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-   -   6.5 Grendel Trajectory Reality Check (http://www.firearmstalk.com/forums/f30/6-5-grendel-trajectory-reality-check-24964/)

NavArch 03-22-2010 01:10 AM

6.5 Grendel Trajectory Reality Check
 
I have been interested in finding an upper for my M-4 lookalike in a caliber with more punch at 300 yards than 5.56 provides. The 6.5 Grendel data I have found has been zeroed for 600 yards as the table presumed the shooter is into 600-1,000 shooting. At least that's my guess. Those tables show a mid-trajectory altitude of 45-55 inches, which strikes me as odd for a round touted to be "flat shooting."

All of the other calibers' ballistics data I have found is based on a zero of 200 yards (except for 7.62x39 at 100 yds). Can anyone provide a pointer to data that would impress me a bit more?

Dillinger 03-22-2010 01:14 AM

Well, I can't directly point you to what you are looking for, but I can tell you that the best ballistics data you can find is from a guy named Art Pejsa.

He broke the mathematical code on ballistics and his software is very well respected.

If someone is going to have the answer that doesn't shoot this round regularly, Art Pejsa would be my first source.

Good luck.

JD

jpattersonnh 03-22-2010 01:58 AM

What would you consider "flat" at 600 yards? a 6.5x39 is a short cartridge. You hear that it has the characteristics of the 6.5x55, but really comes no where close. 400 yards it is a vg cartridge. 300 it is excellent. http://www.65grendel.com/faq.htm

NavArch 03-22-2010 11:15 AM

Quote:

Originally Posted by jpattersonnh (Post 254324)
What would you consider "flat" at 600 yards? a 6.5x39 is a short cartridge. You hear that it has the characteristics of the 6.5x55, but really comes no where close. 400 yards it is a vg cartridge. 300 it is excellent. http://www.65grendel.com/faq.htm

Perhaps I didn't ask the question clearly. What I was trying to say was that the ballistics data I have found for 6.5 Grendel has been based on a 600 yd zero, which comes from its intended use in long range target shooting. For my purposes (300 yd), I am looking for ballistics data based on a 200 or 300 yard zero. By zeroing the 6.5G at 600, it ends up with a rather large mid-range vertical divergence from LOS.

I was not comparing the 6.5G to the 7.62x39, which has a very loopy trajectory and loses considerable KE after 300 yds. The two start out with approximately the same KE, but the 7.62x39 energy at 300 yds is on par with the 6.5G at 500 yds.

cpttango30 03-22-2010 03:54 PM

This is using a 100gr Nosler BT at 2630fps MV.

With a 100 yard zero your looking at 16.8" of drop out to 300 yards. The 6.5x55mm has 15.4" drom from 100 to 300 yards.

http://i95.photobucket.com/albums/l134/a/65Grendel.png

NavArch 03-22-2010 08:29 PM

Thanks
 
Thanks for the 100 yd zero values. It looks like a 200 yd zero would give a bullet path that passed thru -1.6 at the muzzle, to +2.2 at 100 yd, to 0 at 200 yd. Does that match numbers you've seen?

Mutabam 03-23-2010 01:36 PM

http://www.alexanderarms.com/grendel_ballistics.pdf

NavArch 03-23-2010 11:40 PM

Quote:

Originally Posted by Mutabam (Post 255491)

That's where I went originally, but the 600 yd zero isn't what I'm looking for. If you go back to the first statement in my original post, my goal is not necessarily to make the 6.5 Grendel work for me, but rather to find the right horse to ride (so to speak).

Still looking, I guess.

MikeEzell 08-31-2010 07:57 PM

I know this post is a bit older but this may be of help...if I understand what it is you are asking for. Based on a 20" barrel with 129 Hornady SST(b.c.=
.485), and a scope height of 3.0" and muzzle vel. of 2400fps
100 yds=2.00" high
200 yds=0.00
300 yds=9.89" low
These are obviously numbers based on AR15 data. You can do much better in a bolt gun with longer barrels and the ability of the gun to stand much higher pressures than the AR can.
I love the Grendel case and think it's best served with lighter bullets and kept and ranges of 500yds and under. The problem then becomes quality lighter weight match grade bullets in 6.5 caliber I shoot a 30 cal version that I call a 30 Major in BR. I shoot 118gr bullets at 3000fps and can go faster but brass life begins to suffer at much more than that and my BR loads are WAY beyond what an AR can stand.--Mike Ezell


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