6mmBR

[Nick 53]

Now I have my variation back just after 8 days. I want to look for a new rifle ! There always seems a million questions ! 

Now reading the various forums What is deemed a suitable rifle? Rifle model? Twist ? Barrel Length? Dual port ? Not quite sure what it means.

i am sure I can’t afford full blown built rifle by gun smith, not unless I rob a bank! So are there rifles out there on a shelf or rack that you can buy?

 Cheers Nick 

[No i deer]

You have a calibre in mind.if you enlighten us on that we maybe able to help you decide which route to take

[Nick 53]

Silly me on ticket 6mmBR 

[No i deer]

There is several 6mm BR's variants I am not really familiar with.!

So your going for the strait 6mm br then.

Why!

[Big Al]

19 minutes ago, No i deer said:

Why!

Why not?

Standard 6BR is a great caliber in its own right with very easy brass prep and relatively simple load development - why make things complicated with a variant if you dont need to?

[Nick 53]

To be quite truthful I wasn’t aware of several 6mmBR variations 

now I got to have a chat to the gun pimp let him explain the several variants .

[The Gun Pimp]

Nick,

That 6BR Savage benchrest is still for sale on the Club notice board. Got dies, bullets, brass with it. 

Stick with the 'straight' 6BR - variants are for when you retire and you need to fill in your time!

[Nick 53]

Cheers Vince,

at the 1000 yard comp on Sunday will have a look about this Savage.

nick 

[gbal]

NIck, Big Al and Vince  give good advice-get the 6BR Norma chambering.

You can read about most of the exotic wildcat variants at Accurate Shooter (6BR and 6BR Improved) cartridges-but you really do not want to get into all the issues with a wildcat,for minimal benefits-if any-and more costs.BUt you'd be better informed,and the info on the standard 6BR Norma is excellent too (tho' much US data on powders won't apply herenext year-no problem,euro powders available).

   There are very few 'factory' rifles so chambered -ie by the major manufacturers,and the few that are are not the cheapest of rifles.But do look at the Savage,as Vince suggests,if your use is UK target shooting.Otherwise,it's mainly the specialised (v expensive) european competition models,or  the upmarket options from eg RPA,and then the customs. There are semi customs-usually a rebarreled Remington,Sako,whatever on the used market.

But check out the Savage.

g

[No i deer]

What is this 6mm br savage so I can look for it on the net.cheers no I deer

[Laurie]

9 minutes ago, No i deer said:

What is this 6mm br savage so I can look for it on the net.cheers no I deer

 

The Savage 12 Precision series. Three models are offered in 6BR - LRPV (long Range Precision Varmint), BR and F-Class. 12 and 8 twist rate barrel options exist too.

https://www.savagearms.com/firearms/?type_check[]=Centerfire&caliber_check[]=6 NORMA BR

 

Firedoc on this forum knows the rifle well having held a UK 1,000 yard benchrest group record for a while with one

[No i deer]

Thanks Laurie ?

[Nick 53]

Cheers everyone 

will look at savage 

nick 

[No i deer]

What makes this little cartridge that much better than than most others?

[Laurie]

33 minutes ago, No i deer said:

What makes this little cartridge that much better than than most others?

 

That is a $64,000 question! Likewise, why has the 6PPC won 100/200 yard BR matches for 30, 40 years now and nothing better has appeared despite all the new cartridges, and despite many BR shooters being very technically proficient and inveterate experimenters? It's not just the 6mm version as the .30BR has become the cartridge to use in shoot for score short-range BR disciplines and many UKV members will laud the .22BR as a superlative long-range vermin field-shooting cartridge.

As to possible factors, they include a well designed small case with a short powder column, 30-deg shoulders, small primer and small (1.5mm dia.) flash-hole, and in the 'straight' 6mm version a long neck .

Being 'small' is in itself a big plus. In the days when the Remington 40X series was a world leader in precision rifles, Remington's Custom Shop that produced them test-fired the finished rifle and sent it out with a test target proving it could shoot a suitably small 100 yard group. The company also kept records and after many years published the average group size for each calibre the rifles were available in from .222 Rem (the BR cartridge of its era) up to .300 Win Mag. Perhaps unsurprisingly, each step up in cartridge size saw  a matching step up in group size - more heat, more stress on actions, barrels, and bedding', harder to shoot consistently even off the bench.

The issue about the BR is as always 'horses for courses'. It was widely seen and used in F-Class in the discipline's early days, but as soon as warmer 6.5s, then 7s appeared, the BR became outclassed. Not in precision - a top-notch 6BR will outshoot an equivalent 284 or 7SAUM/WSM in this respect, but in ballistics in prone deliberate competition where atmospheric conditions continually change over the course of a 20 to 45 minute match and external ballistic performance becomes key to minimizing wind change effects. BR shooting by contrast sees the five shots taken very quickly (as fast as 20-30 seconds often) and a combination of shooter skill and luck in getting no condition change over the string is what produces the tiny groups when added to the design's inherent precision potential. The light recoil also assists such precision shooting and speed by minimising rifle disturbance on the bags. Burning ~30gn of powder sees barrels heat up less quickly too compared even to other sixes such as the XC, 6-6.5X47L and 243.

The 'World Record' long-range groups produced in the USA are partly a result of a lot of people shooting the discipline over there - more than the rest of the world combined - partly these people and their gunsmiths having built up enormous expertise, experience, and skills levels, but also if you dig out features on some of the ranges where the smallest groups are shot, because they are basically a narrow 1,000 yard lane cut through a mature forest of dense tall trees and are therefore largely protected from crosswinds. Diggle and Gelston they are not!

[gbal]

Just to add to Laries  comments on the 30BR-it does not have quite the precision potential of the 22 and 6 PPCs,but in score shooting at 300y,it's pretty close (a bit less wind sensitive-not much,but there) BUT it is a bigger diameter bullet-and that can just clip an upwaerd scoring ring often enough to give it the edge.Not a discipline much shot in UK,though -cf and CISM shooting in Europe  the 6BR is favoured (and therefore has excellent loaded ammo available from Norma-no such support for the wildcat 30BR.

    I really like shooting my 30BR (aka 308x11/2 Barnes),though it cannot sustain performance -compared to the 6BR -past  500y-and is a non starter for much greater ranges-good match BC bullets are  lacking,and mostly would be too heavy for the capacity.(say 125g). So  the 6BR is the understandable choice.Just as the 6PPCs (22PPC if you can't have a 6) are for ultimate 100 & 200y precision. The BR  case has found it's niches now,as above and 22 varmint. (It was designed as a rare wildcat parent case-brass but no rifles initially-by Remington's  Mike Walker to challenge the (non USA origin) PPC-220 Russian brass based) but couldn't.

gbal

[No i deer]

So in theory on a good weather day.(No wind ) at all.....!

At 1000yds you would expect the 6mm br to out shoot the 7mm shehane/wsm's etc

[Laurie]

Yes

[Nick 53]

Hi gbal and Laurie ,Vince had a look at the savage web site the 12 Benchrest and 12 Fclass  look like awesome rifles, I see they both advertise Norma 6br . I want to keep the technical reloading down to bear essentials! Don’t want to get to technical I can’t get my head around such things especially if it relates to brass! 

Going to read further, I am keen to see what powders, bullet weights are recommended along with primers. 

Cheers nick.

[No i deer]

The likes of Laurie and Vince would fry your brain with their knowledge but a no neck turn chamber will suit you fine.its surprising how quick you can pick things up.one things for sure they won' give you bad advice. 

[Nick 53]

Yes they could fry my brains but they know my capability on reloading so I am in good hands with these guys. 

[No i deer]

1 hour ago, Laurie said:

Yes

Wow.

At what sort of wind speed does the 6mm br become out classed by the 7mm's.

[Big Al]

1 hour ago, No i deer said:

Wow.

At what sort of wind speed does the 6mm br become out classed by the 7mm's.

Speed of wind isn't an issue, if it was a constant 10mph with no variances then the most accurate round would still be the most accurate round. When the big boys come into their own is when the wind switches during the bullets flight, they will be blown off course less than the smaller bullet so have an advantage.

Even a 1mph change in the wind over 1000yds will blow your bullet away from the last one, the less it blows it away in the smaller the group will be. Big bullets with high BCs cope with switching conditions better wether is a 1-3mph change or a 15-16mph one. 

That said Ive won a few 1000yd matches with a 6 Dasher against much bigger calibers including .338 Lap Mag on windy days so a cartridges inherent accuracy should not be overlooked.

[Laurie]

At Diggle, it is not uncommon to see the prevailing south or south westerly wind run between around high single figures to 10 mph in a lull to high teens to 20 mph at peak gust, (although gust speeds of around 25 mph aren't unusual).  12-15 mph speeds might last for slightly longer periods in between. Since that wind is coming from four to five o'clock the equivalent wind variations as crosswinds could be between 3 and 6 or 7 mph.

So, we're talking about 3-4 mph 90-deg crosswind equivalent wind variations. On Bisley's Stickledown, the prevailing west / SW winds are usually lighter, but as they are nearer true crosswinds directionally, the same sort of shot to shot change frequently occurs. Gelston in Dumfries & Galloway, a 1,000 yard range used only for BR? I've not shot there, but reports say it is mighty windy on many match days and very easy to fail to connect with the target frame. 

In BR, with the five shots off in under half a minute while the shooter has spied a lull or what appears to be a prevalent condition that will last for a little while, there may be very little change over the string and if he or she has got that right, it becomes sheer 'precision' plus shooter gun handling, trigger control etc that determines results.

In F-Class, TR, Match Rifle where the target is pulled and marked between shots, then one's partner takes his or her turn to shoot and the target is again marked between any two shots on the scorecard, it's all about 1) shooting skill (as in any discipline); 2) the cartridge and rifle combination's precision (ie group); reading any wind changes from the time of the last and previous shots and applying changes to the aim; 4) the bullet's external ballistics.

As there is no such thing as the 100% perfect wind reader, if the effective crosswind changes between shots run at 3-7mph as I said for Diggle and Bisley at 1,000, it is the combination of the last two factors that largely win such matches. In TR though, everybody is effectively using the same bullet / external ballistics (in high-level matches at any rate) shooting the 155gn 308 Sierra MK at 2,920-2,950 fps. In F-Class we can shoot whatever like up to 8mm calibre within range rules so that could vary between small sixes, even very hot .22s and cartridges like the .300WSM shooting a 200-215gn bullet.

The 6BR Norma with a 28-30 inch barrel will give a 105gn match bullet between 2,800 and 2,900 fps usually, the 7WSM can push a 180 to well over 3,000 fps but most shooters restrict loads to give around 2,900-3,000 fps MV, and the same applies to the .300WSM with 215/230gn Berger Hybrids. Let's say the three cartridge's have been loaded to the same MV, 2,900 fps even though that is on the high side of the 6BR's  capability and well under for the other two.

The G7 BCs for the three bullets (assuming the shooter has decided to use Berger's Hybrid design in each case) are:

105gn 6mm ........ 0.279

180gn 7mm ........ 0.345

215gn .30 ........... 0.356

Running them through the Applied Ballistics / Berger Bullets 'Ballistic Solver', we get the following bullet lateral movement per 1 mph wind change at 1,000 yards:

105gn 6mm ........ 7.8 inches

180gn 7mm ........ 5.6 inches

215gn .30 ........... 5.5 inches

 

Bryan Litz estimates that 'Expert' match shooters can read the wind to within 1 to 1.5mph; average shooters 1.5 to 3.5 mph and so on. The shooter who habitually gets within 1 mph - a really skilled wind reader - will sees a bit over two inches difference wind driven POI change between the 6BR and the other two at 1,000 yards at the limit of his or her wind-reading accuracy; the average or even more so tyro long-range competitor will make a poorer fist of reading the wind, so gets consequently larger amounts of drift every time he or she gets the wind change wrong.

Let's say the 6BR and a good shooter could shoot 0.2-MOA groups in a 1,000 yard tunnel with no wind and perfect light, 100% consistent air temperature etc; and the 7WSM shooter manages to hold double that over a 20-shot string (20 shots being the norm in an F-Class match or stage) that is a 2.1-inch group v a 4.2-inch group so that if every shot were perfectly aimed dead centre on the aiming mark, the outermost shots would be around 1-inch each side of the target centre for the 6BR and 2 inches for the 7WSM. In theory that would see a 6BR master shooter who reads the wind to within a 1mph change achieve equal results to an equally competent 7mmWSM shooter. In real life, all the tolerances tend to run the other way - the WSMs can shoot somewhat tighter than 0.4-MOA; very few people  can read a tricky wind that accurately over the course of a match, more people run their WSMs at 2,900 fps plus and not 6BR shooters achieve 2,900 fps. As top places these days are usually determined by one or two points even in the better attended club matches, it is the single shot that just leaks over the score line into the next ring and drops a point that is the difference between first and second places - or at shorter distances, the V-Bull count.

I can't remember who it was now, except that he was one of America's top F-Class aces in the discipline's relatively early days who compared shooting the 6BR against the then ascendant 6.5-284. He reckoned that the BR had an advantage in mid-range matches (500/600) in most conditions and he might shoot it at 800-1,000 on 'quiet' days. That was some years ago - I've not heard anybody who actually wins matches say that since. These days, it's hard for the BR to beat the 6.5s and sevens even at 600 yards in anything except near flat calm conditions.

But as said earlier and reinforced by Big Al, it is a different game entirely in BR.

[The Gun Pimp]

"I can't remember who it was now, except that he was one of America's top F-Class aces in the discipline's relatively early days who compared shooting the 6BR against the then ascendant 6.5-284. He reckoned that the BR had an advantage in mid-range matches (500/600) in most conditions and he might shoot it at 800-1,000 on 'quiet' days. That was some years ago - I've not heard anybody who actually wins matches say that since".

But don't forget Laurie, the Americans have the luxury of 'string' shooting - so the wind-reading becomes less of a factor, which brings the 6BR back into contention.