coleman1495
CGN Ultra frequent flyer
- Location
- Whitecourt
Hmm that’s weird I’m only showing 61k psi with the info Marty provided. The predicted velocity would be 2710fps. Which number are you tweaking to get a velocity of 2790 and the 75k psi?
Load dev inquiry- approaching higher end of hot load
- Thread starter MartyK2500
- Start date
Hmm that’s weird I’m only showing 61k psi with the info Marty provided. The predicted velocity would be 2710fps. Which number are you tweaking to get a velocity of 2790 and the 75k psi?
start pressure @ 10,000, assuming he's within .040" of lands
the default of 3626psi would be like 1/4" freebore
coleman1495
CGN Ultra frequent flyer
- Location
- Whitecourt
Perfect thanks. Where are you seeing the freebore vs start pressure data?
Edit- with 10k psi initiation pressure I only get 69k peak pressure. Did you just continually increase the initiation pressure until you got to the measured velocity?
The only thing I seen on Quickload regarding initiation pressure states that if the bullet is seated to touch the rifling add 7200psi. Marty didn’t load the bullets touching the lands.
Last edited:
It's in the QL manual and lots of content on forums, including CGN
3626psi + 7200psi for touching lands, subtract 29psi for every .001" the bullet is jumping to the lands
I get 2719 fps (26" barrel) with 142gr SMK @ 2.8" OAL, 48.0grs h2O case capacity, Weighting factor 0.5, 35.9grs Varget. He's getting 2784 fps, so I adjusted Burn Rate (ba) from default .6150 to 0.6730. Muzzle velocity is then 2784 fps, chamber pressure is 74,190
Just letting you know I have just done this, for other reasons so it’s 2 birds 1 stone type of thing.
Just saw a retailer restock H4350, in large 8 pound jugs, for cheaper I have ever saw in 2020 and possibly 2019.
I figured I may as well buy 24 pounds, enough to burn 2x barrels and out of the American election.
Since Varget is getting so hard to find I’ll keep it for my 556/308
Edit : Took some old load data out, at the time I had problems cause I wasn’t turning necks.
H4350 - 142SMK - CCI 450
36.8 = 2610fps
37.0 = 2638fps
37.2 = 2650fps
37.4 = 2664fps
Was thinking of exploring 37.2 to 38.2 next visit
With a Labradar, insuring I don’t get past 2720-2730
Last edited:
Marty,
Back in the day, I was one of the early adopters of the 6x47 Lapua and had a heck of a time with it at first. I could not get real consistent velocity in strings but especially from one day to the next with temperature changes.
I eventually got creative and fished some fired 22-250 brass out of the bucket at the range. I ran those cases through my 6x47L sizing die so I'd have large primers.
Once I worked out loads for those cases, everything settled down and I never looked back.
Back then I even spoke with Tubbs and Salazar about it and they agreed I was on solid ground.
I never used small primer brass again and nobody on this planet could ever talk me into going back to them.
There are always guys who will jump in about now and question everything I did as a suggestion that I must have been doing something wrong, and to them I question their own ability to collect and asses and diagnose information.
I can only suggest that you at least give it a try. Document your results over significant temperature changes, and decide for yourself if the whole small primer thing is anything more than a two bit marketing stunt.
I already have my answer.
With large primers, that 6x47L became the most accurate rifle I ever owned. I had to turn my chronograph off between shots to confirm it registered the next shot because it was so frequently the same number.
Back in the day, I was one of the early adopters of the 6x47 Lapua and had a heck of a time with it at first. I could not get real consistent velocity in strings but especially from one day to the next with temperature changes.
I eventually got creative and fished some fired 22-250 brass out of the bucket at the range. I ran those cases through my 6x47L sizing die so I'd have large primers.
Once I worked out loads for those cases, everything settled down and I never looked back.
Back then I even spoke with Tubbs and Salazar about it and they agreed I was on solid ground.
I never used small primer brass again and nobody on this planet could ever talk me into going back to them.
There are always guys who will jump in about now and question everything I did as a suggestion that I must have been doing something wrong, and to them I question their own ability to collect and asses and diagnose information.
I can only suggest that you at least give it a try. Document your results over significant temperature changes, and decide for yourself if the whole small primer thing is anything more than a two bit marketing stunt.
I already have my answer.
With large primers, that 6x47L became the most accurate rifle I ever owned. I had to turn my chronograph off between shots to confirm it registered the next shot because it was so frequently the same number.
Lately I’ve been looking at load data.
And combined with the replies in this thread I am frankly surprised.
We see pressure signs in my setup while being well hidden, and we all agree (even myself) that I have to tone it down a notch,
And still I see loads on accurate shooter’s articles, PRS blog, SH and even CGN, going almost a full grain more than me and approaching (even dipping in) the 2800fps velocities.
I live in Ottawa, no abnormal altitude reading by any means.
Still has me wondering, are these guys running rifles in 6.5x47L at 70K psi+ range?
Myself have made an adult decision,
Going on a H4350 load dev, objective is to cover the 2600 to 2700 fps range.
Even at 2600, I’m over 1300fps @ 900M, which is my local range distance I can shoot at.
Won’t even explore the early 2700fps loads unless the 2600fps loads can’t provide me with consistent, repeatable sub 1/2 moa 10 shot groups at at least 200M.
Been shooting the slow node in my 308 for 3 years now, lands haven’t even moved a thou 2500 rounds later, and it’s been real accurate for me out to 800M (900M it sees a drastic jump in group opening)
Maple57
I remember you saying this when I had problems tuning my rifle.
In theory it sure makes sense.
But the practical side of it, is not so feasible.
Working 55-60 hour weeks and going to the range 2-3x a week, my spare time is already much too strained to start modding/fireforming brass into other calibers.
And combined with the replies in this thread I am frankly surprised.
We see pressure signs in my setup while being well hidden, and we all agree (even myself) that I have to tone it down a notch,
And still I see loads on accurate shooter’s articles, PRS blog, SH and even CGN, going almost a full grain more than me and approaching (even dipping in) the 2800fps velocities.
I live in Ottawa, no abnormal altitude reading by any means.
Still has me wondering, are these guys running rifles in 6.5x47L at 70K psi+ range?
Myself have made an adult decision,
Going on a H4350 load dev, objective is to cover the 2600 to 2700 fps range.
Even at 2600, I’m over 1300fps @ 900M, which is my local range distance I can shoot at.
Won’t even explore the early 2700fps loads unless the 2600fps loads can’t provide me with consistent, repeatable sub 1/2 moa 10 shot groups at at least 200M.
Been shooting the slow node in my 308 for 3 years now, lands haven’t even moved a thou 2500 rounds later, and it’s been real accurate for me out to 800M (900M it sees a drastic jump in group opening)
Maple57
I remember you saying this when I had problems tuning my rifle.
In theory it sure makes sense.
But the practical side of it, is not so feasible.
Working 55-60 hour weeks and going to the range 2-3x a week, my spare time is already much too strained to start modding/fireforming brass into other calibers.
I suspect the reason you are having issues are the same as my own.
Inadequate ignition results in erratic internal pressure spikes.
Going to a large primer ensures that you get consistent and enthusiastic ignition every time.
Dialing back the load and sticking with small primers does not resolve the fundamental problem. That just reduces the problematic spikes to a tolerable level.
Caliber: 6.5x47 Lapua
Rifle brand:
Rifle Model: Bighorn Origin
Custom built: Yes
Barrel length and twist: 26" 1:8" IBI M40 (0.920’’@muzzle)
Projectile brand, model and weight: Lapua 139gr Scenar
Powder brand and weight: Varget 35.7gn
LOAD CONSIDERED HOT OR CLOSE TO MAX: ?
Primers: CCI 450
Coal:2.710’’
Ogive length: 2.152’’
Brass: Lapua
Brass trim length: 1.843’’
Distance to lands: .010"
Velocity (average): 2739fps (5 shot Ave, ES=2 SD=0.8)
Outside temperature: 74F
Wind and direction: N/A
Barometric pressure and other relevant data: elevation 69M ASL
It says the 6.5x47 Lapua is intended for 63K pressure.
80K and our friend would be having major problems on his hands.
Maybe something not going in right into the QL?
Anyhow lot’s of americans are pushing 140s Berger Hybrids in the 2800++fps,
Have a hard time believing there’s no pressure going on there!
