I signed up for my first ever training class this fall.  It is a two-day scoped rifle training class which goes over the basics of precision shooting out to 800 yards.  I have two rifles that I think would work well but can't decide which one to take.

1)  An Aero M5 in .308 that I put together that is a lot of fun to shoot.  Has a "budget" 4-16 scope on it.

2)  An AR-15 that has a 16" LaRue Stealth barrel on it with a Primary Arms 1-8 scope.

Neither gun has a great scope on it but I'm hoping I'll learn a lot from this course which will help me find a better scope to invest in.  I'm leaning toward the M5 but the AR-15 would be lighter and cheaper.  I might also take both but then I'm lugging around a lot of stuff for this class.

Any insights or other things I should consider?

Shooting a 5.56 gun out to 800 will be "harder" (meaning you might learn more with wind reading, etc) than a .308 but at the same time a 1-8 isn't ideal for shooting out to 800 whereas a 4-16 is.

Thanks for the replies!  My first choice was definitely the M5 so that helps a lot.

Another question, should I take my suppressor?  This course is in Virgnia so I would have to transport it across multiple state lines to get there.

I have a brake on it but didn't know if using a suppressor was common courtesy to the other students.  Thanks!

My advice would be to take both.  AR-10's are notorious for going tits up.  Unless you've got a high quality rifle and put it through it's paces you don't know how well it's going to run.

A 1moa rifle or better is desirable.  LaRue makes such rifles.  

Things like a good 100 yard zero and knowing the velocity of your bullets leaving the barrel will help you in class.

Now that I tried it, I'm a believer in the Tall Target Test:

Thanks for the info!  I'll watch the video in a bit.

My AR-10 is one I built myself and, if I'm being honest, hasn't been shot much yet.  I got it sighted in at 100 yards and that was all I had time for.  My plan was to get back out to the range a few more times before the class to find which ammo performs the best in it.  I don't have a chronograph but have it on my list of things to buy.  I truly am going into this class a newbie and am glad it is geared toward people of all experience levels.  I just don't want to cause any issues for the other people taking the class.  I know I'll learn a lot.

ETA:  Would a bolt-action be a better back-up?  I have a Remington 700 in .308 that is reliable that I could take.

Bring both if you can, just the .308 if you only bring one. Traveling with a suppressor is not an issue so bring that too.

ETA yes bring the bolt gun. You may want to just run that as it will definitely be easier to run than a large frame gasser.

Remington 700 in .308 is a classic!  Bolt guns are very consistent.

Once you have an AR-10 running right they are VERY nice.  For one reason or another it took me about a year for my PA-10 to get where I'm feeling fairly confident about it.  I installed the retaining pin the wrong direction one time and it bent pretty badly... needed a gunsmith to get it out...and my super light SSA-E trigger was giving me doubles once it broke in.  I ended up using a heavier trigger.    

Heavier grain ammunition of a given caliber will more consistent results in the wind.

There is a fair amount of math in this, but tons of solid info on long range shooting here:
Applied Ballistics For Long Range Shooting 3rd Edition

I was finally able to get to the range today.  My Aero M5 likes Federal Premium Sierra Matchking .308 175gr ammo.  Next range trip I'm going to do the box test on my scope, as well as the test posted in this thread to make sure it's level.  Then, I'll test this ammo in my Remington 700 to see how it does in it to use as a back-up gun.