Search this title or "6mm SMACK" and tell me what you think, please... What's the difference between an Ackley Improved 6-6.5x47Lapua case?? This guy got 3,300fps with RL17 and 105gr bullets.. Do any of you guys have experience with "Ackleyizing" the 6.5x47 cases?? It would be like a "large Dasher.."
The "6mm Swiss Match Ackley" Cartridge
- Thread starter SHootSTraight22
- Start date
Terry said:
Yea, I'm beginning to think I should give up on a cartridge that likes 3,200-3,250fps with 6mm 105 bullets... I was wanting that because a 105gr has to be at that speed to perform like a 140gr 6.5 in the wind... It seems like it's just easier for me to shoot a 140gr 6.5mm at 2,900-3,000fps than finding my soft kicking 6mm that loves 3,200fps.... Damn!!! I'm just looking for the most wind bucking/soft recoiling round available for tactical/practical... If I didn't think recoil was a henderance I would just use a 260 Ackly or 260 Improved 30 degrees and be happy... But, I really believe theirs a major benefit to light recoiling 6mm's!!!
Just for bells and whistles I should chamber a 6mm Creed Improved because of all the cases I have!!!! It would be fun!!
Shootstraight -
Howdy !
Just a couple of FWIW items, from Homer Powley's " Powley Papers " ( 1974 Guns & Ammo Annual ):
Muzzle Velocities in 26" barrel
Calibre Bullet Expansion ratio
Weight 4 5 6 7 8 10 12
.224 66 4050 3865 3700 3580 3400 3170 2990
6mm 85 3890 3740 3575 3435 3225 3090 2910
According an " Expansion Ratio " chart Powley included w/ his tech " papers ".....
In a 28" barrel, a 6mm wildcat would require about 46gr of powder @ an expansion ratio of 7.8; to generate 3,250fps.
That would seem to indicate an initial case capacity of around 54gr H2O would be required for the parent brass, w/ capacity loss incurred as calibre is reduced 6mm final. .243Win is listed as having case capacity of 54gr H20, from the git go.
Extrapolated from Hogdon's load data: from a 26" barrel, a 6-284 shooting 45.5gr H4350 could put around 3,230fps on an 85br bullet.
That correlates pretty good w/ Powley's " Expansion Ratio " table, above. 105s would of course, be slower.
Looking now @ a 6mm wildcat w/ case capacity less than a 6 - .284 :
- IMR4350 has a bulk density of around .885, I've read.
- Reviewing case w/ 49gr H20 capacity: total powder capacity of 43.3gr IMR4350 probably could not be fully-realized, as H2O case capacity is
measured / case full to the mouth; while in practical use..... case neck volumne would be occupied by the bullet.
I believe the 6 XC runs about 49gr H2O capacity, w/ 6 X 47 & 6 Creedmoor also around this ball park.
- I'm not sure you'd want to " blow out " the shoulders on any of the 3 cases mentioned immediately above, as they already have pretty minimal taper.
Sharpening the shoulder angle of the 6 wildcat w/o a concurrent shoulder " blow-out " , will result in increasing case capacity loss ( however
small ) as case design' shoulder angles are made sharper & sharper. If your chosen rifle permits it, a sufficiently long neck length along w/ an
informed shoulder angle choice; will keep the powder combustion " turbulence point " inside the case' neck. 6mm Remington is one example.
In other words.... use adequate neck lg along w/ sufficient shoulder angle in-lieu of using very sharp shoulder angles. Yes, design case length
will grow; in result. What can the chosen rifle accomodate, case oal / cartridge oal-wise ?
Info -
The shorty .284Win-based 6mm wildcat case mentioned in your other post was 1.710 " lg ) and held 44gr D85 surplus " ball " powder to base of neck; case un-fired. Compare to: 6XC @ 1.898" lg, 6 Creedmoor @ 1.920" lg
With regards,
357Mag
Howdy !
Just a couple of FWIW items, from Homer Powley's " Powley Papers " ( 1974 Guns & Ammo Annual ):
Muzzle Velocities in 26" barrel
Calibre Bullet Expansion ratio
Weight 4 5 6 7 8 10 12
.224 66 4050 3865 3700 3580 3400 3170 2990
6mm 85 3890 3740 3575 3435 3225 3090 2910
According an " Expansion Ratio " chart Powley included w/ his tech " papers ".....
In a 28" barrel, a 6mm wildcat would require about 46gr of powder @ an expansion ratio of 7.8; to generate 3,250fps.
That would seem to indicate an initial case capacity of around 54gr H2O would be required for the parent brass, w/ capacity loss incurred as calibre is reduced 6mm final. .243Win is listed as having case capacity of 54gr H20, from the git go.
Extrapolated from Hogdon's load data: from a 26" barrel, a 6-284 shooting 45.5gr H4350 could put around 3,230fps on an 85br bullet.
That correlates pretty good w/ Powley's " Expansion Ratio " table, above. 105s would of course, be slower.
Looking now @ a 6mm wildcat w/ case capacity less than a 6 - .284 :
- IMR4350 has a bulk density of around .885, I've read.
- Reviewing case w/ 49gr H20 capacity: total powder capacity of 43.3gr IMR4350 probably could not be fully-realized, as H2O case capacity is
measured / case full to the mouth; while in practical use..... case neck volumne would be occupied by the bullet.
I believe the 6 XC runs about 49gr H2O capacity, w/ 6 X 47 & 6 Creedmoor also around this ball park.
- I'm not sure you'd want to " blow out " the shoulders on any of the 3 cases mentioned immediately above, as they already have pretty minimal taper.
Sharpening the shoulder angle of the 6 wildcat w/o a concurrent shoulder " blow-out " , will result in increasing case capacity loss ( however
small ) as case design' shoulder angles are made sharper & sharper. If your chosen rifle permits it, a sufficiently long neck length along w/ an
informed shoulder angle choice; will keep the powder combustion " turbulence point " inside the case' neck. 6mm Remington is one example.
In other words.... use adequate neck lg along w/ sufficient shoulder angle in-lieu of using very sharp shoulder angles. Yes, design case length
will grow; in result. What can the chosen rifle accomodate, case oal / cartridge oal-wise ?
Info -
The shorty .284Win-based 6mm wildcat case mentioned in your other post was 1.710 " lg ) and held 44gr D85 surplus " ball " powder to base of neck; case un-fired. Compare to: 6XC @ 1.898" lg, 6 Creedmoor @ 1.920" lg
With regards,
357Mag
Shootstraight -
Howdy !
Here's what I did:
"DEEP 6 " :
- 6mm Remington reamer in " short "
- .466" base diam
- .431" shoulder diam.
- .473" rim diam
- .350" neck lg is VLD-friendly
- 26* shoulder angle makes DEEP 6 easy to form
- 7 X 64 Brenneke brass
- 6.5 X 55 Swedish FL die used for case forming
- Case oal trim, then inside neck ream & outside neck turn to 6mm calibre final
- 51.2gr H2O case capacity
NO custom dies to $$$, no custom reamers to $$$.
DEEP 6 shown in center of pic.
With regards,
357Mag
Howdy !
Here's what I did:
"DEEP 6 " :
- 6mm Remington reamer in " short "
- .466" base diam
- .431" shoulder diam.
- .473" rim diam
- .350" neck lg is VLD-friendly
- 26* shoulder angle makes DEEP 6 easy to form
- 7 X 64 Brenneke brass
- 6.5 X 55 Swedish FL die used for case forming
- Case oal trim, then inside neck ream & outside neck turn to 6mm calibre final
- 51.2gr H2O case capacity
NO custom dies to $$$, no custom reamers to $$$.
DEEP 6 shown in center of pic.
With regards,
357Mag
Attachments
Damn, Your the guy that did the Deep Six?? I was looking everywhere for the pic I saw months ago of that cartridge!!357Mag said:
Why?SHootSTraight22 said:
In your other thread I described a buddy that does just what you're looking for with a 6mm Rem, 3250fps, 105 gr Bergers and R17 for 30mm (1 1/4") groups @ 500 Yds.
Custom throat to match the pill and little else other than a bog standard setup.
Rabbits @ 800+ yds is his PB.
Terry is right. It seems whenever you go over 3000 the accuracy gets lost. If you look at the History of 1000 yard BR and see what they used 40 years ago and now. Back then they used big cases, the 6.5-300, 7-300 and 30-378. They drove them in the 3100 to 3200 and up range. Now they use 300 WSM (2850), 6 Dasher (2950 to 3050) and slower more accurate cartridges. It all comes down to the inherent accuracy. I have worked with both big cases and smaller ones and the smaller ones are just more accurate. It also has to do with bullet stability. Matt
Because of the kind of matches I shoot I will need first round/cold bore hits, so H4350 is almost a must use.. H1000 is harder for me to find these days and most likely thats what your shooting in your 6CM.. What kind of velocity can the 6CM get with H4350?? Besides the 1 degree shoulder angle difference, what are the other differences between the 6CM and 243 Improved 30 degree's??Dgd6mm said:
I'm setting here looking at a 6.5-284, 260 Ackley Improved,6Dasher, and a 6.5x47 Lapua case, all side by side... Just by looking at these cases and holding them up beside one another I see know reason my goal couldn't be achieved by taking the 6.5-284 case and pushing the neck down (extending the neck) the length of a 6.5x47 case and having a 6mmDasher shoulder setting underneath?? What you would wined up with is a shoulder that sets between where the parent 6.5-284 case is now and a 260 Ackley Improved shoulder sets.. It would be right between the two... Add to that the 6.5-284 case is fatter than an Ackley Improved 260 and you should get the powder capacity somewhere between the two cases... Put a 6mm 105 Hybrid in that longer neck (6mm neck as long as a 6.5 Lapua neck) and you should have a 3,200fps H4350 shooter?? I would think??? Just start with the full length 6.5-284 case and don't shorten it at all, just push a longer neck on top, then start forming a Ackley/Dasher shoulder underneath... Should be good???
dkhunt14 said:
I understand you guys that shoot bench or similiar sports looking for bughole accuracy but, all I need is .5 moa or better with a good wide accuracy node ( I would say .4gr is good enough for me, meaning if I shot rounds loaded within my node with that range of charge I wouldn't get more than 12 S-D..) I'm looking to cheat the wind as much as I can, plus flat shooting.. According to my calculations on Applied Ballistics 3,250fps is the magic number for a 6mm 105gr hybrid to get the advantage I would like... Plus, add in a longer than normal neck and I'm hoping for 500-750rds more of barrel life.. But, I think people are getting lost here when not thinking about I shoot tactical/practical steel matches...
You mention blowing out the shoulder of a 6mm Creed, 6XC, and 6-6.5x47 Lapua??? I tell you what, I'm kind of interested in Ackleyized cases in these calibers.. I have plenty of 6mm Creed brass to play with and can get plenty more for nothing.. But, the 6.5x47 case is so much better of a parent case to start off of.. The final product after Ackleyizing it (6-6.5x47) won't have the case capacity as the 6mm Creed Ackleyized case though.. Time has shown the 6.5Creed gets a 50fps node greater than the 6.5Lapua cartridge, so using the more room of the Creed case maybe the best thing to do with these... I had someone tell me that Lake City 308 "formed Creed" is the way to go or Palma cases if shooting a Creed... But all in all, I bet a Ackley Improved 6-6.5x47 or 6mm Creed would be real fun to shoot! Does anyone have any experience with these cases??357Mag said:
Guys, I figured it out! It's simple!! I'm holding a 6.5/284 in my hand beside a 6mm Rem and 243 Ackley Improved case.. All that's got to be done is blow out the taper on the 6.5/284, underneeth the new shoulder that is at the height of the 243 Ackley Improved case.. That leaves enough room to put the 6mm Rem's neck and shoulder on it with slightly varying degrees, but basically a 6mm Rem neck/shoulder on top of a case/body that looks like an 243 Ackley but fatter... Simple..
Brians356
Gold $$ Contributor
The 6.5 x 47 already has minimal body taper. There's but scant "improvement" available from Ackley-izing the 6.5 x 47 Lapua case. In another thread I pointed out the marked similarity between the 6.5 x 47 Lapua and the 250 Ackley Improved, the latter's body being about .010" longer but body taper and diameter at the base of the shoulder are essentially identical.
The only significant "improvement" might be in steepening the shoulder angle from 30-deg to, say, 40-deg, but I gather the perpetrator was aiming for more significant case capacity gains, not just any gains attributable to a steep shoulder (e.g. resistance to brass flow.)
Unless I'm missing something.
The only significant "improvement" might be in steepening the shoulder angle from 30-deg to, say, 40-deg, but I gather the perpetrator was aiming for more significant case capacity gains, not just any gains attributable to a steep shoulder (e.g. resistance to brass flow.)
Unless I'm missing something.
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