I have a Browning Abolt in 300 Win Mag with Boss. The Boss sweet spot chart shows no setting for 180 grain winchester loads.
I shot yesterday and got several 3 shot 3/4" groups at 100yrds. I cleaned the bore after every 6th shot. Moved to 200yrds the first group was just at 1" after firing the fouling shot. The group was about 1/2" low and 1 1/2" to the right I turned the elevation turret 1 click up and the windage 3 clicks to the left. Shot the rifle with the changes and the group went to H---. The group opened up to around a pie plate. Rings and bases are tight, boss was tight. Nothing changed except the adjustments made to change bullet strike. Moved the target back to 100 yrds and printed under an inch just a tad high and just left of center? Anyone have a answer or solution?
My first thought is you had something change in your "rest" postioning perhaps?
Sounds like shooters error for some reason, I know I have a tendency to let the rear sandback creep forward and on occassion get up against the rear of the trigger guard. Groups usually increase in size dramatically when I do that?
Think thru your form process - - I would guess thats where it may be?
I tend to agree with the above but am also curious about how long you waited between shots. I found that my A-bolt begins to drift as the barrel gets hot and I tend to shoot faster when the group isn't what I want.
The suggestions given
Thanks for the suggestions so far.
Smokey, I don't think there is a form problem checkwelds same, eye relief same, buttstock firm in shoulder pocket, left arm crossing not touching under rifle and left hand resting lightly but firmly on right bicep. The only exception that I had was placing a sandbag at the rear for 200 yrds. I will go back to the range over the weekend and try without the sand bag or with it more toward the heel.
LuJon, You might be onto something there three rounds were fired consectutively then I walked 200 yards down and back swabbed the bore fired a fouling round then 3 round group actually more of a pattern (lol).
Looks like you have a couple good places to start for sure - Good point LuJon brought up.
Since you did add the sand bag that's def a "form" change - could be each time you shot the bag settled into a diff position? One summer I took 3 diff 300wmags - A Bolt, Win 70, & an Encore and tried to work up a single load all three would group with for a hunt. I would have a great day shooting all 3 - think OK that's my load - load up some more of same and go out a diff day and sprayed all over the place. About drove me nuts!
Finally a good friend that shoots more rifles than I said its in the rear bag position - thought oh ya - sure - well, he was dead on. I really make sure the bag is fit by kinda tapping the gun into it - well maybe kinda pounding gently - and make sure its in the same spot on the butt. At 100 its not as noticeable but 200 brings out the slightest move for sure!
Keep us posted!
keep you posted
I will fill you guys in on the outcome as soon as i get back out to shoot. Hope I can get it to print as good at 200 as it does at 100.
I have shot plenty of long guns but this one is new to me and I was not sure if the boss was effecting it or if the 180 gr pills were the culprit because the sweet spot chart doesn't have a setting for them.
My 300wmag ABolt w/Boss likes the Nosler 180 partitions VERY well,
tried several powders and it was pretty flexable, ended up with IMR4350 load.
If I was going to shoot it much I would buy the non vented brake and swap out the conventional one & eliminate the blast - sure takes the recoil out but man, its not pleasant to shoot in my opinion.... trade one bad for a worse!
Hey what sweet spot setting are you using on your Boss for 180 grains. Also care to share your load?
When I get home tonight I will look up info and get back to ya !
Happy to share.....
OK, here's the scoop!
Boss set at 3.19
180 Nosler Partitions - overall cartridge length 3.29
72 grains H 4831 ( approx 3150 fps ) - ( CCI Mag Rifle Primer I believe )
Bullets could have been not seated quite as deep but I set this load up for 3 diff guns for a trip - A Bolt, Encore, & Win 70 - all three ate these well!
Browning Boss rec setting is 0,so my limited experience says the book is only a starting point - I think ea individual gun may have a wide swing of sweet spots?
Hope this gives you some places to start!
My son ( 26 ) will be hunting moose with this this fall - I pushed him to shoot a few thru it in March - he cracked off 3 at 200 yards - I thought he missed tgt through spotter - had 3 in a 1.25in group! He looked at me and said "is that enuff? Yep, I replied and we cleaned it and put it away! Smart allec kidz!