The questions that arise are:
1: if the caliper measured OAL differs,the length measured to the ogive-the bullet section that touches the rifling first- may indeed be same.I therefore should not reseat to same OAL as the bullet seating depth would be different.

The resulting advise could be:
1: seat all ammo with the precision Forster die and forget about measuring OAL.
2: get a measuring device that measures from base to ogive rather then the tip.
2a ther then making me feel good,does it matter?
or: can one trust the precision bullet seating die?

3:What about cartridge bases not being perfectly level,thereby yielding different OAL's measured and probably seated?

bullets used:Nosler partitions,Barnes XLC

Thanks for all advise

sheephunter

quote:

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Originally posted by sheephunter:
Gents:
I am appreciating advice on an ongoing vexing problem of mine.
When reloading,bullet seating with the Forster precision bullet seating die,that allows seating to 0.001" tolerance,then measuring the OAL of the loaded round,I am getting about 10% that are significantly longer - maybe up to 0.07".
Part of the problem being that I get slightly different OAL with the calipers,by rotating the round in the calipers,suggesting that the cartridge bases are not exactly level- maybe by 0.02" variation.
This suggests to me that the seating die,seats from the ogive rather then the bullet tip- and bullet variation is responsible for the different OAL's?

The questions that arise are:
1: if the caliper measured OAL differs,the length measured to the ogive-the bullet section that touches the rifling first- may indeed be same.I therefore should not reseat to same OAL as the bullet seating depth would be different.

The resulting advise could be:
1: seat all ammo with the precision Forster die and forget about measuring OAL.
2: get a measuring device that measures from base to ogive rather then the tip.
2a ther then making me feel good,does it matter?
or: can one trust the precision bullet seating die?

3:What about cartridge bases not being perfectly level,thereby yielding different OAL's measured and probably seated?

bullets used:Nosler partitions,Barnes XLC

Thanks for all advise

sheephunter

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Exactness is only for brain surgeons and lasers....

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

ray@atkinsonhunting.com
atkinsonhunting.com

quote:

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Originally posted by Gerard:
Bigdaddy,
I would like to very respectfully suggest that not all bullets vary in length. There are bullets available with ogives so precise that no variation in oal occurs even from batch to batch.

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09-600 Sinclair Bullet Comparator $15.95
www.sinclair intl.com

quote:

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Originally posted by Atkinson:
In the real world where reality takes precedents over theory the differences that you are dealing with are insignificant to say the least and I doubt that you can handle calipers to that kind of exactness..You might with a micrometer, maybe, but the question is Why??

Exactness is only for brain surgeons and lasers....

---

Go on over to http://scripts.xtremeaccuracy.com/? and say that. I dare you. I double dare you.

------------------
Gerard Schultz
GS Custom Bullets

It appears seating depth differences make a lot of difference in the MOA,judging from reports on this forum.My interpretation would be this to be a result of finding the "best bullet jump" for the barrel etc.
Should one then seat c a precision seater and not be concerned c measured OAL to the tip,or should one verify accuracy c a Sinclair or other gauge from the ogive- assuming the ogive to throat length is the variable on wants to keep constant.
As Ray maybe implies,one can always measure,but in reality one measures maybe the wrong dimension

Thanks, sheephunter

Then, cut loose with $25 and get a comparator set. A Stoney OAL gauge setup also helps, but there are several methods to set bullet jump without it.

Good shooting!

[This message has been edited by David M (edited 11-23-2001).]

thanks
sheephunter

If a loaded round measured off the ogive is varying in length at all, there is only two reasons for this. Either the the distance from the base of the bullet to the point on the ogive where it contacts the lands is inconsistant in length, or the point on the ogive where the it contacts the seating plug is.

When you identify where the seating plug is contacting the ogive, measure the diameter there. Then by using the closest caliber insert with the Stoney Point or other comparator you will know where if any variations are occuring, how much, what bullets to use and what you may have to live with.

To go a step farther you could segregate bullets based on length to seater plug contact point, if it were the inconsistant distance, then seat in groups accordingly to maintain distance to the rifling.

To check casehead perpendicularity you should trim the case to square the mouth, then measure. First an unfired case, then after firing, this should tell the tale.

A caliper is very accurate when used carefully, especially as most of these measurements are relative.

Your seating die is a constant, not a variable. I would get a bullet comparator and check your bullets and the COL first.

If OAL of the bullet at the lands contact point on the ogive is inconsistant and you compensate by segragating these and seating accordingly, load density will undoubtedly vary and accuracy may well suffer even more, who knows.

70 thousands variance on the tip is quite a bit, on the ogive not as likely.

PS. Are you sure your primers aren't sticking out. Ok I was just jokin.

Later
Brent

quote:

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Originally posted by sheephunter:
Thanks David,
you are getting close to my actual question:
Do I need a Stoney Ogive comparator gauge to seat bullets accurately?

No. You need a comparator to measure OAL using the ogive as a reference. There are various methods to get a Max OAL to the lands. One such method is to neck size a fired cartridge, slightly. Enough to get a firm grip on the projectile, but not too tight. Takes a small amount of practice. Seat the projectile just enough to hold it. Chamber the round, slowly. Now withdraw slowly. Measure OAL to the tip, unless you have a comparator. Using a bullet puller, pull the bullet slightly and repeat to verify. Now, this is your max OAL. The tip reference is only good with that projectile. An ogive reference is only good with that particular projectile type. Using the seating dies, shorten the cartridge the distance that you want the bullet to jump. Now, your dies are set for that projectile type.

Assuming that I use the Ultra Forstner bullet seater,which I believe seats them from the ogive anyway.

I've never used that seater. Verify the seater contact.

Putting it another way:My rounds maybe alright,its only the measuring variance to OAL that causes my concern.
Putting it yet another way:If one seats c a precision bullet seating die,should one verify reproducible seating depth,distance to rifling?

Yep. Big50 gave you a lot of good advice too. You should have the info here on this thread that you need to do just that. Also, a quality bullet should have reasonable, (that's some where way, way less than .07"), tolerences with regards to the ogive.

thanks
sheephunter

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[This message has been edited by David M (edited 11-23-2001).]

I think this gives you a great excuse to buy some stoney point products ...and any excuse to buy some more tools is valid(needed them, might need them in the future, they were on sale, they looked neat, everybody else have some, etc.)

Phil