50 yard Zero

[rob_s]

A bit pessimistic of your fellow carbine shooters today, heh? l

Shooters? No. Owners? Yes.

[ST911]

Shooters? No. Owners? Yes.

An important distinction.

Add those whose carry of them is compulsory to the list as well.

[barrelwrench]

Come on guys' there are no posers or wannabes on this site.

[Elmer Fudd]

Paul Howe at CSAT has a good article on zeroes. He does not like the 50/200 yard (which is what I use, as much for the fact that my civilian AO does not have many 200 yd+ lines of sight):

http://www.combatshootingandtactics....llpictures.pdf

He has some other articles which might interest folks here:

http://www.combatshootingandtactics.com/published.htm

[jsbsmarine]

Any suggestions for a 10.5in LMT barrel zero? Using a simple aimpoint M2 on it.
Thanks

[JSantoro]

Who said you can't teach an old gunny new tricks.

Heh, it can be done, but one may pay a price. It can be a Phyrric victory

Just suggesting something as simple as a 100m co-alignment of a Marine's PEQ laser with the RCO chevron (instead of the idiotic 300m zero in the TM) has, for me, sometimes resulted in a scene that looked like this:



BUISs are becoming more and more common in the Corps, now. Suggesting ANY zero other than the "book" zero, the reaction (think sodium + water) can sometimes make somebody outside the conversation think I'd just wiped my bum with the national ensign.

The 100 works. The 50/200 works. One can use an Analogue Decision Generator (AKA, "coin") to choose between the two and make the result work, though it helps to futz with both, circumstances permitting.

[barrelwrench]

Hey. That looks like the last wet down I attended. You got a guy by the name of fooley working with you at Q.

[ra2bach]

The only sight-in range that doesn’t have a “Near Zero” and a “Far Zero” is a 100-yard sight-in because the bullet reaches the LOS right at 100-yards and does not go above the LOS. So, at 100-yards, the bullet grazes the LOS and then starts going to the dirt.

even after having been a shooter for many years, I found this concept fascinating.

talking about the common 5.56 carbine, I know that the height the optic is mounted above boreline is a component in this but is there something magical about 100yds.? is there any other distance, possibly further, that this occurs?

I always understood and accepted the concept of "point blank range" in that the POI will never deviate more than X inches from POA over a certain distance. for instance, an 8" kill zone indicates that the bullet never rises, nor drops, more than 4" from the POA. this works well for hunting where animals have an X inch size kill zone. faster, hence "flatter" shooting, cartridges increase this range, as does a larger kill zone.

and I readily understand that this involves the POI being either under or over the POA depending on which side of your zero the target is and either holdover or hold under is required. but it simply never occurred to me that there was a distance at which the POI rose to the POA but did not rise above it.

the fact that with this zero, there are only holdovers is a revelation. it caused an epiphany in me. I don't know why I didn't realize this before! this certainly changes how I'm going to think about things from now on...

[ucrt]

I made a comment on another Thread that if the bullet crosses the LOS at 50 yds for a 200 (or so) Zero, that I didn't think the front post would have enough adjustment to do a Zero at a 100 yds. I thought the bullet would have to cross the LOS around 10-15 yds to be able to drop back down to Zero at a 100 yds.

I was figuring the traj would be about like a slow pitched softball. (Did my "incorrect" thinking make sense)

Well, the Honorable MOLON was quick to graciously correct me. He's the one that explained the traj to me like I stated in my previous post.

LOS is LOS, so I wouldn't think it would matter to an AR if it was RDS or Open Sights, the trajectory would be the same. The height the LOS is above the bore, bullet speed, and weight pretty much dictate this 100-yard traj.

To me, with my T-1, I like the 50/200 yds sight-in. I know that the traj out to 250 yds or so will be covered by (or just inside) the Red Dot.

Thanks!

[Rln_21]

When putting on a new sight or scope, I seperate the upper and remove the BCG... I then peek through the barrel at some object and while holding the upper still I adjust the sight/scope to that object. Then you move to the 25yd paper... Really easy, honest...

Rmpl

+1 to this.

Boresights are a huge waste of money, this works every time with any rifle assuming you have a good rest or just some decent shooting bags...