Then why do people chasing the lands eroding .050" down the bore see no significant accuracy degradation across that much less seating depth?
Varget powder
- Thread starter rebs
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reynolds357
New member
My only thought is distance to land engagement is more important than change in case volume.
Why chase them? Throw barrel in lathe and set it back.
fire cracking of the throat would be my guess. You ever look at a burned out throat through a borescope?
here is the spreadsheet I did last winter, SK Pistol Match Special ( Not SK Match Pistol) and Lapua Midas consistently shot the smallest groups at 50 and 100 yards, the CCI and R100 had the most consistent velocities and smallest vertical spreads at 200.
I also found that sorting a box of ammo by BTO and shooting rounds that were the same BTO length gave me the most consistent groups overall. Just my opinion and not the most scientific test in the world but I have shot my best groups with my CZ 452's using that method.
graphic is 1200 x 680, that is as small as I could get it and have it be legible
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J.G. Terry
New member
Varget in Roberts and 338 Federal
I found that Varget was similar to the old IMR4320. It worked for me very well in 257 Roberts using 100gr. bullets. One rifle was built up and the was a Number One B in the same caliber. Not that I'm partial but there are two more Roberts' in the gun safe.
Likewise, I did some starting work with Varget in 338 Federal with 200gr. bullets. Excellent accuracy here also. My rifle is a T3 Tikka.
RCBS calls the Uniflow a Powder Measure because it measures powder.
I found that Varget was similar to the old IMR4320. It worked for me very well in 257 Roberts using 100gr. bullets. One rifle was built up and the was a Number One B in the same caliber. Not that I'm partial but there are two more Roberts' in the gun safe.
Likewise, I did some starting work with Varget in 338 Federal with 200gr. bullets. Excellent accuracy here also. My rifle is a T3 Tikka.
RCBS calls the Uniflow a Powder Measure because it measures powder.
reynolds357
New member
Yep, it measures powder by volume. Who is disputing that?I found that Varget was similar to the old IMR4320. It worked for me very well in 257 Roberts using 100gr. bullets. One rifle was built up and the was a Number One B in the same caliber. Not that I'm partial but there are two more Roberts' in the gun safe.
Likewise, I did some starting work with Varget in 338 Federal with 200gr. bullets. Excellent accuracy here also. My rifle is a T3 Tikka.
RCBS calls the Uniflow a Powder Measure because it measures powder.
T. O'Heir disputed it earlier. The rest of us have witnessed our wives measuring sugar and flour by volume in cups calibrated in fluid ounces or in milliliters and doing so to good effect in holiday baked goods, so we don't have a problem with the concept.
I read somewhere that Varget was originally intended to compete with IMR4064, specifically. Though there were some lot burn rate control issues with it in the '90s, Hodgdon seems to have got a handle on that now.
If you look at Hodgdon's load data, you find in .308W that Varget produces a smaller change in velocity per grain over the listed load range than 4064. This is particularly evident with the 175-grain MatchKing, where 4064 shows a change of 55.6 fps/grain over the load range while Varget only shows about 35.7 fps/grain change, though its top velocity is also 38 fps slower. It means you can have a charge weight error 1.55 times bigger with Varget for the same effect on velocity and vertical POI from an ideal perfectly rigid gun. The ratio is lower with other bullet weights, but it makes Varget less sensitive to exact charge weight and other pressure-affecting factors like temperature. On the other hand, the same data for the 175 has the maximum load of Varget at about 96% of SAAMI MAP, while 4064 goes all the way to 99% of SAAMI MAP. That means Varget did not produce as tight a velocity spread as 4064 did for the tests. That would seem to trump the load insensitivity, but I note the Varget numbers are in CUP and 4064 numbers are in psi, which tells me they were tested in different barrels and quite possibly by different technicians, so the differences have to be taken with a grain of salt and the shooter would do best to run his own tests in his own rifle to compare the two.
I read somewhere that Varget was originally intended to compete with IMR4064, specifically. Though there were some lot burn rate control issues with it in the '90s, Hodgdon seems to have got a handle on that now.
If you look at Hodgdon's load data, you find in .308W that Varget produces a smaller change in velocity per grain over the listed load range than 4064. This is particularly evident with the 175-grain MatchKing, where 4064 shows a change of 55.6 fps/grain over the load range while Varget only shows about 35.7 fps/grain change, though its top velocity is also 38 fps slower. It means you can have a charge weight error 1.55 times bigger with Varget for the same effect on velocity and vertical POI from an ideal perfectly rigid gun. The ratio is lower with other bullet weights, but it makes Varget less sensitive to exact charge weight and other pressure-affecting factors like temperature. On the other hand, the same data for the 175 has the maximum load of Varget at about 96% of SAAMI MAP, while 4064 goes all the way to 99% of SAAMI MAP. That means Varget did not produce as tight a velocity spread as 4064 did for the tests. That would seem to trump the load insensitivity, but I note the Varget numbers are in CUP and 4064 numbers are in psi, which tells me they were tested in different barrels and quite possibly by different technicians, so the differences have to be taken with a grain of salt and the shooter would do best to run his own tests in his own rifle to compare the two.
reynolds357
New member
T'Oheir surely knows in a consistent substance you can measure mass by measuring volume once you have determined the conversion equation. (Or established a single mass conversion by trial and error.)
pack density is the issue, that's the unfilled space of the volume. With liquids or fine powders that is not a issue but the larger the granules the more of a problem it is. In other words with flake or ball powder the amount filling a volume will be relatively consistent. With stick not so much and the longer the stick the less consistent. Smokeless powder acts funny though. I have seen loads where a difference of .1 gn will make a 70 FPS difference in velocity yet with the same powder a gn or so higher or lower or a different weight or even shape bullet and you can have a difference of .3 or .4 gns and the velocity spread will be within single digits. That is why you develop loads
reynolds357
New member
T'Oheir surely knows in a consistent substance you can measure mass by measuring volume once you have determined the conversion equation. (Or established a single mass conversion by trial and error.)
Hatcher reported developing a National Match load one year between the WW's at Frankford Arsenal for which he had two powders that had burn rates similar to IMR 4320. One was a short grain stick the arsenal's powder measures could throw ±0.3 grains. The other was a coarse stick, like 4064, which the same powder measures could only dispense ±0.85 grains. Nonetheless, the latter powder thrown with that wide 1.7 grain charge weight spread proved to produce consistently more accurate cartridges in machine rest firing tests and wound up being that year's NM load and several records were set with it at the National Matches.
Some powders, and 4064 seems to be one in .308 and 30-06 match loads, tend to compensate for charge error when thrown by volume. A heavier charge with closer together grains burns just enough more slowly to produce little net difference in pressure as compared to a lighter charge in the same volume.
A few years back I bought a JDS Quick Measure, which boasts it will never throw stick powder loads off by more than 0.2 grains. I have experimented with it enough to find the claim true. It uses an unusual metering chamber geometry that cannot cut grains. Grain cutting has to be avoided for best charge weight consistency not because cut grains themselves have any appreciable effect on how fast a charge burns, but because the act of cutting produces a sharp knock in the measure that tends to settle the powder reservoir near the metering cavity, causing the next couple of throws to be heavier than average. By eliminating the cutting, that settling effect is avoided.
One method that measure has allowed me to pursue is to tare a scale with a primed case on it, dispense the powder and set the charged case back on the scale to check the weight of the finished throw, and then sort the charged cases by throw weight for subsequent testing. This gives me weight and volume equality simultaneously. Depending on the powder, I will end up with three to five weights in 0.1 grain increments. I can then keep them segregated for testing or dump some back in the hopper and keep going until they are all the middle value. If I have a good load I can't really tell the difference, but when I am doing load workups, I like to eliminate all the variables I can until I settle on the load. Then I can start dropping controls to see if it makes any difference.
Some powders, and 4064 seems to be one in .308 and 30-06 match loads, tend to compensate for charge error when thrown by volume. A heavier charge with closer together grains burns just enough more slowly to produce little net difference in pressure as compared to a lighter charge in the same volume.
A few years back I bought a JDS Quick Measure, which boasts it will never throw stick powder loads off by more than 0.2 grains. I have experimented with it enough to find the claim true. It uses an unusual metering chamber geometry that cannot cut grains. Grain cutting has to be avoided for best charge weight consistency not because cut grains themselves have any appreciable effect on how fast a charge burns, but because the act of cutting produces a sharp knock in the measure that tends to settle the powder reservoir near the metering cavity, causing the next couple of throws to be heavier than average. By eliminating the cutting, that settling effect is avoided.
One method that measure has allowed me to pursue is to tare a scale with a primed case on it, dispense the powder and set the charged case back on the scale to check the weight of the finished throw, and then sort the charged cases by throw weight for subsequent testing. This gives me weight and volume equality simultaneously. Depending on the powder, I will end up with three to five weights in 0.1 grain increments. I can then keep them segregated for testing or dump some back in the hopper and keep going until they are all the middle value. If I have a good load I can't really tell the difference, but when I am doing load workups, I like to eliminate all the variables I can until I settle on the load. Then I can start dropping controls to see if it makes any difference.
Yes, IMR4064 has been a favorite in 30-06 and 308 target rifles for decades with medium weight bullets. Still, some used slower powders to get faster velocity giving up a few tenths MOA accuracy winning the race to the target.
Metered IMR4895 to a 3/10ths grain charge weights with 155 to 180 grain bullets in 308 cases have tested about half MOA at 600.
Metered IMR4895 to a 3/10ths grain charge weights with 155 to 180 grain bullets in 308 cases have tested about half MOA at 600.
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J.G. Terry
New member
Varget and IMR4320
I was struggling for data for IMR4320. It was suggested to use Varget data. What is the relationship between the two?
It looked as if 4320 is almost forgotten and little used for many years. I find, in limited use, both powders to be highly useful. One power is nearly forgotten and the other appears to be widely used. Just curious. It will be Varget for me since 4320 is more difficult to find. Thanks for the information.
I was struggling for data for IMR4320. It was suggested to use Varget data. What is the relationship between the two?
It looked as if 4320 is almost forgotten and little used for many years. I find, in limited use, both powders to be highly useful. One power is nearly forgotten and the other appears to be widely used. Just curious. It will be Varget for me since 4320 is more difficult to find. Thanks for the information.
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I gave up on Varget powder for loading the .223 Rem. If you feel you need temperature stable powder, I suggest IMR-8208XBR or Hodgdon Benchmark. Both are temperature stable (at least compared to ball powders) and meter much more accurately through a powder measure than Varget, IMR-4064 or other large kernel extruded powders.