Some one has to explain this to me

Tak

Tak

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Why is it that if i seat the same individual bullet in a different case my oal is different (ie non fired case shorter by about .025)

Theres something I'm missing about this and wish to understand. Thanks cheers!
 
First a few questions, how are you measuring the OAL and with what? What press and dies are you using? Could there be damage to the base of the brass? Have you cleaned the seating stem?

There could be many reasons why you are getting different seating depths with the same bullet, from procedures to crud in your die, to a burr on your brass.
 
Measuring the OAL from the bullet tip can cause this difference. Many people use a bullet comparator to measure the OAL from the bullet ogive. It is far more accurate this way. But there can also be differences in the measurement using that method but nearly as much. It depends on the bullet manufacture. I find that Berger bullets are very consistent and that Sierras are not for example. Another variable is that different lots of the same bullet type won't have the same base to ogive measurement. I was loading for my 308 using 168g Match Kings and switched lots half way through the session. The new box of SMK's were .020" longer when measured from bullet base to bullet ogive. Also make sure you are seating your primers fully and they are below the case rim. Cleftwynd makes some good points as well. Good luck!
 
-Measuring from the tip of the bullet with a vernier(I know I'm gonna get the bullet comparator tool but that shouldn't make a difference in this instance)
-Lee single stage press with hornady dies.
-No apparent damage to the brass.
-I have not cleaned the seating stem but the dies are new I have only reloaded perhaps a 100 rounds with it if that.

I have tried it with a couple of my fired cases versus the unfired one, the unfired one is always about .020-.025 shorter for some reason.

When comparing i used the same individual bullet so the comparator shouldn't make a difference here. Bullet is a hornady 68 gr bthp.

I thought about the primers thing, they look well seated.

I just cant figure it out lol
 
Hmmm. That is a bit of a head scratcher. Could it be that your unfired cases are entering the bullet seater die fully and the fired cases are not? Maybe the fired cases are just big enough (at the base) that they are not entering the die fully or the shoulder is preventing it and therefore the bullet would not be seated as far into the case. Do the fired cases seem to stick at little upon removal from the seater die? Just thinking out loud here. Measure the case web of an unfired case and compare it to a fired case. If you can, measure the I.D. of your bullet seater. Also double check that your seater die is set up properly. If it is screwed down too far and is contacting the shoulder of a fire case this could be the source of your problem. Did you clean the preservative out of your dies when you unpackaged them? Let us know how you make out as I'm grasping at straws here. It's a new one on me.
 
Ok, I took the die appart and cleaned it (wich I had not done at first) , everything seemed normal except a bit of copper build up around the rim that crimps, which I removed with a muzzle brush. I'm pretty positive its copper and not brass. I've adjusted the die so it would not crimp and I don't think it does, doesn't look like it any ways, but tou double check I tried running an empty primed case in it with no bullet and it went all the way down without resistance.
IMG_0274.jpg

Cases don't stick at all when I seat the bullets.

I noticed that the seater doesn't grasp all the way down to the ogive, which could account for some error in OAL, (and even then a bullet comparator wouldn't really serve me unless I sorted my bullets and I'm not that meticulous) but doesn't explain why it is consistently shorter.

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Any ways the bullet comparator will help eliminate some possibilities I guess, but I re-did the test and sure enough, a good .015 shorter with non fired round.. go figure... In the mean time I'll just use a fired resized round as a gauge but still... makes you wonder
 
2 things you can check, 1= resize your new case . 2= with the seater out ,test fit both a new & a fired/sized case into the die by hand and check the protrusion of each ( how much of the base of each case sticks out of the die.
???
 
The problem here lies in neck tension and the "schmutz" left in the neck of your fired case versus bare virgin brass of the new case. First, the bare brass is probably letting the bullet slide more easily across its surface, where the fired brass with burned carbon and likely some slight galling from the original bullet sitting in there for a period, offers more resistance when seating. Brass and copper are soft materials and soft materials tend to bond easily under pressure. Have you ever tried pulling a bullet from a very old round? If you get the opportunty sometime, do it and then have a look at the inside of the neck.

Run your new brass through your sizing die just as you would a fired case. Brush the necks of the fired case really well before running them through. Debur all and let us know how you make out.

Rooster
 
I guess I forgot the "second"::redface:
The fired brass is liable to be a bit harder (and thus, less maleable) than the virgin brass. This makes it difficult to get the same tension between the two. There are also likely slight hardness differences between production lots as well (nevermind brand to brand differences).

Rooster
 
Ill try both those!

Ok I understand what you mean about the tension but wouldn't the difference be into having to use more force to seat the bullet? I mean the seater is fixed any ways not spring loaded so wouldn't the travel be the same regardless of the resistance put up by the case?

Btw I know we are splitting hairs in half here but I'm still interested in understanding this one lol
 
Tak said:
I understand what you mean about the tension but wouldn't the difference be into having to use more force to seat the bullet? I mean the seater is fixed any ways not spring loaded so wouldn't the travel be the same regardless of the resistance put up by the case?
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You are correct, travel of the seating stem is "fixed" by contact with the bottom of the Seater Adjustment screw. As long as you are raising the press ram fully to the top of it's stroke, that bullet should be seated to the same overall length no matter how much neck tension a case has. Sorry, I don't have a solution for you, I'll be interested to see if anyone can help you figure it out.
 
Soft material yields to hard material. If there is enough neck tension, the brass will "spring" or deflect as you seat the bullet. Once you release pressure on the bullet from the seating stem, the brass will return to its static state (= longer than when compression was being applied). Add to this, the compression exerted on the bulet itself when seating. Copper and lead are very maleable and will deform a bit if there is enough pressure. Have a look at some of the bullets you've seated - can you see a small ring around them about half way between the ogive and the tip? It will compress slightly when seating and will spring back a certain amount.

I'm willing to bet that if you load only your virgin cases, they'll come out very close to the same length. And if you then load all your fired (and cleaned/brushed) cases, you'll have to adjust the seating stem down a bit but they should then end up very consistant as well.

Rooster
 
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Which means the same phenomenon is probably hapenning when I try to gauge my oal by chambering a dummy round... I really need to get those extra tools lol!
 
Not sure how your dummy round is set up but even with a modified case which lets the bullet slip through the neck with minimal resistance will actually still push the bullet into the rifling a bit further than the true start of the rifling because of the relative softness of the bullet (yielding to the harder material of your barrel). Seating a bullet into a fully sized neck and smoking or colouring has been effective for many thousands of reloaders but is largely unreliable unless you are meticulous about it. Colouring with a Sharpie (especially several times) adds thickness and will give you a bit of a false reading that way too. Yes, we are splitting hairs here. The lead that's cut into the rifling is often around 1-1/2 to 4 degrees (I believe) and will show up somewhat flat on your bullet, which is much harder to identify on a bullet versus a sharp edge. And unless you have a really good eye and "feel" (with ejector & firing pin removed), it's still difficult to tell when you're truly there.

The best way I can figure to determine your rifling location (with the modified case method) is to turn a slug at exactly groove diameter with a perfectly perpendicular face and chamber that. I've never heard of any shooter concerned about where his rifling starts who will consent to having a steel slug pushed into the bore of his rifle;)

My advice; buy one of those Hornady modified cases or take one of your resized cases and sand the inside of the neck until it lets the bullet slip - take the average length of five or six times into the chamber and give 'er! You're not shooting competitive benchrest, are you? I think if you get close enough, your results will be good enough.

I find there's always something to learn and ideas to experiment with! Good luck bud!
Rooster
 
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358Rooster said:
The problem here lies in neck tension and the "schmutz" left in the neck of your fired case versus bare virgin brass of the new case. First, the bare brass is probably letting the bullet slide more easily across its surface, where the fired brass with burned carbon and likely some slight galling from the original bullet sitting in there for a period, offers more resistance when seating. Brass and copper are soft materials and soft materials tend to bond easily under pressure. Have you ever tried pulling a bullet from a very old round? If you get the opportunty sometime, do it and then have a look at the inside of the neck.

Run your new brass through your sizing die just as you would a fired case. Brush the necks of the fired case really well before running them through. Debur all and let us know how you make out.

Rooster
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Interesting. I do agree with what you're saying but do you think your theory would yield a .025" difference every time? That's quite a bit. I'm very curious to see what comes of this.
 
Yes, I was thinking this initially, but it eventually leaked out (known to happen lots):HR: There's gotta be a hell of a lot of neck tension to do that. Still posible I think but yes, a bit extreme.

I have run into situations where two different lots of the same bullet are different in length from the base to the ogive. On top of compressed charges, the resulting seated lengths were different by up to .012.

Tak; get some fired cases cleaned up, brushed out, trimmed & deburred, then let us know if it's made a difference. Further from that, I'm not sure where to go...

Rooster
 
358Rooster said:
Tak; get some fired cases cleaned up, brushed out, trimmed & deburred, then let us know if it's made a difference. Further from that, I'm not sure where to go...

Rooster
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Well that's pretty much what I do to prep my cases, just short of brushing the inside of the neck, I'll try that though see what happens. But otherwise they are all trimmed to the same lenght (fired ones) the virgin one is maybe .005 shorter

To put things out in perspective, the way I found out was I set my seating die with the dummy round (virgin brass) and then loaded a couple real ones, measured them and saw the difference. I thought it was odd, chambered them, they chambered fine, remeasured them (No change, no marks from the rifling) so I thought it was fine, then just out of curiosity, every 5-6 rounds or so, I would take a new bullet, seat it in the dummy round, measure the oal, remove it, seat it in the reloaded round and measure it. Every time it would come out between .015 and .025 longer in the reloaded round. However, now that you talk about compressed charges, all my charges were compressed. Could it be the powder pushing the bullet out ?
 
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You bet. That powder column is a pretty stiff little bugger - it's not likely that it's pushing the bullet back out but rather stopping the bullet from going in any further. From that point to the bottom of your handle stroke is all flex, deflection, deformation, slack.... Have you tried seating bullets in the fired cases without powder or with a couple grains less? Could be your answer right there.

I have loaded ammo as you describe and had marginal gains by going as far as possible, then taking the round out of the press and shaking / rolling it to get the powder moving around the base of the bullet. Run it through the seater again and it'll go a bit deeper (.006 maybe?). Often when you have to do that, the velocity gain is minimal and the accuracy may be just as good or better with a lesser charge. A less bulky powder helps a heck of a lot too. Sorry if I missed it but what cartridge, bullet, and powder are we discussing?

Rooster
 
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