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HiBC · October 6, 2012, 09:26 PM

Pardon me for not being familiar with an M-17.

Are we talking about a 1917 Enfield?

If so,part of the project was removing the sight ears and reshaping the rear bridge.

All this is subject to whatever variables the gunsmith who did the work created.

I will assume you do not have access to a nice granit surface plate ,a height gage,etc,thats ok.

Lets call the bottom of the receiver,the flat part that the mag box engages,the best datum plane we have.Maybe with calipers or a mic,you can get between the feed rails and get a measurement from the flat bottom of the receiver over the top of the scope base.You may need to use a pin or a little flat piece of steel for a bridge over the feed rails.What the number is does not matter,just compare the front and rear.They should be the same,or very close.

A quick,head math estimate,if you have 4 in ring spacing,that is 3 a foot,times 300 ft is a multiplier of error of about 900,to make it easy,lets call it a multiplier of 1000.So,.001(for this mental experiment) error in height would translate to 1 in at 100 yds,approx.I do not know how much scope adjustment you have,but lets call it 40 MOA,or 20 MOA from center,not enough,OK.That would mean an error of about .020 plus or minus in the height between front and rear bases.(based on all of my inaccurate assumptions) That will give you some idea what to look for.

If this is a fine old 1917 enfield sporter,I suggest the handcrafted part of it is something the scope base companies just can't hit right every time,it varies.

If your measurement suggests you have a problem,it may take the handcrafted skill to make it right.

What is really hard on a scope,if the front ring and the rear ring are not in perfect alignment,the thin aluminum scope tube distorts when you tighten the rings.
That is real bad on the close tolerance fits and optical alignments,plus the superglue or sealants they use to hold them together.("pop",oops)

Good luck!

October 6, 2012, 09:26 PM	#5
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,286	Pardon me for not being familiar with an M-17. Are we talking about a 1917 Enfield? If so,part of the project was removing the sight ears and reshaping the rear bridge. All this is subject to whatever variables the gunsmith who did the work created. I will assume you do not have access to a nice granit surface plate ,a height gage,etc,thats ok. Lets call the bottom of the receiver,the flat part that the mag box engages,the best datum plane we have.Maybe with calipers or a mic,you can get between the feed rails and get a measurement from the flat bottom of the receiver over the top of the scope base.You may need to use a pin or a little flat piece of steel for a bridge over the feed rails.What the number is does not matter,just compare the front and rear.They should be the same,or very close. A quick,head math estimate,if you have 4 in ring spacing,that is 3 a foot,times 300 ft is a multiplier of error of about 900,to make it easy,lets call it a multiplier of 1000.So,.001(for this mental experiment) error in height would translate to 1 in at 100 yds,approx.I do not know how much scope adjustment you have,but lets call it 40 MOA,or 20 MOA from center,not enough,OK.That would mean an error of about .020 plus or minus in the height between front and rear bases.(based on all of my inaccurate assumptions) That will give you some idea what to look for. If this is a fine old 1917 enfield sporter,I suggest the handcrafted part of it is something the scope base companies just can't hit right every time,it varies. If your measurement suggests you have a problem,it may take the handcrafted skill to make it right. What is really hard on a scope,if the front ring and the rear ring are not in perfect alignment,the thin aluminum scope tube distorts when you tighten the rings. That is real bad on the close tolerance fits and optical alignments,plus the superglue or sealants they use to hold them together.("pop",oops) Good luck!