got a question about seating depth and the stoney point comparator. I don't have one yet, but i think i just talked myself into buying one after measuring some rounds.

the question is: is the comparator worth it, or can i just buy an extra seater plug and go with that instead? It would seem to me that the two would do the same thing, but one would be a whole lot cheaper.

for those that have them, does the standard C.O.L. measurement go out the window? or do you make up a max length dummy round and make all future measurements derived off that?

I tried measuring some of my 300wsm rounds and got wildly varying readings going off the tip of the partitions. They had an .008" spread in length while measuring off the tip, where measurements using the seater plug were much more accurate. The spread for those was .003", so I guess the rounds weren't as bad as I first thought.

I know the stoney point tool would be worth it, but I was just wondering if the seater plug idea would be viable.

thanks.

L,

I would think the seater would be fine for a specific bullet, as long as it is not measuring off the tip of the bullet. But ogives will vary in shape somewhat between bullets in a batch and produce variation whichever you use.

The comparator will measure closer down to the bore diameter and should give you more reliable starting points when transferring measurements to a different style of bullet. Gives you a better starting point when switching bullets.

The Stoney Point gauge set (if you buy the complete set), will have two gauges. One is used to measure the distance from the bolt's face all the way to the lands, while the other will allow you to measure the cases and see how much forward the shoulder had moved after firing. The gauge measures from the bullet's ogive, not from the bullet's tip.

Since the bullet's ogive varies with different bullets (different weight, different design, different brand, etc.), you will have to take new measurements as you change from a bullet to a different one. For example, if I have already taken the measurements with a 210-grain Nosler Partition, and now I want to load 250-grain Nosler Partition bullets (different weights), again I have to take new measurements with the new bullet. However, the measurement should be fine for the rest of the batch of 250-grain Partition bullets in the box.

Does your 300 mag group so well that such subtle differences in COL are going to be at all significant?

If you're not shooting 3/4 m.o.a. or better, I doubt you should be worrying.

Nothing magical about the Stoney Point comparator but it is very simple, and an effective way to find a starting place. I would recomend one as just that a way to find a starting place. I use other ways to get closer to the lands or to verify what the comparator reads.

You are right in not trying to measure COL from the tip of the cartridge.

Good luck

I might be thinking about the wrong animal here. I was looking for something that would give a measurement from the ogive of a particular bullet size down to the base of the case.

I already sort the bullets for weight and end up skimming about 8 out of 100 for weight mismatch. The idea of sorting out more for length didnt exactly light my fire. but when I did measure them with the seater plug, they were all within .001" even though some of the noses were all dinged up.

so if anybody has a better gizmo than the seater plug, I'd love to hear about it.

sonofagun, the whole reason that i ask is that I was working up a load for my new toy using the OCW system and right in the middle of the supposed sweet spot, i had two shots touching and one flyer about an inch to the left. Was it me, wind, or the round? I can't say for sure. Measuring the cases I have laying around the house, i'm starting to lean on seating depth.

It shoots at an inch right now, but if I can get it to print a mickey mouse with 180partitions, I'll probably piss my pants.

thanks,
leonard

Leonard,

Sorry, when you said "seater plug" I thought you were talking about using one from a seating die with the stem cut off.

I would definitely get the comparator with caliber adapters. They do measure off the ogive but at it's very base close to the bore diameter.

that's exactly what i was thinking of using steve. I use the lee dies and they sell replacement seater plugs for $2.00. It seems to me that one of those and a caliper are all that are really needed.

the plug/caliper setup would measure from the same point on a particular bullet, that point not being on the nose. That would seem to be a reliable method since it would disregard any deformation of the nose and any variation in placement of a plastic tip if used.

I'm not agains the stoney point setup, but if i can get the same results for 2 bucks, guess which one i'm gonna use.

thanks,
leonard

The two shot touching and then one an inch off...is it me, seating depth,???? Maybe it was the case!!! Rounds that go outside of the group always get the case analyzed for neck diameter and thickness, also weighed and measured at the base! A Forster/ Bonanza Co-Ax Cartridge and Case Inspector tool would probably serve your purpose better. You can check the brass for concentricity befor loading and then check the loaded rounds for concentricity! You might be surprised at what you'll find out!! GHD

I found the Stoney Point OAL guage took some getting used to. At first my readings varied quite a bit. This improved as I learned to lightly touch the lands, not try to get a solid contact. I used a one piece cleaning rod from the muzzle end as well as the OAL guage from the breech. Problem is you can't really tell if the bullet is jammed or not. In the process of using this guage I realized that I couldn't even reach the lands with most bullets. The chambers are simply too damn long. Only Sako's chambers came close to the SAAMI recommendations. I checked 11 different calibers (6 to 8 bullets for each one), and came away really disappointed. We are fortunate to have SAAMI. I see no reason to ignore their recommendations. It seems we're freelancing with this. Best wishes.

Cal - Montreal

I would mention that the split case method will give you the way to seat your bullets at the rifling as a starting point for any new bullet. As long as you use the same bullet for each new setting, i.e.( off the lands, at the lands, into the lands) you will be working off the ogive of the same bullet in the batch, so the consistency should be damn near perfect.

I don't use a comparator, because the number is meaningless to me, I use an OAL after setting the ogive on the lands. This way you use a caliper to check the seating die's progress with the same bullet you used in the split case. The split case is free,..and will seat a bullet at the rifling for a starting measurement to within .001" every time. Then the die can be set up or down the amount you wish to move away from or toward the lands from there. Simply take that same bullet,..and resize a case,..then set the die up until the OAL is whatever distance longer or shorter than the measurement you got to the lands with the split case. This is the fastest way there is IMHO.

An extra seater plug would make switching back and forth between bullets and depths much faster,..but you can do the same with the split case,..and always chase the throat,..no matter how much erosion has occured between the last time you checked it,.and now. You will always be at the lands from the initial sizing this way.

[ 09-23-2003, 07:22: Message edited by: JustC ]

I'm with Simdow on this one,If you get the "auto" version,you gan get your "distance to the lands/col",then take it "as is" to your seating die,put it up in the mounted die,and run in the seating screw untill you feel the case being pushed,Gets you in the ballpark in a hurry.Real nice when making a major bullet style/wt. change.Clay

At least in my individual case, the Stoney Point gages have been one of the best reloading tools I have used. It takes little time to get used to them, but once you do you won't forget it. With some bullets, such as Barnes-X, XLC, etc., it takes some time to find the right seating depth. I used the gauges to seat the XLC's .050" off the lands, and I finally found the spot where these bullets became accurate with my .338WM. These gauges have saved me lots of time when reloading.

I would get the comparator. In fact, I did. I was also having trouble measuring from spire points--it is difficult to get your die back to where you want it if you can't measure from the same spot on each bullet (or if the point varies, as with partitions). The comparator cleared it all up. And once you know the difference from ogive to tip for a bullet, you can easily translate the figures.

What I like best is that for another $6 or so, you can pick up the headspace gauge, as it uses the same fitting for the caliper.

I posted this on another site, but it may fit here also. The original poster noted that the exact distance to the lands was not important, since (almost) no one seats the bullet there. The measurement is independent of ogive shape, since bore diameter does not change!

(name deleted), you are a breath of fresh air! Seems everybody else is hung up on the exact distance from bolt face-to-lands. I, too, built a "comparator", and went a step further and modified an old Herters seating die in '06, so that the seater contacted the same place on the ogive that my "comparator" does...no more messing with the die setting! Sure wish I had Herters dies for all my calibers!

http://f2.pg.photos.yahoo.com/ph/short_pour/lst?.dir=/My+Photos&.src=ph&.order=&.view=t&.done=http%3a//f2.pg.photos.yahoo.com/
Regards, Curley

The only problems that would arise from the seater plug method that I can think of is maintaining alignment on the bullet during measuring and the fact that typically seaters bear on the ogive quite a ways up towards the tip- where bullet mfg tolerances will manifest themselves the most.

I agree with curley- I've never actually seated right on the lands. Tolerances there would invite pressure variation though I imagine there are exceptions. I seat either about .003" into them (for benchrest) or some determined distance off them. The comparator simply makes it convenient to get a reference of boltface-to-lands distance to work off of, nothing more.

Convenience is what you're paying for.