What do different group shapes tell me?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by esshup, Nov 2, 2008.

  1. esshup

    esshup Well-Known Member

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    I've always had this question running in the back of my mind when I'm shooting a gun that's new to me and I figure it's a good time to ask people that have a better understanding of accuracy/gunsmithing than I do.

    I shot a couple of different rifles yesterday, all in the same weather conditions (60*F, 2-4 mph winds) from the same bench and rest. One Win Model 70 .270 (great trigger) grouped 2 moa in a perfect triangle, one Rem 700 7mm-08 (horrible trigger) put 2 shots 1/2" above each other and the 3rd shot another 1/2" higher and 1" to the right of the 2nd shot. The last gun is even more puzzling. Brand new Browning A-bolt, Mountain Ti .243. After cleaning the gun, one round was shot to dirty the bore and a test group was fired - 2 shots touching, running from 2:00 to 7:00 with the 3rd shot 1/2" further away straight "down the line". After cleaning and following the instructions on the Tubbs Final Finish bullets (3 finest grits were only used) the gun shot a larger group, with the 2nd shot 1" above and 1" to the left of the first shot, and the 3rd shot 1/4" down and 1/2" to the left of the first shot. Factory ammo was used for all 3 guns, and with the Browning, only 5 shots were fired at a time during the Tubbs process to allow the barrel to cool.

    What do those group shapes tell me? I can post pictures if anybody wants.
     
  2. bigg_sexy1

    bigg_sexy1 Well-Known Member

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    Pictures are always good! I am by no means an expert, but I do not know how much weight can be put on "group shapes". There are quite a few variables to deal with when shooting groupings, especially when using factory ammo. As I'm sure you aready know your breathing, how you hold the rifle, even a heartbeat if your chest is against the bench is enough to change your shot placement. The rifle could just plain not like the ammo that you were shooting and you may need to try something else. Maybe I am way off, but there are my thoughts on it.
     

  3. MagMan

    MagMan Well-Known Member

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    I'm under the impression the horizontal strings are shooter error/body alignment and vertical stringing is seating depth/charge weight and or bedding issues.

    For your situation I'd try 5 shot groups and see what happens.

    Have any of them been properly bedded?
     
  4. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    I would say that all of the rifles would tighten up w/ hand loads. Two years ago I got my daughter her 1st rifle, a Weatherby Vanguard youth model in 7-08. Didn't have much time so we were just going to shoot factory ammo. The target that came with the rifle showed a 3/8" group. Shot the factory ammo and couldn't do better than a 6" group at 100yrds. So, in a hurry, went home and pulled all the remaining factory, prepped the brass, seated 140 Accubonds to the magazine, and ran 1grn under max load per the book. Took the rifle out the next day to the range and printed an identical target to the one that came w/ the rifle.

    I think I got a little lucky, but my point is that the factory stuff generally stinks.

    Good luck,

    Steve
     
  5. esshup

    esshup Well-Known Member

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    The Winny and Remington are a buddy's who doesn't reload. He wanted me to get it on paper for him, and he'll do the final fine tuning for the hunt. He only sent 1 box of ammo for each gun, and not knowing if he had any more I didn't want to burn up the whole box. None of the guns have had any stock work done, I lightened up the trigger on the Browning as much as I could, but at 4# 4 oz it's still too heavy for my liking. A spring kit is in the mail and should arrive tomorrow. The Model 70 had a 2# 8 oz trigger, and the Remington checked in @ 6# 10 oz. Even with the horrible trigger the Remington still shot a smaller group.

    The Browning is mine and I just wanted to run some factory fodder thru it for a baseline to see if there really is a change after firelapping the barrel. I've got some 85g Barnes TSX's loaded up for a ladder load test, .005" off of the lands. Today had 10+ mph gusting swirling winds and I didn't want to try a 300 Yd comparison in those conditions. I'll post a pic of the test when I can get it shot. The weather is supposed to turn bad on Friday, so hopefully I can get it shot before then.

    I'm puzzled at what would cause diagonal stringing of shots. I'm shooting from a pretty solid bench, with a rest that mimics the Caldwell Lead Sled. I can shoot the guns free recoil and minimize my influence on them. That's strictly for load development, when sighting in for a hunting trip, I'll use a regular front rest and bag the back of the gun, and shoot from different positions as well.
     
    Last edited: Nov 4, 2008
  6. MagMan

    MagMan Well-Known Member

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    I just worked up a load for a Savage .243 with the 85 TSX's. Factory stuff was about 1.5 MOA. The loads I threw together were .75 MOA with H4831 @ roughly 3220 fps. They weren't the fastest but they shot well.

    Make sure you double check the torque on your action screws as they may be loose. Can't guarantee anything but its worth a shot.

    If nothing else works I'd suggest bedding it.
     
  7. esshup

    esshup Well-Known Member

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    MagMan:

    That's the powder that I have loaded and ready to go. I started at the low end of the chart and stepped up in .3g increments. The action screws are 40 ip. I had the stock off to see what it weighed after I bought the gun - 1.5#. With a Leupold 3-10x40 scope, Butler Creek flip up scope caps, Leupold DD rings and steel mounts it tips the scale @ 7# even. I was hoping that it would be lighter than that, but it IS 3# lighter than my .257 Wby.
     
  8. MagMan

    MagMan Well-Known Member

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    I started them off the lands .05 as recommended. It my get better with some adjustment but I didn't want to invest that kind of time on something that might see 20 rounds per year. It seems to be a good combination.

    I can't believe what they are getting for a box of those little suckers (the .243 TSX's) not to mention the loaded Federals with the TSX's. It's ridiculous.
     
  9. esshup

    esshup Well-Known Member

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    I know what you mean. I bought 3 boxes, along with 2 boxes of 100gr. Grand Slam's and a box of 100g Sierra GameKings #1560. I figure that the prices won't be dropping, and I should have enough to last for a couple of seasons. The rifle should like at least one of those. I snagged 200 pc. of Lapua brass as well, figuring that I shouldn't have to buy any more. Once I find a load that it likes AND the verify bullet works well on deer, I'll load all the brass and be set for a while. In the .257 Wby, at under 200 Yds I really like the TSX. I had a Nosler Ballistic Tip enter a good sized doe, but not exit @ 80 Yds. She died, and I watched her run 'till she dropped, but there was no blood trail until the last 30 feet. Definately not the performance that I was expecting, but then again, she WAS pretty close for that velocity.....
     
  10. MagMan

    MagMan Well-Known Member

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    I was out shooting the 6mm06 today, working on a load. Two would practically be in the same hole and one would fly high on the first 5 groups. I kept adding powder and it eventually went away. I ended up with 58.5 grains of H1000 @ 3370 fps and a 3/8" group. I didn't load up any higher to see if it would get any better but I more than likely will. If it doesn't I'll be happy with what I have.
     
  11. skeetlee

    skeetlee Active Member

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    something that comes to my mind is paralax. Did you make sure paralax was set properly? Lee
     
  12. esshup

    esshup Well-Known Member

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    Lee:


    None of the scopes were adjustable for parallax.
     
  13. skeetlee

    skeetlee Active Member

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    Then most likely the were pre set for100 yards. Have you come up with anything yet? have you played with seating depths? Lee
     
  14. esshup

    esshup Well-Known Member

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    I've got ladder loads with Winchester Primers, Lapua brass, IMR-4831 and 85g TSX's ready to go except the wind has been gusting between 10 and 25 mph for the past week. As soon as it calms down I'll shoot (the .243). My buddy has the other 2 rifles back at his house. He was supposed to come over yesterday, but the weather was too bad. Looking at the weather, it looks like Tuesday is the day with winds between 5 & 10 mph.