SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    Sighting in 7.62x51
Go
New
Find
Notify
Tools
Reply
  
Sighting in 7.62x51 Login/Join 
Member
Picture of abnmacv
posted
Bore sighted scoped rifle and it will be a couple of weeks before I can get to an outdoor range with targets 100-200 yards out. There is a local indoor range that has a rifle range that's only 25 yards. Considering going there before my trip to the outdoor range. If I want to be dead on at 150 yards where should the target be hit at 25 yards using standard 149gr. FMJ? (And yes, I will wear double ear protection firing that puppy indoors.)


U.S. Army 11F4P Vietnam 69-70 NRA Life Member
 
Posts: 1553 | Registered: June 11, 2005Reply With QuoteReport This Post
Fighting the good fight
Picture of RogueJSK
posted Hide Post
That depends mostly on your sight height over bore, which is partly driven by your type of rifle.

So we'll need more info:

What model of rifle?

What kind of sight?

If a non-standard model and sight combo, what's the distance between the center of your sight to the center of the bore?


(Other factors, like the velocity of your ammo, can affect it as well. But if we know the above factors, we can at least get a close approximation using standard 149 grain M80 ball specs.)
 
Posts: 32494 | Location: Northwest Arkansas | Registered: January 06, 2008Reply With QuoteReport This Post
Member
Picture of powermad
posted Hide Post
Any ballistic app will give you that data.
Federal has one. https://www.federalpremium.com/ballistics-calculator

Using a 2.5 scope centerline, 149 FMJ zeroed at 150 will be 1.3" low or a 5 MOA holdover at 25 yds.
 
Posts: 1477 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
Member
Picture of powermad
posted Hide Post
2.5" is about average and what I used as an example.
Mine go from 2.81" - 3.14" above bore.
 
Posts: 1477 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
Member
Picture of sourdough44
posted Hide Post
I’d think you want to average low at 25 yards. I’d start with 1/2 to .75” low, just guessing without knowing the rest.
 
Posts: 6156 | Location: WI | Registered: February 29, 2012Reply With QuoteReport This Post
Caught in a loop
posted Hide Post
I've been thinking about this myself. I've got a couple of .223 Wylde ARs that need sighted in, and I've tried bore sighting at 100 yards but it was, an unmitigated disaster. I don't even know if I got on paper. I have no idea on other factors as this was an untested load with a new to me bullet (I'm a dumbass and forgot the ammo can of the other stuff for sighting in).

I'm thing about getting it on paper at 25, then bringing it out and confirming/adjusting the changes at 100 as necessary.

This message has been edited. Last edited by: vulrath,


"In order to understand recursion, you must first learn the principle of recursion."
 
Posts: 3349 | Location: Memphis, TN | Registered: August 23, 2010Reply With QuoteReport This Post
Member
Picture of powermad
posted Hide Post
quote:
Originally posted by vulrath:
I've been thinking about this myself. I've got a couple of .223 Wylde ARs that need sighted in, and I've tried bore sighting at 100 yards but it was, an unmitigated disaster. I don't even know if I got on paper.

I'm thing about getting it on paper at 25, then bringing it out and confirming the changes at 100, then setting the 100 yard zero.


I kinda did that with mine using Strelok as an aid.
Bore sighted at 25 yds at home.
The range available to me has 50 and 100 yd ranges.
I dial it in at 50, then using my setup as an example I turn the turret down to put the reticle above the POI 1.5 MOA or .08" for a 100 yd zero.
Then over to 100 yds and see how I did.
Usually really close.
Same with bore sighting at 25 yds, usually within a couple MOA at 50 yds at first.
 
Posts: 1477 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
Member
Picture of sourdough44
posted Hide Post
So are we about.75” for the 25 yard sight in??
 
Posts: 6156 | Location: WI | Registered: February 29, 2012Reply With QuoteReport This Post
Green grass and
high tides
Picture of old rugged cross
posted Hide Post
1-1/2" at 100 yds will put on on target from zero to 200yds. That is the basic method. Outside of that it will be a crap shoot imho. What I mean by that is trying to do it at 25yds or 75 yds or 150yds is a waste of time and money, ymmv.



"Practice like you want to play in the game"
 
Posts: 19158 | Registered: September 21, 2005Reply With QuoteReport This Post
Member
Picture of 1KPerDay
posted Hide Post
1.5” low at 25 should be fairly close at 150 but no 25 yard zero will be good enough to shoot bullseyes at an actual 150 yards.


---------------------------
My hovercraft is full of eels.
 
Posts: 3204 | Registered: February 27, 2013Reply With QuoteReport This Post
Member
posted Hide Post
Would be much better to zero that rifle outside at a range with longer 50-300 yard lanes. If you only have 25 yard indoor range, that’s okay but not ideal. Assuming your reticle height over bore is no more than 1.5” you should be on or maybe just slightly off in elevation at 25 yards depending on how that ammo shoots in your rifle. Using that setup, if your reticle is 2” over bore you would be at least 1/2 high at 25.

At the indoor range I shoot at, DHS, CBP, ICE, Air Marshalls, and assorted other agencies and Local LEO shoot ARs regularly at 25 for zero check. There is a shoot house out back where they train on dynamic entries. ARs indoors, even with good hearing protection are quite loud. Short barrels even louder. A 308 would be very loud. They might not let you shoot that inside. Depends on their back stop.

+
 
Posts: 2838 | Location: Unass the AO | Registered: December 16, 2007Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
posted Hide Post
If you measure you scope height over the bore I can give you a pretty accurate number.


IMHO bore sighting is pretty much a complete waste of time.
 
Posts: 14122 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Green grass and
high tides
Picture of old rugged cross
posted Hide Post
So is sighting in a rifle at 25 yds expecting that
to equate to accuracy at further distances. YMMV.



"Practice like you want to play in the game"
 
Posts: 19158 | Registered: September 21, 2005Reply With QuoteReport This Post
Sigless in
Indiana
Picture of IndianaBoy
posted Hide Post
quote:
Originally posted by old rugged cross:
So is sighting in a rifle at 25 yds expecting that
to equate to accuracy at further distances. YMMV.


25 yard zero is just to make sure that you are on paper when you step out to 100 yards and beyond.


zeroing at a short distance and expecting good results at long range is like driving a car 25 mph and thinking you are a race car driver.

recipe for failure.
 
Posts: 14122 | Location: Indiana | Registered: December 04, 2003Reply With QuoteReport This Post
Member
posted Hide Post
From Army experience, a 25 yard zero is not a good zero distance for rifles. 50 yards is way better. You’re flat at 50 and again at 200 for a 5.56 or a 308. With 50 yard zeroes I shoot plates at 250 easily with just a very slight holdover.
 
Posts: 2838 | Location: Unass the AO | Registered: December 16, 2007Reply With QuoteReport This Post
  Powered by Social Strata  
 

SIGforum.com    Main Page  Hop To Forum Categories  Mason's Rifle Room    Sighting in 7.62x51

© SIGforum 2024