20 moa rail issues

[Farmer Rob]

Hi All,

I am having an issue with my "Budget LRR' its an axis 308 with a 20 moa rail, cheap 10-40x50 scope that has 38 moa total up/down adjustment. Im using hand loads 150gn hornady btsp at 2860fps and the gun shoots 1.25 moa at 600 meters. The rail is an egw rail and the mounts are warne high, the gap from glass centre to barrel centre is 2", i know this is a little high but one day i intent on putting on a 56 or even 60mm scope so i will need them.

The issue is, After sighting in at 100 meters i only have 24 moa of up adjustment but need 27 to get to 800, i don't understand where my extra 20 moa went. If i use the hold over bars in the scope i need to shoot about 1/3 below the crosshairs to hit the 10" target.

In theory i should be struggling to sight in at 100m as i shouldnt have enough down. Any thoughts????

 

[theEMP]

Not to be rude but isthe rail on backwards? I only ask because that is something I would do. Haha

 

[mountainman56]

38 moa total? Really? Sounds like the glass upgrade should be sooner rather than later. Give that B@rsK@ to someone you don't like and get something else

 

[FearNoWind]

Did you bed the rail when you installed it? If the action isn't perfectly flat, front to back, it's easy to "tweak" the rail that much when you tighten in down.

[ame="http://www.youtube.com/watch?v=d6RopWI0-GE"]Gunsmithing Bedding A Scope Rail On a Remington 700 - YouTube[/ame]

 

[Farmer Rob]

Thanks for the replies,

EMP, Im pretty sure its on correctly, higher to the back.

Mountain 56, with 38 travel i should be able to shoot 1200m using the 20 moa rail.

Fear no wind, I'd love to watch the video but when you have no choice but dial up speeds youtube is worst than useless, but still im nor sure how i could have tightened up and negated about 4mm of steel.

 

[FEENIX]

Did you bed the rail when you installed it? If the action isn't perfectly flat, front to back, it's easy to "tweak" the rail that much when you tighten in down.

Gunsmithing Bedding A Scope Rail On a Remington 700 - YouTube

Excellent! Thanks for sharing.

 

[FEENIX]

Not to be rude but isthe rail on backwards? I only ask because that is something I would do. Haha

... and also make sure your rail is "not" 0 MOA.

 

[lhouston78]

take the back screws out of the rail and see if the rail is floating.
on a weaver 20 moa on a remington a lot of times it is and if u tighten it
u will get 12 moa or so. maybe your rail is not perfect for your action then
u will have to shim or bed the back of your rail. it happens a lot.

 

[Kennibear]

38 minutes of total adjustment is not enough to do both sight in and dial-up for range. You need a 30mm scope tube to get more adjustment. You are going to fight the mount for way too long for way too little improvement.

Use the search tool at the top right of the page to look for threads on scope/ rail mounting. Plenty has already been written on it.

KB

 

[7magcreedmoor]

Your original post said your scope has 38 moa total adjustment. Half of that is 19, and you say after sighting in you have 24 moa up available. Manufacturing tolerance stacking is the answer to your mystery. You did gain a few moa with your rail, but between the possible variations in machining your receiver, the rail, and the rings, plus the internals of your scope, and the harmonics of your barrel what you have is not outrageous. I suggest bedding the rail to eliminate any stress (look for a possible gap under the back end- with the screws tight in the front holes, no screws in the back at all. If a gap exists, use bedding compound to fill it.) Then get a set of Burris Zee rings with offset inserts for more elevation if you still need it.

 

[Farmer Rob]

Well after lots of stuffing around, playing with the rail, checking bedding etc and finding no issues i gave up and replaced my scope and mounts with my trusty loupy vari x iii, 20 plus years and still strong.

Although i havent been out to the 800m range The scope is now zeroed at 300m (29mm group) with 34 moa of up left and only 28 needed. So im blaming the cheap scope.

As the original concept was to build a sub$1000 long range rifle, i guess i have failed, but i would value an old loupy at $600 maybe, making my investment
Rifle $459
Rail $48
Scope $600
Mount $0.00 with scope
Trigger job $50.00

Total $1157.00

Pretty close.

Rob

 

[Bravo 4]

You did the right thing and replaced the scope with a proven one. I am not a gear snob (can't afford to be) and understand the budget thing. But there is no way I would ever recommend somebody using a "cheap" scope's turrets for long range hunting. If you check the adjustments on "better" (read: more expensive) you might think twice about using them. I'm not saying a less expensive scope isn't capable, but having a reticle to use for holdover/hold off would be the way to go...if the scope will hold zero.

 

[bigngreen]

Slap a Super Sniper on it from SWFA and you can bring your budget back into line, I'm using a 10x and it has 140 MOA in it and I'm dialing 1500 yards with my 308 and 215 Bergers without any MOA in the base, it's a spectacular optic for $300 that has excellent turrets for dialing!

EGW bases are crap BUT sometimes they are the best you can get, I epoxy them to the action. I clean everything up and put a thin layer of JB weld on the rail then put shoe polish on the screw threads and tighten them up very slightly and let it set then I tighten up to spec and continue on.