30 MOA base set up questions - RimfireCentral.com Forums

Go Back   RimfireCentral.com Forums > >

Notices

Join Team RFC to remove these ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 11-11-2018, 11:09 PM
cctbspencer

Join Date: 
Nov 2018
Posts: 
3
TPC Rating: 
0% (0)
30 MOA base set up questions



Log in to see fewer ads
I have a few questions about setting up a new rig. I'm mounting a Vortex Crossfire II 4-12 x 50 AO on a Ruger Precision Rimfire. This scope has a total of 50 MOA elevation. The reticle is Dead-Hold BDC (MOA). I'll be shooting standard velocity rounds. I'll be using Burris XTR Signature Rings (up to 40 MOA cant). The rifle has the OEM 30 MOA base. I have never set up a scope on a cant before and really don't know how to begin. I won't be trying to set any long range records. The majority of my shooting will be 50 to 200 yards with an occasional 200 to 300 attempt. I know the difference between 200 and 300 yards with a .22 LR is like night and day but most everything will be in the 100 to 200 yard range. Should I zero at 50 or 100 yards? Do I zero on the factory 30 MOA base or use the Burris inserts to cancel out the base cant, get a zero, then install different inserts and re-zero? How much elevation adjustment should I try and keep in the down direction? I know the scope's 50 MOA isn't ideal but it's what I have to work with and hope I can get there. To those of you shooting similar ranges, if this was the hardware that you had available how would you set it up? Besides being locked into the hardware listed I'm wide open to suggestions as to how to set it up and what ranges to shoot for. Thanks in advance for any help.
Reply With Quote
  #2  
Old 11-11-2018, 11:37 PM
Sophia's Avatar
Sophia

That Evil Admin Lady
Join Date: 
Dec 2006
Location: 
Raggedy Edge of the 'Verse
Posts: 
21,946
TPC Rating: 
100% (23)
Generally "cant" means a side to side deflection rather than an up and down deflection. Cant is generally a bad thing as it puts the scope left or right of the axis of the bore.... but we know what you meant from context.

I wouldn't cancel out the elevation adjustment of the factory 30 MOA base.

It's going to depend on a few specifics to get specifics but that 30 MOA of adjustment in the factory base should let you get sighted in at 50 yards at one limit of your scope's adjustment (probably easily) and still get you on target at 200 yards. Whether it will be enough to get you to 300 yards is a question I can't answer since the longest I regularly shoot with 22lr is 225 yards.

So, I would suggest putting the scope on with zero adjustment in the Burris rings and getting sighted in at 50 yards, take notes of the settings, then do the same at 100 yards and 200 yards.

Once you have the settings noted for those ranges see if you can get out to 300 yards. If so, you're golden. If not, you can use the Burris inserts to get out there but expect that will probably cost you the ability to get sighted in at 50 yards.

In your shoes I would probably get sighted in at 50 yards using the factory base, dial elevation on the knob to get on target out as far as I could that way, then use the BDC marks on the reticle for anything beyond that, otherwise you're losing your ability to get sighted in dead on at 50 yards.

Have you a ballistic calculator? If not, you may want to play around with this one.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

Welcome to RFC.
__________________
Down Home Girl

Last edited by Sophia; 11-11-2018 at 11:42 PM.
Reply With Quote
  #3  
Old 11-12-2018, 09:31 PM
Toomany22s's Avatar
Toomany22s
NRA Member - Click Here To Join!

Join Date: 
Sep 2017
Posts: 
3,929
TPC Rating: 
0% (0)
Ok letís do it plain and simple. The 30moa base is angled so that your scope is not parallel to the bore , but rather pitched downward . This is so you can shoot at far away targets where the bullit will significantly drop.

At 50 yards with the scopeat 0 the rifle is going to be shooting way high. So your going to going to turn the elevation turret clockwise , a lot .if your scope has 50 MOA adjustment , thatís 25 MOA above and below 0. Since your rail is 30 MOA youíll never get it to hit a target at the crosshairs at 50 yards. It will still shoot high. You will be able to zero at 100 yards because the bullet drops so much.
Reply With Quote
Sponsored Links
Advertisement
 
  #4  
Old 11-12-2018, 10:20 PM
Sophia's Avatar
Sophia

That Evil Admin Lady
Join Date: 
Dec 2006
Location: 
Raggedy Edge of the 'Verse
Posts: 
21,946
TPC Rating: 
100% (23)
Czech your math, Toomany22s. I think you may be ignoring bullet drop at 50 yards which should be about 4" - 4.5" or so from horizontal (depending on MV)... meaning ~8 MOA below horizontal.

So, a 30 MOA rail with the scope adjusted all the way down to the limit puts it 5 MOA below horizontal, eh? (actually, barrel 5 MOA above horizontal once the sights are on target).

That's pretty close and may be right on, depending on the MV he uses (I went with 1050fps for the calculation). At most all he would need to add would be the 5 MOA insert for the Burris rings, in effect turning the 30 MOA rail into a 25 MOA rail. So I'll amend my earlier advice about getting sighted in at 50 yards "as is" with the just the rail by suggesting going with the inserts to get there if necessary .... but recognize that's going to come at the expense of the longer range. You'll just have to prioritize which extreme you want to accommodate.

I don't remember now if I have 25 MOA or 30 MOA dialed into my rifle with the inserts (and I'm not going to take it apart to czech ) but I can get on at 50 yards as well as on at 200 yards.... but specifics for each case have to take into account the height of the scope above the bore, the actual MV, the amount of adjustment available in the scope, etc).

Please double-czech my math to make sure I'm not too far off the mark here. Hopefully others will chip in with their thoughts and experiences, too.... maybe someone with the same scope and rifle.
__________________
Down Home Girl
Reply With Quote
  #5  
Old 11-13-2018, 08:30 PM
cctbspencer

Join Date: 
Nov 2018
Posts: 
3
TPC Rating: 
0% (0)
Toomany22s, plainly and simply, I understand the form, fit, and function of the base. I am just looking for advice on zero range, whether to begin by canceling the angle of the base or not, and how far from optical center I should deviate before installing a different ring insert.

Sophia, bullet drop had slipped my mind. I agree with your assessment. I believe that on the 30 MOA base and with concentric ring inserts (0 MOA) I should be able to get a 50 yard zero, dial out to 200, and use the reticle for holdovers beyond there. I should be far enough off max adjustment in elevation at 50 yards to still have a little room for windage adjustment if necessary.
Reply With Quote
  #6  
Old 11-13-2018, 10:52 PM
Toomany22s's Avatar
Toomany22s
NRA Member - Click Here To Join!

Join Date: 
Sep 2017
Posts: 
3,929
TPC Rating: 
0% (0)
Well if you donít bottom out at 50 yards Iíd be real supprised to know you could get a 50 yard zero on the crosshairs. But even if you do,that scope is going to be at its limits. And that is never good. And forgive me for misunderstanding your level of comprehension. The use of the word cant mislead me.

As for adjustable rings to offset the MOA, I donít know anything about that. But I do know the more stress you put on the tube the weirder the thing that happen.And I imagine adjustable rings are a bit stress inducing.

So good luck with the RPR. Ps I had one , now I dont!
Reply With Quote
  #7  
Old 11-14-2018, 07:48 AM
GH41

Join Date: 
Feb 2015
Location: 
SEUS
Posts: 
2,076
TPC Rating: 
100% (1)
Quote:
Originally Posted by Toomany22s View Post
Well if you donít bottom out at 50 yards Iíd be real supprised to know you could get a 50 yard zero on the crosshairs. But even if you do,that scope is going to be at its limits. And that is never good. And forgive me for misunderstanding your level of comprehension. The use of the word cant mislead me.

As for adjustable rings to offset the MOA, I donít know anything about that. But I do know the more stress you put on the tube the weirder the thing that happen.And I imagine adjustable rings are a bit stress inducing.

So good luck with the RPR. Ps I had one , now I dont!
NO stress. Watch the video and learn. https://www.youtube.com/watch?v=QWbebwBivyI
Reply With Quote
  #8  
Old 11-14-2018, 08:57 AM
Sophia's Avatar
Sophia

That Evil Admin Lady
Join Date: 
Dec 2006
Location: 
Raggedy Edge of the 'Verse
Posts: 
21,946
TPC Rating: 
100% (23)
Quote:
Originally Posted by GH41 View Post
NO stress.
That's what makes Burris Signature rings what they are.

By default I put Burris Signature rings on my rimfire rifles right off the bat unless there is a specific reason not to. I like 10-15 MOA adjustment for general shooting just to get the scope optically centered at the ranges I normally shoot and the Signature rings are perfect for making that happen. No stress on the tube and completely obviates any need for lapping.
__________________
Down Home Girl

Last edited by Sophia; 11-14-2018 at 10:05 AM.
Reply With Quote
  #9  
Old 11-14-2018, 09:24 AM
Toomany22s's Avatar
Toomany22s
NRA Member - Click Here To Join!

Join Date: 
Sep 2017
Posts: 
3,929
TPC Rating: 
0% (0)
Quote:
Originally Posted by GH41 View Post
NO stress. Watch the video and learn. https://www.youtube.com/watch?v=QWbebwBivyI
Oh... thatís nice. Live and learn. Thanks for the education.
Reply With Quote
  #10  
Old 11-14-2018, 11:08 AM
GH41

Join Date: 
Feb 2015
Location: 
SEUS
Posts: 
2,076
TPC Rating: 
100% (1)
Quote:
Originally Posted by Toomany22s View Post
Oh... thatís nice. Live and learn. Thanks for the education.
The guy was probably looking at the old Unertl mounts they used before scopes had erectors in them and the light bulb went on in his head. It's one of the things you first see and say to yourself... Why didn't I think of that!
Reply With Quote
  #11  
Old 11-14-2018, 11:19 AM
Toomany22s's Avatar
Toomany22s
NRA Member - Click Here To Join!

Join Date: 
Sep 2017
Posts: 
3,929
TPC Rating: 
0% (0)
Quote:
Originally Posted by GH41 View Post
The guy was probably looking at the old Unertl mounts they used before scopes had erectors in them and the light bulb went on in his head. It's one of the things you first see and say to yourself... Why didn't I think of that!
Not really. I was thinking of scope rings with adjustment screws in them that would move the height up and down or left to right. Since I shoot at 50 yards or shorter I have never found the need for a MOA rail or adjustable MOA rings.

My only experiance with this was with the RPR, for which I quickly got a zero MOA rail.

But yeah I wish I thought of that. Just for the license fees.
Reply With Quote
  #12  
Old 01-05-2019, 09:27 PM
cctbspencer

Join Date: 
Nov 2018
Posts: 
3
TPC Rating: 
0% (0)
Well I have finally got around to putting her together. I ended up putting 5 MOA in anyway as there is only one 0 set. I'll post a picture when I get to send some lead downrange. Hopefully it will be tomorrow but the forecast is calling for 30 MPH winds. I may be able to use my north/south lane. We'll see. Thank you everyone for the input.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off




All times are GMT -5. The time now is 03:31 PM.

Privacy Policy

DMCA Notice

Powered by vBulletin
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Search Engine Optimisation provided by DragonByte SEO (Lite) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©2000-2018 RimfireCentral.com
x