HELP!!! PLS identify brass marks

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colin456

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I have a browning Belgian made BAR in 300wm that is shooting way off. I bought this off CGN yearly this year. I finally got a long enough range day last weekend to try it out. I got it bore sighted and shot a nice group about 6" low. I adjusted to roughly where it should be and took another shot, this one was about 2" high and 1.5" right. I didn't just after that but shot the next shot about 6" high and 4" right. The next shot was on the same diagonal line on the very edge of the target. This continued till I stopped about 10ft over the target. I tried re adjusting and it didn't help. I went back bore sighted again and repeated the processes, same result. Changed the scope, same result, put on new rings and bases, same thing. Tried adjusting many times during the processes but never really helped. So I was pissed off after going through an expensive box of ammo and then another box and a half of cheaper stuff, new scope bases and rings and 6 hours in between the range the the range store so I gave up for the day. I went back today and same thing grouped 3, then it started rising in the 5 shots after the grouping it climbed to about 15 ft. I never thought to look at the brass till after that and noticed these marks,these are on all the fired brass.
IMG_2253.jpgIMG_2254.jpgIMG_2255.jpgIMG_2256.jpgthis is 4 piscs of the same case
I leave for moose hunting on wed, and this was going to be my moose gun... guess not. But I would like to know what the @#$% is going on. Thanks


Just took a closer look at comparing the brass/silver casings from the federal premium and it looks like 3 are clean with very tiny marks on the casings, the others look progressvly more carbon/cardon further up the brass after more shots and more marks on them. I guess this means the more shots taken the more space there is in the chamber?
 

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It cycled fine and never noticed anything wrong, the marks are on different parts of each case, not just the same mark in the same place. this was just the easiest to photograph.
 
Maybe some rust or something else on the wall of the chamber. I would think you may be able to see it or clean it somehow. To me that doesn't really give the reason for the walking of your shots. Something in the chamber would possibly cause bad groups but I wouldn't think it would cause what you are describing, at least to that magnitude.
Are you letting the rifle cool after each shot? Or at least after 2-3 shots? Large powder capacity round like the 300 wm heat up barrels very quickly. After 2-3 shots, most hunting (pencil thin) barrels will start loosing their ability to hold groups if they aren't allowed to cool. Groups can, start walking off to one side or the other, or rise like you are seeing. Although, to the extent of 10 or 15 feet is a lot.
 
This sounds very similar to a problem I had with an inherited 10/22 that suffered from a wandering point of impact. It ended up being a bent barrel (yes straight from Ruger). As the barrel started to heat up from being shot, the point of impact would become erratic and impossible to adjust to despite several iterations of scopes, rings and iron sights. This was back before i had a bore light, but the bend was very aparent when I removed the barrel. With a high intensity cartridge like a 300 wsm, the effects of barrel heating with a two piece stock may result in barrel vibration (oscillations both horizontal and vertical) that are very inconsistent. The marks on your brass would not likely result in such huge variations in point of impact.
 
Check the front sling- swivel stud, if you look at it closely the base also holds your fore-end against the gas block. It almost acts like a lock washer for the sling swivel. Check to see if there is any play in the fore-end, if there is, tighten the base and then tighten in the sling swivel. It can be a bit fiddly but you will see what I mean if it is loose. I've encountered this a number of times over the years in BAR's I've owned as well as those belonging to friends. The stringing you describe sounds the same as what I ran into. I hope this helps.
A2
 
I agree with Anglia2 about this, sounds like a forend issue. The BAR is finicky with the tightness of the forend.
Also, were you shooting off a front rest or bag?
 
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