I apologize if this is a stupid question, but I can't find a definitive answer anywhere and it is just bothering the piss outta me. I am planning on running a 100 yard zero on my scope and have 26 mil of total elevation travel. With my 7mm mag that will get me out to 2k+ yards and with my 6.5 gas gun it will take me to the max of that platforms capabilities. My question is why would you need a canted base if the scope has a resettable zero?
Rifle Scopes Scope Base Cant question
- Thread starter Red_Beard
- Start date
My understanding is that it's for a few reasons:
it's supposed to be harder on the scopes to use it at the extreme range of it's windage/elevation adjustment
as you move away from the elevation center, you'll have less usable windage adjustment
Also, in this case your scope has enough travel shoot the rounds that you're shooting at the range you want. If any of those variables changed, you might find yourself running out of elevation. Why wouldn't you want some cheap/easy insurance?
it's supposed to be harder on the scopes to use it at the extreme range of it's windage/elevation adjustment
as you move away from the elevation center, you'll have less usable windage adjustment
Also, in this case your scope has enough travel shoot the rounds that you're shooting at the range you want. If any of those variables changed, you might find yourself running out of elevation. Why wouldn't you want some cheap/easy insurance?
In theory with a flat base you will have a little less than half the total elevation travel available for positive elevation adjustment.
Are you saying that less than 13 mils is enough to satisfy your needs?
I've heard both of the above arguments before.
I have not handled one scope whose erector assembly actually contacted the inside of the scope tube.
Instead, the travel is limited by the turret shafts.
The erector has full windage adjustment available at the upper and lower elevation limits.
I only ever read one report of the erector spring being weakened by being stored in the compressed state and if it did happen, it's because it was a poorly designed spring and/or constructed of lousy material.
The spring steel made today is amazing stuff, capable of hundreds of thousands (and in some case millions) of cycles. Being kept in the compressed state does not weaken them even a little.
The reason to get a canted base (or flat base and canted one piece mount) is to get all of the usefulness available from your scope.
In some combinations of rifle and scope, you may start out with far less than half the total elevation travel available as positive adjustment; only way to tell in your case is to mount it up flat and take it to the range, although bore sighting can give you a close estimate (and reveal and big problems).
Joe
Are you saying that less than 13 mils is enough to satisfy your needs?
I've heard both of the above arguments before.
I have not handled one scope whose erector assembly actually contacted the inside of the scope tube.
Instead, the travel is limited by the turret shafts.
The erector has full windage adjustment available at the upper and lower elevation limits.
I only ever read one report of the erector spring being weakened by being stored in the compressed state and if it did happen, it's because it was a poorly designed spring and/or constructed of lousy material.
The spring steel made today is amazing stuff, capable of hundreds of thousands (and in some case millions) of cycles. Being kept in the compressed state does not weaken them even a little.
The reason to get a canted base (or flat base and canted one piece mount) is to get all of the usefulness available from your scope.
In some combinations of rifle and scope, you may start out with far less than half the total elevation travel available as positive adjustment; only way to tell in your case is to mount it up flat and take it to the range, although bore sighting can give you a close estimate (and reveal and big problems).
Joe
Joe, I appreciate your well thought out answer, but it doesn't address a scope with a resettable zero that allows me to dial up 26 mils.
Why PMIIs' need canted mounting systems
In a nutshell: Riflescopes typically have their reticles optically and mechanically centered at the factory. However, the reticles of PMII scopes are adjusted out of center by 1/2 of the Elevation Turret's full adjustment range. This allows the Elevation Turret to accomodate the full range of travel in one direction ("Up") for long range shooting. However, since the reticle now resides closer to the top of the inside of the scope tube, unless the reticle's position within the scope tube is compensated for by using a mounting system approximating the reticle's mechanical offset, the reticle will still be out of center and the shooter will run into the mechanical "Stop" built into the Elevation Turret before the Turret has reached the end of it's travel.
That said, a lot of shooters will never need to dial beyond the first revolution (13 MILs' on a MIL-based PMII DT), let alone to 26 MILs'. Therefore, in situations like that the 45 MOA base that Schmidt Bender recommends for a PMII 5-25X[56] and allows the shooter to dial to the end of the PMII 5-25X[56]'s DT Turret range really isn't necessary. That's one reason why a lots of people recommend a 20 MOA base for use with a PMII 5-25X[56] (it works for most people). However, if a shooter wants to be able to dial all the way up to 26 MILs' he or she should use a base or mounting system with 40-45 MOA of cant. I've never had to dial beyond 10.5 MILs' to get a bolt .308 out to 1,000 yards, but I've been using a Tac Ops Two-Piece 40 MOA base on my (Tac Ops) X-Ray 51 (.308) just because I wanted the scope and base setup on my X-Ray 51 to be the same as that of my 40XB .22LR. I need about 20 MILs' to get to 400 yards with 40gr. Wolf MT so I want all the Elevation travel I can get out of the PMII 5-25X[56].
Keith
Exactly what scope are you using? While there are several "tactical" scopes that have 26 MILs' of external travel, since you state that your scope has 26 MILs' of travel and a resettable zero my guess is that you're running an iteration of PMII 5-25X[56] or a Premier Heritage 5-25X[56]. I don't recall who said it nor did I inquire about the mechanical specifics at the time, but several years ago someone from Premier stated that the Heritage doesn't require the aggressive base cant that the PMII line does. I say "require" because in order to be able to dial the PMII's Elevation Turret to the end of it's adjustment range (both Single Turn and Double Turn), an aggressively canted base equal to 1/2 of the Elevation travel is required. This is all explained in the PMII Owner's Manual (the German-to-English translation is a little wonky, but should be easily understood by anyone with decent reading comprehension). A PMII Manual may be downloaded from the Schmidt Bender.de site at Information.
In a nutshell: Riflescopes typically have their reticles optically and mechanically centered at the factory. However, the reticles of PMII scopes are adjusted out of center by 1/2 of the Elevation Turret's full adjustment range. This allows the Elevation Turret to accomodate the full range of travel in one direction ("Up") for long range shooting. However, since the reticle now resides closer to the top of the inside of the scope tube, unless the reticle's position within the scope tube is compensated for by using a mounting system approximating the reticle's mechanical offset, the reticle will still be out of center and the shooter will run into the mechanical "Stop" built into the Elevation Turret before the Turret has reached the end of it's travel.
That said, a lot of shooters will never need to dial beyond the first revolution (13 MILs' on a MIL-based PMII DT), let alone to 26 MILs'. Therefore, in situations like that the 45 MOA base that Schmidt Bender recommends for a PMII 5-25X[56] and allows the shooter to dial to the end of the PMII 5-25X[56]'s DT Turret range really isn't necessary. That's one reason why a lots of people recommend a 20 MOA base for use with a PMII 5-25X[56] (it works for most people). However, if a shooter wants to be able to dial all the way up to 26 MILs' he or she should use a base or mounting system with 40-45 MOA of cant. I've never had to dial beyond 10.5 MILs' to get a bolt .308 out to 1,000 yards, but I've been using a Tac Ops Two-Piece 40 MOA base on my (Tac Ops) X-Ray 51 (.308) just because I wanted the scope and base setup on my X-Ray 51 to be the same as that of my 40XB .22LR. I need about 20 MILs' to get to 400 yards with 40gr. Wolf MT so I want all the Elevation travel I can get out of the PMII 5-25X[56].
Keith
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Keith,
That is exactly the kind of information I was looking for, thank you for the help. I didn't realize it would help knowing the manufacturer, but for this round I went with the new(ish) Steiner Military 5-25x56. I didn't catch anything in the Steiner manual that suggests a canted base, but I will certainly have another look to make sure.
That is exactly the kind of information I was looking for, thank you for the help. I didn't realize it would help knowing the manufacturer, but for this round I went with the new(ish) Steiner Military 5-25x56. I didn't catch anything in the Steiner manual that suggests a canted base, but I will certainly have another look to make sure.
Being specific
Keith
No problem Red_Beard. It's always better to provide specifics when asking questions because vague info often results in responses that don't apply to your particular question(s) or issue(s). While what I posted is valuable info, it might not apply to your Steiner 5-25X[56] (see how that works)?
Keith
There are some scope makers that suggest 40+ MOA canted bases. Most people use a 20 MOA base and call it a day. Works unless you are wanting to take your 45-70 to 1000 yds.
OFG
OFG
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