Mystery solved?

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  • Last Post 05 November 2016
joeb33050 posted this 26 October 2016

I have two problems bench shooting. The first record group is generally larger than the next four, and from the sixth group on groups get bigger.

I shoot 10 groups, slow and as carefully as possible, don't clean the gun until I get home. I thought that maybe the gun needed cleaning between sets of five groups.

I shot 1 through 4, then after one shot on the top right, a target change was called. After that, I went to 5 and 6, they were bigger and had moved south., I cleaned the rifle, 2 foulers, 7 was still big and low, 8 and 9 were bigger and low. It didn't seem that cleaning helped.

It was the sun. Shooting early and slow, no sun on the barrel. After ~ 8AM, the sun shines on the barrel, barrel gets hot, groups move south and get bigger. The barrel was hot to the touch by 9AM. This only took a year to figure out. I'll confirm it next time. joe b. 

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John Alexander posted this 26 October 2016

Many of us have struggled, wondered, and speculated over the change in group size and location during a shooting session. Of course some of it is related in the normal variation in group size which is easy to underestimate. I worry a lot about consistency of my shooting which is always suspect.

I will be interested if you are able to confirm your hotter barrel theory.  These mysteries are what keep some of us coming back.

John

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gnoahhh posted this 26 October 2016

Solution: shoot at night. You're welcome.;)

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Ken Campbell Iowa posted this 26 October 2016

joeb :: more data dots that re-inforce my theory that barrel conditioning is a major factor in our mean radius variances ... ooops... grouping problems ...

you might try ...once you shoot 5 or 10 ” fast fouling shots ” .... shoot all your targets as fast as you can chamber and get a 90 per cent sight picture ... the idea is that a “hot condition ” barrel is more stable than one ” heating ” and ” cooling ” the condition ...

my 222 would throw it's first cast shot after waiting 5 minutes ... repeatable ... but then you know how pesky those 222/223 can be ...

permission granted to blame me just in case that is a bad idea ...

ken

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John Carlson posted this 27 October 2016

Or you can just come up here and shoot in January. Barrel heating won't be a problem.:shock:

John Carlson. CBA Director of Military Competition.

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mtngun posted this 31 October 2016

Good data, Joe.   Thanks for sharing. :dude:

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joeb33050 posted this 03 November 2016

Same load, same gun, sunshade in front of barrel, fan blowing on barrel.

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mtngun posted this 03 November 2016

Please help us understand your target.  What is the A, B, C thing about?

Thanks for sharing, by the way. B)

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joeb33050 posted this 03 November 2016

I had completely cleaned the barrel, which has screwed up accuracy for me in the past. A-D are the first 4 groups with the clean barrel, by D it had settled down. It took 20 shots for the gun to start shooting reasonably. I have NEVER found that cleaning a rifle barrel at any interval of shots or time has made the rifle shoot CB more accurately. I always clean after shooting, fear of corrosion. I'm still looking for the cleaning regimen that works. 1-10 are the next 10 groups in the order fired. The groups didn't get crazy, but got bigger as shots increased. I'm convinced that the sun heated the barrel in the past. The sets of 5 groups avg .97” and 1.44".

Next and last test is 65 bullets with LLA, next week maybe.  

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mtngun posted this 03 November 2016

OK, that makes sense.

Yeah, some guns will throw wild shots until they are fouled and/or warm. It's something we need to be aware for hunting rifles in particular.

Joe, what happens if you let the barrel cool completely down without cleaning? Will it shoot good when cold but fouled? I've had mixed results with cold but fouled barrels, but I wasn't really paying close attention at the time. One of these days I'll do some formal tests on cold barrels.

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John Alexander posted this 03 November 2016

I think what we have here is a good example of just how hard it is to get a handle on bore condition. When it take 15 fouling shots bore condition has to be one of the suspects along with warming.   Bore condition is a sneaky and treacherous adversary reminding me of guerrilla warfare. Sometimes overwhelming, sometimes disappearing altogether temporarily only to strike again in another way.  I don't know if we will ever fully understand it.

Early on I went a couple of competitive seasons when I didn't clean at all -- none. Groups in October, after three thousand shots, were just as good as at any time during the summer. One or two fouling shots and I was good to go.  Nothing to this cast bullet game. It made me quite arrogant toward people who cleaned at all.  That was thirty years ago and I am now humble about bore cleaning -- relativity speaking.

I once had a combinations that shot very well after a couple of shots but the first shot from a clean bore would often miss the paper -- not a good hunting load.  Joe's recent experience of requiring 15 - 20 fouling shots is almost as extreme and almost as intolerable.

I suppose the difficulty of solving this aspect of CB shooting is the reason that Eutectic can come up with a list of bullet lubes that numbers in the hundreds. Finding the perfect bullet lube has a lot of similarities with alchemy.  I am glad to see mtngun evaluating lubes for high velocity cast bullets in a systematic and logical way.  We need more such efforts.

Joe might try cleaning the bore after those first 5 good groups.  The problem with the last groups in the string may be neither warming or bore condition but just fatigue. 

John

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Wineman posted this 04 November 2016

Joe,

I'm sure Florida's humidity is brutal, but gun bore corrosion is a bit like Smallpox: pretty much non existent. From my time here on the CBA forum, I have come to believe that a well lubricated bullet, shot at a moderate velocity with modern components, a rifle really does not need down to bare metal cleaning. Stories abound of 22 LR rifles firing 1,000's of rounds and never cleaned that did not rust. There is even stories of 22 LR rifles left outside for years and everything was rusted but the bore. I think Ed Harris has the best regimen: one or two damp patches of Ed's Red after shooting and a couple of dry ones prior to shooting again. Unless you are using recycled Eastern Block or Chinese cases and primers for your cast bullets, leave the bore like a cast iron skillet: well seasoned.

Dave

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joeb33050 posted this 05 November 2016

Cleaned thus, WD40 thru bbl at range, 4-5 patches with 5-10 synthetic motor oil-my cleaner for a while now. To the range, no patches thru, 1st shot on target. A-D foulers/warmup, much better than last time, after #6 = 8 groups, = 40 shots, cleaned as above. All with shade so no sun on bbl, fan on bbl. All loads the same as last target except LLA instead of lyman moly.

It doesn't seem to be the cleaning, it looks like lyman moly works better than LLA, accuracy sorta degrades as groups are shot.

joe b.

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Ken Campbell Iowa posted this 05 November 2016

condition:: to be repetitious again, with my rimfire match rifle....about 6500 serious effort shots were with moly coated to various degrees.... i never found smaller groups....but never found classic cleaning to help. i did decide that a single dry patch each fifty shots was better . and yes an oily patch after a match .

usually 3 to 10 fouling shots were required ... interesting that the zero would sometimes start on the crosshair, then walk up and then walk back down to the crosshair, staying there as long as i shot at least every 30 seconds.

btw, zero never walked down and then back up .....what does that mean ??

notice i say zero changed, not random error. i am pretty sure ... maybe another 6000 shots would be more valid.

oh, moly...easy to get too much... i wound up only glistening every third bullet, over the factory lube.

lapua midas, eley, and the good federal. crap !! 8000 x 20 cents...i coulda bot a v-8 ( chevy .. ok, cheap chevy ) ...

i think the group zero...or center of dispersion... changes with barrel condition .

and it points toward the ” lube “....consider the mj benchers with their routine generally will put first shot into the group . if they used lube would their shots walk ??

ken edit::   my friend dan the mj bencher used dry moly plated bullets ... won a few matches, first shot in group, never cleaned all season. hmmm .

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