So I was looking at the results again from Madpick's Labradar with my: 7mm Mag, 454, and .357 hand loads. The 5 shots of 240 gr .454 Casull averaged 1720 fps, highes=1730, lowest=1712, extreme spread was 18, Standard Deviation of 7.7. Being fairly new at reloading and having never using a chrony, I think those are pretty good results. Am I right? The 162 gr 7mm (4 shots) averaged 2821, High=2862, Low=2793, Extreme Spread=69, Standard Deviation=29.1. I'm thinking that's still pretty good, right??? Then the 7 shots of 180 gr .357 averaged 1269, High=1327, low=1208, Extreme spread=119, Standard Deviation=35.8. The extreme spread is pretty high but the standard deviation is a lot less. So, how should I interpret this info? And remember, I'm not using a Dillon or LNL, I'm using a Lee Hand press.

I would say your .454 is just fine.

Your 357 seems a bit high due to the extreme spread but isn't to bad and I don't think its as big a deal as if you are only shooting inside 25yards.

The 7mm it depends. What range? If under like 300 yards I would say its fine. Over that you could have problems. Also hunting groups or going for as small as possible groups?

Think it really comes down to how you are loading and what you are hoping to get from your hand loads. Are you weighing each charge or just setting a powder thrower and then going to town so to speak. Same if you aren't going for super small groups I would call it good too.

Least that's my thoughts on it.

I almost completely disregard the extreme spread when using my chronograph.

If I have 9 out of 10 shots that are within less than 10 fps of each other and one that is 100 fps faster or slower what useful information does that give me? That one out of 10 rounds was screwed up? What about the 90% that have a "single digit" extreme spread?

My chronograph spits out a different number called MAD (Mean Absolute Deviation). The mean absolute deviation of a set of data is the average distance between each data value and the mean.

It has more value in working up a load than both SD or ES.

Oh yes, ES is extremely worthless if shooting a small sample number.

Unless the sample size is at least 20-25 shots, how does one really know what an accurate average speed is? Ditto for the rest of the statistical calc's.

The best use of a chronograph is to determine the average speed of a load for ballistic's calcs and only then AFTER the load has been tweaked for accuracy. Work your load for best accuracy then run 20-25 of those rounds over a chronograph for average speed.

Then you have a speed that makes all your ballistic calcs accurate. The rest of the numbers are something people toss around on forums and in clubhouses but they don't put bullets any closer together in groups down range.

Extreme spreads are often caused by far more than just charge weights.

The holy grail of "group shooting" in the Benchrest crowd is CASE PREPARATION.

Using neck sized, fireformed, cases that have had all necks turned to a uniform thickness and annealed for uniform metal consistency are just a few items.

If the cases don't hold the bullet with exactly the same tension speeds will vary even if you weigh your powder charges down to plus or minus one "mini-mouse turd".

You also need to match the powder to case capacity, bullet, and expected charge weight/case fill. Wrong powder and you have irregular burn. Wrong bullet, same issue. Too little case fill, ditto.

Thanks! I think one of the things that will probably help the most is after I move and have a place to set up a reloading bench with a good solid press. I weighed all the charges. The biggest issue I have is with inconsistent OAL. Some bullets don't seat as deep and I have to adjust the die to get the right depth.

Some would say Nutella, but I find it too sweet.

How are you measuring OAL?

Technically "OAL" is measured to the tip of the bullet ------Always. (Also referred to as COAL)

Measuring to the Ogive is the best way to achieve uniform measurements. More experienced loaders no longer use COAL but the more accurate CBTO (cartridge/case base to ogive) measurement as it's the only one the firearm really "sees" when it comes to jump to the lands. COAL is only important when you have a magazine limit as to overall length.

If one is going to get totally anal over CBTO measurements being uniform believe it or not there is a die on the market that is not only inexpensive but does a near perfect job of assuring this measurement will be uniform. It's the Lee "Dead Length Seater Die". It's built with no crimping area in it and when set up it's screwed into the press so the shell holder comes into firm contact with the bottom of the die. Absolutely NO possibility for any slop in the press or varying hand pressure from the operator to cause varying CBTO measurements. Every cartridge is set to the length the die is adjusted to-----period. Exception being only lousy bullets that have ogives that are not uniform. I last ran a batch of 140 gr Hornady ELD-M bullets in 6.5 Creedmoor cartridges using the Lee Dead Length Seater Die. When CBTO was measured it varied by +/- <.001". That's as good, if not better, than what I get using a $100+ Redding Competition Seater Die with my .223 bullets.

Mike makes a great point about COAL and it's general usefulness.

In my personal reloading for IHMSA cartridges 22 Hornet, 7mm TCU, and 7mm Remington BR I've also adopted practice of measuring case length in terms of base to bullet ogive measurement as the most consistent and repeatable measurement. Hornady makes an excellent series of affordable comparators:
https://www.midwayusa.com/product/231904/hornady-lock-n-load-bullet-comparator-basic-set-with-6-inserts

You basically attach the red base to the outside of your micrometer/caliper, insert the comparator for your desired bullet diameter, measure the bullet length, and subtract 1" for the standard length of the comparator.

In order to have a basis for comparison you'll need the measurement from the breech/bolt face (single-shot and bolt actions) to the point where the bullet ogive contacts the lands that is key. I typically back off about ten thousandths of that measurement to reduce the potential for undesirable pressure spikes. Our IHMSA match director mentioned best practice is to make a couple small lots of handloads at five, ten, fifteen, twenty thousandths off the rifling and measure group sizes to determine effect on accuracy. Quite a lot of work.

Both Sinclair and Hornady makes an excellent gauge for measuring the distance from breech/bolt face to the point where the bullet contacts the rifling surfaces:
http://www.sinclairintl.com/GunTech/Determining-Bullet-Seating-Depth-/detail.htm?lid=16131

Just now starting to venture into the world of outside neck turning. The only reason I'm getting into this at all is because I have a Remington XP-100 in 7mm Rem BR with extremely tight chamber tolerances.

Again I'm fairly new to reloading. Let's see what Mike and Vantage have to say further.

Really no need for the tools to measure the CBTO. Take a fired case and size just the first couple of thousandths of the case mouth, so it grips a bullet but still lets it be pushed into the case with a few pounds of pressure. Go slow when sizing and when first contact is felt in the die, stop and check with bullet. Only enough to hold bullet from falling into case.

Place bullet in case and push in only until the boat tail and about 1/16" of the bearing surface is in the case neck.

Chamber this dummy round and close bolt. Insert cleaning rod in bore until it touches the bullet tip. As you open the bolt and primary extraction begins, make sure that you feel movement on the cleaning rod at the same time. If not, close bolt and press on cleaning rod a little more as you open the bolt and it starts to extract. The point here is to make sure the bolt doesn't pull the bullet out of the case as the primary extraction occurs.

Remove dummy case and measure from case base to ogive using hornady type bullet comparator. Repeat the process to make sure it repeats.


Using this method ensures you won't have to purchase a special case for every caliber of rifle you own.

Funny thing, about an hour and a half ago I did the same thing. I do own a Hornady tool but don't have the special case for 6.5 Creedmoor. Three readings and all were within .001". Tomorrow I load and Tuesday I shoot. Expect great happenings even though snow is forecast for my Club Range. (at least it won't be crowded )

On the issue of varying "jump". Once you have established a good charge weight for a given cartridge/bullet/powder combination varying the CBTO fine tunes the "Barrel Timing". Call it what you wish, barrel timing, harmonics, etc, it's all a matter of making the bullet arrive at the muzzle when the bore is at it's ROUNDEST state and the barrel is pointing in the same direction, shot after shot.

When you fire a round it sends a shockwave back and forth in the barrel steel. This causes the barrel to change shapes from straight to somewhat sine wave shaped. At the muzzle it can point up, down, left, right, and even straight ahead, depending on where the shockwave is at any given time. Even the bore can be distorted from round to oval and back again. Very minute amounts of movement and change but remember, a change of .001" at the muzzle can mean 1 inch at 1,000 yards. On some rifles these changes are large multiples of the above .001" which explains why some rifles will shoot one brand of ammo like a tack driver and another brand will put up groups looking like a shotgun pattern.

In hand loading we are recognizing that a rifle barrel is more like a limp noodle than a rigid piece of steel as far as ammunition is concerned.

Lastly, it's extremely important to go about load development ONE STEP AT A TIME. Do NOT make several changes at the same time or as an old helicopter instructor once told me: "you'll end up chasing your tail until you disappear up your own a**hole".

Keep records of every step from type of sizing (Full or Neck Only), primer, bullet, powder, powder charge, CBTO, shooting conditions (temp, humidity, barometric pressure) and even your own mood/attitude that day while shooting. If tense and up-tight, you can get one set of results. If relaxed and BS'ing with buddies, another. If totally focused on the task at hand where every part of the shot setup and trigger release is the only thing on your mind, a TOTALLY different set of results can be possible.

Mike, the knowledge and helpfulness in your posts never fails to amaze me.

Well, "never" is a strong word. Let's go with "doesn't usually."

Thanks Steve.

Let's just say that I had a lot of oldtimers in my life that freely shared their knowledge with me.

Being retired with all kinds of time on my hands it's fun to push the accuracy envelope and equally rewarding to be able to share my findings.

The only one I would worry about was the one that never got out of the barrel.

Thanks for providing the details, Mike! This is where I was going with the probing question... the COAL being less important than the CBTO as the round interacts with the firearm. Various length-oriented vernacular can be interchanged colloquially which can create confusion given the different technical definitions.

My process for designing ammo magazine-fed as opposed to a single-shot is to start with maximum COAL to ensure magazine function. Reduce the COAL by an engineer's buffer, which implies a CBTO range to start focusing on. Having a die that can consistently throw CBTOs is critical.

I haven't tried a Lee die before, I'm interested now by your review to give that a whirl.

There are a lot of procedural techniques you can leverage to avoid buying additional tools. Philosophically speaking as well, by doing the math yourself, you gain a better intuition and understanding of the system at hand, rather than blindly relying on a new tool to handle it for you. Once a technique is mastered, by all means - buy more tools and cool stuff to speed up or make the process more convenient, or incrementally more accurate.