Why Cant i have a two shot grouping ?

Discussion in 'Ammunition & Reloading' started by Tenderribbs, Feb 23, 2013.

  1. Tenderribbs

    Tenderribbs New Member

    317
    0
    0
    Because if I can , I can shoot a 1/2 MOA all day but dadgumit , every time that third shot will make it a 1 1-2 MOA . I've tried putting another shell below my 3 shots in my magazine in hopes of helping seating the same every time no luck .heres what I'm shooting....
    1 by 7 DPMS with 16in barrel with DPMS upper and lower the ammo is u55 grain FMJ /BT and 23.5 of H-335. .
    Theory-1the heat from the barrel by the third shot is heating the barrel
    Theory 2 - I'm a bad shot
    Theory3 - go To a heavier bullet
    Theory 4 - this is what I need y'alls help with.
    Any recommendations are appreciated
     
  2. cottontop

    cottontop Guest

    Get a bolt action rifle and then you can shoot 5 shot sub MOA groups all day long.
    ct
     

  3. trip286

    trip286 New Member

    18,658
    1
    0
    Try letting the barrel cool at least five minutes between each shot and see what you can do.

    The heat from even one single shot can throw off the POI on the next shot, and the effect of heat is cumulative.

    The object of shooting groups is not to judge the combat accuracy of a rifle, but to judge the cold bore accuracy, so that an experienced cold bore shooter (such as a hunter or long range marksman who normally wouldn't engage in CQB) will know within a set margin exactly where their first cold bore shot will land.
     
    Last edited: Feb 23, 2013
  4. JTJ

    JTJ Well-Known Member Supporter

    9,678
    391
    83
    2 is a couple, 3 is a group. Bump your load up to 24.8 grains H335 and watch your overall length.
     
  5. trip286

    trip286 New Member

    18,658
    1
    0
    And ct, many of today's modern semi's will hold accuracy on a level easily comparable to modern bolt actions. Many, MANY, ARs are capable of sub MOA accuracy, yet "sub MOA" is still a marketing tag line for selling bolt action hunting rifles.

    And even then, I've rarely seen a shooter more accurate than their tool. It happens though.
     
  6. Tenderribbs

    Tenderribbs New Member

    317
    0
    0
    I'm sure we all wished our talents would exceed our weapons ability but as you say it's far and few. I have a recipee for A 77 g nosler with varget that shoots sub MOA so I'm just curious what would cause this phenomenon . Thanks
     
  7. Tenderribbs

    Tenderribbs New Member

    317
    0
    0
    That makes sense so your saying the heat does affect the bullet the third shot?
     
  8. trip286

    trip286 New Member

    18,658
    1
    0
    Just to point out, I wasn't taking a dig at you or your rifle. That was more directed towards the idea that "this is better than that" kind of rifle.
     
  9. locutus

    locutus Well-Known Member Supporter

    16,638
    849
    113
    If you want to get an idea of the true accuracy of your rifle, at a minimum, shoot 5 groups of 5 shots and average them.

    An even better indicator, and the one used for high dollar SuperMatch guns is 10 groups of 10 shots.

    3 shot groups are all you need for big game hunting loads, but to work up long range target or varmint loads, 5 or 10 shot groups will tell you much more about your load and your rifle.
     
  10. trip286

    trip286 New Member

    18,658
    1
    0
    I'm saying it can, and it's possible that it can affect it quite significantly. One shot will warm the barrel. If the second shot is fired before it cools, then a third is fired in the same interval, then the third shot could be leaving from a bore that is twice as warm as the second shot, and 4 times as warm as the first.

    Just an example, to try and put it into numbers. These aren't accurate numbers, and I've conducted no study to get exact figures or percentages, but with many hours behind machine guns, semis, and bolt actions, I'll stand behind thus theory of mine until or unless someone proves me wrong beyond any shadow of a doubt...

    Let's say your first shot is fired from a bore at an ambient temp of 70 degrees. That shot hits exactly where you meant it to, but it raises the temp of the bore by 5 degrees.

    Now your second shot is fired from a 75 degree barrel. It is only slightly off from the first POI, but if you fire it before the heat from the first shot dissipates, you may have just raised the temp of your barrel to 85 degrees. Twice the increase from the first shot, because the effects of friction (which is what's causing the heat) accumulate over continued application.

    Let's relate that to inches, for the sake of simplicity. Again, I'm making up theoretical numbers for illustrative purposes.

    If your second shot is fired from a note that's five degrees warmer than the first shot, it may be off a half inch. If the third is fired from a bore 10 degrees warmer than the second, this translates into FIFTEEN degrees warmer than the first, and it may be off your mark by upwards of an inch and a half! And in a different direction!

    This is why thicker profile barrels are more popular for marksmanship competitions. The greater surface area dissipates heat faster and the profile adds rigidity.
     
  11. JTJ

    JTJ Well-Known Member Supporter

    9,678
    391
    83
    I have a DPMS A4 and it will shoot 5 shot moa or better with hand loads. The 2 loads I worked up are 24.8gr H335 and 25.8gr Varget. Both with Hornady 55 gr fmj. The load you are using was not consistent. The only mod to mine was I replaced the front sight with a quad gas block. The H335 load was delivering .5 moa in a Savage 10.
     
  12. Tenderribbs

    Tenderribbs New Member

    317
    0
    0
    I Do , my fav is my Sake 243, . 1/2 MOA all day and my Thompson 270 making a bolt like those to shoot 1 MOA is easy making a Ar15 is not as simple that why I like em the challenge peacem
     
  13. cottontop

    cottontop Guest

    Moa?


    You may be right. I have read about and heard of such accuracy from these semi autos, but I have never personally seen it. I shoot at the local range every Friday morning. I see many many semi autos and many many of their targets. I have yet to see one MOA group. But then again, the semi auto guys where I shoot are happy if they can keep their shots in a 10" circle, and the more shots the merrier for them. They don't care about shooting tight groups or about reloading for accuracy. If they reload at all it is for quantity not quality. With a lot of tweaking and patience, I suppose sub MOA accuracy is possible with one of those semi autos. But, I seriously doubt it can be repeated often. But then again, both of my Ruger #1's (one of them custom) shoot sub MOA consistantly, so anything is possible. BTW, MOA is a measurement, not a marketing tool.
     
  14. willfully armed

    willfully armed New Member

    2,096
    1
    0
    Number 1- you don't have a target rifle. That's a "service rifle".

    I built a "target" AR about 5 years ago. RRA receiver set, bolt and LPK with 2 stage match trigger. LMT SOPMOD stock, yhm free float 4 rail. Put a cheap Vulcan 16" .970 stainless fluted barrel. And a cheap 12x Bushnell Scope.

    It would put 62gr Wolf into .400 groups at 100 yards.
    My new barrel is a WOA 18" SPR. It runs MK262 at .375-.400 groups all day long.

    Long story short, your gun isn't really setup to do what you're expecting. I'm assuming here, but maybe you don't have a great technique for precision shooting yet either.

    Breathing control, form, trigger control... It takes practice.
     
  15. Tenderribbs

    Tenderribbs New Member

    317
    0
    0
    Well I may not be the best shot but with my Five Ar15's I can shoot sub with everyone. Now that's with my hand loads so you don't have To have a target rifle to shoot sub MOA . a service rifle is just more picky with the loads and doesn't have the number and range of sub MOA loads that a target rifle has . Since I shoot sub all the time I can't blame it on my skills . Back to my question why on majority of my reloads does it shoot two side by side and the third off ? I think it's been answered tho. Heat . Thanks peace
     
  16. Sniper03

    Sniper03 Supporting Member Supporter

    7,729
    218
    63
    Ribbs,

    Is the third shot higher or ?????
    The heat factor is a very good possibility. We had a sniper rifle years ago that would literally drill em at 100 yards. But if we fired the fourth round it would be an inch off all the others sub 1 MOA group!
    It seems you have good ammunition or you would not be getting the 1/2 MOA out of the first two. Also another factor is the wind. A slight gust that may not be felt at the firepoint but is possible down range. That can certainly effect the 223/5.56 at 100 yards. But as one of the guys mentioned. I would allow the gun to cool for a few minutes between shots!
    AND DO NOT LOOK AT THE BULLET IMPACTS ON THE TARGET! THE AIM POINT ONLY! If you have a good rest if you think that is bothering you turn the scope power down for example. So you can more focus on your aim point and not be distracted by the bullet holes in the target. We are all human and it happens to be mentaly trying much harder for that 3rd or 5th shot since you know you have a H of a group going for you! Been there and done that! ;) Of course with iron sights sun on the front sight post can change things also from one shot to another.

    Some pointers in Order:
    Good Rest
    Aiming Consideration
    Heat Consideration
    Wind Consideration
    Light Consideration

    03
     
  17. willfully armed

    willfully armed New Member

    2,096
    1
    0
    Shooting reloads doesn't automatically mean you're going to get good groups

    Bug hole groups require extensive load development.

    Bullet weight
    Seating depth
    leade length
    Powder
    Charge weight
    Primers
    Good dies.

    You can develop a load for weeks and only get a 3/4-1" group, just to change primers and have them shrink to .375"

    Seating from .010-.015 off the lands can make a huge difference.

    I'm not doubting your ability, just providing possible answers