Ruger Forum banner

1 - 20 of 26 Posts

·
Registered
Joined
·
83 Posts
Discussion Starter #1
I recently bought a small frankford arsenal digital scale to help speed up my reloading time. I was putting 47 grains of R19 into 7mm08 cases and testing a 160 grain speer bullet in my son's rifle. I loaded up five rounds, shot them through the chronograph to see if the actual load agrees with the book loading. Velocity was all over the place from 2620 to 2700. Imagine my surprise. I achieved the goal of over 2600 fps but did not expect that much of a SD or ES.

So I proceeded to load up another 5 loads, except this time check the powder charge with my Lee safety scale after I used the digital scale. According to what the safety beam scale was showing me, that digital scale was deviating any where between .1 and .3 grains on any given powder charge. No wonder my ES was terrible.

Any of you experience this? BTW I only use the beam scale to finish the load now and let the digital scale get me close quicker.
 

·
Banned
Joined
·
1,336 Posts
Well, I had read of some problems with that Frankford scale, over on the THR site. So I spent more and got my RCBS scale instead. They recommend a 15-minute warm-up time, which I follow. Plus, I ditched my overhead fluorescent lamps and got the new LED type instead. Apparently there is a POSSIBILITY of erroneous readings if a digital scale is near fluorescents (which have a "ballast" in them).
 

·
Retired Moderator & Gunsmith
Joined
·
16,003 Posts
Yes, velocities are more uniform when powder charges are +or- .1 grains. If your 47 grain load was off by .3 grains, it would not cause significant velocity variations. Doing the math, .3gr is only .6%. If the powder charge and velocity had a direct correlation (it's close but not perfect), that would account for a max deviation of about .006x2600=15.6 fps. I suspect you have something else going on …. maybe a different powder would work better. I used Varget in my 7mm-08 and got excellent accuracy with velocity spreads under 25 fps in a 10 shot group. Another possibility is your chronograph ….possibly you aren't keeping each round with the exact same point of aim across the sensors. Further, barrel heat will increase the powder's burn rate and change velocity. Using a temperature compensated powder like Varget pretty much eliminates velocity changes caused by chamber heat. BTW, a 7mm-08 optimizes with a 139~145gr bullet so I think your 160gr bullet is too heavy.
 

·
Registered
Joined
·
1,040 Posts
My RCBS "Range Master 750" digital scale has proven to be very stable and reproducible. As noted I let it warm up and stabilize for several minutes and go through the calibration procedure each reloading session.

I spent years using a Lyman/Ohaus triple beam scale and the RCBS is equally accurate and vastly faster to use.

I did buy one of the low price digital scales but it's erratic readings convinced me to return it and get a good one.
 

·
Registered
Joined
·
5,188 Posts
I had the same scale myself.........not to consistent, MV and SD’s were all over the place. Needless to say it’s in a drawer now, back to the beam scale. I’ve never tried R19 but I’ve had excellent results with CFE223, it’ll launch 120’s out of a 15” barrel at 2895fps.

With all the threads on Escales I’ve decided against ever owning one again.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #6
I went to the 160 due to the short ranges and more on target energy that my hunting area offers (<200 yards). It may not be the most efficient or ideal all around load for the 7mm08 but pushing it up to 2600+ fps velocity isn't a problem with the proper powders. R19 is one that does that as does R17, R16, Stabil 6.5, Ramshot Big Game and Hunter, etc. We aren't taking shots at 300-400 yards, so close in thump is best for where I hunt. 160 is as heavy as I would go though, similar performance to a 180 308 load.

Lowegan, I would agree with you about the powder and temperature sensitivity BUT in this case the first shot was right at 2700 fps, then 2650, the 2630, then 2620, then 2695, shot from the same position, same height, straight on through the chronograph, if barrel temperature going up was to affect the powder, it should have made the velocity increase instead of decrease, ending with a increase, just all over the place. Velocity I was expecting was around 2650 due to it being a 22" and not a 24" barrel as Speer and Alliant tested. What I found with the scale was sometimes it was .2 under the charge, sometimes it was .2-.3 over the charge, so we are talking about a .5 grain swing possibly in what is already a compressed load, when just using the digital scale.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #7
I had the same scale myself.........not to consistent, MV and SD’s were all over the place. Needless to say it’s in a drawer now, back to the beam scale. I’ve never tried R19 but I’ve had excellent results with CFE223, it’ll launch 120’s out of a 15” barrel at 2895fps.

With all the threads on Escales I’ve decided against ever owning one again.
R19 wouldn't work that well with a short barrel, too slow of a burn rate. I think most go with something along the lines of R15 if they stick to Alliant Powders when shooting the lighter bullets. R19 doesn't do much for a 7mm08 until you start pushing 150 grain or heavier bullets, giving that powder time to burn, especially in a 22"-24" barrel.
 

·
Retired Moderator & Gunsmith
Joined
·
16,003 Posts
JLS1980, A little known fact about non-temperature compensated powders …. virtually all these powders will burn faster in a hot chamber, however sometimes it does exactly the opposite of what you might think …. especially slower burning powders with heavier bullets. Because they burn faster, chamber pressure elevates faster so more powder gets burned up in fewer inches of bullet travel. The end result is a slower muzzle velocity, not faster. I have never used R-19 so I don't know how it behaves …. maybe heat could have been the cause …. but I can't explain the last shot???

Regardless, I still don't think your scale was responsible for your velocity variations, even though I prefer scales accurate to .1 grains. I think it was your choice of powder. R-19 is pretty slow burning, virtually the same as IMR 4831, which is intended more for larger capacity cases. When I owned my Rem 700 chambered in 7mm-08, I tested several powders and bullets to see what worked best. I settled on Speer 145gr bullets …. heavier bullets just didn't group as well nor chronograph as tight plus they left the muzzle at a slower velocity with an inferior trajectory. I tested many powders and found any powder that burns slower than IMR 4350 just didn't chrono very uniform in my 7mm-08. R-19 is much slower burning than IMR 4350 so I think it is just way too slow for your 7mm-08. My goto powder for my 7mm-08 was Varget. 41 grains chronoed a 145gr bullet (Speer Spitzer Boattail Soft Point) in excess of 2700 fps with exceptionally good accuracy from a hunting rifle.

If you look at the burn rate chart, you will see Varget is #101 in the order of burn rate whereas R-19 is rated at #123, a much slower burn rate. Reloading manuals can tell you a lot too. In this case, the amount of powder needed for a given velocity with the same bullet gives you a clue about burn rates where a heavier powder charge means the powder is burning slower. According to the Speer manual (#14) R-19 requires 47 grains for 2692 fps with a 145gr bullet. The same bullet with Varget requires 41 grains for 2707 fps (very close to R-19's 2692 fps).

Using QuickLOAD with a Speer 145gr bullet, it takes 14.1" of bullet travel to reach a 95% burn with 41gr of Varget. R-19 takes in excess of 24" of bullet travel to reach a 95% burn with 47gr of R-19. At 22" of bullet travel (24" barrel) velocity is very close for both 2688 fps for R-19, 2695 fps for Varget. 41gr of Varget fills the case to 93.4% of capacity whereas 47gr of R-19 fills the case to 103.6% …. slightly compressed.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #9
JLS1980, A little known fact about non-temperature compensated powders …. virtually all these powders will burn faster in a hot chamber, however sometimes it does exactly the opposite of what you might think …. especially slower burning powders with heavier bullets. Because they burn faster, chamber pressure elevates faster so more powder gets burned up in fewer inches of bullet travel. The end result is a slower muzzle velocity, not faster. I have never used R-19 so I don't know how it behaves …. maybe heat could have been the cause …. but I can't explain the last shot???

Regardless, I still don't think your scale was responsible for your velocity variations, even though I prefer scales accurate to .1 grains. I think it was your choice of powder. R-19 is pretty slow burning, virtually the same as IMR 4831, which is intended more for larger capacity cases. When I owned my Rem 700 chambered in 7mm-08, I tested several powders and bullets to see what worked best. I settled on Speer 145gr bullets …. heavier bullets just didn't group as well nor chronograph as tight plus they left the muzzle at a slower velocity with an inferior trajectory. I tested many powders and found any powder that burns slower than IMR 4350 just didn't chrono very uniform in my 7mm-08. R-19 is much slower burning than IMR 4350 so I think it is just way too slow for your 7mm-08. My goto powder for my 7mm-08 was Varget. 41 grains chronoed a 145gr bullet (Speer Spitzer Boattail Soft Point) in excess of 2700 fps with exceptionally good accuracy from a hunting rifle.

If you look at the burn rate chart, you will see Varget is #101 in the order of burn rate whereas R-19 is rated at #123, a much slower burn rate. Reloading manuals can tell you a lot too. In this case, the amount of powder needed for a given velocity with the same bullet gives you a clue about burn rates where a heavier powder charge means the powder is burning slower. According to the Speer manual (#14) R-19 requires 47 grains for 2692 fps with a 145gr bullet. The same bullet with Varget requires 41 grains for 2707 fps (very close to R-19's 2692 fps).

Using QuickLOAD with a Speer 145gr bullet, it takes 14.1" of bullet travel to reach a 95% burn with 41gr of Varget. R-19 takes in excess of 24" of bullet travel to reach a 95% burn with 47gr of R-19. At 22" of bullet travel (24" barrel) velocity is very close for both 2688 fps for R-19, 2695 fps for Varget. 41gr of Varget fills the case to 93.4% of capacity whereas 47gr of R-19 fills the case to 103.6% …. slightly compressed.
Correct. Once you look up in bullet weights, the slower powder begins to show where it belongs in the pecking order. According to speer and alliant data, this was the optimum powder for the heavier bullets in 7mm08. They achieved 2700+ with this charge. The loads I tested came close to that. The bigger question will be how will they group. If the weather cooperates, I'm going to find out this weekend. If I am able to get this load to print decent out of a Savage 111 with a 9.5 twist, one view of it: a 160 grain slug moving at 2650 (2500 ft/lbs) or a 145 grain slug moving at 2700 (2350 ft/lbs). Assuming accuracy is decent. The 160 will have more striking force and trajectory is negligible out to 300. Now some of the older 7mm08's had 1 in 10 or 1 in 9.75 twist rates, much too slow for the 160s and up, which made the 120-145 optimal for the cartridge for those rifle. Manufacturers got with the program and upped the twist, turning the 7mm08 into a better all around caliber being able to shoot 160s and even 175s in some. I do think as far as a semi long range multiuse load goes, 160 is as high as you can go with it before trajectory really limits it. One other thing I did that I typically never do, I used new Hornady brass straight out of the bag. After seeing visual bullet run out in a few of the loaded rounds, I decided to resize the rest to straighten things out, so that could be a possibility combined with a not so accurate digital scale. I will find out more answers when I make it to the range. Thanks for your input lowegan, always appreciated.
 

·
Registered
Joined
·
196 Posts
I have one of the frankford arsenal scales too. Sometimes it changes the tare wight. I always make a mental note of what it was at 1st. I use it for setting my powder drop.
 

·
Registered
Joined
·
93 Posts
Well, I had read of some problems with that Frankford scale, over on the THR site. So I spent more and got my RCBS scale instead. They recommend a 15-minute warm-up time, which I follow. Plus, I ditched my overhead fluorescent lamps and got the new LED type instead. Apparently there is a POSSIBILITY of erroneous readings if a digital scale is near fluorescents (which have a "ballast" in them).
I also turn off the ceiling fan in my reloading room when working with my RCBS scale, as the air current might disturb the thing. I've replaced the fluorescent fixture on my reloading bench with an LED fixture. Lastly, I bought calibration weights. After a 10 or so minute warm up I check the calibration before every loading session.

The only time I've found a problem was during the dry season (not real humid here in AZ) when the load cell can have static problems. RCBS recommends wiping the scale down with a dyer sheet when that happens. They also recommend the "love tap" to bleed any charge off the cell.

Love tap:
1) Lightly tap on the platen, increasing force until the cell is overloaded (OVRLD displays).
2) Lightly and very rapidly tap 50 times on the platen, not with enough force to overload the cell.
3) Calibrate.

I've had to use the love tap a couple of times. No idea why it works but it seems to work. And the scale seems to hold calibration quite reliably.
 

·
Registered
Joined
·
320 Posts
After trying several different brands of digital scales, I always come back to mu Ohaus 5-0-5 beam scale. Ol' reliable might take longer, but I'm in no hurry when I'm reloading, anyways.
 

·
Registered
Joined
·
2,097 Posts
Yes , just about any electrical goings on in the room or near the room causes deviations .
Ceiling fans , florescent lights , air conditioning motors , refrigerator motor , freezer motor . Motors that cycle on-off are the worst and if the scale plugs into a circuit that a motor is on the cycling gives the scale fits. My scale was plugged into a receptacle in a study (now my reloading room) the refrigerator in the kitchen , down the hall , was on the same circuit...took me a while to trace down the problem .
Try to get a clean circuit to plug your scale into ...no TV's either .
Always keep a good old beam scale around for back up RCBS 5-0-5 is mine.
Gary
 

·
Registered
Joined
·
998 Posts
I don't trust any digital scale. I have one and at first had major problems with it, had a fluo. light over my bench.....I understand that a radio or cell phone or who knows what can mess with them. I now use my 1010 and check weights to verify.
 

·
Registered
Joined
·
451 Posts
Myself, mainly use digital scale to check uniformity of Cast Bullets as well as empty Fired and Unfired Cases plus filled with water (filled to point of overflow), while closely following scale directions of use. Then plug the h2o capacity data into QuickLoad, I enjoy using this info when comparing to published loads as well as working up loads. Then check that against Chronograph when I want or need to.

----------

Great powder matching info described above!!

For propellants, I also use digital scale to compare results with 'preferred use' beam scale powder weight, especially when using very light charges but use it for 'velocity spread' projects too.

The 'higher pressure' lighter charges especially, at times are worth a second look for me.

Still, have found RCBS beam scale more reliable regarding consistency and seems less sensitive to environmental variables plus the electronics interferance(but focus on mitigating this with digital).
 

·
Registered
Joined
·
3,401 Posts
After trying several different brands of digital scales, I always come back to mu Ohaus 5-0-5 beam scale. Ol' reliable might take longer, but I'm in no hurry when I'm reloading, anyways.
I've never really considered a digital scale, as my 5-0-5 has served me well since beginning handloading in the mid 1980s.

Early on, I obtained a set of Lyman check weights to periodically verify the scale's accuracy.
 

·
Registered
Joined
·
35 Posts
I have the Frankford Arsenal DS-750 and a RCBS chargemaster. Both give reliable readings similar to my Lee balance beam (which is a PIA to use). I only use the balance beam to check the digitals. Digitals have been great for me.
 

·
Registered
Joined
·
1,855 Posts
I have a Lyman E.scale which I find very consistent. I don't use it for powder as I use an RCBS 304 or a 10-10 beam scale which are more accurate than the +/- .10 gr. at least by interpolation. All three check out at 0.10 gr. though .
 

·
Registered
Joined
·
23 Posts
Frankford Arsenal Digital scale

I too have noticed deviations when using my F.A. digital scale. Mine is about 10 to 15 years old. Still works but I have had to dump charges and or take off the full pan and replace and am getting different readings from the same charge in the pan. I have re-calibrated it many times with no change in deviations. Should I buy a new scale? What one works the best???
 

·
Registered
Joined
·
2 Posts
Old Reliable Balence Scale

Digital scales save time, I use one myself. However, I always have my over fifty year old Redding "balance scale" set-up as a check every 20 rounds or so. Until gravity fails the old scale is always accurate (and it doesn't use batteries!).
 
1 - 20 of 26 Posts
Top