sniperlongshot
Member
i have a springfield gov't model scope calibrated out to 700 yards on my m1a, does anyone know the load specifics for a 168 grn bullet to make it fly right with the range marks on the scope
want to make my bullets fly right
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tightgroup tiger
Member
Boy, you don't want much, do ya!
That's one of the hardest things to do their is. It's so rifle specific, so their is no formula for it and no easy answer.
It's all trial and error and with good reloading skills you may come close.
Not the answer you want to hear but, it is what it is.
That's one of the hardest things to do their is. It's so rifle specific, so their is no formula for it and no easy answer.
It's all trial and error and with good reloading skills you may come close.
Not the answer you want to hear but, it is what it is.
rcmodel
Member in memoriam
Sniperlongshot is it?
Mmmmm?
The markings in the scope don't make the bullets fly right.
The shooter behind the rifle on those 700 yard 'Sniper Long Shots' do however!
Every rifle barrel is different, as will be the exact velocity you get out of every load you load or buy for it.
You are the only one who can determine the exact trajectory of any load in Your rifle.
Rest assured, whatever the marking in your scope are, they did not exactly watch the trajectory of Any load out of your rifle at 700 yards though.
rc
Mmmmm?
The markings in the scope don't make the bullets fly right.
The shooter behind the rifle on those 700 yard 'Sniper Long Shots' do however!
Every rifle barrel is different, as will be the exact velocity you get out of every load you load or buy for it.
You are the only one who can determine the exact trajectory of any load in Your rifle.
Rest assured, whatever the marking in your scope are, they did not exactly watch the trajectory of Any load out of your rifle at 700 yards though.
rc
plmitch
Member
This is interesting.......
From this link: http://www.opticstalk.com/forum_posts.asp?fid=1&tid=8790
The reticle for .308/7.62 is calibrated for a .308 caliber 180gr SP projectile fired at 2650 fps.
Using the Hornady ballistic calculator at: http://www.hornady.com/ballistics-resource/ballistics-calculator
A 180gr SP projectile with a B.C. of .475 (got this from Lyman 49, just to have some numbers to play with) leaving the barrel at 2650 FPS drops 151.4 inches at 700 yards.
A 168gr HPBT with B.C. of .462 leaving the barrel at 2650 FPS drops 153.6 inches at 700 yards, or only 2 inches different than the 180gr projectile. Upping the velocity to 2665 brings the drops to 700 yards almost exactly in line with the 180gr SP.
So.....assuming that your scope is calibrated correctly per the Springfield specs referenced above, a muzzle velocity of 2665 for your 168gr projectiles *might* match your reticle out to 700 yards. YMMV
The reticle for .308/7.62 is calibrated for a .308 caliber 180gr SP projectile fired at 2650 fps.
Using the Hornady ballistic calculator at: http://www.hornady.com/ballistics-resource/ballistics-calculator
A 180gr SP projectile with a B.C. of .475 (got this from Lyman 49, just to have some numbers to play with) leaving the barrel at 2650 FPS drops 151.4 inches at 700 yards.
A 168gr HPBT with B.C. of .462 leaving the barrel at 2650 FPS drops 153.6 inches at 700 yards, or only 2 inches different than the 180gr projectile. Upping the velocity to 2665 brings the drops to 700 yards almost exactly in line with the 180gr SP.
So.....assuming that your scope is calibrated correctly per the Springfield specs referenced above, a muzzle velocity of 2665 for your 168gr projectiles *might* match your reticle out to 700 yards. YMMV
I had one of the 4-14 scopes with the 223 reticle on a Colt 20"HBAR. In order to closely approximate the trajectory out to 300 yds, I had to load WC844 down to about 21 gr with a 55 gr FMJ. The loads were so light they wouldn't properly seat against the bolt face and pushed the primers out of a few rounds. These loads were spot on at 100, within an inch or 2 at 200 and 300, but so underpowered they were close to not cycling the gun. I did not try it any further out, but I did learn the reticle range markings were way off with any of my full power ammo.
I didn't have any access to any of the ballistic programs back in the day, and don't really trust them much now.
I later sold the scope for about what I paid new on GB, seems there is a demand for them. Had a tacticool reticle and a bubble level in the bottom.
I didn't have any access to any of the ballistic programs back in the day, and don't really trust them much now.
I later sold the scope for about what I paid new on GB, seems there is a demand for them. Had a tacticool reticle and a bubble level in the bottom.
JohnM
Member
Heh, that's a good one. I've been shooting for 65 years and I still get a lot that don't fly right.
Read rcmodel's post a couple times.
Read rcmodel's post a couple times.
Which scope?
I assume you have one with long range dots or hash marks. The truth is that almost all modern loadings are so close that it matters little. Take any loading in the 270, 30-06, 308 class with any of the common bullet weights and zero it at 100 yards. The next hash marks are going to be almost exactly right for 200 yards, 300 yards, 400 etc., depending on how many marks you have on the individual scope. The bullet drops with all of them are that close.
With the 7mm and 300 magnums zero at 200 yards and the hash marks will be pretty close at 300, 400 etc.
If you run the numbers through a ballistics program you will find slight differences. For example the 300 yard dot might actually be the zero at 290 yards with one load, and 315 with another. But unless you are shooting a gun capable of 1/2" groups at 300 yards it simply doesn't matter. The group sizes you will shoot at those ranges will be large than the differences between various loads.
If you really want to the most precision buy a scope with an adjustable turret and have it calibrated for your individual load. Leupold sells custom dials and scopes for around $350, Burris for around $250, so it isn't terribly expensive.
I assume you have one with long range dots or hash marks. The truth is that almost all modern loadings are so close that it matters little. Take any loading in the 270, 30-06, 308 class with any of the common bullet weights and zero it at 100 yards. The next hash marks are going to be almost exactly right for 200 yards, 300 yards, 400 etc., depending on how many marks you have on the individual scope. The bullet drops with all of them are that close.
With the 7mm and 300 magnums zero at 200 yards and the hash marks will be pretty close at 300, 400 etc.
If you run the numbers through a ballistics program you will find slight differences. For example the 300 yard dot might actually be the zero at 290 yards with one load, and 315 with another. But unless you are shooting a gun capable of 1/2" groups at 300 yards it simply doesn't matter. The group sizes you will shoot at those ranges will be large than the differences between various loads.
If you really want to the most precision buy a scope with an adjustable turret and have it calibrated for your individual load. Leupold sells custom dials and scopes for around $350, Burris for around $250, so it isn't terribly expensive.
45lcshooter
Member
almost sounds like OP is over powering his bullet, and it doesn't stabilize, or shooting into the wind, or cross wind.
Maybe need to find a different load for the gun. or start back at 50 yards and sight it in again.
Maybe need to find a different load for the gun. or start back at 50 yards and sight it in again.
45_auto
Member
According to the instructions with my Springfield 4x14 scope (same as the ones posted by USMAGator above)
http://www.opticstalk.com/forum_posts.asp?fid=1&tid=8790
on page 4, pargraph A:
The 180 grain SP at 2650 quoted by USMAGator is for a .30-06. I don't believe too many M1A's like the OP's shoot .30-06.
That being said, I put mine on my M1A with a $250 steel Sadlak mount and never shot it. Took the whole mess off because I didn't like the way it balanced with a big heavy scope way up in the air. Anyone looking for one that's never been used PM me with an offer!
http://www.opticstalk.com/forum_posts.asp?fid=1&tid=8790
on page 4, pargraph A:
The 180 grain SP at 2650 quoted by USMAGator is for a .30-06. I don't believe too many M1A's like the OP's shoot .30-06.
That being said, I put mine on my M1A with a $250 steel Sadlak mount and never shot it. Took the whole mess off because I didn't like the way it balanced with a big heavy scope way up in the air. Anyone looking for one that's never been used PM me with an offer!
Vern Humphrey
Member
You've got three problems here:
1. You have to have a bullet matching the weight and ballistic constant (BC) of the round the scope is calibrated for.
2. You have to match the muzzle velocity of the round the scope is calibrated for.
3. You have to do that without compromising accuracy at long range. After all, what good does it do you if your group is exactly where the hashmark says it will land, if the group is two feet wide?
1. You have to have a bullet matching the weight and ballistic constant (BC) of the round the scope is calibrated for.
2. You have to match the muzzle velocity of the round the scope is calibrated for.
3. You have to do that without compromising accuracy at long range. After all, what good does it do you if your group is exactly where the hashmark says it will land, if the group is two feet wide?
I guess it would have helped if I'd read the whole instructions.....I saw the chart and ran with that! Figured the 30-06 ballistic info would work fine since it's the same caliber projectile as the OP would be using. Good catch and thanks for the correction!
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