George Shumways measurements

[Michael]

Working up the mounts and a stock pattern for Number 17 in RCA volume 1. It occurred to me, how accurate are the dimensions listed in the book? Has anyone had the chance to check any of these measurements for accuracy? Don't need them down to the thousands of the inch, just generally how close.

[rich pierce]

Most of us use them as guides as it's tough to make a copy unless you have the gun in front of you.  If the barrel you use is not the same thickness, and the lock bolster the same, then the wrist cannot be the same, etc.  I've always focused on the barrel length and width at breech as the first important measurement and the buttplate dimensions as the second most important measurement, and gone from there to sketch out something inspired by RCA guns.

[Michael]

Pretty much what I do. If the breech width of the original barrel is larger or smaller than my barrel it affects the architecture of the entire gun and modifications have to be made. At the same time trying to maintain the 'feel' of the gun.

[Captchee]

   Im not sure I can explain this but ill giver it a go .

 What the others are saying is true . But only true if  you try and keep the very same measurements of the original .  In which case you should use the same  size  diameter barrel .
If you don’t then what needs to happen is that  you need to concentrate on proportions .

 For some time I was very heavy and deep into building large scale RC aircraft .
As such  many times the only way one could get  needed information was either from small book size 3 views or from photos.
  So how do you do that . Well  you can use the golden mean . OR  you can go down and get you a proportion calculator  and a map    protractor .
 The first will allow you to scale up  or down  either by % or by a numerical measurement .   today many calculators  will do this . but you can also get a wheel that something like a slide rule . 

IE  lets say the original barrel is 1 inch at the breech . But yours is  1 ¼ .  By aligning the  1 inch on the outside of the wheel  to the 1 ¼ existing measurement on the inside wheel . the calculator will give you the % of   enlargement. Using that % as a base  you can  then proportion every last   measurement even from a photograph  . All you need is  a base to start .
As long as you keep  that % of enlargement or in some cases reduction “ has to be one , cant be both .
 You then will stay in complete  proportion based off that original measurement 

 With the protractor you can read angles  such as the angle of the wrist  as it drops away from the barrel flat .
So lets say your  barrel at the breech is .10% larger  then the original . What you will end up with is a rifle that is .10% larger  as a whole .  Resulting in the same lines , same proportions .

[Joe S]

Like Rich said, the photos and measurements are a guide, and only a rough guide at that.  If you measure the photographs, you will find that, due to photographic distortion, you often cannot reproduce Shumway’s published measurements.  So, in my experience, it is not possible to simply scale up from the photos.

[Captchee]

 joe , your not scaling the photo . your scaling the piece .
 IE you will have to use one of the  provided measurments .

while it  wont be exsact it will be closer then TAR

[jwh1947]

George used standard tape measures and calipers to arrive at his numbers;  they are, for all practical purposes, accurate.

I understand your penchant for details, but, keep in mind, if you take a few rifles from one early shop and place them side-by-side for comparison, you might likely find reasonably significant differences in external dimensions that far exceed the fractions that you are looking at here. 

[Bentflint]

I tried a few weeks ago to make a drawing RCA #73. First I went off butt height 5" and wrist 1 1/2" but the pull wouldn't fit. Next I scanned the photo and used my CAD to lay a scaled 1" graf on it and did a drawing by hand on full scale 1" graf. That didn't work either. Then I rescaled the photo (going off lop) and printed it, didn't measure out right either.

Then I went back to my old way. Draw a center line on the blank for the barrel. Locate breech, touch hole, lock and sear lever then trigger. Make a few marks for lop and draw an arc between them, I know the center of the butt plate will be on the arc. Find the drop at the heel and make a line from there to the touch hole (on gun #73 anyhow) and do the same for the toe. Stand back and look at it, it looks good. Now find the bottom of the forearm and draw a straight line from the lower pipe to past the breech, remember you have to fit a lock bolt and ramrod in there. Next look at the picture in the book and draw the bottom of the wrist, when you have that the way you want it draw the top. Look real close at the comb, if it looks right you got it. Next step, bandsaw a 1/4" outside the lines.

The finished drawing looks like the J Newcomer gun.

I'd post a picture but, the stock and barrel are in WA right now.

Here is a little trick for compairing your drawing to the book. Take a piece of Claire plastic (a lid off a CD case) and draw a line on it. Use a straight edge on your drawing and CD lid on the picture in the book to compair where lines cross other lines.

Bruce

[Captchee]

Here is a little trick for compairing your drawing to the book. Take a piece of Claire plastic (a lid off a CD case) and draw a line on it. Use a straight edge on your drawing and CD lid on the picture in the book to compair where lines cross other lines.

 yep thats what a map protractor will do . but it will give you the degree of the  angle