Hey guys, I have a question, about scopes!

[Mark611]

I'm looking to set up an 18'' barreled rifle with a tactical optic, I'm a big fan of the Leartherwood 1x4CMR4 type scopes for a small optic due to my eye sight over a red dot which I do not care for! I'm looking for a tactical optic for my new 18'' barrel AR set up, 1 I can use out to 800m or so, also 1 that once its zeroed I can use the hold overs without doping the scope, on the fly shooting, so to speak, is their an optic out there that will work with what I'm wanting to do? I already have a 24'' AR 6.5Grr That I'm running a 20x SWFA optic on and I like it! What say you!!!

[VASCAR2]

You might look at the ACSS reticle which has stadia lines for hold overs to 800 yards or meters. There are mil and moa models and are pretty popular. Primary Arms sell several varieties of this reticle. I’d probably opt for a 2.5-10 or 4-16x44 but most of the ACSS scopes sold by PA are FFP. I’m using a 4-16x42 Vortex Diamondback HP with dead hold reticle on my 18” 6.5 Grendel. The dead hold reticle has hold over out to about 300 yards and marks for holding into the wind. I personally use second focal plane scopes and like mil dot or Vortex VMR style reticles.

Using a ballistic calculator you can determine if the stadia lines on a scope provide a trajectory similar to the reticle. The trajectory of 168 grain 308/7.62x51 is pretty close to a 120-123 grain 6.5 Grendel. When I ran the numbers my 6.5 Grendel loads were close enough to use the Vortex Dead Hold reticle.

https://www.primaryarms.com/glx-2.5-10x4...56-reticle


Vortex no longer sell the Diamondback HP which was manufactured in the Philippines. I have a 4-12 Diamondback HP on my 12” 6.5 Grendel. The Vortex Diamondback HP can be dialed to your dope if your target shooting past the hold over. Both my Diamondback HP’s have adjustable objectives and wish Vortex still offered them. Vortex has a Diamondback Tactical FFP scope which is pretty popular and has a mil type reticle with markings for wind holds.

There are so many scope options and price might make a difference in what you want and can afford. Here is a link to a Diamondback scope with Dead Hold BDC reticle.


https://aaoptics.com/DIAMONDBACK-4-12X40..._p_44.html

[biodsl]

I got lost a little in this post. What magnification range are you wanting?

[VASCAR2]

I decided to compare the 308 ballistic trajectory with Federal Gold Medal Match and the 123 grain 6.5 Grendel using either the A-Max/ELD-M or 123 grain SMK. The trajectories are very similar and the 308 hold overs calculated out to 800 yards are very close to a 123 grain 6.5 Grendel match bullet.

I used the Hornady standard ballistic calculator to achieve this data. I found the velocity for the Federal 168 grain Gold Medal Match online out of a 20” barrel. I used 2.75” over the bore at sea level in getting this data. G7 data might be more accurate but both 308/6.5G are very similar. For crude combat hold on steel silhouette targets the ACSS 308 reticle might be a better option than 5.56 reticle.

I didn’t calculate the wind drift between the 308 and 6.5 Grendel but basically wind is dealt with by the skill of the shooter.

308 Winchester 168 grain Federal GMM BC .462 velocity 2565 FPS 20” barrel

6.5 Grendel 123 grain A-Max .510 BC 2500 FPS 20” barrel




100 yards 308 2379 FPS
100 yards 6.5 G 2333 FPS

200 yards 308 2200 FPS T -3.4”
200 yards 6.5G 2173 FPS T -3.7”

300 yards 308 2029 FPS T -14.1”
300 yards 6.5G 2019 FPS T -14.7”

400 yards 308 1867 FPS T -33.2”
400 yards 6.5G 1872 FPS T -34.3”

500 yards 308 1713 FPS T -62.2”
500 yards 6.5G 1732 FPS T -63.8”

600 yards 308 1570 FPS T-103.2”
600 yards 6.5G 1601 FPS T -105”

700 yards 308 1438 FPS T -158.3”
700 yards 6.5G 1478 FPS T -159.8”

800 yards 308 1319 FPS T -230.3”
800 yards 6.5G 1366 FPS T -230.4”

[VASCAR2]

The difference with 18” barrel velocities for 308 and 6.5 Grendel. Both are very similar trajectory. Everything was the same except I changed the velocities for 18” barrels. Muzzle velocity for the 18” 308 with Federal 168 grain GMM 2523 FPS. The 18” 6.5 Grendel with 123 grain match bullet 2465 FPS.

100 yards 308 2338 FPS
100 yards 6.5G 2299

200 yards 308 2161 FPS T -3.6”
200 yards 6.5G 2140 FPS T -3.8”

300 yards 308 1992 FPS T -14.7”
300 yards 6.5G 1988 FPS T -15.3”

400 yards 308 1832 FPS T -34.6”
400 yards 6.5G 1842 FPS T -35.6”

500 yards 308 1680 FPS T -64.8”
500 yards 6.5G 1704 FPS T -66.1”

600 yards 308 1540 FPS T -107.4”
600 yards 6.5G 1574 FPS T -108.6”

700 yards 308 1410 FPS T -164.7”
700 yards 6.5G 1454 FPS T -165.2”

800 yards 308 1295 FPS T -239.6”
800 yards 6.5G 1344 FPS T -238.3”

[biodsl]

The trajectory of 168 grain 308/7.62x51 is pretty close to a 120-123 grain 6.5 Grendel

So close in fact VASCAR, that PA now makes a scope with a .308/Grendel reticle.

https://www.primaryarms.com/pa-3-18x50mm...08-reticle

[VASCAR2]

I hadn’t seen that particular scope and reticle but it should prove pretty handy banging steel at various distances. The 3-18 is pretty versatile on a 6.5 Grendel.

[Mark611]

Thank you VASCAR2!!!! you have answered my questions! the Leatherwood 1x4CMR scope is calibrated for the 168gn 308 as well as the 5.56, it has the correct hold overs or as close to what I'm looking for compared to the 168gn 308 That will work with the 120 or 123gn match bullets from the 6.5Grr, The LW CMR4 optic is about the size power wise weight wise and size wise I was looking for for this rifle, I have several of these scope already, so 1 more for this rifle should be just fine! Thank you again! Mark.

[VASCAR2]

Glad I could help, one advantage to using the same optic is familiarity which I try to do with my equipment. Like the old saying, be careful of the guy that only has one well used gun. I’ve seen where guys will put the actual range for their stadia lines inside the rear lens cap or tape a small card on their stock for the actual range for their stadia lines. Some of my scopes are close enough there is no need to write down the specific range.


Range reports are always welcome on new builds!

[Mark611]

Again, Thank you VAS, and biodsl, bio that's an interesting optic, Like Vas has said familiarity with a certain optic, Myself, Me speaking IMO is a plus, I know 4x is not a lot of glass for those ranges out to 800m but the optics, I'm using are rated for use to 800m with the Leartherwood, optic, calibrated for the 308win 168gn bullets out to 800m, the Glass is outstanding! images appear larger IMO at 4x and very clear for this size optic, I'm also looking to keep the weight down, The PA 3x18 looks to be a nice optic, but I'm looking to keep this a small light weight package! I know bigger can be better, if wanted a true long Range set up to 800m I would just use my 15+lb custom built 308win bolt rifle I already have that shoots thumb size nail groups @ 200m, I'm not a big AR guy to begin with, but I do like the 6.5Grr in this plat form, I'm also a LH shooter, so I have to build a lower for LH shooter and I use match grade triggers in all my builds as well and right side side charging upper like an AK set up, That what works for me, so you can get an idea theirs allot of extra money for me to already put together a rifle like this to begin without skimping on anything! Thank you gentle MEN

[Mark611]

To give an update after thinking of my 4x choice I looked at some other scope options, I purchased a Hi-LUX Pentalux TAC-VF 4x20x50 30mm FFP, This thing is a monster! in size, it is nice but way to big IMO to mount on this rifle, So I looked at an Athlon Helos BTR GEN2 2x12x42mm 30mm FFP, this optic is 11.9'' long and I think it's much better suited for this set up and my intended use, it has a useable reticule for on the fly shooting plus the tree ranges out to 800mm, which is what I was looking for in an optic, I have no experience with Athlon optics any feed back would be appreciated on these optics

[SCRhino]

Just for something to think about... I have the swfa 3-15 on my rig and was literally shooting it at 825 yesterday! The biggest benefit I can see is you're already familiar with the reticle and there's almost always one for sale on samplelist.com. I've killed 5 deer with it so far from 30-200 yards and like I said steel to 825. It won't break the bank, isn't too heavy and with a 100 yard zero it's only 1.5 mil's to 300

[PVBoom]

So close in fact VASCAR, that PA now makes a scope with a .308/Grendel reticle.

https://www.primaryarms.com/pa-3-18x50mm...08-reticle

Who do they think is holding under that much?

"Damn! Thank God I can hold under since I'm dialed in at 1.5K"!

[SDW]

FWIW, I took a chance the other day and pre/back-ordered one of the new Arken EP5 scopes, 5-25x 56mm obj. They tout ED Japanese glass, so I just have to have a look at it, at $550. Supposedly a 2-4 week lead time on them right now. It's a tank! LOL 39 oz. 34mm main tube.

If I like it I'll mount it to the 22" Wilson barreled 6.5G upper I am putting together. Not something I'll be doing too much carrying around with.

https://www.arkenopticsusa.com/online-st...p425932116

[Dub]

FWIW, I took a chance the other day and pre/back-ordered one of the new Arken EP5 scopes, 5-25x 56mm obj. They tout ED Japanese glass, so I just have to have a look at it, at $550. Supposedly a 2-4 week lead time on them right now. It's a tank! LOL 39 oz. 34mm main tube.

If I like it I'll mount it to the 22" Wilson barreled 6.5G upper I am putting together. Not something I'll be doing too much carrying around with.

https://www.arkenopticsusa.com/online-st...p425932116

Was wondering if your scope came in and how you are liking it.

Ironically, I am waiting on the same scope and will be using the WC 22" SuperSniper barrel.

Waiting on glass and gun right now.

[MachV]

Tryed a Sightron Stac 4-16 but didnt like the reticle, then put an Arken 4-16 on the 20" Grendel AR. Its a beast but prairie dogs to 525 yards are easy.