Chambering Decisions 6XC v. 6BR v. BRX

[Suicycle]

I have beat my head against the wall and still cannot figure out what I want. I have read all the info pages on the home page here. I figure I could flip a coin and do about as well deciding on which to choose. Looking at a 6BR,XC, or some improved version. I like the appearance of the dasher, but the BRX seems smarter because of the cost of dies. At the moment I have no reloading equipment, house fire, so there will be a decent investment either way.

Use is for F class. Got a short 700 and a Kreiger barrel in 7" twist. Just in case I go with the standard BR to shoot the 115's. Is there a major difference in the standard BR to the XC, or could the difference be made up by a few inches of barrel or a quick vs. slow barrel? Mine should finish at a smidge over 32" so I have plenty of length.

Another option is just do the 6BR and if if aint quick enough to chop off a thread or two, or an inch depending on condition of bore ahead of the throat, and go with the XC. That could be after a thousand or two rounds or so. I still see a useful 30" barrel after I get up to speed at this long range game. Is that a real option, or am I just dreaming.

Anyway got untill Sunday to figure out what I want and looking for some input. I figure I couldn't really go wrong with any choice, except something he would have to rent a reamer for. That might not even be a problem, never questioned about rental reamers. I guess they have to be within specs, not like a worn drill bit.

anyway tell me something I haven't considdered yet.

 

[Forum Boss]

Many folks asking the same questions, now that the 115gr DTAC is available and seems to work well indeed.

First on barrel length. Whether you get any extra Velocity from 32" vs. 30" is questionable with 6BR std or BRX case. You'll probably get full powder burn in under 30" unless you're running some very slow powder.

On 6XC vs. 6BR. The advantages we see to the 6XC are mag feeding and the ability to definitely get the 115gr DTAC to 3020 or so where it likes to run. With a BRX you might be down around 2950 with the 115 based on initial reports. The 115 DTAC enjoys a significant BC advantage over a Scenar 105 or SMK 107. That can make a difference.

I think you have to decide at what distances you'll be shooting most of the time. If it's predominantly 800-1000, we'd probably go with the 6XC to get the BC edge. But as we have more 1:7 Dashers come out this spring, we may learn something new. The jury's still out on this one...

 

[Suicycle]

Mostly 1K range. Not real sure about where else to shoot yet, but a range about 40 min away shoots about 2 times a month. Nothing between 600 and 1000. All I have seen is 1K.

Anyway I am looking at making the gun a single shot with a glue in ramp. Other than that decision and the chambering all left is a stock. Got a few ideas and gonna check out what is at the range this weekend. Really looking at a Richards custom rifles f class, or one of the Trackers as a second choice. Want to touch some of them though.

Thanks for the advice. I was planning on the XC and then kind of got iffy, more of is it needed, and now I feel better.

 

[JeffT]

I couldn't decide either, so I got 2 barrels, 1 for xc and 1 for br




Jeff

 

[Suicycle]

Thanks Jeff. That was a lot of help. ,grin)

 

[AlanWarner]

The 6XC does quite well with 115's at 3150. Pressure is moderate to high. Good brass holds up and pockets are not stressed. Free bore needs to be at a min of .150. .185 keeps them well away from the neck/shoulder junction.

I have not shot any great number of the 115's yet. All so far have been in mild conditions. Grouping was OK, but I'm not at all convinced they are any better than the 107 family by any great measure.

BC does not make you a better shooter, reading the wind does.

Again, the brass makes a lot of the difference in a rifles overall performance. My experience is that Davids brass yields about 40 out of a hundred that are good. Forming and turning it from Lapua yields 99 out of 100.

Alan

 

[sparker]

I have just worked up loads for my 6BRX. It is a Barnard action in a Mastin stock with a Broughton barrel at 31". I started by trying a ladder test at 100 yds. I loaded 11 rounds covering 32.5 grains to 35.0 grains of Varget with mollied Sierra 107s. All 11 rounds went into a group .464" tall by .397" wide. So, I repeated the test only this time I fired 3 shot groups. I found 2 nice spots at 33.5 grains and 34.5 grains. The groups were tiny like .16-.18"
I then shot two, five shot grups with both loads. Both loads produced 5 shot groups under .185". The velocity for the lighter load was 3020 fps. The higher load was 3104 fps. I took the scope off and put on my rear sight. I posted a 100yd reduced prone target. I laid down and shot 100-9x. This is the most accurate rifle I have ever owned, shot or seen. I doubt that the XC with any bullet can match this cartridge's accuracy. I haven't tried the Clinch River 106 bullet yet. But shooters in the know have measured its BC at .55. This bullet at 3100 fps will give up little to no wind drift to the XC with the 115gr bullet. The inherent accuracy will prove superior to the XC cartridge. Hope this helps.

Scott Parker
Bakersfield CA

 

[Suicycle]

My experience is that Davids brass yields about 40 out of a hundred that are good. Forming and turning it from Lapua yields 99 out of 100.

Alan

Does Lapua make 22-25 0 or is the 243 the better choice to form out of? Haven't found the 22-250, haven't looked that hard either. Just looking at the reloading manual for dimensions the 243 is a pinch longer to the neck and shoulder junction.

BTW total beginner on forming and making brass. Little info would be great.


as a side note I have a 280AI that was just built and am about to start loading for. My idea is to use 30-06 brass and just neck down in the FL 280AI die to where the neck forms the shoulder for the chamber. Kind of like the neck up to 6.5 and back down a little ways to 6mm as shown on this site somewhere.

 

[DTubb]

Alan,
So why does the 6XC brass yield only 40 out of 100 that are good.??
What are your parameters?
Body wall run out, neck thickness variations, case capacity consistency? --- or something else?
I didnt sort any of my cases for Perry this year other than weighing and this was done in order to help me keep my quality control on my powder charges,loaded ammo)to within a specific range.
I have finished my working on a powered Meplat Uniformer - and my 10 shot groups at 1000 are now approaching the size of a baseball while still using unsorted brass,it has been weighed) from the 2nd batch.
What makes an acceptable piece of brass?
DTubb

 

[NormHoule]

Alan,
How do you sort your brass.I had 4000 pcs that I weigned after deburing the flash holes.3000 weighed 154.5 +/- .5 grs. 600 at 153.5 +/- .5grs. and 400 at 155.5 grs.I used everyone and was getting 1/2 moa groups.I'm definately open to any procedure that is going to get smaller groups than I'm already getting.
Thanks,
Norm

[Editor's Note: FYI, Norm Houle won the 2004 Camp Perry Cross-course Nat'l Championship, shooting a 6XC.]

 

[AlanWarner]

David and Norm.

Weights and volumes where very acceptable. What I found was a very high number where the neck and shoulder ran out from the body at an average of .005 TIR and some as far as .008 TIR. Parameters for the gun I was building was to run .0015 to .002 total neck clearance. Emil managed a forth place with it at the F Natl's. having never shot the position or rifle before.

Reamer was ground to .2728 and I did not have the time or desire to attempt to true it up first. I'm sure your next lot will be much better.

Trust me, I would have loved to have been able to have enough that I didn't have spend time making it all.,500) Between the die work up, brass cost and time, the reformed and cnc lathe turned,ID, OD with tan radius blend, internal and external champher and length) Lapua is worth close to $3 per. I look forward to acquiring some from the lot soon to be out.

Alan