OAL Measurment


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bhw4235
January 2, 2012, 03:07 PM
I am trying to measure my OAL from rim to ogive. I am using a hornady OAL tool. First question, I am getting pretty inconsistant measurements .003-.015 differences in the measurements each time I try itusing the same bullet, I am doing my best to do everything the same every time, what am I doing wrong? Second question just because I need to know. If I use a new sized case and start a bullet in the case and close it in the action, then take that dummy round out and measure it the same way with a comperator from rim to ogive, I am getting a difference in length by .020-.050" than I am using the hornady tool, how can that be?

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rcmodel
January 2, 2012, 03:18 PM
If I use a new sized case and start a bullet in the case and close it in the action,You can't use a sized case.

It would or should take more force to slip a bullet in a sized case then you can put on it just from rifling leade contact.

If one did somehow slip and seat deeper occasionally, it would be so inconstant it would be meaningless anyway.

I would try using a fired unsized case with the mouth flattened slightly so the bullet can move when chambered, but stay in place when you pull it back out.

rc

918v
January 2, 2012, 03:24 PM
You CAN use a sized case if you cut a slit in the case neck from the case mouth all the way into the shoulder.

30Cal
January 2, 2012, 03:38 PM
You don't need to slit the neck. Stuff the dummy (sized case, bullet seated) into the chamber with your thumb. If you need to pry it out with a thumbnail, it's in the rifling. Seat deeper in small increments. When it falls out from gravity alone, it's not touching the lands.

rcmodel
January 2, 2012, 04:01 PM
I have used a candle smoked long seated bullet for 50 years to do just that.

Keep seating a frog hair deeper and smoking the bullet again until the soot stops rubbing off and the ogive is just touching the rifling leade.

I seriously doubt any gage set-up can get any closer to exactly right then that.

rc

gamestalker
January 2, 2012, 05:08 PM
I've been doing the way 30Cal described for many years, with great results. But unless your going to buy the more expensive precision bullets, expect to have some into the lands while other's will be off the lands by several thou's or more. With the inconsistent olgive bullets now days, I just try to make sure they are at least touching the lands for the short sided one's, and into the lands on the long side. Using this method to cope with the inconsistent olgives has kept me shooting sub MOA with my production rigs.

GTS Dean
January 2, 2012, 05:31 PM
I strictly differentiate between OverAll Length (total length of loaded cartridge) and Cartridge Ogive Length. The chamber's bolt face to rifling land distance (Chamber OAL gauge measurement) plus the bullet's Base to Ogive Length is what the Cartridge Ogive Length should max out at. If you don't sort bullets by Base to Ogive (with a comparator), some of your rounds may end up with the bullets forced against the rifling giving inconsistent pressures/groups. Most commercial bullets I shoot will vary up to .005"-.006" within a box and I sort them down to .002" variance for my loads.

I have a tack-driving 6MM Remington that is highly unforgiving of variance in Cartridge Ogive Length.

918v
January 2, 2012, 05:32 PM
The problem with chasing lands is they always move.

30Cal
January 2, 2012, 08:15 PM
True.

bhw4235
January 3, 2012, 10:29 AM
I tried a fired case last night and squeezed the neck a little so that it would hold the bullet with a little pressure, but nowhere near the neck tension of a sized case. I tried it 5 times and came up with a .003 difference in the 5 tested which was alot better than what I had been getting. Then I tried 5 more with the Hornady OAL gauge as careful as I could be with the same result, then tried 5 times with a new piece of brass and used a candle to soot the bullet and came up with the same result +/- .003 on all tests. So thank you to all that replyed. Maybe I have it close to figured out.

fguffey
January 8, 2012, 01:49 PM
#2
rcmodel
Member


Join Date: September 17, 2007
Location: Eastern KS
Posts: 29,543 Quote:
If I use a new sized case and start a bullet in the case and close it in the action,

You can't use a sized case.
___________________________________________________________________________________________________________________________________________________

You have my permission to use sized case, a neck sized case, a full length sized case or a partial full length sized case with neck sizing, it helps to know the difference, it helps when reloading to be able to keep up with more than one thought at a time.

bhw4235, You can use sized cases, because? Bullet hold!, I want all the bullet hold I can get, and? I am the fan of transfers and standards, I could shred the neck of the case and make squid neck cases, that works if all I was going to do was talk about it or look at them, I want to take a measurement from the chamber to a test case to the seater die that can be zeroed (all of my seater dies are adjustable in thousands and zeroed to .000 off the lands or to any dimension I have a standard for).

You are also allowed to use a fired case, my first choice would be to neck size for bullet hold, I would not waste my time pinching the neck, again, I want ‘ALL’ the bullet hold I can get, buy if I did decide to pinch the neck I would accept readings that would be all over the place, meaning I would pinch the neck of one case and use it over and over and etc.. Because?

Again, I drill the flash hole/primer pocket to a diameter that will accommodate a cleaning rod, I then seat a bullet that is to be used for loading, the depth of the bullet is to be seated deep enough as to avoid the rifling before the shoulder contacts the shoulder of the chamber, after chambering the test round, I push the bullet out of the case with a cleaning rod until the bullet contacts the rifling (if the bullet is pushed out of the case before the bullet contacts the rifling get a longer bullet, if that does not work, work up 200 + rounds in groups of 5 and head to the range to determine what narrow window of combinations of loads the rifle likes, there will be a few bullets with starting loads that shoot good but will not shoot better by increasing or decreasing powder charge or by increasing or decreasing the design or weight of bullet) And I was asked why and how something like that could happen and I say/ask to see the reamer and the answer was “we broke it, by accident” and I say someone heard about Weatherby’s and the long throats, instead of saying “interesting, very interesting” they purchased a neck reamer and got after it.

Back to pushing the bullet out of the case with bullet hold, after removing the test case from the chamber it becomes a transfer, the transfer does not need to be placed into a Hornady/Sinclair, home made dial caliper with a round hole in it, BUT! if the transfer was placed into the Hornady/Sinclair, Home Made devise, what would the reloader do with the measurement? The measurement needs to be transferred to the seater die, there is no harm in looking at it, I suppose, the point being the Hornady/Sinclair, dial caliper home made devise with the hole in in from Home Depot is not necessary, nice? Yes, just not necessary.

Again, all I want to know is ‘Where are the lands? What is the distance from the bolt face to the lands and it is not OAL or COL, or COAL, after determining measurement from the bolt face to the rifling with the transfer, I place the transfer in the shell holder, raise the ram then adjust the seater down until the die/crimp contacts the mouth of the case, then stop, back the die off 1/2 turn then secure the die to the press with the lock ring. After securing the die to the press I adjust the seater stem/plug down until it contacts the bullet, then stop and secure the stem/plug to the die with lock nut on the stem. THEN I use a height gage or dial caliber to measure the height of the stem above the die, after measuring the height of the stem above the die, I adjust the dial caliper to .000 and call it .000/zero off the lands, again without a Hornady/Sinclair or home made too,

After adjusting the seater stem for .000 I use the .000 as an Index (write it down) then lower the stem and measure from .000 for seating bullets off the lands. Example, if I decide the adjust the bullet .030 off the lands I would use the dial caliper to adjust the seater stem from the .000 index .030 thousands, not forgetting to secure the locking nut on the seater stem/plug.

With bullet hold, the transfer can be stored for future use, again, my rifling contact point does not move, on my 30/06 chambers the contact point is always between .300 and .308, but that is for another day, so if you choose to use cases with sized neck in any combination you choose, it is OK with me.

F. Guffey

Walkalong
January 8, 2012, 03:29 PM
Anyone who thinks they are holding .001 tolerance every time in bullet relationship to the lands, is mistaken.

Close? Yea, but not to .001 every time. :)

918v
January 8, 2012, 04:34 PM
and even if they could, it would not matter one bit.

k4swb
January 8, 2012, 05:56 PM
Anyone who thinks they are holding .001 tolerance every time in bullet relationship to the lands, is mistaken.

Close? Yea, but not to .001 every time. With the right bullets and dies you can pretty much do it every time.
A good match bullet and Wilson dies with an arbor press will do it better than 99% of the time. If it wasn't so darn slow, I'd seat all my ammo this way.

I don't have a lot of rifles but I use Wilson micrometer seaters on all of them.

Walkalong
January 8, 2012, 07:12 PM
As someone who shot Benchrest, and used dies such as you mention with an arbor press, using Benhrest bullets that were all made in the same bullet die, I understand how exact you can be, but to the same .001 every time? Really?

But, I'll give it to you.

We were talking about regular (Not Benchrest quality, as in all from the same bullet die) bullets and regular seating dies. :)

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