Will a 40 MOA rail work?

[Brice63281]

I just purchased a Ruger Precision Rifle in 338 LM and during my initial cleaning, I noticed that the rear of my scope rail was not exactly level but the front part is. It's not a drastic difference but it struck me as odd. While researching all the options and upgrades available, I came across the Anarchy Outdoors rail with built in bubble level. I figured it would be an easy swap for peace of mind. Plus with the built in level, it was a nice add on. It is only available in 0, 40, and 60 MOA and since the rifle comes with a 30 MOA cant already, my lack of knowledge assumed it would still work. As I learn more, I am concerned that I won't be able to zero at 100 yards because of lack of elevation adjustment at that angle. I'm not confident in the math to know for sure so I figured I would ask for input.

I will be running a Vortex Viper PST Gen 2- 5x25x50 with an advertised elevation adjustment of 70 MOA. It will be mounted on a set of Seekins Precision 1.26" high rings. Can anyone tell me if this will work within the usable elevation adjustment for a 100 yard zero? I ordered the rail before confirming but it hasn't shipped yet. I will be picking up the scope this week so I figured I would slow down for a second to make sure I am doing the right thing. Thanks in advance!

 

[Huskydriver]

*Generally* the rule of thumb is to take half the total travel of the scope so 70/2 = 35 moa max inclination with still being able to safely zero at 100... So 40 moa probably is going to be a tad much for that scope

 

[Brice63281]

Thanks for the reply. I'm not sure that I will need to shoot at 100 yards often but it would be nice to have that option. I guess my options are to keep the stock rail or look for a different scope that has more adjustment.

 

[Huskydriver]

So when you say that the stock rail doesn't look level what does that mean exactly ?

Because a canted rail is taller towards the shooter and shorter towards the muzzle end is this what you are seeing?

 

[Brice63281]

The left to right was slightly off at the back of the rail but the front was perfectly level. It was still within the bars on the bubble level but not dead center like in the front.

 

[Huskydriver]

The left to right was slightly off at the back of the rail but the front was perfectly level. It was still within the bars on the bubble level but not dead center like in the front.

Can you remove the rail? It sounds like it wasnt seated squarly before torquing everything down.

 

[Brice63281]

Yeah, I originally planned on doing that but saw the new rail with built in level and thought I would just replace it. I will pull it and try to reinstall it. It was definitely odd and even with the slight difference, I didn't want to chance it.

 

[Brice63281]

I appreciate the input.

 

[Huskydriver]

I would start there honestly

 

[Matthew488]

Some scopes will travel slightly more than advertised so you might still get your 100 yard zero. Or use a slight hold under I'd reticle has it. I have 70 moa total on my 375 with a 7-35 Attac Nightforce. Literally zeroed 100yds with the scope bottomed out. Just dont store the rifle between using with the scope bottomed out, just dial it up a turn while storing.

 

[Howland]

I've got the same RPR and was concerned about the 6-24 Tango 4 I already had which I planned to press into service on this rifle with advertised 56 MOA total travel both ways. I opted to zero at 200 which did work out. It had just a bit more adjustment than listed but not by much. I thought I might have to go to 300 or even 400.

Yes, divide total adjustment by half but if you just center the windage travel and do the same with elevation but come up 40 MOA and it zeros without adjustment it's a minor miracle. Mine was within 1 MOA elevation but almost 3 MOA windage. I did have one rifle that was within 1 MOA for both. Too bad it wasn't a shooter.

 

[Brice63281]

Thanks for the information. I know a lot of people are running the same scope on the standard 30 MOA base but it sounds like the 40 is stretching it. I've been maxed out at around 1,000 yards with my current set ups (M1A in 7.62 and custom built 6.5 Grendel AR). This was my step up in longer distance shooting. I've got a lot of learning and practicing to really take advantage of the rifle. The range I shoot at has a 1000 yard and a separate 20000 yard range but it will be some time before I am ready to stretch it.

 

[SIDS01]

Some scopes will travel slightly more than advertised so you might still get your 100 yard zero. Or use a slight hold under I'd reticle has it. I have 70 moa total on my 375 with a 7-35 Attac Nightforce. Literally zeroed 100yds with the scope bottomed out. Just dont store the rifle between using with the scope bottomed out, just dial it up a turn while storing.

You're on the factory preset zero stop, that scope has nearly double that travel. Its nearly centered in its travel, so there is no need to move the turret for storage.

I have one on a 338 RPR with a 20 moa one piece mount on top of the 30 moa factory rail. It has over 32 mils (110 moa) up from a 100 yard zero.

 

[SIDS01]

I just purchased a Ruger Precision Rifle in 338 LM and during my initial cleaning, I noticed that the rear of my scope rail was not exactly level but the front part is. It's not a drastic difference but it struck me as odd. While researching all the options and upgrades available, I came across the Anarchy Outdoors rail with built in bubble level. I figured it would be an easy swap for peace of mind. Plus with the built in level, it was a nice add on. It is only available in 0, 40, and 60 MOA and since the rifle comes with a 30 MOA cant already, my lack of knowledge assumed it would still work. As I learn more, I am concerned that I won't be able to zero at 100 yards because of lack of elevation adjustment at that angle. I'm not confident in the math to know for sure so I figured I would ask for input.

I will be running a Vortex Viper PST Gen 2- 5x25x50 with an advertised elevation adjustment of 70 MOA. It will be mounted on a set of Seekins Precision 1.26" high rings. Can anyone tell me if this will work within the usable elevation adjustment for a 100 yard zero? I ordered the rail before confirming but it hasn't shipped yet. I will be picking up the scope this week so I figured I would slow down for a second to make sure I am doing the right thing. Thanks in advance!

If there is a problem with the RPR out of the box, Ruger will make it right if you ask. The mount might not seem like much, but what if its the mounting holes in the receiver? A little ways down the road, Ruger might not be as accommodating.

My eyes are old enough that bubble levels at the back of the mount aren't really an option. If you're under 40, they might seem like a good idea, but they also might be more trouble than they're worth. Assuming your eyes are still young enough to focus that closely, will you be able to even see it without moving your head out of your shooting position? Matching the level to the scope will require rotating the scope in the rings and then tightening things up without rotating the scope. That's tough to do, and it'll need to be done every time the scope comes out of the rings. The next problem is you'll also need to match the scope to the level from your shooting position. If you do it on the bench looking straight down on the gun, the bubble won't appear in the same position unless you break your shooting position and look through it with your right eye. If you try to look through it with the left eye, assuming you can even get that cross eyed, the apparent bubble position will shift because you're coming at it at an angle. Using a scope mounted bubble ahead of the front ring is the ugliest position to have it, but it's the easiest to set up and use.

Burris makes rings and a 1 piece mount that use inserts to dial in cant. You can use them to back into the maximum cant that'll still give a 100 yard zero. For fixed bases and factory barrels, I like to leave at least 5 moa less than half the scope travel, and 10 is less likely to run out of travel. With the Burris adjustable setups, enough cant can be dialed in to get to the last turn on the turret. A zero stop isn't really needed at that point.

With the RPR, and many chassis style guns, there isn't much drop at the recoil pad, but you have an adjustable comb height. The use of 1.5" or higher rings may give a more comfortable prone shooting position.

If you must have something new for that gun, you can do a lot better than the factory brake.

 

[TheBoctor]

Thanks for the reply. I'm not sure that I will need to shoot at 100 yards often but it would be nice to have that option. I guess my options are to keep the stock rail or look for a different scope that has more adjustment.

100yd zero isn't so much for being able to shoot back to 100, but truly zero-ing the mechanical aspect of the rifle. If you zero at further ranges, wind, temperature, pressure, altitude, etc all start effecting the trajectory and your "zero" will change day to day depending on the conditions. At 100 yds, those effects still exist but have minimal effect, so you're removing all outside variables from your zero and it makes it a much more consistent base for your ballistics calcs.

 

[1moaoff]

The left to right was slightly off at the back of the rail but the front was perfectly level. It was still within the bars on the bubble level but not dead center like in the front.

Forget the bubble level

 

[Matthew488]

You're on the factory preset zero stop, that scope has nearly double that travel. Its nearly centered in its travel, so there is no need to move the turret for storage.

I have one on a 338 RPR with a 20 moa one piece mount on top of the 30 moa factory rail. It has over 32 mils (110 moa) up from a 100 yard zero.

Sorry, guess I didn't word it right. Lol. I have a 50 moa base with a 20 moa one piece mount for 70 total moa. Scope will then dial up 3 full turns (36 mils) from the 100 yard zero. Still fireforming brass so haven't stretched it out yet.

 

[SIDS01]

Sorry, guess I didn't word it right. Lol. I have a 50 moa base with a 20 moa one piece mount for 70 total moa. Scope will then dial up 3 full turns (36 mils) from the 100 yard zero. Still fireforming brass so haven't stretched it out yet.

Sorry, I wasn't sure. I thought mine came with the zero stop bottomed to prevent that misunderstanding. It does happen with some scopes though.

I was going to ask you to mail me your unused travel.

 

[Brice63281]

I appreciate all the feedback. They were able to cancel my rail order before it shipped so that worked out well. I will pull the factory rail and inspect it see if there is an issue or not. I really hope not because I don't want to wait several weeks to send and get it back from Ruger.

 

[Brice63281]

100yd zero isn't so much for being able to shoot back to 100, but truly zero-ing the mechanical aspect of the rifle. If you zero at further ranges, wind, temperature, pressure, altitude, etc all start effecting the trajectory and your "zero" will change day to day depending on the conditions. At 100 yds, those effects still exist but have minimal effect, so you're removing all outside variables from your zero and it makes it a much more consistent base for your ballistics calcs.

This makes a lot of sense- thanks. The sight in lanes at the range I use are all at 100 yards so this is very relevant.

 

[Brice63281]

If there is a problem with the RPR out of the box, Ruger will make it right if you ask. The mount might not seem like much, but what if its the mounting holes in the receiver? A little ways down the road, Ruger might not be as accommodating.

My eyes are old enough that bubble levels at the back of the mount aren't really an option. If you're under 40, they might seem like a good idea, but they also might be more trouble than they're worth. Assuming your eyes are still young enough to focus that closely, will you be able to even see it without moving your head out of your shooting position? Matching the level to the scope will require rotating the scope in the rings and then tightening things up without rotating the scope. That's tough to do, and it'll need to be done every time the scope comes out of the rings. The next problem is you'll also need to match the scope to the level from your shooting position. If you do it on the bench looking straight down on the gun, the bubble won't appear in the same position unless you break your shooting position and look through it with your right eye. If you try to look through it with the left eye, assuming you can even get that cross eyed, the apparent bubble position will shift because you're coming at it at an angle. Using a scope mounted bubble ahead of the front ring is the ugliest position to have it, but it's the easiest to set up and use.

Burris makes rings and a 1 piece mount that use inserts to dial in cant. You can use them to back into the maximum cant that'll still give a 100 yard zero. For fixed bases and factory barrels, I like to leave at least 5 moa less than half the scope travel, and 10 is less likely to run out of travel. With the Burris adjustable setups, enough cant can be dialed in to get to the last turn on the turret. A zero stop isn't really needed at that point.

With the RPR, and many chassis style guns, there isn't much drop at the recoil pad, but you have an adjustable comb height. The use of 1.5" or higher rings may give a more comfortable prone shooting position.

If you must have something new for that gun, you can do a lot better than the factory brake.

I definitely hope it's not an issue that requires sending back to Ruger to address. I will pull the rail this week and hopefully it is just a matter of re-installing it. Your thoughts on the bubble level make a lot of sense as well. I think my eyes are still doing ok at 44, but the point of having to move your head to view it defeats the purpose is valid. I appreciate it!

 

[CoryT]

You can simply check how much down you have now, presuming you have 100 yard zero. Unlock the dial and reset it at 11 MOA up. Dial down to zero, if it stops before you get there the 40 MOA rail will be too much, if not, you are fine. You only need 10 MOA, I'd expect it to be fine.

 

[jasent]

Never put your zero past 100 yards. But it is ok to zero high at 100. Example my 37XC is currently zeroed 15” high at 100. Conditions have little impact on the zero and you still get the extra dial. Most ballistic programs have a zero offset option. I have gone as high as 26” high at 100 with no troubles

 

[Brice63281]

I ended up pulling the rail and the mount holes appear to be fine. I did find a gash in the bottom of the rail right at the location where the pin holding the bolt release is on the receiver. It was likely done when the rifle was assembled so it must have tweaked the rail just enough to make it slightly offset. The good news is that it should be an easier fix and not require sending the rifle to Ruger. I just need to find a new rail.

 

[SIDS01]

Good catch, you might have saved yourself all kinds of pfm scope problems. Grind or file the ding down below flush from the bottom and you'll be gtg.

I'll bet if you contact Ruger they'll send you a replacement. The factory rail should work well with your scope. If you switch to another with more travel, a one piece mount with 20 moa built in will let you use more of it.

 

[Brice63281]

I called and emailed pics to Ruger today. Hopefully they are quick to replace the rail. I would really like to shoot it soon.

 

[Pappasniper]

You can always zero at 200 or 300 if need be. It doesn't mean you can't shoot groups at 100, it's just your POI will be off. So if you want the big rail, go for it.

PB