Sight Base selection issue

Thedrifter · Post by **Thedrifter** » Tue Mar 20, 2012 11:15 pm

Hello All I Just had my rifle rebarreled and i have an issue, i think i have it solved but i just want to share before i purchase stuff that is wrong.

-My old setup-
1607 Rifle
26" barrel
Barrel Dia. at muzzle .913
Sight base Height .225

-New Setup-
Same 54 Action.
20" Barrel "Benchmark" 10" Bloop tube
New Barrel Dia. .920
Bloope tube Dia. 1.066
Sight base height ???

I hope that covers what im looking for so using what i knew i did the following.

1.066 Dia "Bloop tube" minus .913 Old Barrel = .153 the differanc in dia

.153/2 = .077 this is how much taller my .225 sight base sits?

so .225 minus .077 is .148, would this be the height i need now?

smallest i see on champs choice is .175 this would work right? it would still be slightly taller than what i use to have but would this be enough?

O before i forget the reason i need a smaller front sight base is because sighted in at 50 yards now i only have 20 clicks left to max "20 click sight"
so i cant sight in at 100 yards. this is the real issue.

I just want to make sure i figured this out right.

Thanks ahead of time
Cameron.

Tim S · Post by **Tim S** » Wed Mar 21, 2012 3:35 am

Cameron,

rather than mess around finding an extra-low foresight tunnel, have you thought of a raiser block under the rearsight? Centra make a 4mm raiser (the Block4) that would jack up the rearsight enough.

I also use a tube and my rearsight also ran out of elevation adjustment as I use a tall 22mm foresight. To compensate for the foresight/tube I have a taller raiser block under the rearsight (18mm), than under the foresight (16mm).

Tim

Thedrifter · Post by **Thedrifter** » Wed Mar 21, 2012 11:43 pm

I do have an 8mm rear base and that's to tall creates the opposite effect, so I think that a 4mm could work, I called mt guns and there going to trade/ Exchange with me to get it corrected so looks like it won't cost me anythin they mailed the smaller front sight base so I will try this first,

Thank you
Cameron

justadude · Post by **justadude** » Thu Mar 22, 2012 7:57 am

The other factor here that you may have missed: When you put the extension tube on to increase the sight radius you decrease the shot movement per click of the sights. Doing some quick math, your 20 click sights on the original barrel now need about 23 clicks to get the same effect. Not a terrible difference but if you are near a travel limit then it can make a huge difference.

I worked out the math for a guy on a similar but slightly longer arrangement a few months back and the answer was just shy of 4mm under the rear sight to get out to 100 yards. So if you get that 4mm riser for the rear that has been discussed you should be fine.

Cheers,
'Dude