Input on my AR build

Epicyclic swerve may actually happen, but it's going to expand your groups over distance, not tighten them. It sounds like you understand that 1 MOA is a fraction of the radius of the horizon, so you understand that 1 MOA is the same angle at 1 yard as it is at 1000 yards. By saying your groups tighten by MOA over distance, you're still saying that the trajectory angle of a bullet is increasing at short distances and then decreasing at longer distances. Just doesn't happen.

You may very well be able to shoot smaller MOA groups at longer ranges - I know smaller targets help me shoot better, for instance. Perhaps that's what you meant in your post and I just took it incorrectly. But if you could somehow measure the same group at 100 yds and again at 400 yds, you're not going to see a measurable decrease in MOA from 100 to 400 yds in the same group.

 

Have you ever heard of a bullet "going to sleep"? This is the theory I am talking about. The transition the bullet makes from the forced stabilization of the rifling of the barrel to the relative unstable atmospheric conditions means the bullet is actually having to settle into its spin, also known as "going to sleep".

And it's not a true epicyclic rotation, if that were the case bullet groups would be a constant. Now, since the spin rate is "self stabilizing" the projectile acts in a epicyclic motion but as the radius of the deferent approaches zero.

For a good video to explain ACTUAL bullet behavior YouTube "pitch, yaw and bullet path"

 

a lot of Youtube and Call of Duty will definitely make you Black Ops Super Sniper. Awesome.

 

Obviously you didn't watch the video, there smart guy. I would recommend some books for you to research it but that's obviously too much to ask..

 

I'm just a dumb old lead farmer.

 

Funny you would reference that video. it was done by a guy named Bryan Litz. Serious dude - AE degree, air-to-air missile engineer for the USAF, Chief Ballistician for Berger, etc.

You can read about the software behind the video in his words here, and also about how it doesn't lead to smaller angular groups at distance:

http://www.appliedballisticsllc.com/index_files/epswerve.html

I also happen to have his book: Applied Ballistics for Long Range Shooting.

A quote from page 192:
It should now be clear that the mechanism of epicyclic swerve cannot be responsible for the observation of bullets systematically shooting smaller angular groups at long range. The swerve radius is just too small. I believe that the answer to the mysterious shrinking group question lies with optics.

And from page 193:
To sum up this subject, when a rifle produces 1" groups at 100 yards and 1.5" groups at 200 yards, I believe it's because of the aiming error introduced by parallax at close range.

(both quotes courtest of Bryan Litz, used without premission)

It's NOT physics (at least not bullet physics).

 

Well it randomly popper into my head that I measured wrong and I feel like a huuuuuuuuge idiot! I should have measured from the end of the threads on the upper receiver. Once I measured from there it showed I would have about almost a quarter inch of the gas block showing. Ooops .

Good news - everywhere else is selling the MI SS 10" for around $150 so I shouldn't have a problem getting just my money back on it considering I only paid $110.

Bad news - The sale that Primary Arms was having on the 11" Troy TRX rails is over so now I play the waiting game. Only have myself to blame.

As soon as I saw that LaRue graphic I had a feeling I messed up.

Thanks for the discussion on the life of a bullet. Learned quite a bit from it.

 

There are so many variables in long range shooting, if it was easy we would all shoot dime size 5 shot groups at a mile. But when it comes down to it for this AR build, build what you like and shoot a lot of groups with every ammo you can get a hold off. Put a good trigger, sear, and springs and get a good optic (buy cheap buy twice). Just decide if you want to build a plinker that will shoot 5 inch groups with garbage ammo at 50 yards or a tack driver that will shoot sub moa at 100 yards. Build what you want because after all its yours and your money.

 

I want to get quality optics and quality low profile folding sights. Money isn't really an issue; I still like to find the best price I can on those items though.

 

Oh yeah - what was the topic of this thread? Lol.

Good plan on the quality optic. Definitely somewhere where you shouldn't skimp.

 

Andrew are you looking for magnification or red dot? I have an Eotech its pretty cool but limits you. I really like the Burris 3-9 fullfield with the speed bead III on top of the scope ring, best of both wolds and its about $500, plus you can use any scope you want with the rings. Stick quality brands, Leupold, Nikon, Night Force, Zeiss, Millet, Trijicon, and Vortex.
Iron sights are another issue, any flip up will not be as stable as a one piece sight, but buis (back up iron sights) Magpul MBUIS are pretty sweet, light and cheap and solid. I have acc. like magpul BAD lever which allows me to operate the bolt release with strong hand, and a good foregrip if you're gonna do a lot of off hand shooting. Trigger will be the most noticeable thing in an AR stick with a Timney or Jewel pricey but worth it.

 

I'd like a red-dot with a flip up magnifier but I haven't even started the research on any optics yet or pros/cons yet. I'm kinda back looking to rails again...

How do you think the eotech is limiting?

 

Accuracy at 200 with a 5 MOA for is nearly impossible the dot is nearly as big as the target. Plus to get the flip up magnifier is close to a $1000.

 

Check Riflegear.com
They're my normal local source and decent prices.
You can beat them, but you have to put some effort into it.

 

Andrew, IMO I would get my barrel mounted and gas system connected, get the gun in firing condition, and then look for a rail, and a flash/compensator. Check JP enterprises they make some awesome recoil reducing comps. As for the red dot with magnifier, you can kiss the rear iron sight goodbye.

 

A couple extra shifts would easily cover it. I'm kind of looking at this as being purchased by picking up overtime so my actual savings/spending money isn't affected at all.

Will check em out now. Thanks Rich.

 

Check palmettostatearmory.com

 

For what it's worth, I always recommend a quality 1-4x scope over a red dot and magnifier. You get the benefit of clearer and brighter optics, a non-illuminated reticle (when you want it) and a reticle with useful holdover. Add a throw lever and it's just as fast as a fold-over magnifier. I like the Viper PST as a baseline, and they just get better from there. And you're spending a couple hundred less on a setup like this:

 

I've been checking them all. Primary Arms had the 11" Troy TRX for $109 shipped. That was my chance but I let it pass cause I thought the 10" would have been a perfect fit and still light weight. The Alpha rails are a bit heavier so I'm just gonna have to wait for another deal on them. I honestly liked the look the the holes more than the slots which was another factor in my decision.

Thats a nice rifle. Is that a MI SS handguard I see?

 

Thanks - yep. 11.5" SBR using a Daniel Defense barrel and MI SS-series rail.