Comparing 6BR to 6 dasher

[londonhunter]

OK
Planning for another project
for paper punching
up to 600 yards shot prone
other than speed
is there much to gain or loose if I go 6 BR ?
Also what is the shortest barrel I can go before there is significant lost of velocity up to 600 yards ?

 

[rcw3]

For a prone course of fire at 600 yards I would always go for the Dasher over a 6BR. On a windy day with on and off conditions, the performance of a Dasher is sufficiently better that it's really "no contest" (in my opinion). The 6BR is a great little cartridge (on a calm day or with steady conditions it's always great) but the Dasher makes it easy to run 2950 fps for 22 shots straight with the 105-108 gr bullets without having to push things to the max. With a 6BR, for me it was always a 2750-2800 fps cartridge for prone shooting 22 shots in a row and that's just a little anemic for a windy day at 600 yards.

I know there are a lot of people who tout "hot rod" velocities with both the 6BR and the Dasher, but a lot of them are not shooting prone courses of fire where they have to put 22 shots in a row down the barrel without a break. What I have found many times is that "hot rod" loads for a particular cartridge may run fine for 10, 12, 15 shots or so without issue, but 22 shots in a row is another story, and if you want your load to stay "tight" the whole way, many times you have to back things down.

I tinkered a lot with powders in both my Dasher and BRX and by far H4895 seemed to deliver up the best in terms of consistent 22 shots in a row accuracy (31.3 gr with a CCI BR-4 primer and Berger 108 BT loaded .015" in the lands - right around 2950 fps).

Robert Whitley
http://www.6mmar.com/6mm_Dasher.html

 

[londonhunter]

Thanks for sharing your experience
So bottom line we are talking about 150 fps difference when shooting in the wind

OK I shoot mainly at Bisley UK and wind is a big factor there

How about if I use the newer generation of powders 8208 XBR or Reloader 17

I am confident to get the 150 fps without a lot more extra pressure

then is there any more advantage in favour of the dasher ?

What I am really saying is the Dasher more accurate if all parameters remains the same ?

 

[6BRinNZ]

Hi Robert,

what is it about running the 6br at high MV that causes issues for extended strings to be an accuracy issue...not doubting just interested in understanding further....

Thanks

 

[rcw3]

Hi Robert,

what is it about running the 6br at high MV that causes issues for extended strings to be an accuracy issue...not doubting just interested in understanding further....

Thanks

The phenomenon is not just limited to the 6BR. I cannot say I know the exact cause, but I know it exists because I only do 22+ shot in a row load testing for F-Class and prone courses of fire, and I see it repeatedly with many barrels and cartridges. My suggestion is try it yourself, take a 6BR (or another cartridge) with a top end loading that seems to shoot well, and in 15 minutes or so, run 22 shots straight with no break and see what size group you get. What I find is there are a lot fewer loads (mostly milder loadings) that will hold a tight group for all 22 shots than will typically hold tight for, 5, 10, or 12 or so shots in a row. If you have a load that will run the whole way and do it day after day, in all kinds of weather conditions, then that's the load to use to try and win. It's not about "walking the tightrope" and getting away with it on one day in one match, it's about steady and consistent day to day performance. Once in a while you can also find that magic hot load that will run the whole way (but it might just be a one in a hundred barrel you have for that rifle too).

Years ago I lost placement in a lot of matches because I dropped points on the back end of 22 shot prone courses of fire. I used to think it was fatigue (eyesight and/or body fatigue) and now I realize that mainly it was because I used to only do load work ups and testing with a couple sighters and a 10 shot group. One day I did that and shot a great 10 shot group, but then continued and shot another 10 shot group and the second group was very poor (huh - what the heck?). The next day I tried it again - same thing, lousy second group (hmmm - wheels started turning). The next day I tried it with another rifle and the same thing. I dropped the loads on both rifles and the next day both of them held for 22+ shots in a row.

Now when I see bench rest shooters or "velocity hounds" touting how fast they shoot their bullets, I always tend to disregard or discount it for the F-Class, highpower or prone disciplines (mainly because those other shooters typically don't run a very long string with no break, so they never run into the issue).

Robert Whitley

 

[6BRinNZ]

Hi Robert,

thanks heaps for the prompt reply.....I learnt a little while ago that wind is king and consistency is the other king...LOL....so I was quite interested in your comments....

 

[deadlyswift]

Hi Robert,

what is it about running the 6br at high MV that causes issues for extended strings to be an accuracy issue...not doubting just interested in understanding further....

Thanks

The phenomenon is not just limited to the 6BR. I cannot say I know the exact cause, but I know it exists because I only do 22+ shot in a row load testing for F-Class and prone courses of fire, and I see it repeatedly with many barrels and cartridges. My suggestion is try it yourself, take a 6BR (or another cartridge) with a top end loading that seems to shoot well, and in 15 minutes or so, run 22 shots straight with no break and see what size group you get. What I find is there are a lot fewer loads (mostly milder loadings) that will hold a tight group for all 22 shots than will typically hold tight for, 5, 10, or 12 or so shots in a row. If you have a load that will run the whole way and do it day after day, in all kinds of weather conditions, then that's the load to use to try and win. It's not about "walking the tightrope" and getting away with it on one day in one match, it's about steady and consistent day to day performance. Once in a while you can also find that magic hot load that will run the whole way (but it might just be a one in a hundred barrel you have for that rifle too).

Years ago I lost placement in a lot of matches because I dropped points on the back end of 22 shot prone courses of fire. I used to think it was fatigue (eyesight and/or body fatigue) and now I realize that mainly it was because I used to only do load work ups and testing with a couple sighters and a 10 shot group. One day I did that and shot a great 10 shot group, but then continued and shot another 10 shot group and the second group was very poor (huh - what the heck?). The next day I tried it again - same thing, lousy second group (hmmm - wheels started turning). The next day I tried it with another rifle and the same thing. I dropped the loads on both rifles and the next day both of them held for 22+ shots in a row.

Now when I see bench rest shooters or "velocity hounds" touting how fast they shoot their bullets, I always tend to disregard or discount it for the F-Class, highpower or prone disciplines (mainly because those other shooters typically don't run a very long string with no break, so they never run into the issue).

Robert Whitley

Robert,
I am interested in your testing also? I have a cpl of questions tho. Not to debate you or that any of your findings are not ture at all!

I recently shot a F/class match at 500yrd with my 6br. I'm loading the 105s touching the lands. This is a 28" Broughton 5c 1in8 twist. The 105s are running 2960fps with 30.7grs of varget. I did not see the results that you are speaking of. Actually the results were the oppsite? I only dropped points due to Horizontal and pretty much could explain every point dropped due to my own mistakes. All weekend long I shot 5 individual relays, and 1 team match. So that is a total of 132rnds. Plus add 44 more rounds that I shot on the practice day, and that is 176rnds. I didn't clean the barrel until I got home from the match that Sunday afternoon. My lowest score was a 193 and my highest a 197. Those aren't the best of scores but not bad for a Rookie.

Now here is where my questions are. The weekend I shot this match it was extremly cold weather and Sunday morning had us laying in about 1 1/2" of snow. Do you think I did not see any of the issues that you speak of because of the cold weather? As well I shot at a avg. rate of 12min for 22rnds. So yes I shoot kinda fast. I will do more testing myself when the weather turns hot to see for myself. I understand using the 6brx or 6 dasher past 600yrds due to the extra 150fps.

Your post makes since and is interesting info. It mostly caught my attention because I didn't experince those results, and I was just curious if it was due to the conditions I was shooting in? I also have found a node at 2820fps in my barrel. So it could help to shoot that node and may even be more consistent. I want be shooting my 6br past 600yrd but only because I think it is a waste of time. The 6br is a fine round but for 1000yrd F/open I think I'd be better off sitting at home or pulling targets in the pits! I have deadicated myself to FTR next year anyway so this isn't a big deal, but I do find it interesting. Thanks for any comments! Again these questions are only out of curiosity and not to despute what you have posted!
Thanks
Mark

 

[Forum Boss]

Every point that Robert makes is well-reasoned and I won't dispute his recommendations when it comes to prone shooting.

However, I'll give you a perspective from a club-match and varmint silhouette perspective.

Velocities: With a long-freebore, some guys can get 2900 pretty comfortably with the 105s from the standard BR. A smaller minority are able to shoot closer to 2940-50, which narrows the Dasher/BRX gap considerably. Those are MAX loads with a benchrest action. However, AND THIS IS VITAL -- there is no guarantee you can get those velocities (2900 and above). We have learned that the speed potential of your 6BR is very BARREL SPECIFIC. We have seen some custom barrels top out at 2840, and others shoot almost 100 fps faster with the SAME LOAD, same bullets, same barrel length, and (sometimes) even the same bbl manufacturer. A slow barrel is a slow barrel and sometimes there is nothing you can do about it.

RE 6BR Hot Loads not holding up for extended string:
Our club runs a 600-yd paper match as well as a varmint silhouette match. To save time, we run two paper targets back to back. When the waddies are up to task, its not unusual to shoot 4-6 sighters and then five for record really fast. This is then followed ASAP by another 4-6 sighters and five shots for record. The better shooters are getting their record shots off quickly most of the time. Anyway, we're talking about 20 or so shots in 15-20 minutes. I've seen no evidence that the accuracy starts to go south with 6BR 2900 fps+ loads, as long as the shooter is using a custom barrel that doesn't copper really fast. Barrel heat can be an issue in the summer, but it still usually pays to put the pedal to the metal on the record rounds.

From this I draw the conclusion, at least in the benchrest environment, that a 2900 fps load won't necessarily lose accuracy in 20-25 rounds any worse than a 2850 fps load. That said, your 6BR brass will last longer at 2850 fps. You may not notice the difference after 2 or 3 firings, but after 4 or 5 you will.

 

[deadlyswift]

Forum Boss,
Thanks for taking the time out of your busy scheulde to post your comments! I didn't mention how much my Broughton barrel seems to do so fantastic with fouling or clean up! I have been told that some of the Broughton barrels have not shot so well. Due to something that I really don't understand myself. More less the Broughton's are a hit or miss deal right now. I can't say any of that is ture! This Broughton barrel gives awesome vel. and accuracy Even after 176s rounds down the barrel I ran 5 wet patches of Butch's down the barrel then 5 passes of a wet brozes bush. then 5 more wet patches and the barrel was squeaky clean! This is however a fact! I comfirmed it with a Hawkeye borescope! (Note not a trace of copper on the patches)

My brass is just now on it's 2nd firing so I will keep that in mind as well. I have pushed my 6br to the toy status for now. (learning curves) as well maybe some fun shooting egg matches and ground hog matches. With only 400rnds exactly down the tube I have plently of barrel and throat life to play with. This barrel has a very short throat. But however it still allows me to seat the 105s just at the shoulder/neck juction. So I should get a little more out of it than guys shooting longer thorats. I'm interested to see if I can shoot ths load in hot weather. I expect that I will have to drop down a few tenth off the powder. (varget) However I seem to believe I will be able to obtain the same vel. due to hotter weather raising pressures but yet give me the same Vel. with less powder? The 30.7 gr was found in 45 to 50 degree weather. Varget isn't as temp sensitive as RL-15. So once the 80, and 90* weather gets here I will see where I end up! The post that Robert made does raise some questions for me? I'm sure I will do some testing this summer and see what happens. The wrost that could happen is I might learn something! I have two other Broughton's and a PT&G reamer for 6brx. I may do some testing with those barrels as well. If funds will allow it. Like I said in my post above, most of my funds are tied up in getting geared up for FTR this year! But I would just like to see whats going to happen and how well I can keep my 6br shooting! Fun stuff either way!
Mark

 

[londonhunter]

Some very interesting points being posted here

Still does answer my original question in the original thread

Advantages of 6dasher compared to 6th other than speed

Has anybody thought about some ways of cooling the action in any dicipline

Surely this will change performance

Just for discussion purposes

 

[rcw3]

I will not debate whether what I observed in terms of 22 shot prone hot load strings holding (or not holding) accuracy is a reality or a fiction, as I have seen it too many times in testing. In my recent work with the Dasher and BRX (Krieger and Broughton barrels respectively) I found they both exhibited this issue and I had to do a bit of work to get great loads that would hold for 22 shots straight in a row with no break. If people want to dismiss it as fiction, that's up to them, but I save my targets and its right there on the paper for me.

I also did not say in my prior posting that the phenomenon is always an absolute. Included in the posting was: "Once in a while you can also find that magic hot load that will run the whole way (but it might just be a one in a hundred barrel you have for that rifle too)."

Bear in mind, there is also typically a significant difference between the barrel contours for a prone rifle and a bench type gun (i.e. palma contour vs something like a heavy varmint contour) and that might affect things as well.

Robert Whitley

 

[GLC]

London hunter, having shot at Bisley many times at various distances over they years I would go with Roberts suggestion of a 6 dasher or even to be so bold go to the 6x47 or 6xc or similar to get to the 2950mark and use the 115 Dtac for a BC advantage.
I shoot a 6x47 Swiss match with 115 Dtac at around 2950 and have done pretty well with it, however when the wind fishtails on century and Stickledown the bigger the better!

Do not discount the 6.5x47 either especially if throated long for the 139 scenar or 130 Berger vld.

Just my opinion and experience on the range you shoot.

Regards
Gary Costello
UK

 

[londonhunter]

Gary

We have met at Short Siberia
Benjamin here
I wonder do you remember
you were doing load development on bench 5 some time ago with all those toys
I was zeroing my Blaser K95 ?
Anyway I have a 6 x 47 lapua which I love and I am shooting OK at 600
have not tried anything over that to date
I will try 115 but I only have a 1 in 8
will it stabilise ?

 

[GLC]

Hi Benjamin,

Yes I remember!
My 6x47swiss is on a 1:8 twist and works very well however on the flip side I have a 6x284 that I cannot get to shoot 115's, I have not tried 105's or 107's yet but for some reason I am confident they will work.
I doubt very much if a 1:8 will work in a dasher or br though.

Enjoy your shooting and let me know what you decide, if I recall you have a very nice 6.5x284 which would work a treat at 600 on century!
Regards
Gary

 

[londonhunter]

Yup
That's exactly what I was told when I called Berger

Its really down to the barrel and environmental factors if a 1 in 8 will stablise a 115 projectile.

I was shooting a 6 x 47 lapua at century

My 6.5 - 284 build by Peter Walker has never been shot ashamedly and is collecting dust in Aftab's cabinet. I have been advertising it on the UK F class site without takers

I really wanted to join the league however I just do not have the time to spare

Heard a lot about your achievements since we met

Congradulations .....and wish many more to come in 2011 !

I will call Aftab to get a box of 115 DTAC or Bergers to try my barrel