Hi guys,

My reloads tend to fall well within a 1% variation of the fastest load in any given batch.

This sounds okay, but what's a normal level of variation for home loaders (and what do the manufacturers achieve)?

------------------

One percent variation is generally pretty good (30 fps at 3000 fps).

Most careful handloaders will acheive generally better (less) deviation than factory loads, for a couple of reasons.

One reason, but not the most important, is that handloaders usually measure their charges a little more accurately. This helps, but is secondary.

The main reason is that factories use powders which are faster burning for a given load, therefore using less powder (cause it's cheaper, dummy), than most handloaders do. Faster powders almost always give greater velocity variations than slower powders, perhaps because of the lower loading density (more left-over space inside the case).

Although I've found some factory loads that do better, 100 fps variation is typical for centerfire rifle loads. (Of course, percentage-wise, this is even greater variation than 3 or 4% since today's factory loads are so g*&d^#m slow to begin with!)

Some of my most accurate loads have the highest load variations, so I let the target dictate my loads...

We need to get away from this theoretical BS that gets repeated so often it becomes excepted fact...most prevelent in the gunworld...

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

If you have a load that is grouping well at 100 yards (or 200 yards) you won't have nay problems at normal shooting ranges....the extreme spread comes into play when you start to get out to ranges where the bullet approaches going sub-sonic...this will give you elevation changes.

Pete...

The best measure of variation is either variance or standard deviation. Standard deviation is just the square root of variance, so you can use either.

It's usually a pretty good assumption that your muzzle velocities are normally distributed. 95% of all shots will fall within plus or minus 2 standard deviations of the mean (average).

In my .223, I can get standard deviations in the mid 20's. I can trim this a few fps if I sort bullets according to weight.... using H322 puts me in the mid to high 40's.

In my 29" 6.5x55, it is no sweat to get into the mid to high teens.

The commercial .223 ammo I have tested seems to run about 35 fps.

Getting good accurate stats on how much the velocity standard deviation affects group size is very tedious, and I'm not aware of anyone having published anything that really shows how good your SD needs to be, but I believe that there is not much point in trying to get below an SD of 35 fps. Many successful bench shooters do not individually weigh their powder loads, but still achieve good groups.

dads 40x 222magnum with 52 gr bergers and h335 has an extreme spread of almost 100 but it makes 5 shots in the high 1s or low 2s.cant explain it.

Hello,
You know, there has been a lot of talk about the SD's, and prior to personal chronographs, nobody cared. I think a lot of components are wasted every day on the altar of low SD's and sometimes to the exclusion of all else. This makes little sense, if you have an accurate load for your rifle, and it has consistent performance at under the ranges/conditions you desire, there is no reason not to use it.

I am not posting this as encouragement to do sloppy craftsmanship, just as a little reality check.

------------------
Safety & Ethics,Accuracy, Velocity, Energy
Joe M

Joe M,

Having posted the question I feel I ought to respond to your very shrewd comments.

I've been reloading now for about a year, with more time spent loading .22/250 for accuracy and .303 for blasting than I have with either of my other two, .243 and now .308.

Someone once warned me against complacency with handloading - "don't just work to improve on what factory ammo will do in your rifle and then stop. See what you can achieve."

Well, that's just what I'm doing; checking my results and finding out whether I should be able to achieve even more

Cheers guys

------------------

If we want to dispell 'handloading myths' we probably ought to do the same for some 'factory ammo myths'. I heard that some factories are making some ammo available with triple-base powders. From what i can tell, this will give us handloaders a real 'run-for-the-money' in the fps catagory and it's possible that we are now at a 'disadvantage'?

I'm continually amazed at how these subjects can be "hijacked", Pete. Your original post simply asked about velocity variations -- yours as compared to other handloaders and to factory ammunition.

I responded to those issues.

Then, everybody takes off on accuracy. You asked nothing about accuracy (which, of course doesn't necessarily correspond with velocity variations, or lack thereof).

For example, through the years I've always found IMR 3031 to be one of the least consistant in velocities, but amazingly consistant in accuracy.

most chronographs will get to about 5% accuracy.so how do you really know you got 1%.it could be 4 or 6.

Eric,

You've touched my worry-nerve

Is that exactly 5%, plus or minus 5% (beign a range of 10%) or up to 5%?

What's your advice to a novice handloader who wants to get better?

Eric...

I don't mean to contradict the good folks who post here, but I think modern chronographs are much more accurate than plus or minus 5%.

Accuracy won't be better than resolution, so I checked my chrony out, and it runs on a 12 MHz crystal. That allows the 1 foot between the two sensors to be resolved down to 1 part in 4,000. That resolution will not limit accuracy on a 4 digit chronograph.

Accuracy will mainly be determined by the crystal controlled time base. Even cheap crystals are stable to about 10 parts per million per degree C, so temperature drift from 0 C (freezing) to 30 C (about 85 F) would be about 300 ppm, or just a fraction of 1 fps.

There is some uncertainty in the trigger point of the sensors, but I don't think it is a big factor. I don't have any way to check to see that both sensors trigger at the same point, but even if they are not perfectly matched, I can't see how they would make more than a fraction of a percent difference.

i stand corrected. i went back to the manual and it said gaurenteed to .5% not 5%.sorry.
if your getting 1% extreme spreads your are on the right track.but still the proofs in the groups.