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Adjustment value of PU scope hashmarks?
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08-31-2018 03:48 PM
# ADS
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leeshall: My understanding is that 1 unit of windage on these scopes is 1 milliradian. That's roughly 3.5" or 3.5 MOA at 100 yards. I'm going by memory here as I've lent my 91/30 Sniper manual to my brother. The range units are hundreds of meters.
As far as the shims go, I have no idea what the rules are but I believe the Soviets had slightly different ideas from the Finns. I have one Soviet diagram that shows shims in the usual Finnish spots but, importantly, another beneath the barrel reinforce. The text indicates the shim on the flat at the front of the receiver is primarily to preclude stressing of the receiver by tightening the screws with bearing only at the reinforce and the rear tang. All of the Finn rifles I have that are shimmed (and many are not) only have the front receiver flat shim and no bearing under the barrel reinforce. Could you scan and post the diagram you have? I'll attempt to find a scan of the one I've got.
Ridolpho
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Ridolpho,
Can't seem to get the copy & paste to work on this reply to your post. What is your e-mail address. Maybe it will work that way.
Thanks,
Lee
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leeshall: Try scanning and saving as jpeg then just attach as a photo. Here's the one I have seen- unfortunately I can't track down the full reference at present but some Red Army manual. The key to this is, of course, the translation. My own simple-minded attempts regarding the labeling of the shims suggests that the shim under the barrel reinforce is the means of lifting the barrel up to achieve float, aided and fine-tuned by the rear tang shim. The shim near the front of the receiver flat is indicated as being there to prevent bending of the receiver when large shims are necessary under the barrel reinforce. This seems to make sense and is consistent with practice with other bolt action military rifles like the '03, P14/M1917, Mausers, ect. Most or all of the Finn rifles I own that have shims ignore the bedding of the reinforce and simply raise the barrel up out of the channel with the two receiver shims- to me a quick and dirty wartime expedient method of getting rifles to shoot. I have postwar rebuilt Finn rifles that have old fashioned full-length barrel bedding (a 91/24) and floating without shims (M39). As an experiment I took a post-war refurbed Soviet '27 upgraded Dragoon which came from refurb with very carefully full length bedded barrel, shot it to get a baseline, and then played with shimming. It shot decent 2" groups pre-shims and Finn style shimming, with or without barrel wrap didn't show any improvement. However, by throwing out shims and carefully bedding at the positions on the diagram (full float ahead of the reinforce) it suddenly would yield the occasional 3-shot cloverleaf in a 5 shot group of about 1.5".
Ridolpho
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The image you sent me is from a post war Soviet book about sport shooting by Yuriev.
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leeshall: yes, I've seen it posted elsewhere that that is the source of this diagram. I'm currently contemplating ordering a copy in English, but rather expensive. The diagram does appear to relate to a rifle with full military stock and I wonder if it might have its origins in military accurizing practice? I've scanned many official government documents on the M91 and M91/30 and have yet to find specific reference to design standards relative to bedding. It may be that it is simply assumed the reader will know that it is to be full length bedded (along the barrel). Unfortunately, with limited Russian reading ability I've probably missed the key stuff. My best source of info on original bedding are the non-refurbed Mosins in my collection.
Ridolpho
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