which scope ring height

Horse2132002

Hey guys Im looking to mount a vortex viper pst 6-24x50 with a 30mm tube and a 20 moa picatinny base on a tikka t3 lite .243. Im looking at the burris xtr quick detatch rings im just wondering what is the minimum height rings I could get away with including scope covers without sacrificing distance as I will be shooting at 1000 yards. I appreciate some help.

TriggerPL

Horse2132002 wrote: »

Hey guys Im looking to mount a vortex viper pst 6-24x50 with a 30mm tube and a 20 moa picatinny base on a tikka t3 lite .243. Im looking at the burris xtr quick detatch rings im just wondering what is the minimum height rings I could get away with including scope covers without sacrificing distance as I will be shooting at 1000 yards. I appreciate some help.

Just a question ? This tikka t3 light , 20" barrel ?

What are you shooting out to 1000 yards?
targets ?
Animals ?

Horse2132002

Targets and its a 20" barrell

TriggerPL

Horse2132002 wrote: »

Targets and its a 20" barrell

I stand to be corrected but ul be doing well to shoot targets at 1000 yards with 243 with 20" barrel constantly !!

Have you this rifle bought ?

Horse2132002

Ive purchased a contessa 20 moa rail from alan rohne and the vortex has 70 moa which should be plenty to get me out there. I know that it isint going to be constant because hand loading and ballistics have a big part to play but ive seen loads of footage of the same gun hitting 1000. And yes I have the rifle. The second pic with the top scope is whats goin on it..

Cass

To pick the rings you need to measure the height off the barrel needed.

Usually what i do is;

• Take the diameter of the objective lense, say 50mm.
• Add 3mm for the width of the housing and 3mm for the minimum height off the barrel.
• That gives 56mm.
• Split that which gives our height from the barrel to the centre lineof the scope tube. So 28mm.
• Now measure the height of the rail.
• Say its 7mm.
• Take the 7mm from the 28 mm leaving you with 21mm and thats th height of the rings you need. (21mm = 7/8" (or a tad less))

Once you have this number you simply need to find out how the manufacturer measures their rings.

For example some measure their's from the base of the ring (the flat piece that sits on the rail/receiver) to the bottom of the curve (where the tube sits). Measurement B in the picture.

Some measure from the base of the ring to the centre of the ring diameter (centre line of the tube if you will). Measurement A in the picture.


Once you figure this out you choose accordingly.

Horse2132002

cheers cass

i previously done the exact same method and i have ordered a set of burris xtr quick detach mediums, hope all goes to plan.
just wondering what kinda setup you have, from the pic it looks like you have nothing to spare

Cass

That is the Remmy .308. There is almost no clearance.

With the flip Cap on the cap was touching the barrel. With the flip cap off there about 3mm of clearance. So i stuck the flip cap on, but before doing so i sanded the underside of the cap that would touch the barrel so there is no contact. Works a treat.

With the other scopes/rifles the clearance is about 4mm by using the method above. So the Flip Caps can be putt on with no touching, and room for the barrel to "vibrate" without the cap/scope touching and affecting the harmonics.

One piece of advice. Always give that little more. The rings so up in increments of 0.125 off an inch. About 3mm. So if one height seems perfect allow for the next one up. The method above is spot on and always works for me, but the fault lies in my measuring ability. It's almost impossible to get the exact measurement so i usually air o the side of caution. The maximum clearance you want is 6mm. Anymore and you loose elevation.


The other thing to remember is a 20 MOA rail may not give you 20 MOA. Depending on make/model you may get between 14 - 20. The other thing is if you use say 29 MOA to get 100 yard zero and you stick on a 20 MOA rail it does not mean you will now use 9 MOA. Because of the imperfections in a rail, the way it sits on the rifle, how tight it is torqued you will loose approx 2 - 4 MOA. So you may find yourself using 12-13 MOA with the rail to get your 100 yard zero.

The .243 will reach 1,000 yards, but with factory ammo, and the 20" barrel you will struggle to maintain accuracy, and consistency. Anything under 85 gr is going to be subsonic at 1000 yards, and anything over 85 gr will need to be doing at least 2,800 fps to maintain supersonic speeds. However with anything from 85 or up you need a fast twist rate to stablise the bullet, and as said the 20" barrel will not help with bullet stability.

Cass

Meant to say i've the Burris Zee signature rings. They come with 0, 10, 20 MOA inserts.

This means that without a rail i can put the appropriate insert in the ring, and gain between 10 to 20 MOA. The rings are purposely bigger than the 30mm tube of the scope to accommodate the inserts and scope tube. They hold tight, and have yet to loose zero after years of shooting.

Vegeta

Cass wrote: »

Meant to say i've the Burris Zee signature rings. They come with 0, 10, 20 MOA inserts.

This means that without a rail i can put the appropriate insert in the ring, and gain between 10 to 20 MOA. The rings are purposely bigger than the 30mm tube of the scope to accommodate the inserts and scope tube. They hold tight, and have yet to loose zero after years of shooting.

It's good to hear a first hand review of these, I've seen them in the past and thought about getting them but was always worried about their quality.

Horse2132002

Yea i get ye lads the gun will primarily be shooting 0 -600 and the 20 moa for the rest and I know its not gonna be knocking straws outta glasses at 1000 I just wanna push the rifle and scope and see what their made of. Everything will be torqued into place with a proper torque wrench and yes I know there is still gonna be some inconsistencies but there ones that I cant help .Thanks for all the constructive advice lads. I have ordered the the burris xtr mediums now the next question is to see do they do they job. Ill post pics after.

Cass

Burris measure their rings from the flat piece that sits atop of the rail to the bottom of the curve for the scope tube. In the XTR this is 0.5" (12.7mm). Allowing for the 30mm tube that is an extra 15mm so your total height is 27.7mm (say 28mm).

You have the Tikka T3 lite which has a slight taper from the action meaning you "gain back" a little room. Your average rail sits between 8 - 11mm high so we'll take the lowest possible setting of 8mm. Combine that with your clearance height of 28mm and you have 36mm.

The scope has a 50mm objective lens with 3mm for the housing. Divide that and we get 26.5mm minimum clearance needed. Between the 28mm needed clearance and the 36 you should have that leaves a clearance of 8mm. As the rifle is not a bull barrel, and with a possible higher clearance of the rail (more than 8mm) you could bee looking at a clearance off the barrel of between 9 - 13mm.

That's either side of 1/2". By no means the "end of the world", but a little high for my liking. However with the 20MOA rail, and 70 MOA off the scope coupled with a projected 35 - 40 MOA for 1000 yard shooting you should be more than fine in terms of available adjustments.

meathstevie

With Cass on this one, mount as low as you can go.

Horse2132002

Yea i decided to go with mediums just because I cant get the quick detach rings in low they only come in 1/2" or 1" so I chose the latter. Cheers for all the help guys.

FISMA

I order rings like footwear. Order the two closest sizes and return the one that does not fit. I would rather have to pay the return shipping once than return + new shipping.

Always best to take the kit to a place that, if possible, has them in stock and try before you buy.

The problem with rings is that spacing itself is tough to measure, let alone considering caps.

Glad to hear you're sorted.

Robotack

Fisma, where do you order that takes them back? I'm about to order rings for a new scope (same viper as op has) and I'm confused about whether medium or high will do it. I currently have high with a sidewinder 30 but that has a 56mm obj. It would be nice to be able to try both.