6mm BR vs 6.5x47?

[mattri]

How does the 6x47 fit in to this, what are the pros and cons to it?

 

[johara1]

Change the BR to a Dasher and the 47 slides down the list a little further……. jim

 

[Laurie]

How does the 6x47 fit in to this, what are the pros and cons to it?

The '47L case has in round figures ~20% greater capacity than a standard 6mm BR and 17% more than the 'improved' Dasher version. The rule of thumb is that you get a quarter of the % capacity increase as a % MV improvement (if barrel length and maximum pressures remain the same).

So, the 6X47L (6-6.5X47, it's often called) will give roughly 5% higher MVs than the standard BR and 4% more than a Dasher which doesn't sound a lot but adds 150-200 fps for 105s and is better suited ballistically to 115s should those take your fancy. There is an existing cartridge there which is ballistically close to this combination - the 6XC which has a marginally greater case capacity. However, the 6X47L appealed more than the 6XC to many due to the high-quality and very strong Lapua brass allied to its being a small primer / small (1.5mm dia.) flash-hole design like the PPCs and BRs. (The XC uses Large Rifle primers and the standard 2mm / 0.080" dia flash-hole.) With this size of cartridge and not normally employed in really cold way below freezing conditions, small primer ignition is regarded as a plus for a precision cartridge, the primer power and heat better suited to the relatively small charge.

With a parentage of the very accurate 6.5 and many BR / Dasher features, this looked like the wildcat developed in heaven, only needing the neck sized down one step - no case fireforming etc as in the 'improved' BRs with a considerable step up in MVs on the cards. Some people predicted in the '47L's early days that the 6mm wildcat version would be 'bigger' than the parent in a few years.

However, whilst it's probably unfair to say the promise wasn't realised, it proved difficult to achieve. Not on velocities which are fine, but obtaining top-notch and really consistent precision. Some people have made it work as a mid and long-range BR number, but the general feeling is that the Dasher is much easier to tune and loses little from its lower MVs. There are some 115gn fans amongst 6mm aficionados, but most people have decided that 105-108gn is the optimum bullet weight for the calibre, so increasing case and charge size to handle the heaviest bullets isn't the advanatage it was once thought.

In F-Class, it's back to 6.5mm bullets' BCs v 6mm and most people will drop fewer points to wind changes with the stock 6.5X47L than to a hotrod 'six', even one shooting 115s.

 

[johara1]

It all sounds good, but in accuracy everything is down hill from the Dasher at 600 - 1000……….. You may once in a while beat it with a single group but not in a yearly agg. The best day with a 47 is an average day with a Dasher. As far as the wind the only thing it won't do is make up for your inability to read the wind and no caliber will do that ………. jim

 

[BOB LEE SWAGGER]

What is the conjecture on how the performance will be once the factory dasher brass is made/released/for sale?

 

[johara1]

I would guess we will know when some of factory made Dasher brass gets out in our hands. I would think it would be a step in the right direction if you can't make it yourself, and be a lot easier for those that do……… win win……. jim

 

[people]

I've about had it with my 6.5x47. It has been the most frustrating gun I've ever owned. I've got over 500 rounds in it and it doesn't shoot anywhere close to the brx or dashers I've owned.

It will throw 1 of 5 shots 1/4 to 1/2 inches off the group with no pattern of which one it would be. I've shot every primer you can think of and 136's and 130 vlds. I've only shot H4350 and my next step is switching powders.

I'm not 100% sure but I also believe the .123 freebore is part of my problem and should you go with a x47 do at least a 150 freebore.

To answer your question, an improved 6br does everything a x47 will do less than 700 yards with no downside (and cheaper) except feed reliable through a mag.

Sounds like a junk tube to me.

 

[Changeling]

Well I certainly don't have any experience with either of these cartridge cases yet, but would like to add a thought.

The "47" might just be having some problems because of barrel twist rates relative to what bullets you are shooting and there Ballistic Coefficients.
Everyone seems to say (here) that the 123 -130's shoot best. Haven't heard any great positive results about the 140's ! This kind of brings up the probability that due to the lower velocities (6.5 x 47L case capacity) everyone has been shooting somewhat on the "edge" of stability, witch can also be relative to your elevation above sea level !

Totally my thoughts/idea but it definitely needs more research. So don't blame anyone but me!

As for me, my intention is to build a switch barrel and the first barrel will include my above thoughts on twist rates.

 

[Judd]

Two good points...Dallas is around 430' above sea level and the barrel is a Kreiger 8.5 twist. Oh and if I have to go down to 120/123's then that pretty much negates any advantage the 6.5 has over a 105 hybrid...even past 700, at 1000 the 105 would have 71.9" to the 123 has 77.7" (both numbers using 3000fps and I'm running most of my hybrids closer to 3100 than 3000).

Feels like I just need to pull this barrel off and save the powder and bullets...not sure I'm not more hard headed than that though ;D I could also have the gunsmith deepen that throat .050 and give that a try too.

 

[mattri]

Great information- very grateful to all for making this a very interesting (to a newbie like me) read.

It sounds like the heavy for caliber 6.5s aren't popular with the 6.5x47 crowd because of lack of boiler room to get them up to speed, is that accurate?

It would seem that if you're shooting long range the 140s with their .585ish BC would be better than the 120s with their .510ish BC.

 

[Erik Cortina]

Well I certainly don't have any experience with either of these cartridge cases yet, but would like to add a thought.

The "47" might just be having some problems because of barrel twist rates relative to what bullets you are shooting and there Ballistic Coefficients.
Everyone seems to say (here) that the 123 -130's shoot best. Haven't heard any great positive results about the 140's ! This kind of brings up the probability that due to the lower velocities (6.5 x 47L case capacity) everyone has been shooting somewhat on the "edge" of stability, witch can also be relative to your elevation above sea level !

Totally my thoughts/idea but it definitely needs more research. So don't blame anyone but me!

As for me, my intention is to build a switch barrel and the first barrel will include my above thoughts on twist rates.

Great information- very grateful to all for making this a very interesting (to a newbie like me) read.

It sounds like the heavy for caliber 6.5s aren't popular with the 6.5x47 crowd because of lack of boiler room to get them up to speed, is that accurate?

It would seem that if you're shooting long range the 140s with their .585ish BC would be better than the 120s with their .510ish BC.

And this is how rumors start! Many shooters use 140's in their 6.5x47's I have used 139's exclusively but will try the 136's soon. Ryan Pierce shoots 140 gr. Hybrids and has shot a 1398 out of 1400 at 600 yards with over 100X's. He has also shot groups under 5" at over 1,100 yards with 140's. The "47" has enough boiler room to push the heavy bullets, and in my opinion, they work best. I use a 1:8" twist.

Forum member CSS has also had great success shooting 140's out of his 47. He has shot multiple cleans with it at 1,000 yards on the F-Open target.
Here is a picture of one of his 1,000 yard cleans.
http://forum.accurateshooter.com/index.php?topic=3854177.msg36455906#msg36455906

 

[mattri]

Glad to hear the 6.5x47 can shoot the 140s well. What load are you using and what velocities are you seeing?

Honest question- than why is so much information, even posts in this thread focused on the 120/130gr bullets?

 

[Patch700]

My 6.5x47 uses an 8 twist and was throated to utilize 139 scenar OTM bullets.

With 40.5 grns of vv N-550 I am able to achieve 2800fps .... ironically enough when I came from a 6.5x284 my best groups were when the speed was kept to 2850-2900fps while using the 140 class bullets.

My best guess as to why most folks find a niche with 120-130 class bullets and not 140's is too short of a throat and the fear of committing to an 8 twist or even 7.5.

 

[Erik Cortina]

Glad to hear the 6.5x47 can shoot the 140s well. What load are you using and what velocities are you seeing?

Honest question- than why is so much information, even posts in this thread focused on the 120/130gr bullets?

I push mine to 2,880 fps. using N550 and a 32" barrel. I will soon develop a load using N140 or N150 using 136 gr. Scenar L's. My daughter will start shooting my gun, so I will probably load it down around 2,800 fps.

I don't really know why guys use lighter bullets than 136-142. I personally never have in my competition guns. In my hunting rifle, I use 123's simply because whitetails are not very tough to kill and they shoot flatter than the heavy bullets.

 

[stinnett1981]

My 47 shoots in the 1's on the bench. I never shot a 6 br though. At 600 yards I can hit clay bird basically every shot. Well as of today i did! I was shooting 140 grain Amax with H4350. My freebore is .170 and i run it pretty hot so i wont post my exact load. I thought my custom .308 was accurate until I had a 47 built. It shoots inside of it by 1 half literally. I'm absolutely stoked for next year's F class season. I think I will win a lot of matches! The 47 is awesome!

 

[johara1]

My 47 shoots in the 1's on the bench. I never shot a 6 br though. At 600 yards I can hit clay bird basically every shot. Well as of today i did! I was shooting 140 grain Amax with H4350. My freebore is .170 and i run it pretty hot so i wont post my exact load. I thought my custom .308 was accurate until I had a 47 built. It shoots inside of it by 1 half literally. I'm absolutely stoked for next year's F class season. I think I will win a lot of matches! The 47 is awesome!

See... there you go, it shoots 1's off the bench…….. A dasher shoots 1.s all the time and mostly groups in the zero's and at 600 it where you hit the clay bird and the same at 1000…….. jim

 

[Erik Cortina]

My 47 shoots in the 1's on the bench. I never shot a 6 br though. At 600 yards I can hit clay bird basically every shot. Well as of today i did! I was shooting 140 grain Amax with H4350. My freebore is .170 and i run it pretty hot so i wont post my exact load. I thought my custom .308 was accurate until I had a 47 built. It shoots inside of it by 1 half literally. I'm absolutely stoked for next year's F class season. I think I will win a lot of matches! The 47 is awesome!

See... there you go, it shoots 1's off the bench…….. A dasher shoots 1.s all the time and mostly groups in the zero's and at 600 it where you hit the clay bird and the same at 1000…….. jim

Jim, I'm sure with the right barrel and load the 47 can also shoot in the 0's.

This 47 only shoots in the 2's but it was good enough to set a record. I don't shoot BR so I don't know if it's good or not, so I compared it to your record targets and the 47 shot smaller than your smallest group with the Dasher. I understand they probably only shot one small group and you shot more than that, but a small group is still that, a small group!

http://bulletin.accurateshooter.com/2014/05/aussie-sets-southern-hemisphere-1k-record-with-borrowed-rifle/

 

[johara1]

Erik, I'm still looking for the right barrel, but the average one's are ok i guess……... …….. Oh by the way the .2's won't get you a world record …... jim

 

[mattri]

Sounds like if folks are loading to the same velocity as a 6.5-284 pressure is probably a bit higher.

 

[stinnett1981]

My 47 shoots in the 1's on the bench. I never shot a 6 br though. At 600 yards I can hit clay bird basically every shot. Well as of today i did! I was shooting 140 grain Amax with H4350. My freebore is .170 and i run it pretty hot so i wont post my exact load. I thought my custom .308 was accurate until I had a 47 built. It shoots inside of it by 1 half literally. I'm absolutely stoked for next year's F class season. I think I will win a lot of matches! The 47 is awesome!

See... there you go, it shoots 1's off the bench…….. A dasher shoots 1.s all the time and mostly groups in the zero's and at 600 it where you hit the clay bird and the same at 1000…….. jim

When i say off the bench that's with a harris bipod and rear bag. I'm not set up benchrest. When i was shooting clay birds I was shooting with a AICS mag and blasting them fast! I was shooting for fun with friends.