Page 1 of 2 12 LastLast
Results 1 to 10 of 18
  1. #1
    Join Date
    Sep 2009
    Posts
    8,754

    Default MOA point of impact 26” vs 18”

    If anyone knows the MOA drop for 7.62 x 51 out of an 18” barrel at 1000 yards let me know. I’ve been searching for a week and can’t find it anywhere. I’m guessing since with my 26” pss barrel and 168 sierras, it about 28 Moa, it’s probably around 34-36 Moa. If someone out there knows I would like to know.
    Nothing says Fuck You like a shotgun.....

  2. #2
    Join Date
    Feb 2009
    Location
    Colorado
    Posts
    8,806
    It will be more a function of velocity and quality of the barrel than the length. Also 168s at 1000 aren't supersonic anymore. It drops off around 800 yards and causes instability in the projectile when it goes transsonic. which effects accuracy. 175s will stay super sonic at 1000.
    Geek Warlord
    Dungeons & Dragons & Deadlifts

    Muscle Wizard Casts: Fist


    CRG-1 DPS
    CRG-2 CRG x 2
    SGF-1 Shotgun Gunfighting
    Trauma care under fire
    Spetsnaz Sniper
    HRO-5 Terrorist & Active Shooter Interdiction
    HRO-6 CQB: Fighting in Structures
    CRG-4 Force on Force
    HRO-5 Terrorist & Active Shooter Interdiction - 3 day
    TWOTU edition
    Trauma Medicine for the CCW Operator
    Pistol Ground Fighting (Taint Shooting Progressions)

    TWOTU since May 2015

  3. #3
    Join Date
    Aug 2005
    Posts
    2,940
    To get accurate dope, you're going to need an accurate measurement of velocity for both barrel lengths in YOUR rifles. That said, assuming a ballpark estimate of around ~2650fps from a 26" barrel and ~2500 fps from an 18" and a 168gr .30 caliber bullet with a BC of .462 and 100yd zero, I plugged the numbers into the ShootersCalculator.com ballistic calculator and got the results in the chart below. The difference is not that big.

    308 Calculation.png
    We don't have the Second Amendment because Bambi is coming.
    "Zen? Meh! Who needs it? All that effort to achieve nothingness and what do you got? Bupkis!"

  4. #4
    Join Date
    Sep 2009
    Posts
    8,754
    Cool man, I my guess was close. I have the availability of a range that I used to frequent that is a 1000 yard range. I know that it’s not a whole lot, but I wanted to start somewhere mentally with something.
    Nothing says Fuck You like a shotgun.....

  5. #5
    Join Date
    Sep 2009
    Posts
    8,754
    Quote Originally Posted by Dorkface View Post
    It will be more a function of velocity and quality of the barrel than the length. Also 168s at 1000 aren't supersonic anymore. It drops off around 800 yards and causes instability in the projectile when it goes transsonic. which effects accuracy. 175s will stay super sonic at 1000.
    That’s all speculative. I still used to group Moa or better with 168 grain bullets at 1000. 175 grain hits harder though, drop I think between those two is around 2 Moa. 168 grains actually group better out of most guns. Been my experience, but I’m sure others will disagree. Also I heard of a lot of kills beyond 1000 with 308, not saying that’s what I would use. But it will kill accurately further then you think.
    Nothing says Fuck You like a shotgun.....

  6. #6
    Join Date
    May 2006
    Location
    NWFL
    Posts
    16,581
    Quote Originally Posted by chad newton View Post
    That’s all speculative. I still used to group Moa or better with 168 grain bullets at 1000. 175 grain hits harder though, drop I think between those two is around 2 Moa. 168 grains actually group better out of most guns. Been my experience, but I’m sure others will disagree. Also I heard of a lot of kills beyond 1000 with 308, not saying that’s what I would use. But it will kill accurately further then you think.
    For which wt shoots better- Might that not also depend on barrel twist and details of chamber dimensions. I see many .308's are 1 in 12 for twist. The ancient military twist for the 30-06 was 1 in 10 twist IIRC.

    Below are just some comments on chambers that is way beyond my understanding, but is relevant for those setting up rifles for long range shooting. All of the below have a bearing on velocity that is a factor in trajectory and drop along with wind resistance being due to projectile shape.

    What is the difference between SPC and SPCll?
    SPCII has a longer freebore/throat/leade. This lowers chamber pressure by allowing the bullet to get moving before being stopped by the rifling. Therefore you can shoot higher pressure loads safely in the SPCII chamber. All iterations of SPCII are longer than SAAMI spec chamber, ARP chamber, PT&G chamber, etc. There is no difference in case dimensions, it simply allows hand loaders to run higher pressures. Personally, I run 110gr BTHP(typo?) at 2800 fps, can't do that in a spc chamber.
    SPC has a .050 freebore
    SPCII has .100 freebore
    https://68forums.com/forums/showthre...ade-and-throat


    Last edited by barnetmill; 01-19-2020 at 09:57 AM.

  7. #7
    Join Date
    Sep 2009
    Posts
    8,754
    For sure, have you ever reloaded match rifle ammo before? The biggest gain you can get grouping size for a rifle is to set the bullet as tight to the lands as you can without touching it. Basically You size a piece of bass, put a bullet in by hand, loosen it up enough so the bullet has some resistance, and chamber it. This is the crude way of finding out your bullet depth without a gauge. Then what I did(from recommendations of a competition shooter) was take the die down quarter increments until you get the best grouping. Just that simple step will shrink group sizes in half. What I was told is that factory barrels are set to that deeper standards because then there would be no chance for overpressure to take place, liability reasons. Even “match” barrels you still have to figure in bullet depth. Even with match ammo, say out of a LaRue obr, if you are able to obtain 1 to 1/2 Moa. Handloads with the right bullet depth would get you under half Moa or even 1/4. I was able to get 1/4 Moa out of a factory pss barrel in both 308 and 300 ultra mag.


    What my conclusion was after all of the fine tuning of my guns wasn’t fun anymore, was that 1 Moa out of a long range gun is good enough. If you have your shit together you can hit a man size target at 1000 yards all day long, and not have to work very hard at it.
    Nothing says Fuck You like a shotgun.....

  8. #8
    Join Date
    May 2006
    Location
    NWFL
    Posts
    16,581
    I know a little bit about reloading also and yes one was supposed to seat out the bullet to almost touching the leade.
    The Weatherby rifles used to be known for having high velocity and a lot of free bore, but could get one MOA that at one time was the gold standard. Fact is an MOA with my shooting abilities when not using a rest is more than sufficient.

  9. #9
    Join Date
    Sep 2009
    Posts
    8,754
    Quote Originally Posted by barnetmill View Post
    I know a little bit about reloading also and yes one was supposed to seat out the bullet to almost touching the leade.
    The Weatherby rifles used to be known for having high velocity and a lot of free bore, but could get one MOA that at one time was the gold standard. Fact is an MOA with my shooting abilities when not using a rest is more than sufficient.
    You what I think I’m going to do, is savage is making their version of the ar 10. I know they have good barrels, and I have not been able to find anything wrong with the long range version ar 10. Plus they take Magpul mags, I like that idea. This is all about my DMR setup I want to do. Give em a try on this setup.... Thanks bro, I appreciate your knowledge...
    Nothing says Fuck You like a shotgun.....

  10. #10
    Join Date
    Sep 2009
    Posts
    8,754
    Nothing says Fuck You like a shotgun.....

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •