You may want to focus more on conditional/technique issues, such as direct sunlight on your chrony, angle of sun, is the sky overcast, is your barrel clean?, barrel cooling?, quality of the chronograph, temp/humidity conditions, are you firing directly thru the middle of the uprights each time?, case length and capacity, are you close to or touching the lands?, powder/primer type of course, eventually you will narrow it down.
.270 velocity variations
- Thread starter kstrick
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bwaites
Well-Known Member
+/- .1 or even .2 grains is NOT going to change velocities by 100 FPS!
Think that through...We push powders up 5-6 grains to get that much velocity increase quite often!
Thus, I doubt that it is the scale, but borrowing a quality lab scale to give you some peace of mind about it isn't a bad idea.
I found that my velocity variations DROPPED significantly when I started using a Chargemaster vs. a beam scale. Beam scales can be very accurate, IF everything is perfect and consistent, but most guys using a beam scale will be NO more accurate than a Chargemaster. Beam scales are very dependent on you having a view of the scale that is consistent charge to charge, and most guys aren't good at that! (To achieve best accuracy, you should have a perpindicular view of the beam, and most reloaders don't do that, because it requires getting the scale to eye level, or bending down to it. Try bending to the same exact spot 10 times, much less the 100 or more that most reloaders use each time!)
I have fiddled with my Chargemaster, and it is faster than it was from the factory, and I haven't seen an great degradation in accuracy.
Large extruded powders don't meter quite as well as fine powders like Xterminator or TAC, but the soda pop straw trick helps with that issue, too.
I think there is something more significant than simply the powder charge causing that kind of variation!
BTW, my 7mm WSM varies less than 20 FPS with a WHOLE GRAIN of H1000 at 2930 and 2950 FPS between 64 and 65 grains. 66 grains pushes it only to 2960-2965 FPS.
Look elsewhere first, once you have convinced yourself that the scale isn't grossly off!
Bill
Think that through...We push powders up 5-6 grains to get that much velocity increase quite often!
Thus, I doubt that it is the scale, but borrowing a quality lab scale to give you some peace of mind about it isn't a bad idea.
I found that my velocity variations DROPPED significantly when I started using a Chargemaster vs. a beam scale. Beam scales can be very accurate, IF everything is perfect and consistent, but most guys using a beam scale will be NO more accurate than a Chargemaster. Beam scales are very dependent on you having a view of the scale that is consistent charge to charge, and most guys aren't good at that! (To achieve best accuracy, you should have a perpindicular view of the beam, and most reloaders don't do that, because it requires getting the scale to eye level, or bending down to it. Try bending to the same exact spot 10 times, much less the 100 or more that most reloaders use each time!)
I have fiddled with my Chargemaster, and it is faster than it was from the factory, and I haven't seen an great degradation in accuracy.
Large extruded powders don't meter quite as well as fine powders like Xterminator or TAC, but the soda pop straw trick helps with that issue, too.
I think there is something more significant than simply the powder charge causing that kind of variation!
BTW, my 7mm WSM varies less than 20 FPS with a WHOLE GRAIN of H1000 at 2930 and 2950 FPS between 64 and 65 grains. 66 grains pushes it only to 2960-2965 FPS.
Look elsewhere first, once you have convinced yourself that the scale isn't grossly off!
Bill
kstrick
Well-Known Member
Thanks,
In my earlier posts I mentioned that I have access to a pharmaceutical grade scale that weighs out to .0000. I was a chemistry major way back when and I cut my teeth on beam scales. Everything you said about using the beam scale is %100 right on. I trust digital!!!
I am going to throw some different charges and have them checked. Have to wait until next Tue....going out of town. I will let you know.
I AM going to figure this out.
Thanks
Ken
In my earlier posts I mentioned that I have access to a pharmaceutical grade scale that weighs out to .0000. I was a chemistry major way back when and I cut my teeth on beam scales. Everything you said about using the beam scale is %100 right on. I trust digital!!!
I am going to throw some different charges and have them checked. Have to wait until next Tue....going out of town. I will let you know.
I AM going to figure this out.
Thanks
Ken
Fitch
Well-Known Member
That is why mine is on a shelf at eye level. Works great.
You make some good points.
Fitch
bwaites
Well-Known Member
Take a McDonalds straw, (they are almost perfectly sized to do this, most straws are too small), cut a small piece, and insert it into the end of the dispensing tube. Most people find a small piece of duct tape or medical tape is helpful in keeping it in place.
Since the straw is slicker than the metal tube with threads, not as much powder climbs the side and there is less chance it will fall into the tray and upset your measurement.
Hope that helps!!
Bill
How close is you crony to the shooting table? Ive had some funny readings in certain light conditions when shooting with the chrony to close. i chalked it up to the exhausting gas and not quite right angles on the chrony.
There was a series of articles from Ken? ohler in 2007-2008 shooting times magazine that talked about the way chronographs work and how errors are introduced... seems that the distance between the eyes is very critical. loose construction and many other things put a surprising error in the works. (like shooting across a folding type chronograph that isnt all the way open. think sitting on a table with some junk under one end)
There was a series of articles from Ken? ohler in 2007-2008 shooting times magazine that talked about the way chronographs work and how errors are introduced... seems that the distance between the eyes is very critical. loose construction and many other things put a surprising error in the works. (like shooting across a folding type chronograph that isnt all the way open. think sitting on a table with some junk under one end)
kstrick
Well-Known Member
OK guys.
I had my powder charges weighed by a commercial grade pharmaceutical research scale.
My RCBS Charge Master is weighing dead on.
One weight was 45.5 gr on the ChargeMaster...pharmaceutical scale 45.53 gr.
the other was 52.3 gr on the ChargeMaster ... pharmaceutical scale52.22 gr.
So..we are talking about less than part of a single stick of IMR 4350. There is no way a balance scale can match this.
Now that I know the scale is right on I have to figure out what else can be giving me the velocity variations. Maybe it is the chronograph.
gun)
I had my powder charges weighed by a commercial grade pharmaceutical research scale.
My RCBS Charge Master is weighing dead on.
One weight was 45.5 gr on the ChargeMaster...pharmaceutical scale 45.53 gr.
the other was 52.3 gr on the ChargeMaster ... pharmaceutical scale52.22 gr.
So..we are talking about less than part of a single stick of IMR 4350. There is no way a balance scale can match this.
Now that I know the scale is right on I have to figure out what else can be giving me the velocity variations. Maybe it is the chronograph.
gun)
bwaites
Well-Known Member
Thanks for reporting back! I have the utmost confidence in my Chargemaster and know it weighs powder more accurately than I do with a balance!
Keep working on those variations!
Bill
kstrick
Well-Known Member
The chrony is about 8 - 10 feet out. I am going to move it to 15 feet and see what happens.
I will keep working on this. Guess it just means more reloading and more trips to the range....sigh. Well better get out to the bench...yeee HAAA!!!
I will keep working on this. Guess it just means more reloading and more trips to the range....sigh. Well better get out to the bench...yeee HAAA!!!
Are you seated too deep? I'd play with the seating depth first. Sort your brass by weight as well. remove as much of the variables as you can. I prefer h4831 in the 270 and from summer to Nov I see 25fps ES. I would guess that if those 2 variables I suggested don't improve go to the 215 match primer and check The 270 in my testing does best with a mag primer. It's a long for bore powder columm so put more fire to it.
kstrick
Well-Known Member
Thanks
I seat right off the lands. I mostly shoot Bergers. I have not tried 4831. What kind of velocity do you you get? I mostly load 140s but I also have some 150s.
I have sorted brass an keep it separated into lots. I do not mix brass from different manufactures.
Merry Christmas
Ken
I seat right off the lands. I mostly shoot Bergers. I have not tried 4831. What kind of velocity do you you get? I mostly load 140s but I also have some 150s.
I have sorted brass an keep it separated into lots. I do not mix brass from different manufactures.
Merry Christmas
Ken
