1903a4 shims

[Embalmer]

Cant tell if theres one on mine, and the mount screws are staked in place, so I dont want to tamper with it. whats the function of them, and are they crucial? Any way to tell that it is there? past a4's I had always could see one peeking out somewhere.

[Herschel]

The shims are visible under the base on number 3979470.

[Tom06]

Can anyone tell me the thickness of the shims. I may have some material that is similar.

[Johnny in Texas]

There were 4 different thickness shims They are needed on most if not all A4's to level the base so the scope would zero at say 100 yards and still have enough adjustment for 600+ yrds. I have a few real ones mostly .020 or .015 I think they were .010 and .005 also I have seen a few original A4's with 2 shims under the front.

[4F4Nam]

Mine appears to have 2 shims. 1 thicker than the other.

Ed

[jgaynor]

The shims are visible under the base on number 3979470.

might want to recheck that s/n Herschel

Regards,

Jim

[jgaynor]

Cant tell if theres one on mine, and the mount screws are staked in place, so I dont want to tamper with it. whats the function of them, and are they crucial? Any way to tell that it is there? past a4's I had always could see one peeking out somewhere.

Yeah don't mess with the screws. The purpose of the shims was to level the base in the vertical plane so the scope could take maximum advantage of the elevation adjustment in the scope. They were hoping for a 1000 yard max (!). But you are right on original rifles a corner is almost always peeking out. On rebuilds sometimes they appear to have been omitted.

Regards,
Jim

[Marine A5 Sniper Rifle]

Mine has two shims, both visible.

jt

[Nate]

Would a diopter tell if shims were needed?

[Embalmer]

Yeah don't think mine ever had them.

[wolley]

On my A4orgery I used a caliper to check the height of the scope from the flat base of the receiver. It took .040" to make it level. Two pieces of .020 shimstock.

[jgaynor]

FWIW here is a link to the TM...Scroll down to Paragraphs 54 - 58 where the use of shims, adjustment etc are discussed.

http://photos.imageevent.com/badgerdog/generalstorage/dutchmansmanuals/TM9-1270-1903-Springfield.pdf

Regards,
Jim

[Col. Colt]

What were the shims made of? Was hardness a factor? Could a guy just make some out of brass shim stock for an 03A4forgery? CC

[Johnny in Texas]

They are soft blued steel I have a few still they come in 4 thicknesses .005, .0.010, .015, .020 I think

[jgaynor]

FWIW the shims were necessary to provide the full range of elevation adjustment for the Weaver 330C(M73B1) telescope. A lot of the the rebuilt rifles I have seen have had the shims removed during the refinishing process. In some cases the bases were recycled and the mounting screws have a second pair of stake marks. At least the later rebuilt rifles may have been intended to be used with the M84 or Ordnance might have realized that expecting to get 1000 yard utility out of an A4 with an under 3x scope was not realistic.

Could the shims be improvised out of brass or thin sheet steel? I suspect so. I think the ability to control the overall thickness is the most important consideration. If you could achieve that with a selection of stock from a hobby shop you should be good to go.

Regards,
Jim