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Posted: 3/25/2017 3:09:22 AM EDT
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anyone else have this issue? Shooting at 100 yards, it seems pretty extreme with a spread of about 4" in the vertical. Horizontally I am staying within +/- .5" as I go up and down the target.
I used to shoot 100 yards and farther quite often, but last several years I have gotten busy and rarely do it seriously. This week got to shoot off a bench and am disappointed. Not much experience with this gun, I ran it suppressed with an SDN-6. I did dismount the barrel to install the AAC mount and thought I followed the correct torquing instructions but maybe I messed something up. I used to be a pretty decent shot. Will get the scope adjusted so I am dropping rounds right in the target center with about 1.5" grouping (3-4 shot groups). The gun then cools down during breaks and its way off again when I start. |
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Test the scope on a different rifle.
My 17S busted the erector assembly on a new Vortex in twenty shots. I shot five 5-shot groups after mounting the scope to spec with a NIST calibrated torque driver (Bobro dual-lever mount. Vortex scope). Zero'd in the first five-shot group. Shot 4 more 5-shot groups. 4th group started to open up. The 5th group had the vertical dispersion you describe. Tried adjusting the elevation and realized the elevation knob no longer did anything, turning it from one end all the way to the other. Good thing Vortex has an excellent warranty. Max |
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I thought about the scope breaking, but would you have only a vertical issue in such a scenario? Horizontally I am tracking pretty true. I don't have any other rail mounted guns in 308. If broken, a 556 gun might not have enough recoil to duplicate the issue. Somehow, that part of the erector assembly was knocked loose in just the first twenty shots on the 17S. So far, a Razor HD Gen II 4.5-27x seems to be holding up, but there are threads floating around about the 17S/SCAR-H killing scopes. Prevailing theory is that scopes are built for the rearward force of recoil (even up to .50BMG), but some can't handle the forward forces created by the heavy 17S bolt carrier group slamming forward. Max |
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OK, never heard of the 17S breaking a Trijicon before.
Max |
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OK, never heard of the 17S breaking a Trijicon before. Max |
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Are you using the same ammo with each shot string? Ive had issues with massive poa changes while changing ammo. But first shot from the last time I had zero'd informally was way high, I immediately got a bad feeling. And then after rifle cooled during a cease fire, it was off a couple inches from prior group. And this is all within a narrow range horizontally. Plus its not like its throwing shots everywhere, even after a big shift it will settle down and start grouping within 1.5 MOA. I just need to get back to the range but this potentially really sucks. If this is how its going to be, I am going to go to an Aimpoint and put my extra magnifier mount on it. I was really hoping to have a decent longer range semi auto with a can. But as its shaping up, even my M1A is more consistent. |
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I just bought this TA11E-g lightly used on the EE two weeks ago. I do not think it is broken, I think that's all me. That was at 100 yards. I am no sniper and I think my breathing has something g to do with it. Max |
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I think it is me. The next time I go to the range I will be with a better shooter than I and let him take a crack at it. I will see what it looks like then. /btw I really love this gun. What a jewel. All I need now is a Super Scar trigger. Max |
| did you seat the prism after each adjustment? |
| What ammo are you using? Match ammo? I have seen this with ammo that is loaded to varying degrees of powder. A hotter load hits high and a lighter load hits lower all on the same vertical axis. I have this quite often when shooting ZQI 308 and you can feel the difference in each load with the recoil and brass ejection pattern. I was spotting my neighbor shooting the same ammo in his LaRue tOBR and when the brass went forward on ejection the round hit higher because it was a hotter load and when the brass went backward he hit lower because the load was lighter. I got to the point by watching his brass I could ask him was that high or low depending on the ejection. The only way to get around it is use match ammo or handload your own setup. Commercial plinking ball ammo is notorious for this. Not a problem with the rifle but with the ammo. |
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Are you using the same ammo with each shot string? Ive had issues with massive poa changes while changing ammo. WIN White box- Vertical stringing. PNW Defense- head sized shotgun groups GemTech 187 sub blems- 2 inch groups. |
| Many moons ago when 17s first came out, there were reports of 17s breaking scopes like the FAL use to, due to the unusual recoil impulse when the rifle is fired. Just reporting what was said. (I never had any problems with the FAL and scopes, but I didn't shoot 1000's or rounds either.) |
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I finally got it out again. I ran out of time to do as much testing as I would have liked. All shooting done with the SDN-6 I had on before.
But here is what I got with Federal 150gr PowerShok which is what I mostly used before. First shot was close to 2" high from what would be the eventual group. Second shot was 1" high from the group. 4 of the next five shots clustered pretty tight in one group. There was one flyer maybe an 1" lower than the group. I ran the gun hotter with 5 rounds of Winchester white box which resulted in a pretty sloppy group of 3-4". Ran 5 rounds of Portuguese to keep on heating up the gun, about a 2" group. Went downrange to tape up the target and ran 5 rounds of the Federal again. It pretty much landed in the same impact zone as rounds 3 through 7, maybe shifted to the right by 1/2 inch. About 1.5" group with a flyer. I then went to another lane to try out my G19 after making some mods to it. Went downrange again to tape targets. Poured some water over the can and barrel in an attempt to cool it down further, but it was still lukewarm. I assume warmer under the handguards. Ran another 5 rounds of Federal and they landed in the same impact zone as the prior two Federal groups. Again 1.5" group with a flyer. Range was closing and I only had time to try another 5 rounds of Portuguese, this turned in the most impressive group given it was milspec ammo, a 1.5" group. It impacted in the same area as the prior 5 round grouping of Port. So from a stone cold gun from round 1 to round 7, it was close to a 4" dispersion vertically. Unfortunately I didn't have time to repeat the exercise with a completely cooled gun. Other observation, the accuracy is nothing to write home about, especially as the rifle has a geissele trigger. I get that I wasn't using top notch match ammo, but these loads shoots better through my M1A Loaded model. Next time to the range I will try out some M118 I have been hoarding for a special occasion. |
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I finally got it out again. I ran out of time to do as much testing as I would have liked. All shooting done with the SDN-6 I had on before. But here is what I got with Federal 150gr PowerShok which is what I mostly used before. First shot was close to 2" high from what would be the eventual group. Second shot was 1" high from the group. 4 of the next five shots clustered pretty tight in one group. There was one flyer maybe an 1" lower than the group. I ran the gun hotter with 5 rounds of Winchester white box which resulted in a pretty sloppy group of 3-4". Ran 5 rounds of Portuguese to keep on heating up the gun, about a 2" group. Went downrange to tape up the target and ran 5 rounds of the Federal again. It pretty much landed in the same impact zone as rounds 3 through 7, maybe shifted to the right by 1/2 inch. About 1.5" group with a flyer. I then went to another lane to try out my G19 after making some mods to it. Went downrange again to tape targets. Poured some water over the can and barrel in an attempt to cool it down further, but it was still lukewarm. I assume warmer under the handguards. Ran another 5 rounds of Federal and they landed in the same impact zone as the prior two Federal groups. Again 1.5" group with a flyer. Range was closing and I only had time to try another 5 rounds of Portuguese, this turned in the most impressive group given it was milspec ammo, a 1.5" group. It impacted in the same area as the prior 5 round grouping of Port. So from a stone cold gun from round 1 to round 7, it was close to a 4" dispersion vertically. Unfortunately I didn't have time to repeat the exercise with a completely cooled gun. Other observation, the accuracy is nothing to write home about, especially as the rifle has a geissele trigger. I get that I wasn't using top notch match ammo, but these loads shoots better through my M1A Loaded model. Next time to the range I will try out some M118 I have been hoarding for a special occasion. Here is the easiest way to explain what is happening. You have 5 rounds each leaving the barrel at different speeds. 2600 2675 2540 2590 2650 They will all have different impacts because they are all taking different trajectories. This is why you cannot develop a dope sheet for loads that are not very consistent. I know the a 168gr FGMM will have a pretty close speed each time it leaves the muzzle but a surplus round can be all over the place and will have stringing like you are seeing. It gets worse with these loads as the distance increases. The only other possible issue could be that the muzzle device has changed the harmonics of the barrel you should remove it and shoot no muzzle device and see if your issue goes away. If you are worried about the barrel torquing take it down and retorque everything to spec. |
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My focus was on the Federal 150gr PowerShok, I fired the other cheaper loads mostly to get the barrel hot to see if the groups wandered once the barrel got fairly hot.
I noted their respective group sizes just out of curiosity. The groups fired with Federal 150gr PowerShok pretty much ended up at the same zone on the target with the exception of the very first two rounds fired out of a stone cold barrel. I fired 17 rounds of the Federal, going from stone cold (7 shots) to fairly hot (5 shots) and back to lukewarm (5 shots). Only the first two rounds where out of the impact area where rounds 3 to 17 landed. |
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None of the ammo in question performs well when shooting for groups... it's minute of deer vitals... nothing wrong with that, just don't expect moa.
If you want to really test your scar for accuracy try some top shelf 125gr -155gr match loads... you'll get clover leafs if your a good shooter and your optic isn't crap. |
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