Why an Improved BR?

[Bob3700]

I am wondering about the wisdom of improving the BR case.

With all the postings of 2900 - 3000 fps from a standard BR case, why would I want to go thru all the headaches and expense of an improved BR like the Dasher or BRX?

Surely, the std BR makes the most sense. Top velocities and no fire forming of brass.

The improved BRs don't seem to have any velocity or accuracy advantages over the std. case. A Dasher or BRX shooting 3050 fps is only 50 fps faster than a std BR case. So why bother with the wildcat? Three grains more powder for 50 fps doesn't seem like a good trade.

Bob

 

[357Mag]

Bob -

Howdy !

Just a W.A.G. .....

If they are going from a 30* shoulder angle to a 40*,
they may be trying to enhance barrel life; and/or reduce case
stretching, reduce need to trim case oal ).

Regards,
357Mag

 

[DukeDuke]

I never had a 6BR, so not sure about the 50fps faster. I do have a 6BRX that shoots 117DTAC at 3000fps and I LOVE it! My barrel may think otherwise, we'll see. At the beginning, I thought the fireforming was going to be a difficult and uncertain procedure, turned out to be very simple. Would have gone with 6BR, but this JOHN708 changed my mind! Good one Rustystud and JOHN708!!! Thanks a LOT!

 

[Bob3700]

Gents,

The hassles and expense involved in shooting a wildcat far outway the advantages if all you are seeing is +50 fps or the same velocity.

Extra expense to shoot a wildcat includes custom dies for loading and all important bbl life for fireforming the brass. None of this includes the valuable time to perform all this extra work. If you utilize the 'False shoulder' method of fireforming, you want to talk about extra work!

Those are some big factors when you consider that the benefits are slim to none! Why not just pick the std. 6BR brass up out of the box, load it, shoot it and be done!

Shooters make claims,velocity etc.) for their wildcat cartridges that are hard or impossible to duplicate. So I am left to believe that much of their retoric is nothing but hype.

Either their chronographs are providing incorrect readings, or they are carelessly loading to very dangerous pressure levels to see any velocity improvements.

I know for a fact that my shooting friends Oehler chronograph reads 100 fps high. Velocities recorded on his machine cannot be duplicated on two other Oehler 35P chrono's. So if you take his readings as gospel, you are way off base and you wouldn't even know it.

So far, the velocity results from three bbls,all different makes) chambered for the 6 BRX have velocities that are equal to or less than what folks on these boards claim for the standard 6BR. With these results in mind, Only two conclusions can be made. Either the velocities claimed for the wildcats are a bunch of BS, or those claimed for the std 6BR are BS.

Bob

 

[AlNyhus]

You might want to ponder the fact that if nobody ever worked with wildcats/improved type of cases....the 6BR would not exist.

Today, you can buy the best brass in the World for your 6BR, scoop 'em out of the box, load 'em and toss 'em into a properly dimensioned chamber....all courtesy of those that came before you and did all the hard development work.

Many of the advantages sought by people that tinker with case designs to this day are not strictly a f.p.s. increase. Many of the improvements are subtle in nature and not readily apparent to the casual observer.

 

[Moderator]

For Bob...

Regarding claimed velocities, our tests have shown that identical ammo,in our case Lapua 105gr factory-loaded ammo) can range in velocity up to 100 fps in different guns. I've personally seen the same ammo, over the same chron, shoot at 2750 and 2830, when shot through two different 6BR rifles back to back.

With a stout load, some 6BRs can indeed get 2900 fps+,with 28' or longer barrel) with the 105s, as confirmed by multiple chronographs.

On the other hand, other guys won't see much more than 2820 fps, max, with the 105s/107s etc.

With 3 grains more capacity than a standard case, the 6BRX or 6 Dasher will give more velocity at the same pressure level than the standard case. For most folks, this will get them comfortably into the 2950-3000 range, which has proven to be a very accurate node.

Richard Schatz has won just about everything there is to win in medium-distance BR, shooting a 6 Dasher with Reloder 15. Does that mean a 6BR improved is the only way to go? Hardly. Consider that Sam Hall spanked everybody last year and Sam shoots a straight 6BR, albeit at pretty high pressures.

 

[JOHN708]

Hi Bob,

The extra velocity generated by the improved cartridges make them more competitive at 1000 yds than the straight 6br cartridge. In my opinion, that's the sole reason for their existance. If I was just shooting 600 yds or less I would just go with a 6 br.

Oh, and Dukeduke, thanks for the compliment.

John Skowron

 

[Bob3700]

John708,

I have read every post that you have made and followed your progress with great interest. With all the info available on the BRX I purchased a BRX reamer and have now chambered up four bbls. all with 30' finished lengths.

In load development, all those bbls have shown good accuracy in the 2950 fps bracket with the 107 gr bullets and Varget. Getting to 3050 fps with Varget is at the expense of greatly increased pressure. When the primers are cratered, you have extractor marks on your case head, and the bolt clicks at the top of the lift, I believe you are at the top velocity stop for that rifle. 3000 - 3020 fps with decent accuracy is certainly possible with RL 15 and Berger bullets but you have to hope that your bbl has an accuracy node at that velocity.

Now, that said, folks are posting that they are getting that same velocity ranges from a standard BR case. I truly question if that is possible with the standard BR. Tomorrow, I am going to actually chrono a standard BR with 30 gr of Varget and a 107 SMK and see what reality actually it. While you certainly can't draw conclusions from one gun, it will certainly put some real world numbers against what has been posted.

My fondest hope is that the BRX will be a very competitive cartridge in my two rifles for both 600 and 1K shooting. I feel that if I have an accuracy node at 2950 - 3020 fps, then I will have a very competitive cartridge at 1K as well.

If not, then the BRX will in reality not be worth the extra work a wildcat entails.

Thanks for your posts and sharing your development work. It is greatly appreciated.

Bob

 

[JOHN708]

Hi Bob,

In my opinion, cratered primers are not a sign of increased pressure with this cartridge, with a non sleeved firing pin. With that said, ejector marks are, except with fire forming. Depending on the rifle, 3000-3060fps is doable and safe with 105 Berger's. You might get less velocity with the 107s. I haven't measured them, but I believe they have a longer bearing surface than the 105's.

My goal with this cartridge is 3000-3050fps, depending on the bullet and gun. This is all the velocity you'll need to be competitive. With the 107's, 10 MPH X-wind at 1000 yds is 70' @3000, and 67' @ 3100fps. In my experience, a difference in wind drift of 6-8' between different bullets is insignificant.

Over the years I've been squadded with more than one current or former national champion. It doesn't happen alot, but I've beaten them in a given relay with the 6brx when they were shooting 6.5-284's or 300 win mags. When I lose it's usually because of bad shot placement or wind reading mistakes vs wind drift.

John Skowron