doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Problem: O/U Barrel Regulation

Chuck --

I have now had a chance to view the pictorial overview of the Parker barrel reconditioning:

(http://www.picturetrail.com/sfx/album/view/18691676/297178486

I must say I think you did a great job in putting this instructional overview together.

Very Nice !

Your point about the sequential use of acid and then rosin fluxes is now clear. Your discussion on this point is absolutely correct, important and well done. ( At one time I did research on the new, lead-free, solders for IBM -- before retiring in May. )

Thanks for the reference.

Best Regards,

Don

Don,
Thanks for the vote of confidence. I was treading on new ground for me and while I have soldering and jigging background, I had not done nor seen the process except for bits on video clips. But, past learned experiences and those bits took me thru it well. I'm now armed to buy a gun most would shy away from due to the cost of re-laying ribs and re-blueing.

I did buy some homogenized solder with rosin flux mixed in, but didn't find the need for it. In some of Oscar Gaddy's notes or correspondence, he suggested the use of such. I found it fairly expensive and not necessary.

How come no one has just told Don to take Galazan's offer, and be done with it?
It's a nice discussion, but is also the long way around his original question.

ClapperZapper --

In response to your question, the critical point is that I have had no response from Rizzini with respect to the tolerance on the respective points of impact for the two barrels on a new set. I sent an e-mail over a week ago with a formal inquiry and I made two telephone calls and left messages. To date, no response.

I would hate spend the money on a new set of barrels and find myself in a situation with little or no improvement in the barrel regulation .... and more wasted time. Without some sort of guarantee on the maximum, barrel to barrel, point of impact tolerance that Rizzini will stand behind -- there is clearly a problem and no clear solution.

Right now, the "compensating choke" solution seems to be the leading candidate. I sent a formal inquiry to Briley, yesterday. No formal response, yet. But, in an initial telephone conversation, the Briley representative felt very confident in achieving a good technical solution. This approach may be cost effective. as well.

Best Regards,

Don

Don,
I'd sure give Mr Eyster an opportunity to assess it and give an estimate based on his reputation alone.

Chuck --

I will give Kyster a call, tomotrrow. I was able to run down some additional information on him. The article I found was quite laudatory.

But, it appears to me that -- in the absence of new barrels -- the only recourse will be to use modified chokes which compensate for the present barrels', point of impact, divergence.
I cannot vizualize another, workable, physical solution.

We will see what Kyster has to say and I will let you know what happens.

Thanks.

Best Regards,

Don

Don,
Best luck to you on this.

Chuck --

Well, I contacted Eyster Heritage Gunsmiths, this morning.

Very interesting discussion ..... Very

Ken is no longer actively engaged with the business. So, I spoke with Tim, Ken's son, concerning my B. Rizzini O/U patterning (point of impact) problem. It appears that my particular problem is not an isolated one. Apparently, there are a large number of B. Rizzini, O/U, owners which are "beating a path" to the Eysters' door for help -- all with similar problems. There would seem to be -- or, at least, has been -- a systematic production problem at B. Rizzini. Interesting .... if it was not for my bad luck, I would not have any luck at all.

It turns out that Ken's son, Jim, is the individual in thier gunsmithing group who, now, handles the "barrel work". Jim is presently away at the Olympic trials with his own son, who ostensibly has a "shot" at making the team. I will call Jim next week to discuss what may be done to correct my problem. But, Tim commented that the 16 inch divergence ( at 40 yds.) for the points of impact for the two barrels on my gun was very large and their standard approach, to correct such problems, may not work. I will know more when I speak with Jim on Monday or Tuesday. But, they are presently "swamped" with work. Tim sounded harried.

For the recond, Chuck, here is the contact information for the Eysters. Their phone number has recently changed.

Eyster Heritage Gunsmiths
6441 Bishop Rd.
Centerbug, OH 43011
Ph: (740) 6250-6131

No word from Rizzini / Galazan ... or Briley, yet.

Best Regards,

Don

Don,
That information certainly is helpful to those that may have been considering a B. Rizz gun. I had seen some of their guns and thought of them for some of my hunting uses, but that's not on the table now.

Given that this condition may exceed the ability of EHG to eliminate completely, I'd would think there would be some visual cues. If you lay the barrel on its side and sight along the upper barrel, does it noticably 'swoop' up?

Chuck --

In response to your posting directly above ....

Now, this problem is getting really interesting -- if confusing.

I undertook your suggested evaluation by coating the barrels lightly and uniformly with oil and viewed the sides of the barrels against a uniformly lit, blue, sky. There was no obvious "swoop" at the muzzle for either barrel. But, the barrel profiles could obscure a slight swoop.

Pursuing the point, yet, further, I undertook the following evaluation. I have extended Briley chokes for the gun. The extension for the chokes is about 0.5 inches in length. And, indeed, the extension of both choke are round by caliper measurment, as would be expected based on the machining techqiue used to fabricate them. They show no measurable difference in diameter over their extension length, i.e., they have no taper, +/- 0.0005. The seperation between the chokes at the muzzle appears to have been designed to have an approximately 1 mm gap. Placing a 0.0385 shim between the choke extensions, it just snugly fills the gap between the choke extensions. This shimmed choke configuation can then be viewed "side on" against a back light, to determine whether there is a taper in the shimmed gap - between the shim and the extensions -- from the muzzle to the end of the choke extensions. The answer to this experimental question is that I can discern no taper in the gap. Based on using the calipers as a gauge, I think I should be able to discern a taper in the gap in this shimmed configuartion, if it were 0.001 to 0.002 inches or larger. If a lack of parallelism between the chokes, alone, was the cause of the 16 inch divergence, I should see an increase in the gap of 0.0055 inches from the muzzle to the end of the choke extensions. ( 16/ 1440 X 0.5 inches) Obviously, I did not find this result.

I then undertook an additional evaluation. re: barrel to barrel alignment. Placing the barrels on a cushioned support, I position the barrels, such that I could view the apex of a tall tree against the sky at approcximately 40 yards distance. The barrels were positioned and then fixed, such that the apex was centered in the view through the upper barrel, using the concentricity of the muzzle and chamber image rings for eye alignment. Without touching / moving the barrels, I viewed the apex through the lower barrel along the axis of this barrel in the same manner. The apex was centered in the view. The two images were not discernably different. This result indicates that the bores of the barrels are approximately parallel.

Interesting ..... if confusing. So .... now where ....

Thus, far I have not considered gun dynamics (recoil) before the shot charge leaves the muzzle. There is an intrinsic difference in torque and barrel movement generated by the upper and lower barrels in association with recoil. This would provide for a difference in upward barrel rotation from upper to lower barrel -- the upper barrel producing a larger rotation. But, I have always considered this effect to be very small. On the other hand, I have never tried to qualtitatively estimate this difference. If this effect is a contributing cause, the differential in the upward movement of the muzzle during recoil would have to be a none trivial fraction of an inch. On the face of it -- this seems to be a very large differential movement in the short barrel transit time for the shot charge. I could attempt to make such a calculation, but, it would take some time to characterize the parameters needed for even rough estimates. Do you know whether anyone has made and published such estimates? I suppose I could use some 3 inch - 1 1/4 oz loads in point of impact pattern testing. This would magnify the differential in the point of impact between the barrels -- if recoil is a significantly contributing parameter.

So, to date .... Not much progress in providing for an understanding of the origins of the problem. Interesting, though.


Best Regards,

Don