Consistent bullet seating depth, and why can't we seat off the ogive?

[FroggyOne2]

I just found this thread after starting to sort a batch of SIE bullets that I had recieved. 1200 175gr 7mm bullets. This is the first time that I have decided to seperate the bullets by COL base to ogive. What I have found is that I have recieved two different lots of bullets. Started with opening one box and picked a bullet and measured it using a digital caliper and a Stoney Point 7mm comparator. So far through 700 bullets I have found starting with that bullet (I am calling that bullet the 0.0 bullet) because I zeroed the caliper on that bullet. I have a varience from
-.013 to +.006 in the COL. So then I was thinking, when I am done, I will take the shortest ones and call them the 0.0 bullets, to which I will use to determine the seating depth and load with. After that seating depth, as I shoot the bullets I will change the seating die up so that as the next set of bullets used with have a new seating depth, but the volume in the case will remain the same. I also figured by doing this should in theory stay somewhat close to the same distance or so from lands, fore as you shoot, the erosion of the throat will move. So in theory, as you keep the same volume in the case, you also keep somewhat the same distance from the lands and you shoot the bullets in this way. The bbl that I currently have already has a 1000 rounds on it and it is chambered in .284. I normally have used the Hornady 162 Amax, but this year I was forced to pick another bullet for the year. I buy bullets only once a year and what is available at the time that I am ready to buy is what I get, I will not buy Berger bullets because the price has just gotten out of hand for me to afford using them. It was then that I found this thread, after thinking about what I just stated when I was sorting the bullets.

 

[BoydAllen]

Small point...COL stands for "cartridge overall length", in other words the length from the bullet's tip (meplat) to the head of the case. This is not meant as a criticism of anything that you posted. I think that sorting bullets, especially those that come from multiple dies, is a very good idea. One thing that you may want to do is to check the length of each sorted set of loaded ammo to see what the variance is, from where the rifling will make contact, to the cases heads. It may be that these variations are more important than the slight differences in case volume produced by your sorted groups, particularly if you have not sorted cases by volume, or neck tension.

 

[FroggyOne2]

OAL = Over all length (Point to base)

COL = Cumulative Over all Length (Ogive to base)

This is the way that I have always done it and have known it to be.

 

[FroggyOne2]

Lynn,

I don't shoot for groups per sey.. 1/4 moa is more than enough for me.. everything I do is for vertical dispersion. In the past I have just seperated by weight and load and shoot.. I do that with my .223 with the 75 Amax.. and it has a 1/4 inch V.D. at 300 yards..

 

[bozo699]

Froggyone
If you were to visit the 600/1000 yard forum at benchrest.com you would see my post were 0.013 bullet ogive variation is actually quite normal.You need to sort those bullets into individual lots that will get shot together.
You also need to recheck them when your seating them as you will once again get alot of variation.No seating stem currently on the market will make any difference at all as they all make contact to far up on the bullets ogive to be of any use at all.
If you have a micrometer top on your seating stem and A comparator you can seat the bullet a bit long then adjust the micrometer top to get an exact number WHILE USING YOUR CALIPER MOUNTED COMPARATOR.
Without using that method on vld type bullets you will never be competitive.If you want to shoot 3 inch groups at 1,000 yards your seating depth down to 0.001 is the most important part of the equation and uit takes very little extra effort to get it done.At 100 yards as you incrementaly adjust your seating depth your groups will shrink into little clusters and then open up again.If your shots never went into a single hole it is because of the ogive variation and your searting variation due to it.
Nothing you can do while reloading vld type bullets will improve your accuracy as much as getting this one procedure done correctly.
Lynn

Lynn,
Your post is quite intersting, I have never went to those extremes, I think I will give it a try, thanks for the post.
Wayne.

 

[normmatzen]

Lyn,

You must go to the Two Rock farmer's range. Actually, I was born and raised in Petaluma, and my family has been there since the 1890's. But, I now live in El Dorado Hills and shoot with the Folsom Gun Club at the Sacramento Shooting center. Come out some Monday for long range bench practice, we shoot both 600 yd and 1000 yd. We start about 7:30 sign in at the office and go to range 12.

Anyway, about the seating die. Originally, the die was set up in the press by the included directions. With those directions and the spring that was coil bound before the inner sleeve entered the outer sleeve, the actual seating depth was controlled by how much pressure you put on the spring as it became coil bound, and the press flexed. I saw variations of COL of up to 0.004".
Now with the shortened spring and the die lowered in the press, the inner sleeve can go into the outer sleeve by 0.010-0.020" and the seating depth is precisely set by the seating die and not how much pressure you put on the die with a coil binding spring. once the shell holder compresses the inner sleeve to the depth of the outer sleeve, the bullet is seated. No more, no less. And, by dropping the die into the press more, you can feel the actual seating resistance the neck imparts on the bullet. My new spring came in todays mail so It will be installed before I use the die again.
Oh! Yes! My vertical spread has improved noticeably. Unfortunately, it has done nothing for my ability to read the wind!!!

 

[normmatzen]

Lyn,
I didn't completely answer your question.

I didn't mention adjusting for ogive shape or location. I load for a specific Cumulative Overall Length and now that my seater die is performing, my Hornady comparator sees less than 0.001" variation. And, as the actual bullet jump is a first order effect in maintaining the best load and both MV and impact point are very sensitive to jump, that's my main concern. Surely, where the ogive begins with respect to the bullet base can slightly change the ultimate case volume as well as slightly change the aerodynamics, these are second order effects. With the too long spring, the COL was varying according to my comparator along with jump distance. Now it don't!

 

[thefitter]

Froggyone
If you were to visit the 600/1000 yard forum at benchrest.com you would see my post were 0.013 bullet ogive variation is actually quite normal.You need to sort those bullets into individual lots that will get shot together.
You also need to recheck them when your seating them as you will once again get alot of variation.No seating stem currently on the market will make any difference at all as they all make contact to far up on the bullets ogive to be of any use at all.
If you have a micrometer top on your seating stem and A comparator you can seat the bullet a bit long then adjust the micrometer top to get an exact number WHILE USING YOUR CALIPER MOUNTED COMPARATOR.
Without using that method on vld type bullets you will never be competitive.If you want to shoot 3 inch groups at 1,000 yards your seating depth down to 0.001 is the most important part of the equation and uit takes very little extra effort to get it done.
At 100 yards as you incrementaly adjust your seating depth your groups will shrink into little clusters and then open up again.If your shots never went into a single hole it is because of the ogive variation and your searting variation due to it.
Nothing you can do while reloading vld type bullets will improve your accuracy as much as getting this one procedure done correctly.
Lynn

This is what I have been doing.

For each type of bullet I have a .001-.004 range on my die that I logged.

e.g: 4 rings / 33-37

I start at the highest setting (33) see what I have with a particular bullet and then adjust the Wilson micrometer. If it's .002 too long go to 35.

The nice thing about the Wilson is that if you dial .001 you get .001 adjustment. The only problem I have had is remembering to always turn it back to the starting point.

Another thing I have found that helps me is I got a Davidson comparator set. It has a nose piece AND a base. I feel I get more consistent measurements with it.

Thanks

 

[BoydAllen]

FroggyOne2,
Hornady Manual, 5th addition, volume one, page 63, Seating Depth: "...we list maximum Cartridge Overall Length (C.O.L) according to SAAMI specifications."

Speer manual, number 13, page 77, Step Eight Bullet Seating "...the cartridge overall length (C.O.L.) used by Speer for load development. In many cases this is under the maximum SAAMI cartridge length specified in industry standards."

No big deal, but I think it a good idea to use standard definitions in our discussions.
Be well.
Shoot small.
Boyd

 

[normmatzen]

Lynn,

Yes they sure do sound familiar!

Then, you must be the Lynn that won the last 1000 yd national. You know, my first national where I kindly made sure no one else would have to come in last!!!
And you must be the guy with the heavy gun that is like a Sherman tank!!

 

[Cameron SS]

What you are suggesting is a great idea in theory. The problem is in making a die do it. By definition the ogive point is when the slope of the bullet nose goes virtually flat. When you measure to the ogive you are using a very small force. However when you seat a bullet you can be using significant force, depending on the neck tension. Because the slope of the nose is so flat you have the extreme mechanical advantage of a thin wedge. To truly seat on the ogive you need a very thin point of contact. So this mechanical advantage of the wedge will swage into the bullet and most likely damage it, and worse still grab it to the point it will pull the bullet back out when you withdraw the cartridge from the die.

Ron AKA, you are a man of wisdom, and correct on all counts.

I conducted a little experiment using my redding competitiong bullet seater and an RCBS precision mic (PM).

Seating 210Gr SMKs with my redding competition seater and measuring with the precision mic I had a variance of just under .001".

I then tried using the PM itself to press the bullets a mere .001"-.002" of a thou further to get them down to a uniform depth. It took alot more hand pressure then I thought it would to get the bullets to move at all. (I guess this is why we use a press in the first place). Every one of the ten loaded rounds I tried got stuck in the PM and I had a hell of a time getting them out. While I tried to be as gentle as possible, most of them required a pretty firm twist and wiggle to get them out.

Once I got the rounds out of the mic, I remeasured them, and almost all of them had been pulled out, some of them as much as .020". Much worse than the .001" I started with.

Also, most of them also showed slight denting at the junction of ogive and BSL. After reseating these bullet with the comp seater, I fired the 10 round group at 300 meters. Results were about 1/4 MOA worse than usual. I attribute this to the denting, all other things being equal.

Not the most scientific, but I hope that sheds some light as to why we are stuck with the seaters that we have, and not the magical ones we want.

 

[gunner69]

Watch this video for the answer that solves this problem with consistently seating bullets to the seam depth.

http://www.youtube.com/watch?v=etgIVSSl8L8

 

[bozo699]

Watch this video for the answer that solves this problem with consistently seating bullets to the seam depth.

http://www.youtube.com/watch?v=etgIVSSl8L8

Gunner,
I know this is a little delayed but the video is what heavies was telling us in post #66 just different measuring devices but both used the seating stem from the Redding die, it does work I tried it.
Wayne.

 

[gunner69]

Here is how you deal with inconsistent bullets

http://m.youtube.com/watch?v=etgIVSSl8L8

 

[tripcrow]

A couple years back I had my gunsmith make me a comparator insert that was very small so as to measure up close to the bullet tip. After first sorting into lots for bearing surface using a pair of standard comparator inserts, I then started into sorting each lot using one standard comparator insert and the small custom insert. Figuring to get lots of more uniformly shaped ogives. Thing was my calibers and tools were not accurate enough to find any difference in ogive shape among bullets within the same bearing surface sorted lots. Now maybe I just had a great lot of bullets, I’ve since converted the tool for another experiment, but I think that once you have sorted BT bullets by bearing surface or flat base bullets from base to ogive the difference in ogive shape between those sorted lots is very hard to find. And while my Wilson seaters, that contact a little further down the bullet, consistently seat better than my Forster or Redding seaters that contact higher up, I’m thinking the Wilson seater’s better performance isn’t just because of where it makes contact.

 

[lmorrison17]

I didn't read all of this thread but from the first few pages.
Bullets have variances between where the stem contacts and where the bullet becomes full diameter.
Here is what you need to sort those differences.
http://greensrifles.com/New_Products.html

 

[Fotheringill]

I am glad that I was referred to this thread by another board member before I pulled out the few remaining hair follicles I have left on my head.

I am brand new to reloading and was getting frustrated over many things including my obvious lack of measurement skills both with calipers and RCBS Competition Seating Die micrometer, hand loading skills, and everything else. I was getting varying readings on the OAL of 75gr A-Max with new brass from hand caressed round to hand caressed round by as much as .015. Maybe it ain't me.

 

[Mozella]

.... snip..........
Which seating stem seats off the ogive? Not my Forster Micrometer die or my Wilson micrometer hand die.

I'm not quite sure what you mean by "off the ogive". I would say my Forster Micrometer die seats by contacting the ogive; i.e. as the case is raised into the die, the plunger which controls the seating depth contacts only the ogive of the bullet. After seating I can see a faint ring on the bullet ogive where it contacted the die. That is to say, the die does not contact the tip, it touches the ogive.

 

[clowdis]

Why not use your throating reamer or chamber reamer to make a stem for your seating die? You will probably need to make some mods to your die or make a completely new one, but you will be seating inconsistent bullets to contact your throat or rifling at the same point each time. Flame away!

 

[Dusty Stevens]

Why not use your throating reamer or chamber reamer to make a stem for your seating die? You will probably need to make some mods to your die or make a completely new one, but you will be seating inconsistent bullets to contact your throat or rifling at the same point each time. Flame away!

I have done this and while it seems like a great idea the bullets stick like mad with that much contact area. If you can make that stem contact farther down its better(getting into a more consistent area of the bullet) but make the contact patch on the bullet as small as possible