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Posted: 10/16/2016 11:07:12 AM EDT
i just picked up a 18 inch 6.5 upper and am trying to decide on a optic.are either 556 or 308 ballistics close enough to use a "factory set" optic intended for either?ill probably never shoot beyond 500 yds.
Link Posted: 10/16/2016 11:32:51 AM EDT
Why not get a mil based reticle and then calculate the distance each half mil mark stands for?
Link Posted: 10/16/2016 11:36:49 AM EDT
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Originally Posted By jaqufrost:
Why not get a mil based reticle and then calculate the distance each half mil mark stands for?
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well,to be honest ive never done that before..i guess i have got used to my acogs...lol..is that really that tough to do that?
Link Posted: 10/16/2016 11:43:47 AM EDT
It's really not hard to do. Here is a chart I ran for my Creedmoor. One of the uspides is no matter what load you use, you can build a chart for it, so you aren't stuck with M855 or another matching load.

Link Posted: 10/16/2016 11:44:20 AM EDT
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Originally Posted By hanker71:

well,to be honest ive never done that before..i guess i have got used to my acogs...lol..is that really that tough to do that?
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Originally Posted By hanker71:
Originally Posted By jaqufrost:
Why not get a mil based reticle and then calculate the distance each half mil mark stands for?

well,to be honest ive never done that before..i guess i have got used to my acogs...lol..is that really that tough to do that?

No, not really. You can print off a dope sheet from JBM if you know what bullet and how fast it's going that will give you drops in mils.

Most scopes that have a reticle like that usually have exposed turrets to facilitate dialing your range correction.
That makes it easier, for me at least, to hold for wind on the horizontal.
Link Posted: 10/16/2016 11:48:48 AM EDT
wow,thanks guys!i think ill give that a whirl..maybe one of the swfa offerings would be nice?
Link Posted: 10/16/2016 12:00:33 PM EDT
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here it is!..cant wait to shoot it!
Link Posted: 10/16/2016 3:35:27 PM EDT


This is my 18inch Grendel.

I really enjoy this Vortex Viper PST 2.5-10×33 FFP with EBR-1 Mrad reticle. Not a terribly expensive scope either.


I have had pretty good luck with that Hornady Ballistic calculator too .
Link Posted: 10/16/2016 3:49:24 PM EDT
You might look at the Sig 2-12 Tango6 FFP. Glass is made by LOW. Optics planet has it marked down to $999 from $1800 and Jesse Tischauser has a 12% off coupon code if you PM him.
Link Posted: 10/17/2016 5:02:36 AM EDT
6.5 G ballistics don't really match any BDC reticles out there that I know of. The fact that this cartridge offers superior ballistics is the main reason for its popularity. I wouldn't go for any kind of BDC reticle optic, and would opt for a mil/mil optic that you can figure out your exact dope for. Even if you don't ever shoot it past 500 yards, you can work on being wickedly accurate inside that distance... like consistent brain shots.
Link Posted: 10/17/2016 12:04:00 PM EDT
A 107 grain 6.5 Grendel fired from a 24" barrel is nearly dead on the money compared to a 7.62x51mm M80 ball load. The M80 has 150 fps higher velocity and the same B.C. bullet.

The ballistic charts are very close. Using Lapua's 108 grain Scenar bullet you have nearly a one to one match with .308 168 grain Sierra Match Kings. Leupold's 2.5-8 Mark 4 midrange scopes with the TMR reticle is a nearly perfect match.

The higher B.C. heavier weight .264" bullets are traveling much slower than the 107/108 class match bullets and they drop quicker because of it.

I suggest you buy a scope that has external rings and dial in your bullet drops based on what you discover in the field. Trijicon and similar BDC scopes are specific to a very narrow window and aren't easily adjusted on the fly. They work fantastic as intended, but don't work as well when matched with a different caliber. JP Rifles sells a custom BDC ACOG designed for 69 - 77 grain 5.56mm ammo traveling at 2750 fps. This would be close to 6.5 Grendel when shooting 107/108 grain bullets.

The JP Rifle ACOG reticle eliminates the 200 yard hash mark making the 100 yard crosshairs very precise. The 300 yard line is the next increment and this works fine because there is very little drop from 100 to 200 yards.

You can "balance" any scopes BDC to your rifle buy using the 300 or 400 yard hash mark and actually zero the rifle at that distance. Zeroing the rifle at 400 yards using the 400 yard hash mark will balance the BDC across the useable range. You may be a little high at 200/300 and a little low at 500/600 but the utility of the system will be maximized.
Link Posted: 10/17/2016 6:14:40 PM EDT
Hanker71, I like that clean look. What non-forward assist upper is that?
Link Posted: 10/17/2016 9:40:50 PM EDT
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Originally Posted By BluntForceTrauma:
Hanker71, I like that clean look. What non-forward assist upper is that?
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thanks man!..its just a cheapo anderson from aim.i think it was like 40 bucks!
Link Posted: 10/23/2016 8:01:43 PM EDT
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Originally Posted By jaqufrost:
It's really not hard to do. Here is a chart I ran for my Creedmoor. One of the uspides is no matter what load you use, you can build a chart for it, so you aren't stuck with M855 or another matching load.http://www.ar15.com/media/viewFile.html?i=89754


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That looks like that's for a 6.5 CM velocity not Grendel.
Link Posted: 10/23/2016 8:11:10 PM EDT
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Originally Posted By CurraheeBeer:

That looks like that's for a 6.5 CM velocity not Grendel.
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Originally Posted By CurraheeBeer:
Originally Posted By jaqufrost:
It's really not hard to do. Here is a chart I ran for my Creedmoor. One of the uspides is no matter what load you use, you can build a chart for it, so you aren't stuck with M855 or another matching load.http://www.ar15.com/media/viewFile.html?i=89754



That looks like that's for a 6.5 CM velocity not Grendel.
Yep, that's what I posted
Link Posted: 10/24/2016 11:06:14 AM EDT
I had a fixed 10 power Bushnell with turrets I have had maybe 25 years or more. Think it is a 3200. Not very expensive even now.

It has proved to be excellent out to a 1000 yards. Plenty of adjustment ( I am using a 20 mount). Extremely repeatable.
Link Posted: 10/24/2016 12:41:27 PM EDT
[Last Edit: 10/24/2016 12:42:30 PM EDT by LRRPF52]
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Originally Posted By borderpatrol:
A 107 grain 6.5 Grendel fired from a 24" barrel is nearly dead on the money compared to a 7.62x51mm M80 ball load. The M80 has 150 fps higher velocity and the same B.C. bullet.

The ballistic charts are very close. Using Lapua's 108 grain Scenar bullet you have nearly a one to one match with .308 168 grain Sierra Match Kings. Leupold's 2.5-8 Mark 4 midrange scopes with the TMR reticle is a nearly perfect match.

The higher B.C. heavier weight .264" bullets are traveling much slower than the 107/108 class match bullets and they drop quicker because of it.

I suggest you buy a scope that has external rings and dial in your bullet drops based on what you discover in the field. Trijicon and similar BDC scopes are specific to a very narrow window and aren't easily adjusted on the fly. They work fantastic as intended, but don't work as well when matched with a different caliber. JP Rifles sells a custom BDC ACOG designed for 69 - 77 grain 5.56mm ammo traveling at 2750 fps. This would be close to 6.5 Grendel when shooting 107/108 grain bullets.

The JP Rifle ACOG reticle eliminates the 200 yard hash mark making the 100 yard crosshairs very precise. The 300 yard line is the next increment and this works fine because there is very little drop from 100 to 200 yards.

You can "balance" any scopes BDC to your rifle buy using the 300 or 400 yard hash mark and actually zero the rifle at that distance. Zeroing the rifle at 400 yards using the 400 yard hash mark will balance the BDC across the useable range. You may be a little high at 200/300 and a little low at 500/600 but the utility of the system will be maximized.
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Litz BC for the 107gr SMK 6.5mm is higher than what people often defer to.

Sierra listed BC: .420
Litz: .461 G1, .230 G7

It's better than a .308 168gr SMK BC.

Sierra: .462 G1
Litz: .437 G1, .218 G7

Then when you factor in twist rates, you see the Grendel with 1/8 has much better spin stability and longer time before gyroscopic decay.
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