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6mmBR Accuracy
mrbruce
Member Posts: 3,374
Any one out here have a good starting point of what can be expected accuracy wise with a 6mmBR shooting 107SMK's at 300yds.
Can I assume that anything under 1 inch is good enough to go ????
Gun control is hitting what your aiming at.
Can I assume that anything under 1 inch is good enough to go ????
Gun control is hitting what your aiming at.
Comments
For comparison, the current world record at 600 yards is 1.174" and no that isn't a typo. The website, www.6mmbr.com has an interview with James Phillips who shot that record. Good reading. I bring this up specifically because it is a worthwhile site for reading about the aspects of the 6mm BR. There is some good reloading information also.
In answer to your question, anything under 1" should be terrific. However, I think that accuracy is a system not a specific thing for only one part of the whole. To 'expect' that kind of accuracy without knowing or testing your equipment and yourself would be kind of uninformed. It takes the equipment, the cartridge, the loads, the shooter and the conditions of that particular day to achieve goals such as you refer to.
Starting out with the 6mm BR or the 6mm Dasher is certainly a good decision for intermediate or long range accuracy. There is a variety of top quality brass and bullets to choose from and powder selection is great. Barrels are easy to come by and the cartridge is mild for the shooter. It will work for the beginners as well as the experienced target shooter. Be aware that there are other bullets besides the SMK for shooting the 6mm BR especially at 300 yards. The higher BC boat tail Match bullets don't necessarily perform the best at short ranges although they can. Get a selection of bullets and settle in for some testing. The website above has a section on bullets also.
This cartridge is a pleasure to work with for doing load work ups. Accuracy loads are not hard to come by and the mild recoil makes it easy to sit at the bench and test. Full cases of appropriate powders are more conducive for accuracy with this cartridge.
Best.
Corrected the link above. Sorry.
Would a 8 twist barrel shoot a lighter bullet better at 300yds than the heavier
105 -107 grain bullets ?
My 6br XP-100 20" varmint pistol with a 14 twist loves the flat base 66 gr Fowlers, but I never figured they would work out in the 8 twist barrel.
Gun control is hitting what your aiming at.
You will get the best accuracy with a wide range of bullet weights by using a twist that's correct for the heavy ones, then use the best quality lighter-weight bullets when those are desired. You could use the lighter bullets at reduced velocities and their accuracy may well (and does) improve. This is due to a reduced rotational velocity which allows the lighter bullets to perform better. But some compromises are needed when bullet weight range is larger for a given twist rate. You get to decide which bullet you want the best accuracy with, then pick a twist to produce it.
When I shoot short range or point blank (100, 200, 300 yd) I am usually using a twist rate like 14 or even 15 to achieve the absolute minimum rotation possible to keep the bullet stable over the distance. This is supposed to get the very best accuracy from the bullet.
But I have on ocassion fired light bullets from a fast twist barrel and gotten very good accuracy. Here the problem is, with the increased rotational velocity, any little variation or flaw in the construction of the bullet will be magnified and show up as less accuracy. In the instance of the 6BR and 300 yards, I don't think that you'll have a problem shooting the lighter bullets, it's just that you won't get the best accuracy possible as if you were using a 14 twist. One of the things that you need to pay attention to is loading the highest quality bullets that you can find. The Fowlers are in that group. Jef makes some of the best, most consistant bullets in the trade. An alternative would be Berger 80 gr. Match, Fowler 80 gr. FB, or my choice, Berger 88 gr. FB Low Drag. The 88 gr. FB LD work very nicely in an 8" twist when using the same rifle in multiple competitions.
On the other hand, something else to consider would be a switch barrel rifle. I've seen some shooters using this at 300, 600 and 1,000 yard matches. They get 2 or three barrels chambered exactly the same but vary the twist rate. That way you get the best of all worlds as far as accuracy is concerned. I don't use this system because I prefer to concentrate on the loads, shooting and weather conditions rather than taking barrels off and putting barrels on. Maybe my accuracy isn't the very best possible but I'm not a top tier shooter either. Close sometimes but not the very top.
I hope that helps a little.
Best.
Thanks for putting the thought process in a higher gear.
Gun control is hitting what your aiming at.
My pleasure. The 6BR is a terrific cartridge and lots of fun to load and shoot. I know you'll enjoy it!
Let me know what you decide to do, I'm interested. I fixed the link above so that it works now...
Best.
I thought that you might appreciate an update on the 6BR in 600 yard competition. The records are awaiting confirmation but it seems that two guys are now under 1" at 600 yards! Here's the article:
MATCH NEWS--Piedmont Shooters Break 1" Mark at 600 Yards: It's not official yet, but it appears two shooters, Terry Brady and Wolf Beuhner, have shot sub-inch 5-Shot groups at 600 yards. Shooting a 6-5-284 with Clinch Rivers, Wolf Beuhner nailed a .960" group that earned him Piedmont's cash bounty for the first sub-inch group, a group that would set a new IBS World Record. Shortly thereafter, not to be outdone, Terry Brady eclipsed Wolf's mark with an amazing .860" group. Terry shot a .266"-neck standard 6BR with Berger 105gr moly-coated bullets pushed by VV N540. At the same match, Larry Isenhour set a pending new Heavy Gun score record with a 54 single-target score. Though the sub-inch groups were shot in Heavy Gun Class, Terry's 6BR and Wolf's 6.5-284 were both Light Guns smithed by Dave Tooley. Even with a 27.5" Krieger barrel and an 8-42x Nightforce, Terry's gun is only 15.5 pounds. Terry told us "Conditions were good--calm and clear--and I could see bullet holes at 42x. I just held on the 10-ring and let 'er go. Guess the wind gods were smiling on me." He says his 6BR, which has a Borden action and Borden BR stock, has grouped in the 1.4" range in 600-yard practice sessions. To put Terry's pending record in perspective, his .860" group is the equivalent of 0.1433" at 100 yards.
I was happy with my latest .936 average @ 300 yards till now 'O(
Gun control is hitting what your aiming at.
I didn't intend to make you unhappy, I just wanted to pass on some information since you expressed an interest in the 6BR.
I read the initial report on the "bounty" that the Piedmont club put on the sub- 1" group for 600 yards and laughed, thinking that it would take a bit of time before all of the vagaries of long range benchrest target shooting came together to allow this to occur. Surprise! That was a quick takedown!
Even more thought provoking is that it wasn't all THAT long ago when most folks considered a 1" group at 100 yards from a factory rifle to be perfectly acceptable. Those time have definitely changed!
Your sub- 1" groups at 300 yards are a terrific accomplishment that most shooters would take in a heart beat. Excellent shooting on your part.
Best.
I'm not unhappy it will just make me work harder to do better.
Thanks for the update, and I find myself on that site a lot lately, tons of info I really needed.
My legs don't work very well but my trigger finger is working better the more i use it.
You just wait until I get my new Three Blue MBR Shehane stock inletted for my XP action, then maybe I can cut my 6br groups at 300 yards down to 3/4 for at least a little while, then I'll be looking to find 1/2 inch groups at that distance.
I may have made a BR monster out of myself as I'm already starting to gather stuff for my 249nk 22BR project with a 26 inch 8 twist SS/SM Pac-Nor they just shipped to me last week.
My first stock 22/250 700 Varmint rifle back in the mid 60's had me pretty happy with it's 1 inch groups @ 100yds with factory ammo, and a 10X Weaver, and less than 3/4 inch most of the time with handloads.
I just never figured I could do better than that, but what did I know I was just shooting a 22 rim fire most of the time back then. [:)]
I'm in desperate need of some more custom BR rigs...they're just so darn expensive.