I'm fairly new to long ranger precision, but I've noticed a pattern with my rifle. When I first set up to shoot, after I've fired a fouling shot, I get really tight groups (around 1/4 moa) then it starts opening up. After I clean it and fire another fouling shot it tightens back up for 5 or so shots. Is this common, or do I need to have my gum looked at? I built a 6br from a remi 700 with a magpul pro 700 fxt chassis, factory action bolt and trigger.
Grouping issue
- Thread starter MarkO76
- Start date
Forum Boss
Administrator
Who Made the barrel? What are you using for support? Is the rear bag moving?
You should be able to easily shoot 40 rounds or more with no accuracy loss with a 6BR and a good barrel.
You should be able to easily shoot 40 rounds or more with no accuracy loss with a 6BR and a good barrel.
More info on distance, number of shots in a “group”, and shooting setup for sure please.
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Maybe they ain't heard that the social distance thing is over...
Couldn't pass it up...lol
Couldn't pass it up...lol
26" urban rifleman heavy varmint barrel, magpul pro 700 fxt chassis, BE front rest, vortex viper scope (torqued to specs). I think my rear bag is part of the problem, as I don't have a good rear bag yet so I'm using a fortune cookie. Shooting at 100 yards, first 5 rounds is consistently meassuring 0.25" after that it opens up to about 2". I know I need to try shooting with a good rear bag to see it that does the trick, because the loose sand in the rear bag moves too much and allows too much movement, but I haven't had a chance to try one to see.
Its a little hard to believe that a .25 inch gun opens up to 2moa after the first 5 rounds, but if thats really what its doing you need to look for something mechanically wrong in the system IMO. Is the barrel tight to action, muzzle brake/tuner/silencer if you're using one. Are your action, scope base, rings torqued properly?
Your rear bag can be an inconsistency issue, particularly if you haven't figured out how to make it optimal in terms of placement and consistency. But there is no reason you should start off with a small group and then have them open up, it should be "random" if you get a good group. Is there any chance you're trying so hard on that first group you're actually fatigued mentally and give up on the second or more? Are you getting off the gun taking a few minute break and coming back?
I've never had a .25 moa gun (not sure I've even had one of those) become a 1moa gun, let alone a 2moa gun unless something was wrong mechanically.
Your rear bag can be an inconsistency issue, particularly if you haven't figured out how to make it optimal in terms of placement and consistency. But there is no reason you should start off with a small group and then have them open up, it should be "random" if you get a good group. Is there any chance you're trying so hard on that first group you're actually fatigued mentally and give up on the second or more? Are you getting off the gun taking a few minute break and coming back?
I've never had a .25 moa gun (not sure I've even had one of those) become a 1moa gun, let alone a 2moa gun unless something was wrong mechanically.
What is your accuracy level on a 6mm at 100 yds? mine is a .1 to be competitive and no way would I subject a good barrel to 40 rounds. 20 is max. till accuracy will fall off.
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Forum Boss -- for the original poster's set-up, basically a PRS rifle [magpul pro 700 fxt chassis], we are talking about sub-half-MOA.
Every barrel is different, obviously, But I am really surprised you say a barrel can't go 20 past rounds. 5x5 targets is 25 rounds, add sighters, you can get to near 40 for a single relay.
FWIW, some years back we tested a 6mm Beggs in a tunnel and after a cleaning session, best accuracy did not RETURN until over 15 rounds were through the barrel. Honest. Gene was shocked. Before cleaning the groups were improving the more we shot… well past 40 rounds.
Every barrel is different obviously. With my 6BR at 600 I have gotten the best 5-shot group of the day at 40+ rounds. It will easily hold accuracy upwards of 60 rounds.
Talk to John Whidden about his Palma rifle accuracy after 100 rounds.
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This year I had two new barrels and neither one will shoot, neither will put 3 shots together and repeat it if it did. when over the gun changed scopes and mounts everything those two barrel were terrible put an old Lederer that was set back and it shoot 6 groups in a row .1 or under. It did well at the World Open in heavy gun at 16 lb 7 oz. and 20 shots max. and clean..... no way would I subject that barrel to 40 rounds without cleaning.
Point is whats the odds of getting two new barrels that don't shoot? Shit happens..... jim
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Your problem may be in the ignition and your shots opening up after cleaning may just be a coincidence.
Just a crazy thought......
Coyotefurharvester
Silver $$ Contributor
Is a velocity change happening? If velocities are consistent, check your optics system and stock. Can't imagine you have a repeatable bag system problem. As in works perfectly after each cleaning, unless you clean at the bench and move bags for cleaning and shooting?
jelenko
Gold $$ Contributor
What do the groups look like after the first 5? For example, are 4 of the 5 close together with one out? Is there anything common about the horizontal and vertical dimensions of the groups?
As NZ FClass mentioned, it would be interesting to see the first 10 shots with each one labeled with it's sequence.
What is the profile of the barrel? E.g., varmint, Sendero, etc. How many rounds on the barrel? What is the break weight of the trigger?
From my experience, there's a reasonable chance that you are doing something differently after the first few shots. While I do my accuracy testing from prone with a sling, it's not unusual to start a 20 shot string with the first 5- 8 shots within the X ring, then start getting mid to wide 10's and, gasp, a nine or two.
So, my first 5 shot 'group' would be ~ .6 MOA, then open up to 2" - but it's all me.
In my experience, as a competition barrel [~ .750" or more] heats up, the point of impact may move, but it will still group good once it's warmed up.
As NZ FClass mentioned, it would be interesting to see the first 10 shots with each one labeled with it's sequence.
What is the profile of the barrel? E.g., varmint, Sendero, etc. How many rounds on the barrel? What is the break weight of the trigger?
From my experience, there's a reasonable chance that you are doing something differently after the first few shots. While I do my accuracy testing from prone with a sling, it's not unusual to start a 20 shot string with the first 5- 8 shots within the X ring, then start getting mid to wide 10's and, gasp, a nine or two.
So, my first 5 shot 'group' would be ~ .6 MOA, then open up to 2" - but it's all me.
In my experience, as a competition barrel [~ .750" or more] heats up, the point of impact may move, but it will still group good once it's warmed up.
Well here again you are saying this and what were your group sizes at 40 rounds at 600 yds. 1" or less? or did the conditions. give you your best results ?
5x5? if you are talking group, that barrel will cleaned between each relay that would be every 5 shots for record plus sighters. In score they use a 30 so they can go the match without cleaning.
Whidden is shooting at a very large target, shooting score only, not trying to shoot 3"or less 10 shot groups. and stay in the middle of a 7" 10 ring..... jim
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as far as velocity, I do not know because I have not chronoed recently. I do move the bags and clean at the bench
Forum Boss
Administrator
Group at 600 was about 1.6“. Mostly horizontal. But in any case, I have NOT seen a decline in accuracy at 40 rounds. YMMV. Every barrel is different. But I bet if you were to talk to the top 40 F-class shooters in the United States they would not expect a significant decline in accuracy at 40 rounds, so long as barrel was in the normal useful life zone.
Jay Christopherson, who WON the F-open title at Berger SW Nationals recently, shot the entire long range cycle without cleaning at all.
But back to a 6BR shooting Varget with 105s. I see no reason to expect a notable accuracy decline up to 40 rounds. But every barrel is different. Different powders at different pressures can yield different results.
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Jay Christopherson, who WON the F-open title at Berger SW Nationals recently, shot the entire long range cycle without cleaning at all.
But back to a 6BR shooting Varget with 105s. I see no reason to expect a notable accuracy decline up to 40 rounds. But every barrel is different. Different powders at different pressures can yield different results.
.
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I had a 1996 NIB Remington 700 VS in 308 that with match full monty preprd Federal case, V-140, BR-2, and either Nos 165 BT or Sir 168 MK Moly that firing a string of ten shots the first three shots would group 1/4”, but it would then string the subsequent shots out to 1” away from the first three in to the 2:00 position with shots seven through ten. After that the shots would stay in the 2:00 position with a final 1/4” group until the barrel cooled down. Then it would start all over. I didn’t want a killer cold barrel three shot rifle, so I removed the barrel, checked the threads on the barrel and receiver which speced good and square. I shipped it to be cryo treated. Got it back and it still shot two distinct groups when heated up. Waisted $100. Ordered a Krieger 308 blank, machine it and was happy as a pig in mud after that.
I agree with you. I think a 6BR and its variants will go a lot more than 20 rounds and still shoot competitive LR BR groups. Last match, my 6 BRA managed a 2.326 5-shot group at 1000 yds on rounds 45-50.
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joshb
Gold $$ Contributor
I’d say it’s simple, from the info given. When your barrel heats up, it “moves”. You think it’s because it’s dirty so you clean it. I think that the time taken to clean your barrel allows it to cool. Then you start over.
What contour is your barrel?
Doesn’t matter, really. Your barrel moves when it gets hot. Maybe, just maybe, it’s not torqued into the action enough but that’s a long shot. Check your barrel torque and action screws.
What contour is your barrel?
Doesn’t matter, really. Your barrel moves when it gets hot. Maybe, just maybe, it’s not torqued into the action enough but that’s a long shot. Check your barrel torque and action screws.
Mine will shoot all weekend without cleaning if necessary BTW 1.6 agg at 600 is only a couple tenths off the record so great shooting Boss !j
Forum Boss — that was just one 5-shot group at 600. our club shoots combo of steel and paper at monthly fun match. I just cited that as it was last group of day, around 50 rounds.
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How many rounds are thru your barrel total? Could your barrel be shot out? Hence the velocity question also.
I can’t believe , like some others here , that your gun will shoot that well and then go to 2” groups. I would think you would realize this if it was your technique if you have a bit of experience. Something Is fishy here
I can’t believe , like some others here , that your gun will shoot that well and then go to 2” groups. I would think you would realize this if it was your technique if you have a bit of experience. Something Is fishy here
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