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25 yard zero questions

3K views 7 replies 4 participants last post by  Shadow 
#1 ·
Okay, so here's the scoop -

18.5" criterion bbl
LRB receiver
XS 24/7 tritium FS and large aperture rear sight
SEI Gas Lock Front Sight base w/ dovetail, 22" model

Now, shooting @25 yards required an astounding 25 clicks to zero about 4" above point of aim... Wow! GI3 - I know. My question is this, What the Heck?!?!?! I'm thinking that this is an awfully large amount of 'come uppance' to get on target. Am I wrong? I know I should technically want a point of impact 1.8" above point of aim @ 25 yards to get BSZ (Thanks John!), so that means I'm still at 16 clicks or so, which is not unheard of, but still a bit much if you ask me... (but better)

My direction of thinking is this: try the 22" xs front sight instead of the 18", as it would be shorter (I think), and allow me to lower my rear sight accordingly. Would this work? I'm concerned about this only because of the Airborne mount that sits on the rifle as well. With so many clicks up, it is a bit hard to be sure that I can see through the channel under the scope.

This may not be as coherent as I think, as it's late, I'm tired and my brain's fried. Plus I think I kinked my neck staring at the eclipse tonight, blocking the blood flow to my brain...

Thanks guys,
SF
 
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#3 ·
Change out that 22" GS dovetail for the 18" version, that is your first problem. 16 clicks of elevation is what it takes to get an M1A in the black at 600 yards coming up from a 100 yard zero, at 25 yards you would need closer to 2 or 3 clicks up from your 100, similar to a 200 yard zero, target zero not battle zero.

I suggest you change out for the correct height dovetail and target your rifle at 200 yards, instructions for doing so are in the M1A section over on Fulton's site. Once you have your rifle dialed in you can get your zeros and come ups dialed. MCORPS1
 
#4 ·
Small Fry
I agree with Octane Junkie. Swap out the standard lock for the MK14 one. Then use a standard height front sight and you will be fine.
SE I designed the lock sites as to be able to use standard height posts on either one. This is done due to the amount of sights left in .mil's inventory.
The taller sight is SA I's idea to compensate for the shorter barrel.
BTW out to 700 yards the comeups will work with the 18'' barrels with the correct sight heights. (As me how I know)
HTH
 
#5 ·
See, now here's where that tiredness shows. I started with a 18" GLFS and the same FS. I had to come up so high to zero at 100, that it was VERY hard to see through the channel under the scope. So that's why the switch to the 22" GLFS currently.
I don't remember how many clicks it took to zero at 100 yards... Didn't worry about it as we planned on changing out the GLFS.

If you picture the rifle and sights having two planes that intersect on target, you'll see what I'm thinking. There is the plane that is the rcvr and bbl and extends to the target, and the plane that runs from rear sight to front sight to target. Now, if I drop that FS, wouldn't the rear sight need to come down an corresponding amount to level that plane out to join up with the bbl plane?

That's why I'm hesitant to just put the 18" GLFS back on and trade out for a 22" FS. It seems to me that's just keeping the FS about the same height, and not solving anything... I'm not convinced that's the way to go Shadow/Octane... Convince me... I don't want to pay for shipping too many times to figure this out exchanging parts...

Am I just being stubborn? I can be and not realize it at times. The 'numbers' just don't seem to add up for me.

SF
 
#6 ·
What ammo are you using? Super hot or heavily crimped will print wildly high at close distances. Are you sure about your hold/weld on the stock? An inconsistent weld on the piece, head too far forward or back, will affect where your rounds print on the target. What hold are you using on the target? 6:00, 12:00, center mass, POA? As it turns out the M14 platform is not an easy rifle to shoot consistently accurately (that's gotta be double something grammatical), it is up to the shooter to learn their rifle and develop a good hold that they can repeat. That means lots of practice; ask me how I know.

Shadow mentioned a good point, there are 2 sights out there. A standard sight and a scout sight made by SAI. You have 2 choices, keep your 22" dovetail and get a scout front sight from SAI or get the 18" dovetail and use any standard USGI or NM front sight.

As far as convincing you, we don't need to convince you, you need to convince yourself. You are not a pioneer, all this has been done before and it works. GI2 The better way to visualize the sighting plane is to picture the front sight as fixed, since it is, the move the butt end of the rifle up or down, pivoting at the front sight, just like the rear aperture moves up and down as you adjust elevation. The only other plane is the bullet path, which is actually not flat. How you adjust your sight plane affects bullet path, the bullet's trajectory will affect where the round prints on the target at a given distance. If you raise the rear aperture, the butt of the rifle goes down, hence the bullet path goes up, and vice versa.

Best practice is to get your rifle on paper at 100 yds (6-8 clicks up from mechanical zero is optimal) and target your rifle in at 200 yds (should be around 9-12 clicks up from mechanical zero) as most ammo is considered to print 0" at 200 yards (by the mfgr), which obviously means it will print higher at closer distances and lower at distances farther than 200 yds. MCORPS1
 
#7 ·
I'm using a 6 o'clock hold, Port. ammo and a solid, consistent weld. I'm getting less than 3 moa outta another M1A @100 yards, same day/conditions/etc, slinged up in prone...

Shadow and I've worked out a plan - he has a diff GLFS lock to try, and XS is willing to send me a std height FS, so we'll get to it in the next week or two, when our schedules collide.

I'll keep you posted as I know more. Thanks O.J.!

SF
 
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