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Front sight base selection 50/100 yards

Posted: Sun Dec 13, 2009 4:18 pm
by Telecomtodd
I shoot a 1913. First, it was suggested to me to purchase two 1/8 click scopes, one pre-sighted for 50 yards, the other for 100 yards. This reduces the amount of time I need to adjust 80 clicks and re-sight when going between 50 and 100 yard targets. I had some incredible luck in buying two identical scopes at a very economical price. Two Anschutz 6811 scope bases, one under each scope, also work great.

I would love to do this duplication with my Anschutz 1/8 click rear sight, but it's too bloody expensive to do that. I'm considering putting a two-step riser block under the front sight so I can simply move my front sight on one of two steps and not have to significantly adjust the rear sight.

I use a 10" bloop tube that has both a dove tail and three tapped holes for a sight block.

I'm looking at one of two blocks from a vendor. The first has a height of .175" and .229", and the second has a height of .275" and .329". I'm assuming the lower of the two should work - both have a difference of .054" - but I'm not sure. Any advice? Thanks!

Re: Front sight base selection 50/100 yards

Posted: Mon Dec 14, 2009 3:02 am
by RobStubbs
Telecomtodd wrote:I shoot a 1913. First, it was suggested to me to purchase two 1/8 click scopes, one pre-sighted for 50 yards, the other for 100 yards. This reduces the amount of time I need to adjust 80 clicks and re-sight when going between 50 and 100 yard targets. I had some incredible luck in buying two identical scopes at a very economical price. Two Anschutz 6811 scope bases, one under each scope, also work great.

I would love to do this duplication with my Anschutz 1/8 click rear sight, but it's too bloody expensive to do that. I'm considering putting a two-step riser block under the front sight so I can simply move my front sight on one of two steps and not have to significantly adjust the rear sight.

I use a 10" bloop tube that has both a dove tail and three tapped holes for a sight block.

I'm looking at one of two blocks from a vendor. The first has a height of .175" and .229", and the second has a height of .275" and .329". I'm assuming the lower of the two should work - both have a difference of .054" - but I'm not sure. Any advice? Thanks!
In the UK you can buy a foresight that twists around to enable you to shoot at both 50M and 100Y without significant changes to the rear sight. A guy called Barry Neeson makes them but I don't know where/if you can obtain them elsewhere.

Rob.

Posted: Mon Dec 14, 2009 9:07 am
by Freepistol
The front sight base should be selected so the height of the rear sight is the same as your scope. I had to shim the front sight base to raise the rear sight to match my scope. It is best if you can install the rear sight and the scope at the same time to check the height. I slide my scope in the rings forward enough to allow the mounting of the rear sight. After sighting with metallic sights and the scope removed, I shimed the front sight until I had the proper height so when I put the scope back on, I could see through the rear sight and the scope at the same time.

If you do this before you buy one of the two step bases, you will have a good idea which of the two heights you need.

If this doesn't seem clear, Telecomtodd, let me know and I will try again later when I have more time.
Regards,
Ben

Posted: Mon Dec 14, 2009 9:19 am
by BJ
Personally I never liked the one piece two step bases that you buy from Champion's choice etc. The tolerances are strange and instead of being like a staircase with two defined steps they kinda slope together. It is hard to describe easier to show. Also you will have to drill and tap your bloop tube because they are installed via screws.

I found that the easiest and most accurate way of establishing a two step base for 50 and 100 yards is to use custom riser blocks. Go out to the range and sight in at 50 yards. Then take a pair of dial calipers and measure a reference point on your rear sight. You need a fixed place to measure from to the movable section of the rear sight. This is easy to figure out with the Anschutz rear sights. Then click your sights up to 100 yards and measure from the same reference point on your rear sight. The difference in the two is the amount of difference in riser you need to go from 50 to 100 yards. Do this several times to get a rough average of how much adjustment you need. Then you call up Bill Earnest or your machinist friend and get them to make you two riser blocks to the specs that you need.

Brian