Need some help with an S'G' front band

[frankderrico]

Bob, thanks for the update. Your pics show the differance in the holes. Glad you got it fixed. Now how about the carbine on the table in your last pic?.....Frank

[USGI]

Bob, thanks for the update. Your pics show the differance in the holes. Glad you got it fixed. Now how about the carbine on the table in your last pic?.....Frank

Somehow that one missed going through the arsenal rebuild. It's a little rough with the front sight wings filed off and the stock is that one I posted about ealier that had a piece added onto the butt. It's got all the right parts - I probably should have had you or Charlie do the stock for me. - Bob

[Harlan (Deceased)]

Hey Bob - sometimes just replacing the band spring with a new one that has a nice square 'lug' is enough to solve the problem. (Let us know)

~ Harlan

[JimF4M1s (Deceased)]

Bob,

I love that chair, maybe skids on the bottom will help add some excitement on those icy mornings.
But you are showing our age with those calipers. I still occasionally race my slot cars and got ribbed by the younger guys for using dial calipers to check tire height. So I caved in and bought digital calipers.

I have used the wooden match before too. After someone buggered up the hole. A guy took all the metal off his stock then tried to swell up the nicks and dents. Of course this semi closed the spring hole. So he drilled it out, (meaning too large) that was the reason for the inserted wooden match stick.

Merry Christmas

Jim

[firstflabn]

Excellent photos; not so great on the math. Your reported .050" offset is not from the centerline; you have doubled the actual offset.

With no convenient reference point and no drawings, we can't know whether the hole and/or step down in the stock nose are mislocated (but if they couldn't manage to drill a hole perpendicular to the stock centerline, it doesn't exactly inspire confidence). Add the .025" skew in the hole location to the +.010" tolerance on the spring length and I'd guess by the eyeball method that you're approaching what shows as a gap between rear edge of band and stock step down. Distance from 'D' cutout in the barrel band to rear edge of band figures in too. Proper angle on the spring really matters if the wood has shrunk a bit from sanding.

[painter777]

I had a similiar situation on a OI Hi-wood stock set. Just for the heck of it, After removing the band spring and bending the right outer end outward. Found it seated and gripped much better. HG and band stayed in place and stayed tight. Easy enough to try.
Also had another stock that came with no spring, it looked as though the band spring had been knocked out with too big a diameter punch. Spring never would seat tightly. I packed the right side hole with JB weld, pushed in with a cut down Q-tip and while still soft pushed a #6 (or #8, which ever is closest to the band springs inserted part) finish nail with some cellophane wrapped on the nail. I had looped twine to each exposed end of the nail pulling it back towards the receiver and tying it. When Epoxy had dried I tapped out the nail and put in the band spring. Worked very well, without any JB to be see when spring was in position.
I know........... sounds a little whacked, but both methods worked for me.

Just passing along some Country Boy methods that worked for me.

FWIW,
Charlie-painter777

[USGI]

Excellent photos; not so great on the math. Your reported .050" offset is not from the centerline; you have doubled the actual offset.

With no convenient reference point and no drawings, we can't know whether the hole and/or step down in the stock nose are mislocated (but if they couldn't manage to drill a hole perpendicular to the stock centerline, it doesn't exactly inspire confidence). Add the .025" skew in the hole location to the +.010" tolerance on the spring length and I'd guess by the eyeball method that you're approaching what shows as a gap between rear edge of band and stock step down. Distance from 'D' cutout in the barrel band to rear edge of band figures in too. Proper angle on the spring really matters if the wood has shrunk a bit from sanding.

The hole on the SA stock is about .05" closer to the "step down" on the right side than it is on the left. The difference between the two sides is the same whether you use the center line or the edge of the hole (welding rod) - hope this helps on the math question. Kuhnhausen's book does give the dimension for where the "step down" should be. The "step down" and the handguard dimensions all checked out. I didn't measure the cutout in the band though. The location of the hole on the left side is about where it ought to be according to comparisons I made with my other stocks. It's too bad Kuhnhausen's book doesn't show the actual dimension for hole location. - Bob

---------- Post added at 07:44 PM ---------- Previous post was at 07:38 PM ----------

I love that chair, maybe skids on the bottom will help add some excitement on those icy mornings.
But you are showing our age with those calipers. I still occasionally race my slot cars and got ribbed by the younger guys for using dial calipers to check tire height. So I caved in and bought digital calipers.

I broke down and bought the dial caliper when I couldn't read my vernier anymore without getting a headache. I do have a digital, but since I can't actually see what makes it work, I don't trust it unless I check back and forth between the two! Also, it's too easy to leave it on and run the battery dead! - Bob

[firstflabn]

I think you're on the right track, Bob, and the excellent photos helped me follow your analysis. What I meant on the skew was not related to measuring from edge of hole or centerline, but skew from normal to the stock long axis. If we were both marching band members and told to line up on the 50 yardline, but you lined up on the north 49 and I lined up on the south 49, we would be off by a total of two yards, but each of us would only be one yard from where we were supposed to be. Since any mislocation would only matter on the stock's right side, I used offset from hole location if hole was drilled normal to stock long axis (rather than total skew).

Ignoring my training by adding dimensions on a drawing (and also ignoring the stated tolerances), the stepdown should be 1.3565" from back edge of hole. You measured 1.323" on the right side. That's 0.033" too short and looks like it could account for the great majority of the gap between band edge and stepdown. Left side is .018" from ideal (too long). A bit of tolerance stacking could account for the remainder, though the band doesn't have to fit tight up against the stepdown (as long as the band is tight and assuming the hole in the band is properly located); it can stand a small amount of rotation.

The real lesson is how difficult it was to design these things even using such a simple, static element as this as an example. Like the Three Bears' porridge - not too hot; not too cold; just right. Close tolerances required for function; loose tolerances required for constructability.

[USGI]

Thanks for the detailed explanation. I think the left side of my band spring hole is on the 50th yardline and the right side is on the 48th! I've drilled some "skewed" holes myself by not having my work laying flat on the drill press - perfectly straight holes that started out in the right place, just didn't come out the other side where I had planned! - Bob

[firstflabn]

Thanks to your efforts I now have a better understanding of the system, Bob. Wonder if it was that the drill wasn't set on 0 deg or if the stock wasn't shimmed up under the nose to keep its longitudinal centerline parallel to the bed? I shouldn't ignore the possible contributing role of a rounded off catch. Looking at Kuhnhausen, I see the 90 deg (-) callout on side of the catch to the short leg of the spring. If it's rounded off, it is also a tad shorter and, thus, has less bearing on the edge of the slot in the band (for a Type 2 or 3; from the outside of the band for a type 1).

I have an original Saginaw that the band occasionally pops off like yours. I didn't want to alter it or swap springs, obviously. The hole was tight, so I installed the spindle without pushing it all the way down. I rarely shoot it, but that seemed to cure it. Now I'm going to have to take another look at it to try to puzzle out which element (or combination) caused the problem. You didn't know it, but you were helping diagnose mine along with yours!

Can't do much about wood shrinkage or oversanding without using a shim, but absent those factors, I think this exercise may have produced a new diagnostic procedure: 1) check hole to assure it's not wallowed out - spindle should fit tight; 2) check location of hole on right side relative to stock stepdown (dimensions above); 3) assure catch is sharp on face and about .053" high; 4) and one more - where flat leg breaks, assure angle is about 12 deg and the angle of flat leg to spindle is about 83 deg (that's what makes it spring).

I just dug out a new spring that I got in a parts grouping. Had always suspected it was non-USGI. All measurements are fine except the angles - 87 deg + (should be 83) and 7 deg (should be 12). That's awful. It's in the trash. Glad there were some really nice small parts in that group otherwise.