When loading, what is an acceptable +/- in grains?

[JimSC]

Gee, I wonder how all those guys back in the 70's and 80's who set short and long range records some of which are still on the books managed to do it ?

Seriously, when developing a load I am anal to the .01 gn, but I look for a load where I can load + or - .1 or .2 and have no appreciable difference in velocity

 

[Idaho-Lefty]

Drop low and trickle up.

Every round. I am not in a hurry and I load for accuracy.

Yup,. I do this with, my Stick Powders, but "Throw" charges of, Ball Powders +- One tenth of, a Grain and,..
they ARE, Better Loads than, I can shoot,.. IF, I've worked up the Load and, Tuned the Bullet,.. "Properly" !
I've got a 6 XC load with, StaBall 65 powder, shooting One Hole groups, in the 2's and 3's with, Sierra 107 MK's.
I like, Ball Powders and USE them, whenever, I can.
I've seen, Flake and Stick Powders "Bridge", in Powder chargers and I will NOT throw them, WITHOUT weighing them
I tried "throwing" Unique ( 9 MM loads ) in, a Lil' Dandy & noticed One charge was LOW,. so I Pitched that,.. "idea",.. Quickly !

 

[hornetguy]

It also depends on the size of the charge..... a 3.8 gr charge of Bullseye needs to be within a tenth, preferably a little tighter than that.
A 60 gr charge of extruded for a .35 Whelen doesn't need quite that level of accuracy.
Even so, I strive to be within a tenth for pistol loads, and not over two tenths on rifle loads....

 

[762plinker]

Loading 28.5 LT32 in a 6PPC as long as it’s between 28.500 and 28.510 I call it good

at the range with that setup ...ppc id not normaly a load at home, but load at the range

 

[mac86951]

It's really a percentage change impact analysis combined with sensitivity of your load work up and shooting conditions. I've seen a 0.5gr wide spread on a particular 30-06 where velocity was mostly flat. In that case, I'd load +/- 0.1gr with confidence.

I also painfully know that 3 kernels of Varget is 0.1gr. how do I know this? Shoot a 223 at 600y, and you'll learn too.

Truth is, what's good enough is wholly up to you. Hopefully safety is good, then for accuracy it a matter of what are you comfortable with and the rest is just suggestions and what we've found to be acceptable practices. +/- 0.5% should be a good ball-park figure for you to determine if reduction in variation is an improvement.

-Mac

 

[cfreeman]

Yup,. I do this with, my Stick Powders, but "Throw" charges of, Ball Powders +- One tenth of, a Grain and,..
they ARE, Better Loads than, I can shoot,.. IF, I've worked up the Load and, Tuned the Bullet,.. "Properly" !
I've got a 6 XC load with, StaBall 65 powder, shooting One Hole groups, in the 2's and 3's with, Sierra 107 MK's.
I like, Ball Powders and USE them, whenever, I can.
I've seen, Flake and Stick Powders "Bridge", in Powder chargers and I will NOT throw them, WITHOUT weighing them
I tried "throwing" Unique ( 9 MM loads ) in, a Lil' Dandy & noticed One charge was LOW,. so I Pitched that,.. "idea",.. Quickly !

Not to derail the thread, but how much Staball in that XC?

 

[Goodcat]

.02gr for me

 

[Mr Wick]

You have all given me a great deal to think about.

For those of you who have read my posts you know I started shooting rifles a year ago completely and utterly green. I shoot almost everyday. I got into reloading about a month ago and have amassed a beautiful collection of instruments.

I'm trying to learn, absorb, and apply as much as I can. I want to be a serious competitor. Overnight? In a month? No. In time, yes.

Thank you all for helping me on this road.

 

[Idaho-Lefty]

Not to derail the thread, but how much Staball in that XC?

I had worked it up to, 41.1 grains and it was going, 2,975 / 2,980 FPS, chrono'd,.. but that, was, a bit too HOT, so I've backed the load off to, 40.5 grains of, StaBall 65 with, the 107 SMK's, F-210 Match Pr's, Once fired
( Fireformed ) Norma Brass and a COAL of 2.685" which is, IN the Lands ( at Lite "Jam" ), in My Criterion Barrel with, a .104 Freebore. A SAFER Velocity ( & lower pressure ), should BE around, 2,925ish, FPS.
This Load IS, close to, Max pressure, so "Work Up" carefully and Watch your Bullet seating Depth and look for pressure "swipes" on Brass and for, Cratered primers.
I will Chrono and further Test, this New, 40.5 gr. Load, as soon as the Wind quits blowing, a Little.
This load, will be Re-Tested AGAIN, in the Summer, when warmer weather to, be SURE that, it's,.. SAFE !
Use Extreme Caution and start Charges, LOWER by, a Grain or Two and "Work Up" carefully for, YOUR Rifle.
Good luck and BE,..Safe ! Note; For Velocity,.. I'm using, a 24 inch Barrel.

 

[Benchrest Braxton]

Test and see.

Or take your average velocity at 38 and 40 gr (assuming 40 is a safe load)? Now divide the difference of those velocities by ten and you have the average effect of .2 gr variance. Plug that velocity variance into your ballistics program, what vertical is that?

Whether that’s acceptable depends on your application. Whatever that is because it’s not been provided.

this is the way

 

[1shot]

I'm a competitive 1K sling shooter, and this is what works for me. If my target weight is 43.5, I will take 43.52 but will add powder if the FX120i reads 43.48. I only use stick powder so this equates to adding 1 maybe 2 kernels of powder.
I hope this helps,

Lloyd

 

[M-61]

I think you all know me by now.

I certainly don’t. But I doubt that’s of much importance.

 

[cfreeman]

I had worked it up to, 41.1 grains and it was going, 2,975 / 2,980 FPS, chrono'd,.. but that, was, a bit too HOT, so I've backed the load off to, 40.5 grains of, StaBall 65 with, the 107 SMK's, F-210 Match Pr's, Once fired
( Fireformed ) Norma Brass and a COAL of 2.685" which is, IN the Lands ( at Lite "Jam" ), in My Criterion Barrel with, a .104 Freebore. A SAFER Velocity ( & lower pressure ), should BE around, 2,925ish, FPS.
This Load IS, close to, Max pressure, so "Work Up" carefully and Watch your Bullet seating Depth and look for pressure "swipes" on Brass and for, Cratered primers.
I will Chrono and further Test, this New, 40.5 gr. Load, as soon as the Wind quits blowing, a Little.
This load, will be Re-Tested AGAIN, in the Summer, when warmer weather to, be SURE that, it's,.. SAFE !
Use Extreme Caution and start Charges, LOWER by, a Grain or Two and "Work Up" carefully for, YOUR Rifle.
Good luck and BE,..Safe !

Thanks for the detailed data!!!

 

[PracticalTactical]

I would respond to the original question by saying load variance consideration depends on two factors.
1) If the variance may exceed safe parameters (If too much variance)
2) How far you shoot relative to your accuracy expectations.

Focusing on the second point, accuracy expectations... We can translate load variance to vertical impact shift at any distance.

For example, referencing the Nosler load data for 308 with 175-180 grain projectile...
43.5 grains of Varget goes 2599 FPS
41.5 Grains of Varget goes 2475 FPS
So 2 grain variance translates to 2599-2475 = 124 FPS
124/20=6.2 FPS per 1/10th grain of powder in this example.

124 FPS at 1000 yards equals about 4.3 minutes of elevation for 2 grains of powder variance.
That translates to 0.215 MOA of vertical for every 1/10th of a grain of powder.

If a kernel of Varget averages 0.02 grains, then for this example, each kernel of Varget accounts for 0.043 MOA at 1000 yards or about 0.43 inches of vertical on average.

All the above is in addition to all other variables.

 

[David Milisock]

I do measure each charge. But if I'm a grain over or under, it gets to be a pain in the rear to dump it back and recharge when doing 200 loads in a single sitting. I'm also case trimming and case prepping all at the same time.

Do you have a powder trickeler?

 

[David Milisock]

Drop low and trickle up.

Every round. I am not in a hurry and I load for accuracy.

I do this even for the M1 Carbine, safer to be a tad under and a quick trickle up. It's 15.75 grain, I throw 15.5 average and trickle up. I just did 400 rounds and I'm sure it added maybe an hour to the task but it allows safer near max loads.

The safe performance improvement is really worth it in this cartridge.

 

[ebb]

Buy a Chargemaster and let it do the work . If at some time in the future this is not good enough get enough get the latest greatest scale (it changes every month) and one of the super cool tricklers that hooks up to the scale. Chargemaster will get plus or minus .1 grain

 

[davidjoe]

I like Adam’s candor in his paper, very good read. I’d have this question though, how wide is the range where there is a “linear” and directly proportional relationship between the weight of powder added, and an increase in velocity?

I’ll illustrate with his .308 example, … loading only a few grains of powder mistakingly, probably won’t even generate muzzle exit, at one end of the spectrum. At the other end, adding powder to a max charge will, it seems, soon start damaging brass, more and more, but not appreciably increase velocity.

 

[PracticalTactical]

I like Adam’s candor in his paper, very good read. I’d have this question though, how wide is the range where there is a “linear” and directly proportional relationship between the weight of powder added, and an increase in velocity?

I’ll illustrate with his .308 example, … loading only a few grains of powder mistakingly, probably won’t even generate muzzle exit, at one end of the spectrum. At the other end, adding powder to a max charge will, it seems, soon start damaging brass, more and more, but not appreciably increase velocity.

Over a sample size of one, you may find a negligable velocity difference, but if you take an average over 10 or 20 rounds, you are likely to see the difference, assuming the variance is detectable by the chronograph being used. Even if the chronograph is not capable to detect such differences, that does not indicate the variance does not exist.

Now having said that, powder charge weight is not the only variable, and for that reason small differences may be perceived to get lost in the noise, but the influence is there and apparent if you look closely enough over several rounds.

 

[divingin]

I do measure each charge. But if I'm a grain over or under, it gets to be a pain in the rear to dump it back and recharge when doing 200 loads in a single sitting. I'm also case trimming and case prepping all at the same time.

How do you measure? Are you throwing a charge into a pan that goes on the scale?

Until I got my V4, I was using either a powder measure or a Chargemaster, and putting the charge on a scale (similar to a A&D, but not Mag Force Restoration), and adjusting the charge by hand (usually using a small scientific spatula to add or remove a suitable number of grains.) It worked, but it was God-awful slow and frustrating. But it got me to within about .04 grains of target weight, as far as I could tell. I didn't use a trickler as I kept overshooting and resorting to the spatula method anyway.

One other thing that may come into play is the scale you're using. Most non-scientific (read: consumer) scales are something less than consistent. Drift in zero and drift in calibration will affect what you see as the charge weight. You can see it by throwing a single charge, and reweighing it several times during your loading session.