Foresight Modification Question

[sabretech2001]

I have seen No4 foresight bases modified to accept the P-H FS22 tunnel foresight.

Does anyone have a drawing with the measurements so that I could do this myself?

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[Peter Laidler]

Don't bother, send me your address and I'll send you one that I think I have in my armourers shop somewhere. You can back engineer all you want from that!

[Thunderbox]

I've got about dozen here.

Looking at them, there is evidently no real "drawing with measurements" involved - the top of the foresight block is simply filed flat to remove the gradient, and then the FS22/Matchmaker forced into the dovetail. Only two appear to have had the dovetail slot recut to give a perfect fit; these are solid blocks. Most of the others are split blocks. One or two have the tube soft-soldered onto the block with the dovetail removed.

I also have three or four where a Matchmaker or similar tube has been soldered between the ears of a foresight protector, just high enough to clear the corresponding block. These seem perfectly adequate as target sights, and one heck of a lot easier to get on and off the rifle if you are switching between iron and target sights.

P.s. If you use a Matchmaker, its best to have the knurled ring facing forwards (ie with the sight back to front), as otherwise it will usually foul the front handguard.

[sabretech2001]

Thank you both for replying.

Peter: PM sent.

Thunderbox: I have both split and solid block bases in Ye Olde Parts Bin, and I was going to use the solid one, as I also have dovetailing files to complete the mod. My goal is to be able to use the range settings on the MkI sight with the Parker Hale added windage adjustment without change, hence the inquiry about the height of the base needed.
Good idea about installing it backwards: simply holding the tunnel sight in place makes it obvious, now that you mentioned it!

[Thunderbox]

I'm not sure you are going to be able to use the elevation settings on a Mk1 sight - both the FS22 and Matchmaker centre their sight elements significantly higher than the original foresight blade. Matchmaker is 2-3mm higher again than an FS22.

What you perhaps need instead is one of the very hard-to-find No4 foresight elements made by Parker Hale and others, where the blade is replaced by a target ring centred at the same height as the tip of the blade.

[Peter Laidler]

I think that you will struggle to achieve your aim there Sabre....... The reason being that every rifle shoots differently and that's the reason why the PH adjustable rearsights had an adjustable zeroing plate fixed to the side. Just so that once you'd zeroed in at X yards, you could re-set the zero. And those little windage adjustable backsights made by Parker Hale were (if I'm thinking what you're seeing) made for the mauser action L81 A1 Cadet target rifle. It wasn't done on the cheap, but the cheaper than cheap. So to keep costs down to less than zilch, they used old No4 and 5 rifle backsights. In doing so, they reported back that the range marks could be read as metres when using 7.62mm ammo.

I say no more than that..........................

[sabretech2001]

To both: agreed on all points. I could afford the P-H sight, but not the 'real' ones (5C, etc), so I'm trying to make a silk purse here.

I can, and still might, measure the sight blade that's installed and then mill/sand/file the solid base down so that the insert's height matches the issue sight blade. I figured that I couldn't possibly be the first one to try this, and so I asked if there were any drawings around with the measurements. I'll wait until the foresight base that Peter has so very kindly donated arrives, and then I'll decide on how to proceed. I'll post some pictures eventually and let you all know how I got on. Thanks again for all your insights.