws]

If the one piece is bonded to the receiver with epoxy, and has not been popped off, but is still stuck, then THAT IS there at high frequency and would make the receiver stiffer, a little.

But I cannot imagine that tiny increase in stiffness translating to a measurable increase in accuracy.

13 December 2007, 05:22

tiggertate

quote:
Originally posted by Marc_Stokeld:
Also, unless all three of the scope base holes are in alignment (they won't be) and the action holes are in alignment (they won't be) then you could add a torsional force to the action. This would be anti-good.

That's where the 1/8th low hydrogen rod comes to play. And be sure to burn the puddle well into the receiver rings; just to the bottom of the threads on the front ring. Quench rapidly in cold water to restore some hardness, screw the barrel back in and you're good to go.

And that's MR. bubba, thank you.

14 December 2007, 06:32

ted thorn

quote:
Originally posted by tiggertate:
quote:
Originally posted by Marc_Stokeld:
Also, unless all three of the scope base holes are in alignment (they won't be) and the action holes are in alignment (they won't be) then you could add a torsional force to the action. This would be anti-good.

That's where the 1/8th low hydrogen rod comes to play. And be sure to burn the puddle well into the receiver rings; just to the bottom of the threads on the front ring. Quench rapidly in cold water to restore some hardness, screw the barrel back in and you're good to go.

A welder by trade I wonder why not use parent metal to weld with? Don't forget to pre-heat and be carful with any quench (oil or water) your palaying with some complicated metalurgy with unknown temperatures. Also remember to normalize after you weld.

As far as a one piece base making an action stiff or strong....it is a bolt on part with small screws....I would say myth. Just a guess though.

And that's MR. bubba, thank you.

14 December 2007, 11:56

vigillinus

In the 1930s Ralph Packard had a rifle built with the scope tube integral with the receiver. It was written up in the Am. Rifleman and later was in the Smithsonian, I guess it is still there. There is also the Lloyd mount, somewhat similar to Miller's, which one occasionally sees on British rifles. I don't think any one piece mount, Miller, Lloyd or Redfield Jr., adds any useful rigidity to a receiver .. but that is just my opinion.

14 December 2007, 15:11

Marc_Stokeld

CZ has integral scope bases and look how good that is working for them. Search here and find how many of the magnums shoot too low with all scope or iron site adjustment used up. Now in something like the custom BR actions it would be fine, but not in a mass produced arm.

Personally, I like tigger's idea of running a 7018 around the base/reciever joint!

14 December 2007, 19:03

olcrip

All the stress on the action on battery is in the bolt locking lugs..... All the stress is therefore transmitted to the receiver at the point of bolt lock up.... What stress is put upon the back or free portion of the action? None... I suppose a person could make the action totally closed like

naval guns and feed thru the back with the bolt removed ya think? If anything a solid one piece base would contribute would be to keep the scope stabile.

14 December 2007, 21:43

458_wanderer

I'll echo the opinion of mechanical engineer Marc, not only because I'm an ME too, but because he's right.

A one-piece base will make any action stiffer, period. The magnitude, and effect, of this increase in stiffness depends on many factors. In practice though, I would be very surprised to achieve a measurable improvement in accuracy in a human-fired field rifle.

In a laboratory, with a special "rifle" that likely wouldn't resemble anything of the sort, you may be able to measure a change in accuracy....interesting to know, but totally useless in the field. If you really want a stiffer action, all you have to do is get one.

With all this said, I would find the results of an FEA study on the matter to be very interesting.