Question:
Do M1A rifles of varying lengths follow the same pattern of come ups once zeroed at 25/200 meters?
I can see this two ways:
1. In my experience, shorter sight Radii exaggerate sight adjustments. Come-ups might be 2,2,3,3, etc...
2. Clicks are clicks. Sights are probably calibrated to account for barrel length.
Can't find a straight answer on the interwebs. Help me out, riflemen...
BD
The best answer to this question is to shoot and find out. In general shorter barrel will mean greater number of MOA per click. I think that there might be something in the Instructor Handbook. But what you can do is test it by shooting a box at 25m or 100y and see what the results will tell you how many MOA each click turns out to be.
If you don't remember how to do it. You shoot a box as follows.
1. zero your rifle at 25m and 100 yards. Know these as base numbers.
2. At 100 yards, post a target spot in the lower left quadrant of a piece of paper (11x17). fire a shot at this target spot.
3. Move your windage 10 clicks right, aim at the same spot and fire another shot. If you have 1 minute windage (~40 clicks from full left to full right on the rear sight). You should have moved 10 inches. If you have half minute you should have moved five inches (both of these are with a standard barrel.
4. Move 10 clicks up and shoot. On a non match rifle this would be ~10 inches with the standard barrel. Use the original point of aim.
5. Move 10 clicks left and shoot. Use the original point of aim.
6. Move 10 clicks down and fire a shot. You should be back in the same spot.
Note that on most rifles the adjustments are most accurate in the middle area. But sometimes you get really lucky.
On a normal rifle your 400 yard zero should be ~8+ clicks up from 100. YMMV Give it a try and report back with your findings.
Record this data in your rifle book along with the Ammo that you used, date, location etc. Add you specific zeroes when you have a chance to shoot KD.
Mike
If I actually owned a scout, this is exactly what I would do. Since I don't, I'm looking for a rifleman who has been through this process with a scout or SOCOM and has the answer.
BD
This is great stuff, thanks for posting. O0 O0 O0 O0 O0
CM
Quote from: jmdavis on October 27, 2011, 11:44:44 PM
The best answer to this question is to shoot and find out. In general shorter barrel will mean greater number of MOA per click. I think that there might be something in the Instructor Handbook. But what you can do is test it by shooting a box at 25m or 100y and see what the results will tell you how many MOA each click turns out to be.
If you don't remember how to do it. You shoot a box as follows.
1. zero your rifle at 25m and 100 yards. Know these as base numbers.
2. At 100 yards, post a target spot in the lower left quadrant of a piece of paper (11x17). fire a shot at this target spot.
3. Move your windage 10 clicks right, aim at the same spot and fire another shot. If you have 1 minute windage (~40 clicks from full left to full right on the rear sight). You should have moved 10 inches. If you have half minute you should have moved five inches (both of these are with a standard barrel.
4. Move 10 clicks up and shoot. On a non match rifle this would be ~10 inches with the standard barrel. Use the original point of aim.
5. Move 10 clicks left and shoot. Use the original point of aim.
6. Move 10 clicks down and fire a shot. You should be back in the same spot.
Note that on most rifles the adjustments are most accurate in the middle area. But sometimes you get really lucky.
On a normal rifle your 400 yard zero should be ~8+ clicks up from 100. YMMV Give it a try and report back with your findings.
Record this data in your rifle book along with the Ammo that you used, date, location etc. Add you specific zeroes when you have a chance to shoot KD.
Mike
What JM said. If you have one, shoot it and see. Just remember that not all the same type of rifles will exhibit the same behavior. Maybe every rifle just really wants to be shot so they all shoot a little different just to make their owners (that really want to know) shoot them more to find out.
Internet wisdom is quite often just a broader version of what used to be said around the pot bellied stove down at the General Store.
Remember what you read/hear about different weights of bullets shooting to different points of aim? This is very true with many (most?) rifles. However, I have a Browning BAR Gd. 2 that will put Remington 180 and 220 grain corlokts into the same 5" circle at 300 yds. My father-in-law's rifle. He was a very experience rifleman (he told me in 1975 that you should be able to lie down on the ground and shoot your rifle's bullets into a 1" group at 25 yds. If you and your rifle/ammo could do that then you could hit anything you needed to hit with it.
Unfortunately way too many folks today buying these rifles did so for the looks or the "CQB" mind set they read about on the internet and not because they are really going to learn to shoot those rifles. Hopefully, as large as the RWVA is (and since we're supposed to be shooters) we've got some folks who have shot their short barreled M1A's enough to be able to give you their results.
Good luck with your quest for knowledge to share with others.
I don't own one. Hopefully someone here does.
And I know all rifles are going to be slightly different - I'd just like to hear some KD results from someone who owns / has shot a short-barreled M1A.
These guys are about 95% M14/M1A oriented. Lots of short barreled M1A's owned, shot and reported on over there.
http://m14forum.com/
The Scout, SOCOM and M1A standard all use the same sight system. Sights are not calibrated for barrel lengths.
So the come ups will be different due to velocity loss, especially in the SOCOM which is 250-300 fps. depending on ammo and conditions.
We found this out at our last RBC.
A chrono and velocity tables from a load manual/online calculator will really help as "published" ammo data can be considerably off.
Checking the inches of drop between each yardage, you can convert the inches to minutes, then to clicks and sorta make up your personal range card. This is a good starting point.
Like jm does, we do something similar to check the value of our M1's sights. Sight in first at 25M sight on the "25M Squares".
This is usually the same as 200M on the M1A or close depending on ammo and conditions (altitude, temp, etc.).
Then dial up 10 MOA (the MOA's roughly needed to get to 500M), shoot again and see it the center of your group came 10 MOA up. This is a quick and dirty baseline to see if you sights are really 1 click per 1 MOA. Make notes.
Check at KD to verify. Compare notes.
Mas Ayoob did a complete SOCOM review with ammo tested with a chrono in the July 2005 Precision Shooting rag.
The SOCOMS do show up at Appleseeds and have horrendous noise/concussion with the brake.
It's not just the velocity loss, it's the different sight radius between front and rear sights that change the click value. The rear sights are designed for the full-length rifle. The shorter sight radius of the shorter barrels increases the angle of change per click movement. A friend of mine had one a few years back. I seem to recall that we figured the SOCOM had a 1.3 MOA value per click.
In addition to all of the great info above you may want to email Springfield and get their input/response (sales@springfield-armory.com). I have emailed them on three or four occasions. Each time I got a very quick and informative response to my question.
csw
Quote from: Colorado Pete on October 29, 2011, 04:28:39 AM
It's not just the velocity loss, it's the different sight radius between front and rear sights that change the click value. The rear sights are designed for the full-length rifle. The shorter sight radius of the shorter barrels increases the angle of change per click movement. A friend of mine had one a few years back. I seem to recall that we figured the SOCOM had a 1.3 MOA value per click.
My notes confirm C-P's 1.3 MOA/click number. Standard M1A/M14 barrel length is 22" with a 27.25" sight radius. The SOCOM barrel is 16" with a 21.25" sight radius. If the SOCOM rear sight uses the same elevation and windage pinions as the standard rifle, each click is worth 1.3 MOA.
I guess I see two questions. What are the click:MOA ratios,? and What/how will the come-ups be different from the standard M1A?
If you know the click:MOA ratios for one barrel length, you can get them for the other barrel length by multiplying by the ratio of sight radii (assuming the rifles and iron sight hardware are the same). This would be true for both windage and elevation. As the sight radius gets shorter, each mechanical click will move the hardware the same amount but at a shorter separation, so you sweep through a larger angle per click. So the sight radius of the standard M1A goes in the numerator of the ratio of sight radiuses that you use to multiply the MOA/click values.
If you know the Threads per inch on your hardware, and sight radius, you can figure out a lot of click:MOA stuff without ever firing a shot. For instance, 38 TPI with 5 clicks per revolution on a rifle with 10/22 tech sights means__________ MOA/click for the carbine length Ruger 10/22 (which has about the same sight radius as the Scout Squad M1A). Do it for one barrel length, and then multiply by sight radius ratio to get other barrel length values of MOA:click. OK, I know you didn't ask about this, I just added it to annoy Mike. 1.05" per MOA per 100 yards. Use 1.05"/((1 MOA)×(100 yd)) or its reciprocal.
I have been shooting 147 gr PPU (Prvi Partizan) in my scout. My 300 to 400 come-up is about 4 MOA. But my eyes are horrible and getting worse, so that is all I will claim to. (Maybe that makes a little sense, if the MOA/click values are higher but also the muzzle velocity is lower. ) So the standard 3,3,4,4 for M1A should be good enough for getting on paper. Check BTP's Gun Bible for the standard come ups for 168 grains bullets. I don't know and won't hazard a guess on the SOCOM.
Good luck Jesse!
Whats the ambient temp, what is your density altitude, Humidity, etc. etc. what round are you shooting? 175? 168? ok say your shooting 175, what load, what bullet? M118, which load? there are 3 or 4 that I know of. what if its 175 Prvi? then your gonna be all over the play right from the get-go. Try to guesstimate socom vs M1a ballistic relationships, its all compounded now. What if your shooting a 1aMatch with a match rear sight. what if its an M1a standard with a hooded rear sight that has the .5moa hooded ap. How does a cold bore Socom compare to a full size?
theres literally a billion variables to all this, that is why comp shooters use data books and always work up their own dope, and only rely on what their rifle will do in their hands. trying to make predictions as if everything will remain constant as the variables change will never work. At least for for anything out past 100. If your just trying to get on paper or do the math I guess that's a different story, buts its still ballpark at best.