Load dev inquiry- approaching higher end of hot load
- Thread starter MartyK2500
- Start date
I am not really clear on what is referred to a node. To me it is a barrel time (eg: in a 26" bbl. one node would be at 1.1905 mS), what this represents is the barrel is at its calmest and tightest at the muzzle when the bullet is released.
The handloader will have to use QuickLoad (QL) to determine where the 'node' or Optimum Barrel Time (OBT) is. Ultimately it is powder charge that will determine if you achieve the barrel time that coincides with the 'node'.
In handloading it is consistency of the round is a must, that is low Extreme Spread (ES). When you have single digit ES's you can be assured that the round is assembled properly. It now comes down to concentricity of the loaded round and charge weight. Charge weight can be manipulated to get to the correct barrel time.
Another concept that must be resolved is that of Optimum Charge Weight (OCW). This is using the correct powder, at the correct pressure and bullet. In QL the pressure curve will have a broad plateau at peak pressure, also at peak pressure, will have all the deterrent chemicals consumed. This is an OCW load.
As you change bullet seating depths, minor charge weight variances, and case volumes you will not see any notable changes in peak pressure, ES, or accuracy.
This is what is known as an inherently accurate cartridge/round. Some are 308 Win, 7mm-08, 6.5x55 SM, 6 Dasher with H-4350, 300 WM with the correct powder for bullet weight among others. Inherently, means with many different barrel lengths, bullets, charge weights and type, and rifle types the round will be accurate by comparison to others.
An inherently accurate load can be had, but not always*, with use of QL and knowledge of internal ballistics.
* some cartridge combinations of bullet, powder and barrel length will not line up to get an OBT and OCW at the same time.
A load that responses to seating depth is not an OCW load as the powder choice is not correct for components used. This is a narrow window as you are manipulating start pressure by that function.
Velocity is a by-product of the functions of OBT and OCW.
The handloader will have to use QuickLoad (QL) to determine where the 'node' or Optimum Barrel Time (OBT) is. Ultimately it is powder charge that will determine if you achieve the barrel time that coincides with the 'node'.
In handloading it is consistency of the round is a must, that is low Extreme Spread (ES). When you have single digit ES's you can be assured that the round is assembled properly. It now comes down to concentricity of the loaded round and charge weight. Charge weight can be manipulated to get to the correct barrel time.
Another concept that must be resolved is that of Optimum Charge Weight (OCW). This is using the correct powder, at the correct pressure and bullet. In QL the pressure curve will have a broad plateau at peak pressure, also at peak pressure, will have all the deterrent chemicals consumed. This is an OCW load.
As you change bullet seating depths, minor charge weight variances, and case volumes you will not see any notable changes in peak pressure, ES, or accuracy.
This is what is known as an inherently accurate cartridge/round. Some are 308 Win, 7mm-08, 6.5x55 SM, 6 Dasher with H-4350, 300 WM with the correct powder for bullet weight among others. Inherently, means with many different barrel lengths, bullets, charge weights and type, and rifle types the round will be accurate by comparison to others.
An inherently accurate load can be had, but not always*, with use of QL and knowledge of internal ballistics.
* some cartridge combinations of bullet, powder and barrel length will not line up to get an OBT and OCW at the same time.
A load that responses to seating depth is not an OCW load as the powder choice is not correct for components used. This is a narrow window as you are manipulating start pressure by that function.
Velocity is a by-product of the functions of OBT and OCW.
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coleman1495
CGN Ultra frequent flyer
- Location
- Whitecourt
I’d need your actual case capacity and COAL for more accurate predictions.
My Quickload would give roughly 65k psi for your hottest load.
My Quickload would give roughly 65k psi for your hottest load.
The 139 scenar has been a great performer in my x47. The 140 142 SMK and 130 TMK were not as good of a performer. Personally I would back off on the load a with your varget load to one of the mid 35 grain charges. I don't push the pressures in my x47 and I have over 20 firings from some of my brass. So far no loose primer pockets but I don't push this case much. I don't compete so if it has an ejector mark I back off.
I've also found the scenar in both 123 and 139 to be more forgiving of jump than say the Berger vld which shoots best for me with a slight jam.
I've also found the scenar in both 123 and 139 to be more forgiving of jump than say the Berger vld which shoots best for me with a slight jam.
139 OTM Load dev cranked up and ready to go for tomorrow morning wish me luck and a steady hand!
Took extra precautions such as individualy measure runout and toss anything over 1 thou, and running my FX120 with tweezers, adding or discarding the 1 varget kernel if needed.
I know it’s only 3 shot groups at 200M, but am loading from 34.9 to 35.5 in .2gn increments so 5 shot groups would of been lots of ammo.
But am hoping it will give me a hint to where focus on before moving up to 5 shot groups.
Also bringing out my CGN handmade rifle cooler to cool barrel 6-7 minutes between groups.
Took extra precautions such as individualy measure runout and toss anything over 1 thou, and running my FX120 with tweezers, adding or discarding the 1 varget kernel if needed.
I know it’s only 3 shot groups at 200M, but am loading from 34.9 to 35.5 in .2gn increments so 5 shot groups would of been lots of ammo.
But am hoping it will give me a hint to where focus on before moving up to 5 shot groups.
Also bringing out my CGN handmade rifle cooler to cool barrel 6-7 minutes between groups.
Attachments
If the case head is starting to extrude the solid case head into the ejector hole, you are in proof pressure range.
The fact that your bolt lift is ok just means it is a well made rifle.
It usually takes 3 factors to blow a gun, and you have loaded with 2 of them....
The fact that your bolt lift is ok just means it is a well made rifle.
It usually takes 3 factors to blow a gun, and you have loaded with 2 of them....
The first 2 being heavy bolt lift and good ejector markings?
Would the 3rd one be pierced primers?
I downloaded everything since, will not play around 36.0+gn of Varget anymore in this rifle.
Excellent luck.
It's very preliminary, as it's only 3 shot groups given the amount of loads I wanted to cover.
So far, it's the first outing that I make that my 6.5 actually showed potential to beat my .308 in the accuracy department, sure is refreshing!
Here are the 4 loads I will explore further, they are much lower end on speed than what I was running, and show nice potential.
Maybe it's the perfect excuse maybe it isn't, there was a LA magnum braked rifle right next to me, I timed my grouping with his breaks, while on group #4 he surprised me, it may be operator error like it may be a true flyer. Don't know as I didn't follow through with all that concussion blowing back!
Next outing it will be 5x35.1, 5x35.3, 5x35.5, 5x35.7
And we'll get a better idea of what's going on.
Although only 3 shot groups once again, in the 35s all my loads we're looking something like this, SD 0.8, ES 2 on the labradar.
Just input my lowest charge in my ballistic app, seems like I still make it to 900 with some steam left.
At 1000, if I ever get to make some good testing done as my local range is 900M, don't know if the Lapua will make it accurately...
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Nothing to do with external ballistics. Faster powders burn hotter then slower, and will erode the throat faster. Also loads with near or at 100% load capacity tend to be the most stable and accurate. Just because you have a load that works well with Varget doesn't mean that you should be generally using a slower powder for ~140gr bullets.
That being said, OP is selling his H4350 so a powder switch looks unlikely.
In fact sold all my H4350
What I like about Varget, one powder to load em all
5.56, .308, and 6.5x47L
Rifle wise it’s the only 3 cals I stick with since I got the tooling and components.
In fact when searching which of the 3x 6.5s I’d use, the 47L being Varget friendly compared to the 260rem and 6.5CM helped my choice.
With the looks of it, I’m down to 18lbs of Varget and don’t see a restock anytime soon, getting nervous should of kept the H4350 as a bargaining chip!
What I like about Varget, one powder to load em all
5.56, .308, and 6.5x47L
Rifle wise it’s the only 3 cals I stick with since I got the tooling and components.
In fact when searching which of the 3x 6.5s I’d use, the 47L being Varget friendly compared to the 260rem and 6.5CM helped my choice.
With the looks of it, I’m down to 18lbs of Varget and don’t see a restock anytime soon, getting nervous should of kept the H4350 as a bargaining chip!
Quickload suggests your 35.9grs Varget (2790 fps) load with 142SMK is running @ 75k psi
35.7grs with 139 Scenar @ 2740 fps would be 61k psi. That's more reasonable.
Varget is very fast burning for this application still, with 95% of the powder charge consumed by the time the bullet is 6" down the bore, 100% @ 15". Barrel life will be much shorter
In comparison, H4350 would be 95% burn @ 15". The throat of the rifle will thank you
35.7grs with 139 Scenar @ 2740 fps would be 61k psi. That's more reasonable.
Varget is very fast burning for this application still, with 95% of the powder charge consumed by the time the bullet is 6" down the bore, 100% @ 15". Barrel life will be much shorter
In comparison, H4350 would be 95% burn @ 15". The throat of the rifle will thank you
I’m 10 thou off, just copycating what Andy is doing here!
I’m trying hard to find BCTO but don’t know what it means sorry.
Cartridge OAL is 2.720’’, and when using a hornady comparator, Ogive is at 2.149’’
I get what you are saying and will consider it in the future,
For now that I’ve got something working I’ll just use it until it burns.
IBI prefit barrels are cheap and quick to change at least.
Looking at pressures you posted I feel like a dumbass to have gotten close to that.
Tonight I’ll drink to it that everything survived in 1 piece.
I’m serious too this is not sarcasm!
My 223s or 308s we’re so good at showing me pressure signs.
This effing build is out to wacko specs by the time I feel a mild resistance in the bolt!
I swear bolt lift is always ultra smooth and primers didn’t leak or flatten.
Since the bolt has such a huge ejector slot I was seeing the ejector markings as somewhat ok...
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