Hello to all.
I have a CZ 527 in 6,5 Grendel mounted with a Sightron SIII 10-50x60 with 1/8 moa clicks (not my preferred becouse have a fine cross reticle...).
After many shoots at 100 meters a would to try at 675 meters...but the software Stelok (free) tell me that I need to down the cross for more than 48 MOA or 386 clicks...!!!
I shoot a handload with a brass S & B, primer Federal Match LR, 24,7 grains of VW N135, a bullet Sierra Match of 107 grains and a speed at the muzzle of 731 m/s...
The question is...I need a +20 (or +30) MOA picatinny rail to shoot at 675 meters???
Thank to all.
Ciao
Nino
10-09-2023, 10:18 AM (This post was last modified: 10-11-2023, 01:41 AM by Klem.)
Nino,
You will need between 30 and 33MOA of elevation depending on whether it's the 107TMK or plain 107HPBT Match King (don't know where 48MOA comes from as this would be unusual for all long range calibres).
Your Sightron SIII has a vertical range of 50MOA, so 25 up, and 25 down. You will need to cant the scope to reach 675M. With a standard 20MOA rail you'll get 45 up and 5 down.
At 675M with that bullet and velocity you are right on crossing into subsonic (350ms @ 700M). After 500M the bullet will be transonic (411ms) and groups will start blowing out. Control of accuracy gets wobbly as you approach subsonic. It's all doable with the 20MOA rail however.
Im using a Dip (Diversified Products) 25 MOA mount with my Cz527 with 23.5 barrel. If you have access to different powder maybe you could increase your velocity. Im running 28.0 grains IMR8208XBR and get around 2600 FPS or 795 MPS. Sierra list 28.5 grains of IMR8208XBR as max load with 107 grain SMK.
you are going to want to push that bullet to around 2700fps / 823m/s. 20 moa rail and you will be fine but stop pushing the 107s so slow, you are going to change BC and deal with all kinds of wind + nonsense the longer that bullet is in flight. burris xtr rings will get the job done for you as well with the included inserts. +- up to 40MOA in the rings alone... they just really really suck to get right and require way more effort than necessary.
10-10-2023, 06:45 AM (This post was last modified: 10-10-2023, 07:18 AM by Klem.)
Nino,
I will add that you do not need more than 20MOA forward cant to do the scope in this calibre justice.
The Sightron SIII is a large scope at 16.9". The scope's objective end is 2.7" (69mm) diameter. This large bell sits a fair way down the barrel. The more you cant it, the more likely it will hit the top of the barrel, depending on the height of the rings and thickness of the barrel of course. In other words, you may not be able to mount it at your preferred scope height because the cant is too severe.
Also, if the cant is too severe then the cross hairs, even maxed out downward elevation may not be able to coincide with where bullets are impacting the target at normal zeroing ranges, like 100. You may have to calculate the vertical difference between line of sight and trajectory impact at whatever range you zero at. For example, your 107SMK and velocity will climb to 13.8cm at 100M (4.8MOA). With 30MOA downward cant the bullet almost reaches the edge of where the reticle can coincide, but not quite. While it is convenient to have those two points able to coincide for short range hunting, zeroing is still doable at any range if you know the bullet's trajectory.
With a 20MOA (6Mil) forward cant you still have 5MOA of downward travel. This leaves enough horizontal space in the turret for windage at close range, while avoiding any optical aberrations at the edges of the field-of-view. It is always good to have whatever you are shooting at preferably in the middle of the scope, where it is clearest and there is the least distortion.
Unfortunately the simple Sightron target reticle does not permit the use of any other aiming mark than the center of the reticle. There are no other hold points.
While the specs say 50MOA of elevation you may find it's a little more, say 53. It all helps. What is your total travel when you crank it till it stops, then crank it all the way to the other end?
Ciao to all.
In summary...I may try N133 or N110 (too bright in my opinion), other powders are hard to find in my area. I should also find a lighter bullet but this is not good for long distances. This should give me a higher speed and therefore a lower POI drop. However the inclined track is necessary...
Thanks everyone for the help, I'll let you know the results after I find the material...
Ciao
Nino
I'm not a VV expert, so I did come searching...
Rifle shooter mag website has some info that could help...
The 135 you mention is similar to I-4064 according to these guys, which would be too slow and too granualr for the smaller case grendel.
Look for something more in line with IMR 8208xbr for example, or maybe H335. N133 may be a better choice.
[URL="https://www.rifleshootermag.com/editorial/vihtavouri-powder-reloading-data/372672"]
I also found the VV data for Grendel online...
this is separated by tab marks, it is in table form in the VV load data: Bullet 7,0 g / 108 gr Lapua, Scenar C.O.L. 57,1 mm / 2.248 inch
Hallo to all.
Hello greyfox.
Thanks for your help...
I am living in Italy and in this country the N133 not is so easy to find. I am 4 month that are waiting this powder...
Ciao
Nino
10-13-2023, 03:28 PM (This post was last modified: 10-13-2023, 03:31 PM by Zeneffect.)
well, what powders DO you have available? maybe we have tried it, maybe not. we will gain information or be helpful in delivering information, so either way everybody wins. Normally, the further out I get, the heavier bullet I tend to prefer due to the ability to carry over distance and generally higher ballistic coefficient.
Hello to all.
At the end...
This is a try with tge N133 powder. Those are 26.3 grains of powder with a 108 grains Lapua, S & B brass (LR primer). The average velocity was about 798 m/s and the range was 675 meters. The wheather war so cold and with a bit of wind...
How is the group?
Ciao
Nino
