Tonight I started loading some 39 gr Varmint Grenades from Barnes in front of 36.5 grs of Varget. Once I adjusted my seating depth to exactly what the Barnes manuel said I began loading them. After I finished 10 or so I checked OAL to make sure I was consistent. 4 of the first ten I loaded were seated below what the other 6 were. I checked to make sure everything was tight. What gives? 6 were 2.350" which is what the OAL in the book says. 4 came out 2.348

Normal, as much as .005" to .010" is common. Best to measure off the ogive, not the meplat. http://www.barnesbullets.com/w...-250RemingtonWeb.pdf

Just curious here, but how much bullet is seated down in the case neck with that 39 gn bullet?
Rule of thumb is one caliber depth, at the minimum.

Your variation is well within the norms.

Lee Info > Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

Thanks for all the info. Everything makes since now.

The old adage to seat one caliber deep was to insure the old lead bullets wouldn't fall out in normal handling, that's rarely a concern with jacketed bullets.

Check the length of your bullets.
You will find they easily vary in length more than .002 inch.

it is to give proper neck tension to insure consistent powder ignition.

To get an idea of variation in bullets, buy a Hornady or Sinclair bullet comp guage. Measure a box of bullets and keep them separated by ogive length. You will find out quickly just how much difference in ogive length there is in some brands and how uniform in others.

You will usually find that most of the bullets fall within 0.001-0.002" of each other but some will fall way outside this range.

Just separate the "outliers" into groups of the same length and shoot them together...your groups won't be so large and the difference in seating depths won't mean a thing.

I've been doing this as matter of course with my small caliber shooters for probably 30 odd years in my varminters and when I was competing. Doesn't take much time and you can do it while watching Monday night football or in the winter when the snow is azz deep to a tall giraffe.

I also weight sort the bullets on a balance beam weight scale as digitals, unless it is an analytical digital scale, isn't accurate or precise enough to measure the small weight difference.

Again I just sort into piles of 1 grain difference and shoot them as loaded. I put them in my bullet boxes starting with the lightest difference in the lowest left corner and continue from left to right, bottom to top.

With an accurate load I see very little difference in size of the group, it just shifts fairly uniformly some way determined by the bullet and powder combination. I progress through the 50 rounds...but the sage rats don't seem to notice the difference...

Brennan; One thing you will learn quickly in this reloading thing is that NOTHING is necessarily EXACT. What works with my rifle may not work in yours and what cartridge OAL makes mine shoot tiny bugholers might cause yours to toss shotgun patterns.

Pick a length, don't get too anal, shoot some groups, experiment with OAL's in a uniform mannor, I use 0.005" plus or minus to see if the group starts getting bigger or smaller and from 0.2 to 0.7 gr difference in powder weight depending on the size of the case...2 tenths for .223 size, 5 tenths for 308 size and 7 tenths for '06 and larger size. Some people call this a "ladder" method...whatever...this method has been used since very early on and it works.

DON'T make more than one change at a time. You will soon develope a technique, but once you see which way the groups are going, THEN you can change BOTH seating AND powder weight in the same increments to arrive at the smallest group size.

243XB listed other very good points and is spot on...do some research on other forums such as LONG RANGE and 6MMBR...you will find tons of data on the hows of reloading, what is the most important aspects and which things do little or nothing to add to accuracy.

Most of the hard won information us "Oldies" learned the hard way is realily available online and much cheaper also.

Luck