6 Dasher vs 6x47 Lapua

[ChrisNam]

I currently shoot F Class with a 6 Dasher,1:8 twist 30” Border barrel with 107 gr Sierras) over the 300, 500 and 600m and a 284 Win,1:10 twist 30” Krieger barrel with either the 168 gr Sierras or Berger VLD’s at 2970 fps) over the 800 and 900m.

I’m very satisfied with my present setup, but must consider my next 6mm barrel if the Dasher needs replacement.

I’m considering the 6x47 Lapua,6.5 necked down), but I’m not totally convinced that a bigger 6mm,including 6CM or 6XC) will be a better option than the 6 Dasher for my specific application.

6 DASHER ADVANTAGES:
-very accurate with 105gr Bergers/107gr Sierras as well as lighter bullets
-Lapua brass
-reamer, dies, etc already available

6 DASHER DISADVANTAGES:
-operate under relative pressure
-do not shoot 115gr DTAC/Bergers
-not competitive at 800 and 900m

6x47 LAPUA ADVANTAGES:
-accurate
-able to shoot 115gr DTAC/Bergers
-Lapua brass
-will be able to shoot 800 and 900m
-interesting new project

6x47 LAPUA DISADVANTAGES:
-very few it seems - probably not as accurate as Dasher
-new reamers, dies, load development, etc

Any opinions out there?

 

[steveyrock]

I made the 6x47 my choice because there is no fireforming to the extent of the dasher and other BR improved versions.

Dies are also readily available now but I did purchase my own reamer and go gauge.This reamer is the no neck turn version set to cut.272. and I hope I don't regret that move but it has been very successful for others in the BR.

My goal is a few hundred feet per second gain over my standard BR with 105 and 107 grain bullets.

 

[mysticplayer]

When I did my planning in F class shooting, I went with the 6.5 cal but with a 260AI type case design,6.5 Mystic). I wanted one combo to go from 300m to 1000m and this cartridge with the 139gr Lapua does it very well.

Recoil is significantly lower then the 7mm with wind drift quite similar. A 162/168gr 7mm is similar in BC. The 180gr bergers going fast would be much better in wind drift but OUCH.

Running the numbers with the 115gr 6mm vs the 139gr Lapua, the 6mm needs to go 3100fps to equal the wind drift of the 6.5 at 2900fps,what my Mystic gives me). I feel that even the XC/47L sized 6mm are going to have to be pushed very hard to get a 115gr that fast. Better would be the 243, AI and 6CM.

If you have the luxury of two rifles for different distances, why not just stick with your present combo? It works for you now.

Going to one for everything would mean a very fast 6mm or a 'normal' speed 6.5. That is why I have built what I am now shooting.

Jerry

 

[LESLEY]

i have the 6cm i love it its easy to load 47 to 48.5 h1000 easly shoots a 115 over 3100 with no molly and around 3000 to 3500 rounds of life. I like it enought to have 1 now and 2 being built with bat actions and 1 other fot tac. shooting

 

[JOHN708]

I've been using the 6brx out to 1000 yds. in competition, over the past several months. I'm running 105 Bergers at 3080 fps. At that speed,Im giving up little to no cross wind drift, at 1000 yds.,compared to the 6XC or 6.5-284. My 10 mph Xwind deflection at 1000 yds. is 68 in. based on a .556 BC. With the 6-47sm, shooting the same bullet at 3150 fps. you gain only 2 in. The 6.5-284 shooting 142 gr.mk's at 2950-3050fps will give you an Xwind deflection of 69-65 in. The 115's in 6mm will be slightly higher. By the way, based on my own extensive experience shooting the 139 Lapua's plus numerous articles, including Tubb's work, the BC of the 139's are more like .595 as apposed to the .617 that they claim.
The only way you're going to beat the 6mm Dasher and the 105's is to go with the 6.5's with 140 Bergers or shoot the 168 and 180gr. in 7mm, at 2950-3050 fps, which is what your already doing. Good shooting. John Skowron

 

[ChrisNam]

Thank you very much for the responses - I really appreciate it.

Steve, have you shot the 6x47 Lapua yet? If so, what was your speed and accuracy with the 105 & 107's? Have you tried the 115's?
I've incidentally read on this forum or benchrest.com that a guy said that his 6x47 Lapua neks measured 0.271 after being necked down

Jerry, I've never seen the 6.5 Mystic - can you post a photo or provide a link perhaps? What, in your opinion, is the advantages of the 6.5 Mystic over the 6.5x284? What's barrel live with the 6.5 Mystic?
We have great difficulty in obtaining new barrels over here. Some guys started shooting the 6.5x284, but soon moved on due to poor barrel live. Very few people shoot 6.5's over here, mostly due to the popularity of the 7mm's, but I/m sure that will pick up if you can get longer barrel life as with the 6.5x284.

Lesley, I'm really impreesed with the 6 CM from what I've read, but the import of chambered barrels are problematic.

Gunamonth, I'm a Dasher convert and really impressed with the cartridge. I merely meant that at 3080 fps with a 105 or 107 you can not really increase your velocity,not that it is necessary) or shoot the 115 at 3000 fps,which I am not yet convinced have any real advantages).
I know that the 6 Dasher holds numerous records and on a calm day any other cartridge will have great difficulty competing due to the inherent accuracy of the 6 BR or improved versions. I've read that a lot of the guys shooting the 6 BR Improveds tried the 115's but subsequently returned to the 105 and 107's.

John, I think you've convinced me to stay with the 6 Dasher. I don't think the 2" advantge of the 6x47 Lapua over the 6 Dasher is significant enough to really matter.
Do you experience any pressure with the 105 Bergers at 3080 fps?
What will the wind drift with a 10 mph crosswind be for the 284 Win at 1000 yards with the 168 gr Bergers at 2970 fps? I'll appreciate it if you can run that through your program.

I understand from other shooters on this forum that almost all 6mm's have an accuracy node with the 105 & 107's at approximately 3050-3080 fps and then,with the bigger 6 mm's) at approx 3250 fps, although pressure may start to appear. The most guys, even with the bigger 6 mm's, therefore, if I understand it correct, shoot at approx 3050 or with the 115's at 2950 or 3000 fps

The figures run by Jerry and John means, IMO, that the bigger 6 mm's will not necessarily have a very big advantage over the 6 Dasher, at least not out to 600m. I just want to be convinced that some of my friends building 6 Bayetes,243 Win wildcat with AOL of 49mm, long 40 degree neck of approx 7mm, seems very accurate with 105 Bergers at 3250 fps) do not have an unfair advantage over me.

 

[mysticplayer]

Chris, the 6.5 Mystic is my version of the 260AI. I use 308W brass to form a tight fit in the chamber. The throat is moved out to an OAL of 2.90" with the 139gr Lapua.

Using H4831SC,46.5 to 47.5gr), I can push these bullets to 2900fps with excellent brass life,30" match barrel). I can touch 3000fps but accuracy and case life is poor.

Some cases have seen 15+reloads and still have tight primer pockets. I use Win brass which seems to work as well as anything else and is very durable. I do anneal my brass and each case gets the shoulder bumped during reload.

The rifle #2 has digested some 900rds and the throat has moved approx 20thou. If the wear is linear which I doubt, it could see another 3000rds before needing a set back. I would be happy with another 2100rds. I can easily seat the bullet out another 125thou and still have lots in the neck.

So the advantages over the 6.5-284 are high load density,100% with present set up), similar velocity,of course the 6.5-284 can go faster), looks like very good throat life, cheap and readily available brass.

I looked hard at the 115gr 6mm before building this rifle but can't get bullets readily in Canada. Plus I would need to run them very fast to equal the wind drift I get in my 6.5.

The 7mm simply recoil more then I care to shoot in an unbraked rifle in competition. The 162/168gr bullet is not much better ballistically then the 139gr 6.5 Lapua. Only the 180gr Berger gets interesting but needs a magnum case to push it to where there is a difference. Recoil is simply way too high for this shooter. I also wonder if the barrels will overheat in a 22rds relay.

Pics are of the case next to the 308W and pics of the prototype rifle and the one I am presently campaigning in F class.

Jerry

6.5 Mystic next to 308 parent case.


6.5 Mystic Rifle #2


6.5 Mystic Prototype rifle.

 

[steveyrock]

Chris
I have not completed my 6x47 yet because I am waiting on my Broughton 8 twist barrel which should arrive with in a couple weeks.I have everything else to complete this switch barrel project.

I am expecting this gun to shoot .250 and better 100yd groups as do my other rifles built by the same smith.

I will skim the necks on a turner to achieve a .270 loaded round for the .272 neck if needed.I have not measured this brass as it has been on backorder.

I am finished putting mileage on barrels fireforming improved cases,I have owned several Ackley's and don't want to be bot hered with this task.The 6x47 lapua is exactly what I was looking for in a higher capacity case than the standard BR to push the heavier 6mm bullets past 3000 fps easily with minimum hassel in case prep.

 

[reverend]

Some thoughts on the 6 X 47. Some of the following figures are rounded off.

I have loaded my 6 X 47 brass 14 times and have only neck sized the brass. I've had no brass failures. Lets say I get 15 reloads out of this brass and want to shoot 2000 rounds. At current prices $0.71 each times 2000 divided by 15 reloads equals $0.0473 a round, or $94.66 for 2000 rounds.

The same numbers for the Dasher $0.51 each times 2000 divided by 15 equal $68.00. $26.66 less than the 6 x 47. I'm shooting 105 Lapuas, $0.215 each times 2000 equal $430.00. If you include the initial fire forming of the Dasher with the same bullet it raises the cost of the brass to $0.725, more than the 6 X 47. I've had several case failures with the Dasher, and it's certainly more work than the 6 X 47 to form. You sacrifice the first loading to form the case. I have never gotten 15 reloads out of my Dashers. In my hands it's cheaper to shoot the 6 X 47 and the case prep is much easier.

I run my 6 X 47 at 3250 fps. My Dasher at 3000 fps. Wind drift for a 10 mph cross wind at 1000 yds for the 6 X 47 is 52.5 inches, 59.1 inches for the Dasher, 6.6 inches less, a greater than 11% improvement. Drop for the Dasher at 1000 yds is 253.6 inches, 210.9 inches for the 6 X 47. 42.7 inches less for the 6 X 47, a 17% improvement. Drop for a 284 WIN with a 168 gr Sierra at 2970 fps at 1000 yds would be 270.4 inches, 59.5 inches more than the 6 X 47, a 22% difference. Wind drift with a 10 mph crosswind would be 66.2 inches, 13.7 inches more than the 6 X 47, a 21 % difference.


Even with using the figures slanted in favor of the Dasher I'm only saving $26.66 for a loss of at least 11%. The time spent fire forming the cases including driving to the range is worth different amounts to different people, my time is worth much more than $26.66. I have spent thousands of dollars in equipment for much less than an 11% gain.

I guess the major question is the inherent accuracy of each round. In my guns, in my hands, the 6BR beats both up to 300 yards, and the 6 X 47 does better than the others at longer distances. My 6 X 47 is much more accurate at 3250 fps than it is at 3000 fps. I understand there are questions about excessive pressure at this velocity but I haven't experienced any problems. Barrel life could be an issue, I have 2800 rounds through my 6 X 47 now and it still shoots great, don't know how long it will last. All these rounds are pleasant to shoot, low recoil.

I think the 6 X 47 is going to be hard to beat.

John

 

[steveyrock]

John
Thanks for that information on the 6x47 good to hear from someone who has been shooting it.I know others are building and shooting this chambering but are not saying to much.

Your findings are very encouraging.

 

[Forum Boss]

Stevey,

We've been real excited about Reverend's reports on his 6-6.5x47. Just be aware that he's been able to operate in the high end of the velocity range. Some guys have been maxing out a little over 3100 with the 105s.

At 3250, the ballistics on the 6-6.5x47 are spectacular, but realistically, you may want to figure on 3150 at the upper end, and use that for your comparisons with a Dasher, which is pretty comfortable at 3030-3050 with the 105s. So, figure you're picking up 100-120 fps with the 6-6.5x47, with no fire-forming chores.

 

[mysticplayer]

With the awesome results shooters are getting withe various 6mm's, I wanted to compare wind drift with the 6.5 bullet I am using. Using the defaults in the JBM program on the internet, this is what I got. First is wind drift at 600yds, then 1000yds at muzzle velocity posted


107grMK ,3150fps 22.2", 71.9")
105gr Scenar ,3150fps 22", 70.8")
105gr Amax ,3150fps 23.7", 76.7")

115gr Tubbs,3100fps 20.5", 64.9")

139gr 6.5 Scenar ,2900fps 20.8", 65.7")
,3000fps 19.8", 62.4")

168gr 7mm Berger ,2950fps 19.1", 59.7")
180gr 7mm Berger ,2950fps 17.5", 54.3")

There is no doubt that BC is a flaky thing and varies with the barrel/velocity but the results are interesting.

Jerry

 

[CAB]

Something to consider, w/ the 6x47 Lapua, if one has one's reamer throated properly, there is another option. While it hasn't been discussed, some slower powders do work very well in some rifles.
I will not get specific charge wgt.'s as we all know the variation that exists in the way different 6mm barrels handle pressure. I personally have been playing with a particular lot of RL22, and have topped 3250,...by a meaningful number of FPS.
CCI450's only. Pressure was undetectable. Yes it's cold right now, but I think these results will be usable in the spring summer season from what I'm seeing so far. Accuracy was at very least encouraging. These charges have to be dropped through a funnel/drop tube combination. Not saying this to be sensational, just don't rule out some slower propellants.
The question is,.... are the bullets available able to generate the kind of accuracy we expect at velocities exceeding 3200 consistently?

 

[mysticplayer]

So far it doesn't look promising for long high BC bullets to travel over 3200fps. Many don't like going much over 3000fps. The rotational stress can distort or tear the bullets apart,8 twist or faster). Where there has been success is in 30 and 338's. I suspect that the larger diameter makes for a much stronger bullet plus they usually only need a 10twist to function.

Be interesting to see how the 6mm shoot at 300yds and beyond when pushed over 3200fps.

As someone said, when we need a twist rate faster then 7, we are approaching the structural limits of bullets to be pushed fast.

If that is so, we are at the limits in the 6mm with the 115gr. We may be able to go 120something but this bullet is unlikely to enjoy going fast,should still go 2900 to 3000fps though). Unless, someone comes up with a different way to build bullets.

That leaves the larger 6.5 and 7mm the bores to see higher BC bullets. Of course, the 25 and 270 cals have enormous potential but no one wants to tool up to make bullets yet.

Jerry

 

[JOHN708]

Chris,
I'm not experiencing any pressure problems running 105's at 3080fps. Currently I have 12 reloads through the cases and haven't lost one to pressure problems,or have had to trim them.
Berger changed their BC's on the 7mm 180 from .698 to .685. With a 10 mph Xwind at 1000 yds with 180's at 2970fps, using the old BC's the wind drift is 53 in. Add 1-2 in with the new BC.

Running 105 Bergers at 3250fps gives you 5 in. less wind drift at 1000 yds than 105's at 3080 fps. I would figure 900 to 1200 rds of barrel life out of that 6mm improved case. Hardly worth it, in my opnion.
My 6brx fireforming loads are giving me .46 in 10 shot groups at 100 yds. Great practice load in prone.
John Skowron