My RCBS Powder Measure: Is this Accurate enough

[s-works]

I put one pound of powder in to break the measure in per instructions

My AR seems to like 25.8 grains shooting 55gr bullets (223)

I loaded 28 cases and rechecked their numbers on a lee digital scale

The following were the load results

25.7 = 3 times
25.8 = 2 times
25.9 = 7 times
26.0 = 5 times
26.1 = 8 times
26.2 = 3 times

Average 25.84 grains

For you experienced reloaders out there. Is this acceptable?

 

[42769vette]

it depends on what your loading for. if you making plinking ammo its plenty accurate enough.

if its precision ammo that would not work for me

 

[s-works]

it depends on what your loading for. if you making plinking ammo its plenty accurate enough.

if its precision ammo that would not work for me

too much spread in the grains?

 

[42769vette]

too much spread in the grains?

for me it is. .5gr is alot for precision. i use a acculab that measures each charge to .02 gr on precision ammo. if you put the same charge up there 10 times there will be about .04 variation. with that scale i keep tweasers (spelling) beside to scale and pick out individual kernals. this is entirely to extream. there is no way im close to a good enough shot to tell the diffrence in 1 kernal of powder. for me when i lay behind a rifle and am trying to make a precision shot i want to know i did absolutly everything possibable to make that hit exactly where i want it. the plucking kernals thing is more of a confidence thing than a "better ammo" thing. i just have a thing where i have to have complete trust in everything that has anything to do with the exact spot a bullet hits

i in no way shape or form recomend plinking kernals of powder out of your charge with tweasers. but a happy medimum would probably be about right.

 

[45fan]

Too much spread in the grains.. I like to keep even my plinking ammo within .1 of the intended weight. If I am loading something that I intend to make small groups with, I throw the powder load underweight by a tenth or two, and trickle up to weight.

As long as the load isnt over a recomended load, and it is safe, I would try them to see where you end up with your combination.

 

[Fishersjohn48]

The other variable here is to consider the accuracy of the scale. I'm not sure about the Lee digital scale per se but temperature and any draft in the room can alter the readings. In fact, I am not familar with Lee making a digital scale. Have you done any testing with check weights to see if it reads accurately?

 

[45fan]

for me it is. .5gr is alot for precision. i use a acculab that measures each charge to .02 gr on precision ammo. if you put the same charge up there 10 times there will be about .04 variation. with that scale i keep tweasers (spelling) beside to scale and pick out individual kernals. this is entirely to extream. there is no way im close to a good enough shot to tell the diffrence in 1 kernal of powder. for me when i lay behind a rifle and am trying to make a precision shot i want to know i did absolutly everything possibable to make that hit exactly where i want it. the plucking kernals thing is more of a confidence thing than a "better ammo" thing. i just have a thing where i have to have complete trust in everything that has anything to do with the exact spot a bullet hits

i in no way shape or form recomend plinking kernals of powder out of your charge with tweasers. but a happy medimum would probably be about right.

You are not the only one!! I am the same way when I am loading for my .308. I figure I can use all the help I can get, its one less thing I leave to chance if I am anal about the charge weight down to the last kernel. My .223 stuff I usually load with BLC-2, and I am not about to start picking out individual pieces of that powder, LOL!

 

[patience0830]

Ball powder usually meters more consistently so if you're trying to load for bulk shooting you'll be much happier with a ball type propellant.

If I'm loading for absolute best accuracy I'll weigh every charge by throwing charges that are about .2 gr light and trickling up to perfect. A powder trickler is cheap and much easier than the tweezers.
Happy medium is weigh every 5 charges and trust the measure if those 10 out of 50 are close enough.

The same # of taps and a consistent stroke when you are throwing charges makes a difference as well. I always tap twice on the upswing.

 

[42769vette]

Ball powder usually meters more consistently so if you're trying to load for bulk shooting you'll be much happier with a ball type propellant.

If I'm loading for absolute best accuracy I'll weigh every charge by throwing charges that are about .2 gr light and trickling up to perfect. A powder trickler is cheap and much easier than the tweezers.
Happy medium is weigh every 5 charges and trust the measure if those 10 out of 50 are close enough.

The same # of taps and a consistent stroke when you are throwing charges makes a difference as well. I always tap twice on the upswing.

i use the tweezers after the trickler. somtimes 2 kernals fall out when i only wanted 1. thats why i got out of bulk reloading. i just never trust a powder throw and weigh/trickle charge everything wich really slows a dillon 650 down

 

[s-works]

sorry it is a dillon digital scale.

this is mainly plinking ammo.

I have RCBS Powder Combo measure for more accurate loads. I guess my question should be "is this spread consistent with the RCBS powder measure."

 

[Broom_jm]

Yes, that spread is perfectly acceptable from your powder measure.

Before you put a lot of stock in the responses you get here, I recommend you do three things, so you know for yourself:

1) Perform a statistical analysis of the numbers you got, looking at more than just average. Standard deviation is a FAR better predictor of uniformity than a simple, or even weighted average. In your case, you mention how many times you got certain results, which gives you the ability to really understand just how accurate your powder measure/scales are, in tandem. With a slight adjustment down, 22 of 28 cases would have been within .05 of your exact goal...and that is PLENTY close enough.

2) Look up Dan Newberry's OCW (Optimal Charge Weight) method of load development. You may find that your load is already optimized, which means that you could be off as much as 6 tenths either way and your groups (out to a reasonable distance) just won't show it. This illustrates that the weighing of powder has a whole lot more to do with the amount of volume taken up and the remaining powder volume left in the case is more important, in terms of accuracy, than the actual weight of the charge. This is something a lot of reloaders never really wrap their head around, but the Newberry method brings it home in VERY clear focus.

3) Load up 3 sets of 10 rounds. Hand weigh each charge, using a trickler. Load up 10 at exactly 25.8, 10 at exactly 25.5 and 10 at exactly 26.1 grains. Set up 3 physically separate targets of the same size at 100 yards, or 200 yards is even better. Shooting them in round-robin style, taking lots of time between rounds, shoot 1 of the "low" charges, your standard charge, then 1 "high" charge. Keep shooting until all 30 rounds are gone. Don't shoot all of one and then move on to the next, as that will skew the results, usually with better groups in the beginning or middle.

When you've done this, examine the targets side-by-side and even overlay them on one another. You'll be surprised, maybe even STUNNED, by just how little difference being high/low by 3 tenths actually means on the target.

I learned this at the elbow of a guy who used to place in the top 10 of major long-range shooting competitions. His opinion was that it wasn't a great load unless it had this kind of flexibility...and his targets were the outline of a postage stamp at 100 yards. Most of his groups never even creased the edge of the stamp, so I listened close when he told me stuff.

 

[s-works]

Oh man good info. I havent messed with standard deviations since stats in college. Betas, deltas, frequency distributions oh my!

 

[indygunguy]

What kind of powder are you throwing to get that kind of variance?

 

[s-works]

Hodgon H335

I had a brain fade when setting up the powder measure.

Looks like I need to pull 30 bullets.

24.9 is what I am shooting for

 

[blamecharles]

I had one of those also, I got to the range and noticed I was under the recommended starting weight by .5 grains. I shot them anyways and they really weren't that bad accuracy wise and never misfired in any way, they definitely had less recoil than the other batch that was 1.2 grains higher.

 

[Broom_jm]

Hodgon H335

I had a brain fade when setting up the powder measure.

Looks like I need to pull 30 bullets.

24.9 is what I am shooting for

If this thread did nothing more than bring that to light, it was worth it!

Try the experiment with slightly different charge weights and see what you find.

 

[mac45]

I agree that you should be fine for plinking ammo, but.....
H335 meters pretty well out of my Lee measure. Typically +/- .1gr
I guess I'm just surprised the RCBS has such a spread with that powder.
Which measure is it anyway?

 

[Slapstick]

I have a 30 + year old RCBS Uniflow that keeps the charge weight within +/- .1 gr. no matter what powder I'm using. Heck even my cheap Lee keeps them within +/- .1 or .2 gr. I'd say your spread is to way to far apart.

One thing to watch for when using the RCBS powder throw is that the once you set the charge weight make sure the lock ring is screwed down tight and check it every 10 throws or so. They do seem to like to loosen up and can really add the variances of the powder throw.

 

[Electronrider]

I would be very thorough on your process, and your setup. I have never had that bad a spread with my RCBS powder thrower. Heck, I am .2 gr. variance with varget, let alone H335! I usually go for .1gr less than my desired charge, and trickle up on my digital. I am almost ( 9 times out of 10) with .1 using H335.

A few tips:

Make sure that lock ring is hand tightened well, as said above.

Make sure you use the same amount of force when you operate the handle. I make sure that I have a very consistent feeling thunk on the upstroke and downstroke. It is important for both, as the upstroke dumps the current measures worth ( and you want to be sure to get it all out), and the downstroke is where it is refilled(by thunking it in the downstroke, you are ensuring a good drop).

Make sure the powder thrower is securely mounted. If there is any play at all that can affect it too.

Check and see if you are having a lot of static cling with the powder. About once a session, I will lightly rub the inside of the hopper with a dryer sheet. This keeps the static down. ( you can also do this on your powder pans, to keep the granules from sticking to them as well).