Advanced Marksmanship Mil Ranging with the Weaver

[gunnyart]

I bought a Weaver Tactical 3-10 from Midway. My concern is how precise is the mil magnification relationship. At exactly 100yds with a measured 11" tall target (sheet of paper) and scope set to 10x the mil spacing isn’t exact. (I essentially run out of magnification)
1) Is some error to be expected?
2) How much is too much? (11" x 27.8 / 3.25mils observed = 94.09yds)
3) At longer ranges the problem will get worse not better, am I correct?
4) Should I send the scope to Weaver to be checked or did "I get what I paid for"?

 

[DCR]

Re: Mil Ranging with the Weaver

Was the paper at exactly 100 yards? Sometimes ranges aren't set up exactly at 100 yards. I milled the paper I was shooting at the other day and it milled to 106 yards. Could be me. Could be the retical. Could be the range isn't set up exactly at 100 yards.

Only way to know for sure is to test your scope.

 

[DCR]

Re: Mil Ranging with the Weaver

Couldn't find this earlier. Good info. Might as well test your turrets while you're at it.

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/ScopeChecking/

 

[gunnyart]

Re: Mil Ranging with the Weaver

I verified the range with a Nikon laser range finder and got exactly 100 yards, also it is on an established range. I'll try the yardstick trick and take a survey wheel to verify the distance to the target also. Thanks for the input.

 

[gunnyart]

Re: Mil Ranging with the Weaver

Okay, Update.
I didn't have the range to myself this morning so I wasn't able to measure it with a long steel tape like I wanted to. According to the survey wheel the actual distance was 302'6" (I don't trust the calibration on the wheel and am fairly certain the actual distance is a true 100yds.) I hung a measured yardstick with a plumb bob and read 9.75 mils exactly.
( 36 x 27.777778 / 9.75 = 102.56yd )
I think I can live with that for a scope costing under $300.

What say you?

Thanks DCR for the good link.
With a true vertical reference and my anti-cant device I was able confirm my scope level and check tracking and total travel of my turrets. Incidentally due to the fact that its mounted on a RRA AR-10 with no added MOA base it only has 3 mils of up elevation from 100 yd zero. I will probably re-zero for 200yds to get a bit more usable turret travel.

 

[DCR]

Re: Mil Ranging with the Weaver

Were you able to adjust the magnification to get 10 mils on the yard stick?

 

[gugubica]

Re: Mil Ranging with the Weaver

Pretty common, but still unaceptable. You need to map you scope, any scope, both the reticle and the adjustments. Even really high end scopes can be off.

I would send it in, personally. It needs to mil correctly or it is of no use as a ranging tool. That is, unless you are willing to adjust your formulas for this particular scope.

Oh, and get a Badger 22 moa rail for it.

 

[gunnyart]

Re: Mil Ranging with the Weaver

I was not able to get exactly 10 mils on the scope. It runs out of magnification. I didn't think the error was big enough to be significant. I do plan to use it for mil ranging but I'm not sure if under real world conditions I am good enough see the error.

 

[DCR]

Re: Mil Ranging with the Weaver

It was enough error for you to see it in the first place. That's big enough. Have 'em fix it.