DDustin Posted November 7, 2013 Share Posted November 7, 2013 Well a little back ground. This is an ACR that I use for matches. Prior to the work I had done, it shot consistent 1 MOA - 1.5 MOA groups and the barrel only had around 200 rounds max. I had the barrel cut down to 14.5 with a pinned and welded brake, re-contoured and fluted. It ended up being undergassed and had cycling issues so I sent it back and had the gas port opened up to .625 and also had the bolt lightened. I got it in just in time for a match and went to zero at 200yrds using a Vortex Razor HDII 1-6x with DRT 55gr frangible match ammo that's sold at the match. I didn't get any on the paper. I moved it in to 100yrds and ended up with 2"-3" groups. After a while the 100yrd groups went down to a better size so I moved it back out and ended up with 12"-15"groups. Out of 5 shots only 3 were on the paper, which is still better than not even being on the cardboard before. What would cause such a variation from 100-200yrs? Does it seem more likely to be the bullet or the barrel? I will be doing more testing in a week or so. This is the 12" target stapled to standard cardboard silhouette. I couldn't scan the whole target. some groups were on the corner or the target stapled below it. The 200yrd group is marked in green/black, the arrow is pointing to the 3rd shot which is on the cardboard next to the target. Those are the only 3 out of the 5 shot group I found. All other shots are 3 shot groups at 100yrds. I later shot a 2.5in group at 200yrds from my Rock River AR with 62gr handloads to make sure it wasn't me. ETA: This is also my first time using this ammo. Link to comment Share on other sites More sharing options...
Steve RA Posted November 7, 2013 Share Posted November 7, 2013 I'd try it with some other ammunition and see how that works. Link to comment Share on other sites More sharing options...
DDustin Posted November 7, 2013 Author Share Posted November 7, 2013 I will hopefully this weekend. Is it possible for the group to spread out so fast without any key holing or signs of losing stability? Link to comment Share on other sites More sharing options...
Steve RA Posted November 7, 2013 Share Posted November 7, 2013 If the bullet is out of balance, yes. Could be whatever is frangible isn't distributed evenly in jacket or the jacket could be thicker on one side than the other. Easiest and cheapest way to determine what it - problem - is would be to try several different loads, bullet weights, etc. Fire a three shot group with each, should be able to get a good idea from that approach. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted November 7, 2013 Share Posted November 7, 2013 Easiest way to determine what problem is - try several different loads, . Fire a three shot group with each, +1. Most likely the bullet - seems to be falling apart between 100 and 200 yards, but try any other type ammo and see if problem persists. Link to comment Share on other sites More sharing options...
kneelingatlas Posted November 7, 2013 Share Posted November 7, 2013 Did any other shooters complain about the match ammo? It seems to me like the problem is the new crown on your barrel, but obviously more testing is needed. Link to comment Share on other sites More sharing options...
DDustin Posted November 7, 2013 Author Share Posted November 7, 2013 (edited) By falling apart do you mean physically or just it's stability? The crown is what I was worried about too but how would I check the crown when the brake is pinned and welded? When I first got the barrel back it did have some build up, I'm assuming machining dust, filling in the rifling near the throat of the barrel. I had to really scrub it to get the rifling to be visible again. Is it possible that the gap between the brake and the barrel crown is filled up? Any way to clean that out? I didn't hear anything about it from anyone else but I also didn't see anyone with it to talk to. Most people brought their own ammo. Of the reviews online, it's a decent hunting round and no one seems to test past 100 yards in anything I've read. Sunday the weather for the range says it's sunny with 6mph winds as opposed to 15mph and cloudy on Saturday, so I'm taking a led sled to rule me out(first time with that) and a couple types of ammo and going over it all. Thanks for all the replies so far. Edited November 7, 2013 by DDustin Link to comment Share on other sites More sharing options...
Steve RA Posted November 7, 2013 Share Posted November 7, 2013 Look forward to hearing of the results. Link to comment Share on other sites More sharing options...
Croomrider Posted November 8, 2013 Share Posted November 8, 2013 The crown is what I was worried about too but how would I check the crown when the brake is pinned and welded? The "welded part is what concerns me. Just turning a barrel can relive stresses and cause the diameter of the bore to change. You would be hard pressed to ever get me to have one of my target barrels welded on, especially near the muzzle. Who did the work? Are they used to doing work for people who use their guns in competition? Your average tactical timmy might never notice a problem! Mike Link to comment Share on other sites More sharing options...
Flexmoney Posted November 8, 2013 Share Posted November 8, 2013 You have a lot of new and unknown variables there. The one you can work with easily is the ammo. I'd try a variety and get a baseline for them. This will give you ammo data to compare with. Plus, it can serve as a control if/when you make any adjustments to the hardware. Link to comment Share on other sites More sharing options...
DDustin Posted November 8, 2013 Author Share Posted November 8, 2013 (edited) The crown is what I was worried about too but how would I check the crown when the brake is pinned and welded? The "welded part is what concerns me. Just turning a barrel can relive stresses and cause the diameter of the bore to change. You would be hard pressed to ever get me to have one of my target barrels welded on, especially near the muzzle. Who did the work? Are they used to doing work for people who use their guns in competition? Your average tactical timmy might never notice a problem! Mike I don't want to use his name until I get to the bottom of this. But he's pretty well known, he's done a lot with KAC and works with Wilson Combat now. He's done a lot including designing a new adjustable gas regulator for the ACR. He definitely seems to have earned his reputation. Before I had the work done I expressed those concerns and he explained how his process prevents losing accuracy and is safe. I didn't really understand since I'm just getting into barrels and gunsmithing but it made me feel better since he didn't just deny the problems possible, he had an actual solution. Edited November 8, 2013 by DDustin Link to comment Share on other sites More sharing options...
Powder Finger Posted November 8, 2013 Share Posted November 8, 2013 The crown is what I was worried about too but how would I check the crown when the brake is pinned and welded? The "welded part is what concerns me. Just turning a barrel can relive stresses and cause the diameter of the bore to change. You would be hard pressed to ever get me to have one of my target barrels welded on, especially near the muzzle. Who did the work? Are they used to doing work for people who use their guns in competition? Your average tactical timmy might never notice a problem! Mike I don't think the barrel it self gets welded on. the brake and barrel are drilled(part way into the barrel) then the pin is installed and the end of the pin is tig welded to the brake. Link to comment Share on other sites More sharing options...
Croomrider Posted November 8, 2013 Share Posted November 8, 2013 The crown is what I was worried about too but how would I check the crown when the brake is pinned and welded? The "welded part is what concerns me. Just turning a barrel can relive stresses and cause the diameter of the bore to change. You would be hard pressed to ever get me to have one of my target barrels welded on, especially near the muzzle. Who did the work? Are they used to doing work for people who use their guns in competition? Your average tactical timmy might never notice a problem! Mike I don't think the barrel it self gets welded on.the brake and barrel are drilled(part way into the barrel) then the pin is installed and the end of the pin is tig welded to the brake. Yeah, if that's the case, the welding may not be a problem. From the OP's description, it sounds like the guy may know what he's doing. Maybe it's just the ammo! Mike Link to comment Share on other sites More sharing options...
DDustin Posted November 8, 2013 Author Share Posted November 8, 2013 I'm confident in the smith but things happen, and when they happen they happen to me lol. I hope it is the ammo though. Link to comment Share on other sites More sharing options...
DDustin Posted November 12, 2013 Author Share Posted November 12, 2013 I was able to do some more testing with some AE 55gr hpbt yesterday. It was a lot better but still not what I'm used to. The 100yd groups were between 1"-2". The 200 yrd groups seemed to be consistently around 5" give or take. I'll post pictures later today. It was getting dark so I didn't a chance to test any hand loads, just re-zero. I also did it all from a pretty crappy position instead of the lead sled. I'll be retesting this weekend with better light and more time.Is this amount of spread between 100 and 200 yards normal? I was always told to expect +1" every 100yrds and that's about what I got in my old RRA AR. That was a base model rifle and got 1" or less groups at 100yrds and 3" max at 200 yrds. Not to mention my old issued M16 and M4 would hit out to 500 yards. If the group gets any bigger I don't see how 300 yards would be possible let alone 500-600. I tried to hit some 400 yard 8"? steel swingers and got nothing. Link to comment Share on other sites More sharing options...
DDustin Posted November 12, 2013 Author Share Posted November 12, 2013 Here's the new 200 yard zero target with AE 55gr HPBT. Like I said the 100 yard target ranged between 1"-2". Link to comment Share on other sites More sharing options...
Steve RA Posted November 12, 2013 Share Posted November 12, 2013 It's getting better, but, think you need to try more variations of ammunition. One isn't really telling you the whole story, although it's much better than the original trial. Link to comment Share on other sites More sharing options...
Croomrider Posted November 26, 2013 Share Posted November 26, 2013 I would not be happy with that, but I'm not familiar with that ammo. You said they were HPBT bullets, which are generally much better quality than normal 55gr BT ball type ammo. You should be able to get performance equal to what you did in the past, or something is not right! Mike Link to comment Share on other sites More sharing options...
DDustin Posted November 27, 2013 Author Share Posted November 27, 2013 They were HPBT but they were lead free frangible bullets. Those were the first target. The second target was American Eagle 55gr FMJBT. Niether group is where it used to be but I'd still like to do some more tests under better conditions. Hopfully in a couple weeks I can do that. Link to comment Share on other sites More sharing options...
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