Let uis speak of datums and axis and other fabled parts of my Enfield lol

I've spent the evening setting my B square mounted scope on the ol No4 Mk2 and thought I'd ask advice before I alter anything permanently.

I set the rifle on a stand, and put a bubble level across the rear sight axis pin to get the rifle horizontal , mounted the scope mount, set the scope level with a distant, measured horizontal line and firmed up the screws.
Trouble is that when I pick the rifle up, the scope is quite canted, a lot.
So, I put it back in the stand and did the ol screws trick, with the butt plate screw slots lined up and a thread with a weight hanging down the middle to get a perfect vertical. I set the scope to horizontal at this point and then shouldered the rifle.
This time as I hold the rifle the reticle is perfectly horizontal/vertical but which is correct?

Naturally any time a scope is aligned using the butt stock centers when the rifle is shouldered if one is holding the rifle correctly the scope reticle will always look right because the butt is against ones cheek and being held vertically.

Is the correct conclusion here, that the butt stock on my rifle is not correctly square to the rifle and that I should go into the wrist socket and correctly align it to the vertical?

And now I think about it this has to be fixed because if I shoot with the reticle squared to the butt stock then the point of impact will be canted away from the vertical axis, a sore point if one s after accuracy.

Any thought, is my conclusion in the right area, that I need to remount/tweak/put right that the butt vertical axis don't match the rifle vertical axis and should?

Is it safe to assume the rear sight axis is a reliable horizontal line?

I checked the B Square and its not bent or any other problem like twisting as I attach it.

thanks

You are wasting your time and effort with the b-square mount. THE ONLY no gunsmithing mount that is worth anything is the fulton made one from Brian Dick of BDL LTD. they are strong, fit perfectly and are very well made.

It doesn't matter if you can use a jig or instrument to measure datums, continums, condoms or anal retentention because the tolerances in the manufacture of these rifles is such that unless you have a mile or so of adjustment on the u beaut no gun smithing mounts, you may still not be able to colimate the rifle scope to any line!

Thats why they have so big adjustment scales on the scopes so you can "dial " in your correct zero point.

I would suggest that the vertical or horizontal perfection that you ask for will not matter at the other end of the range. all that it will mean is that the adjustments will not be perfectly straight either direction but as some high-power match rifle shooters do with canted sights to accommodate cant in the shooting position, just add or subtract adjustments to suit.

Unless you are prepared to drill and tap with any number of different mounting systems that can be adjusted of datum lines then you are chasing your tail IMHO

Cheers
NED

Interesting problem.

Theoretically, the axis pin for the rear sight should be "horizontal" give or take the tolerances on the drawing (which I'll have a look at when I get home.)

There is a possibility that the butt (being a wooden component) may be a little less than "perfect. Note that the bulk of No4 butts have a round (but tapered) tenon as opposed to the tricky little number on the SMLE.

As for lining up the butt with the sights:

If you play with multi-position match-rifle shooting, you will find that the adjustable buttplates on fabulous toys like the Tubb 2000 are almost NEVER set dead vertical. Many shooters have little tables to tell them how to set the butt for each position. Some better-heeled folk simply have a differently set-up butt module for each different shooting stance.

If the barrel is correctly aligned, the scope reticule should align with the axes of the receiver. However, rifles and bullets being the perverse creatures that they are, some minor canting or other offset MAY be required to match the reality of the bullet's flight in the real world, especially at longer ranges.

Apart from all that esoteric stuff, torquing down the scope-ring screws is a bit like torquing down the bolts on a cylinder head of a motor. Set the rifle up in a rigid clamp so that it it is "plumb". Partially tighten the screws on one side of one ring and note how much the scope has rotated. Tighten the screws on the other side and you will observe rotation in the opposite direction. Basically, the trick is to tighten the screws in tiny steps. Not only that, if you tightne the front ring "clockwise", tighten the rear ring screws "anticlockwise". And keep checking the alignment during the process.

"Weaver" style mounts that have a a top band that hooks over one side of the bottom ring and fixing screws on the other side are guaranteed to make the scope rotate as the lock screws are tightened. Simply start with the scope with an angular offset in the other direction and be patient, very patient.

Thanks gents, that gives me the answers I was after. Pretty interesting to hear that shooters don't always have their butt stocks in plumb with the receiver, that takes customizing for the shooter to a whole new level, gives a bit more room for thought.
Now the sun is up I'll post a pic or two of the issue, the discrepancy was a long way from fine adjustment, lol, so it was a worthy question. I'll compare this to my other r4's and make sure its not just my own clumsiness or faulty set up thats brought this up.

So here's what started it all, with the rear sight axis horizontal this is the lean thats built into the stock. No wonder peopel kept complaining that the reticle was crooked.
I checked my other rifles to see if it was me or my method and after two jc's and a no4 mk1 they allare either correct or just a smidgen off plumb, so its clear that this one rifle is bent.
For now I'm going to leave the reticle squared off to the rear sight axis and if people complain I'll just tell them they're holding it wrong. at least the lean is in the right direction for the shape of ones cheek.
Interesting thing to watch out for though.

That stock would be a lovely fit into the shoulder.

Quote:

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Originally Posted by trooper554877

You are wasting your time and effort with the b-square mount. THE ONLY no gunsmithing mount that is worth anything is the fulton made one from Brian Dick of BDL LTD. they are strong, fit perfectly and are very well made.

It doesn't matter if you can use a jig or instrument to measure datums, continums, condoms or anal retentention because the tolerances in the manufacture of these rifles is such that unless you have a mile or so of adjustment on the u beaut no gun smithing mounts, you may still not be able to colimate the rifle scope to any line!

Thats why they have so big adjustment scales on the scopes so you can "dial " in your correct zero point.

I would suggest that the vertical or horizontal perfection that you ask for will not matter at the other end of the range. all that it will mean is that the adjustments will not be perfectly straight either direction but as some high-power match rifle shooters do with canted sights to accommodate cant in the shooting position, just add or subtract adjustments to suit.

Unless you are prepared to drill and tap with any number of different mounting systems that can be adjusted of datum lines then you are chasing your tail IMHO

Cheers
NED

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The reality is that the S&K type mounts such as the Fultons model are not collimatable, to coin a term. You screw them on and hope for the best. You zero at whatever range you wish and at other ranges you take your chances.

If you want a scope mount that is robust and truly "collimatable", get a repro Soviet PU sniper mount. It will mean drilling and tapping the receiver obviously, so one has to consider carefully the resulting desecration!

I've installed both early and late style S&K mounts. I don't recall them being a serious problem. Maybe 4-6 moa to get on center. I have had to modify the wedge to keep it squared up.

Just to clarify a little, because I know your comments about the mounts are 100% correct, I'm only using the B Square as a temporary way to work with several rifles quickly. I'm going to put some effort into a P14 AGP soon as a repro sniper and I'm considering those repro accumounts on ebay, except for the sky high price!.