Adjustable muzzel brake question

**64Jeeper** · September 23rd, 2010, 07:52 PM

I'm purchasing a Winchester model 70 (300 win mag) with this adjustable muzzle brake on it, and I was wondering if anyone knows how to adjust it. I don't know if it needs adjusting or not, but if I have to adjust it, I need to learn how.

Thanks for any help!! Here is a picture of the muzzle brake:

**Tomcat088** · September 23rd, 2010, 08:32 PM

That is one of Browning's B.O.S.S. muzzle brakes. They are good muzzle brakes and you can tune the brake to shoot factory ammunition quite well. There are actually 2 different versions of the brake, one with holes and one with a solid sides. The solid sided one doesn't brake the rifle much, but it sure works well at letting you tune loads and isn't loud. I guess yours only came with the "holes"? Either way, it's a good brake, but a bit loud for my taste (as are most muzzle brakes). Here's a link for a PDF file that will help you with adjusting it. I'd print it off so that you always have it hand, or at least save a copy on your hard drive. Hope this helps.

http://media.browning.com/pdf/om/boss_02380_om_s.pdf <<B.O.S.S. instructions

**rednecksparky** · September 23rd, 2010, 09:00 PM

Originally Posted by Tomcat088

That is one of Browning's B.O.S.S. muzzle brakes. They are good muzzle brakes and you can tune the brake to shoot factory ammunition quite well. There are actually 2 different versions of the brake, one with holes and one with a solid sides. The solid sided one doesn't brake the rifle much, but it sure works well at letting you tune loads and isn't loud. I guess yours only came with the "holes"? Either way, it's a good brake, but a bit loud for my taste (as are most muzzle brakes). Here's a link for a PDF file that will help you with adjusting it. I'd print it off so that you always have it hand, or at least save a copy on your hard drive. Hope this helps.

http://media.browning.com/pdf/om/boss_02380_om_s.pdf <<B.O.S.S. instructions

A buddy of mine has a 7 mm Mag with the boss system on it and it is very accurate I mean it will drive tacks

**Qtrborecrazy** · September 24th, 2010, 08:48 AM

contact Browning for the chart that will tell you the exact setting for the bullet weight your shooting. After you get close to where it should be lets say a 3.2 for 150 grain bullet, then its a fraction either way until it tightens up with said bullet weight and or ammo. I have 2 Winchesters with the BOSS but niether are a 300 win mag. My 308 with pet load shot a 1 3/4 inch group at 350 yds and my 338 win mag is real beast at 300 yds 2 inches.

**64Jeeper** · September 24th, 2010, 11:41 AM

Thanks guys for all your help!!!

**Tomcat088** · September 24th, 2010, 07:15 PM

I didn't want you to have to call customer service for the numbers, so I found them on Browning's website. I also sent a PM about how the numbers may be different for a "non Browning rifle/barrel". I have no experience with the system installed on anything but a Browning. Either way, don't get discouraged, the system works, you just may need to do a little more tweaking. If nothing else, I found some information that may help you figure it out. If you have a chronograph, it would be a big help because it will give you can compare the velocity of the load to whatever the numbers were for the load that they have a number for. This is off of their website and pertains to adjusting the brake. http://www.browning.com/customerserv...ail.asp?ID=114.

http://www.browning.com/customerserv...ail.asp?ID=109 <<Browning "Sweet Spot" numbers