9mm Inconsistant Seating Depth

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I just started to reload 9mm using the RCBS 20515 set and Hornady XTP 147gr bullet in a 550B I loaded 100 rounds and every single one of them was a different OAL. I would expect some variation but not what I am seeing. I was targeting 1.107 and my range went from 1.083 to 1.240. This was after I set the die to seat so the OAL was 1.107. I looked at everything I could think of as to why the inconsistency, but could not trace it to anything. Any suggestions?

Thanks!
 
Check that everything is tight, especially the shell plate.
Many times, a partially full shell plate will show COL variances not found when the shell plate is fully loaded--though +/- 0.010" is really not great a concern (unless, maybe, you are loading max loads). You can shoot 'em to see how they perform or you can use a kinetic bullet puller to lengthen the short ones and run them all through the seating die again.
Where you have to worry is if the COL is shorter than 0.10" from your target COL.
 
I've found different brass headstamps such as CBC, S&B and Tulammo has extremely stiff brass composition, while cases like Federal and Winchester are like wet newspaper. Sometimes I have to check my LRN as I get variations depending on headstamp, not to mention brass bulge.
 
You shouldn't have variations in every bullet.

Make sure you have the seating depth to where a full stroke of the ram gets it where you need t. And use the full stroke every time. If that still doesn't solve your problem, get rid of those dies and buy some Lyman carbide dies. I've never had a single problem with them - can't say the same for RCBS.
 
Just to make sure: I know Hornady changed the XTP profile at some point to improve feed, so if you are loading a mixed lot, you could sure see a swing. Set a bunch of the bullets up on a flat table and make sure they all look the same.
 
Agree with many of the points already said and want to point out that you have to isolate the problem and your short bit of info doesn't remove many of the pitfalls that could contribute -- and if you add up a number of small things, you can see wide swings.

Is all your brass that same, or relatively the same?

Check the bullets, as Unclenick pointed out.

Totally agree that if you set things up on a progressive and you are only using one round... but you then later load the whole shell plate up in the normal progress of loading on a 550B, you will see variances in COAL.

And perhaps most common (in my experience) is if the bullet profile/shape and the seater plug on the die don't mate up well, it's hard to get an extremely consistent COAL.

One last thing...
I know that Dillon machines or more specifically DIES do things a bit differently, but I am not hands-on familiar with what. I would also look very much at the amount of taper crimp you have your die setting. You truly DO NOT need much taper crimp. Look at a taper crimp marely as a method of removing the case belling, the taper crimp is NOT a method of "retaining the bullet in the case."

Too much taper crimp pretty much wrecks a loaded round.

So I would adjust the die to impart as LITTLE taper crimp as you can and still allow the loaded round to easily and smoothly pass the drop test.
 
Try sorting the brass by head stamp, and seat a and crimp in two steps.
Make sure the primers are seated properly, and you are not measuring off a high primer.
 
I had a similar problem with Remington 147gr Golden Saber JHPs. I had RCBS make me a custom seater plug for $12. It solved the problem. I had to send 5-6 bullets to them.
 
Wow, there is a plethora of possibilities that could be causing this issue. I appreciate everyone's input on this. The brass is used brass that is of all different lengths and manufacturer and not one of them is what the reloading manual indicates it should be(0.754"). Most if not all are way short of this already. I measured 10 pieces and all of them were in the 0.45 range. That's quite a difference from what the Sierra manual says as well as Hodgdon's Reloading Manual (2015). As a matter of fact, not event the brass for Federal factory rounds are what the manual says it should be. To add to this the COL of the factory rounds is way short (1.095) of what the manual says it should be(COL 1.1). So its really tough for me to put blame on the different brass. I suspect that the seater die is not sitting exactly the same each time possibly because of the bullet ogive being inconsistent on the XTP rounds. Just a guess at this point, but I think I will try a different seater die before pulling the proverbial trigger and identifying the culprit variable. I thought of getting some sort of flat surface seater die so I could eliminate ogive inconsistency rather than the concave one but I don't know if one is made.
 
A flat seater stem may fix the COL problem but if you are using mixed brass the case tension will vary. So depending on the integrity of the bullet nose the nose will deform differently depending on the pressure applied, and while having the same COL the bullets will occupy the case differently. This could be worse than your first problem.
 
not one of them is what the reloading manual indicates it should be(0.754")
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.754'' is the MAXIMUM case length for 9x19, if you look at a Hornady manual it will show trim to length .749"
But if you are using mixed brass what difference does anything make?
 
Bullets vary in length plus thew seeater that you are using does not match your ogive so there will be a varience in length from the point thet your setaer makes contact with the bullet on up. This will happen with different lots of the makers bullet.

The only way to prevent this is to use a square faced seater. Further any measurement past the third decimal point is meaningless because it is effected by pressure of the measuring device.

I use RCBS does for 9mm and a FCD and seat and crimp at the same time with no problems so other the the above the contact point length difference if your die is clean then the problem has to be that you are using an inconsistant stroke with your press.
 
This is some preliminary results for the varying seating depths I have been seeing using an RCBS die set. I have now changed to a Dillon Die set. This made a difference in two areas. First there is a better fit into the seating die, and second, I am crimping on a separate die. Here is the results of 20 loads using mixed brass which were plucked randomly from the bucket and using the Dillon die set. Not exactly scientific, but food for thought not withstanding. My target COL is 1.107. Now ranging from 1.095 to 1.115. As I continue to load these, I will record the data to see if there are any significant changes that may occur. Thanks again for everyone's input.

Mixed%20Brass%20&%20COL%20Deviations.jpg
 
I think measuring each bullet length could expose the variance. I too was all over the place with OAL, it hasn't caused any problems for functionality, but it was bothering me.

Ranier, Xtreme, Berrys all had inconsistent lengths, I make sure to set the die for the longest measured bullet length to achieve the correct OAL I am looking for 1.135, the ones that come in shorter are still within a good OAL for 115 gr plated 9mm.

I also came across a very good post somewhere by someone, which stated.

"I stopped having COAL issues when I stopped checking them"

I realize on many loads it's important, but 9mm plinking loads are working out just fine for me.

David
 
I've loaded a lot of 158gr XTPs in 357 Magnum over the years. I had RCBS make a custom seater plug for Xtreme plated flat points years ago. It is coned to fit the bullet perfectly and straightens them out when seating. The custom plug also works great for JHPs and XTPs too. It is all I use when seating. The last couple of boxes of 158gr XTPs I've loaded I had inconsistent OALs when using this plug. Nosler's 158gr JHP hasn't given me any problems nor did a box of 140gr XTPs. Unclenick's post about Hornady changing the XTP and having a mixed lot is the only thing that makes sense. The plug touches the ogive and if Hornady changed the angle on it it would make for inconsistent OALs if it was a mixed lot.

I ended up pulling bullets and seating partially with the custom plug to make sure they were started straight and then finishing with the wadcutter plug. PITA! Hence the switch to Nosler.

Case length and bullet length have absolutely no bearing whatsoever on OAL. It is purely a matter of the shell holder pushing up on the bottom of the case and the seater plug stopping the nose of the bullet. The distance between the shell holder and the seater plug will be the same every time at full stroke. You could seat a bullet in a 9X19 case and then insert a 9X21 case and seat the same bullet to the same OAL, case length is irrelevant. The same goes for bullet length. You could seat a 115gr FMJ and then a 124gr FMJ and if they had the same ogive profile they would both seat to the same OAL. Your problem does not lie there.
 
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I think measuring each bullet length could expose the variance.
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The length of bullet does not effect the COL, if the seating die is adjusted for a certain COL that will be the COL regardless of the variance in bullet length.

If the seating stem is digging into the bullet that's not a good thing, I have corrected this problem by chucking the stem in a drill press and smoothing out the offending area with wet/dry sandpaper 400,600,1000,and 2000grit.

PS, the case length doesn't matter either, but the volume that the bullet occupies in the case does.
 
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