Bullet seating after factory crimp?


January 24, 2013, 04:42 PM
I'm new to reloading, and I have a question about seating the bullet.

I'm reloading 9mm on the Lee Classic Turret Press with the Lee Deluxe 9mm die set. Right now I'm using new Winchester brass with 95 grain jacketed bullets (couldn't find 115 grain :( ).

I've made a few small batches to get to a load I like and right now I have two 8 round batches at home waiting to be shot. My question is can I seat one of these batches a little further?

I've noticed I'm getting a little more bullet setback than I'd like and I want to seat one of these batches a few more hundreths of an inch. I've already put a light crimp on it with the Lee FCD and was wondering if I could put it back in the press and shove the bullet down a little more. I have a feeling the crimp will dig into the bullet and I shouldn't do this but I thought I'd ask the crowd here to see what you all think. Worst case scenario I just shoot them as is or I wait until my bullet puller finally ships and I get it in the mail, pull the bullet and do it over. If I can just toss it in the press and jam that thing down a little more though... that would be sweet :)

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January 24, 2013, 04:56 PM
2nd on this. I've done it once and it seemed to work fine for .45, but in general would it be better to pull and start over?

January 24, 2013, 05:46 PM
Yes you can seat them further if you want,

That being said I do not know what your OAL is or what it should be and also don't know how you are determining "more setback"?? So be sure you do not seat them to deep.

As to actually seating them yes it will seat further and not mess up your bullet or crimp.

January 24, 2013, 06:43 PM
bengals1975, welcome to THR.

First of all, neck tension comes from the friction/pressure between resized case neck and the bullet surface, not from taper crimp. Taper crimp is used with straight walled semi-auto cases and taper crimp will not increase neck tension - in fact, too much crimp can decrease neck tension. Flaring the case neck too much is the usual cause of decreased neck tension, so use the minimal amount of flare that will allow the bullet bottom to just barely sit inside the case mouth - this amount of flare will be hard to see but can be felt by finger tips.

As to the proper amount of taper crimp, I usually add .021" to the diameter of the bullet (to allow for average thickness of brass case wall of ~.010"). So for .355" diameter 9mm bullet, I use .376" taper crimp.

My Quality Control check for neck tension is measuring the OAL before and after feeding the dummy round (no powder/no primer) from the magazine and releasing the locked back slide without riding it. Reduction of a few thousandth to no reduction is to be expected but a decrease of a few hundredth is an indication of poor neck tension that will seat the bullet base deeper in the case neck and increase the chamber pressure.

As to the OAL, you determine the OAL of the round by first determining the Max OAL using the barrel drop test. Starting with the SAAMI Max OAL of 1.169", incrementally decrease the OAL until the dummy round (no powder, no primer) drops in freely with a "plonk" and spin freely without hitting the rifling. Next you determine the working OAL by feeding the dummy round from the magazine and releasing the locked slide without riding it. Sometimes the working OAL is the same as the Max OAL, but often it is shorter to reliably feed/chamber from the magazine.

January 24, 2013, 08:27 PM
awesome! Thanks for the great info @bds!

In my research I've read the crimp doesn't provide any neck tension but the rest is stuff I've tried to find and haven't been able to. Thanks a lot for responding with all this.

Since I normally have shot 115 gr factory loads and my reloads are currently 95 grain with a shorter OAL even in the most extreme cases I was assuming my max OAL with the 95 grain bullet would be good at any length. I am concerned about making sure I have enough neck tension to hold the bullet in place however. I also think I could stand to revisit my taper length.

Two nights ago I made 4 dummy rounds. (1) with new winchester brass, (1) with used winchester brass, (1) with used PMC brass, and (1) with used federal brass. I assembled the round with my dies set as they are now (but with no powder or primer) and cycled them through the gun without riding the slide. I recorded the OAL before any cycles and again after each cycle. I tried to make sure each round was in a different place in the mag each time so the same one wouldn't be first each time etc. Here is what I ended up with. Based on what you said, it sounds like I need more neck tension and therefore would be well served to increase my seat depth. Right now I have a starting OAL of about 1.100, I'm thinking I'll try to reduce this to around 1.080" (which is still way above the minimal OAL of 1.005 in the Lyman's Manual). Thoughts?


January 24, 2013, 08:58 PM
Yes you can seat them further if you want,

That being said I do not know what your OAL is or what it should be and also don't know how you are determining "more setback"?? So be sure you do not seat them to deep.

As to actually seating them yes it will seat further and not mess up your bullet or crimp.

Thx, I'll probably give it a shot then. :)

Sent from my Galaxy Nexus using Tapatalk 2

January 24, 2013, 10:01 PM
Well I did it. I seated the bullets a little deaper (1.075 OAL now) and increased my crimp slightly. They crush the barrel drop test now with flying colors. I'm pretty pumped! I love this stuff, I cant believe it's taken me this long to start loading my own ammo! Can't wait to shoot these things (now if only it wasn't 15 degrees and snowing outside).

January 24, 2013, 10:55 PM
What BDS said, and you shoudn't be experiencing any set back as a standard. You may be over crimping or over flaring, which would in effect decrease neck tension on cases that head space on the mouth.

In my opinion, it sounds as though there is an existing neck tension issue, which seating them deeper will not solve anything for you. I would follow BDS in this respect. Also important is to note that 9mm is already a high pressure cartridge, and is very seating depth sensitive in terms of pressure spiking. So I would go seating deeper with charges you have already worked up to at the current OAL.


January 24, 2013, 11:36 PM
I've tried two small batches already and I definitely had a neck tension issue. The cases wouldn't eject, they'd fire then stick in the slide. After digging into everything with my calipers I noticed I was probably flaring way too much (OAL was the same before and after seating at about 1.080 so I really wasn't seating at all). I feel pretty lucky I didn't hurt myself.

My conclusion (perhaps incorrectly) was that my problem was bullet seating then (it was certainly part of the problem at least). So I redid my dies to flare considerably less (just enough to get the bullet sitting on it), and i raised the seating die to an OAL of 1.100 to get a longer OAL. I thought maybe the round at 1.080 was maybe too short in comparing it to my 115 gr rounds. (These 1.100 rounds are the ones I'm talking about in this thread) . Anyway, after some more thought I decided that I was well above the min OAL in my manual so length probably wasn't it. Then I went and measured one of my cases and a bullet, added them, then subtracted my 1.100 OAL and it came out to a bullet seating of something like 0.020. This just seemed really small. That's why I made my 4 dummy rounds and ran them through some cycles to see what kind of bullet setback I would get. If I'm getting on average almost half of my original bullet seating area in setback each cycle (approx 0.010 of setback) then my neck tension is probably not right. Which is why I wanted to seat them a little deeper. I'm still about 0.070 above the min OAL from the Lyman's manual so I'm thinking that's a good bit of margin. And now I have a little more neck tension to hopefully reduce my setback some.

I also increased my taper crimp slightly to get to the 0.375 at the mouth mentioned by bds. After doing all this I did the barrel drop test and the rounds drop in and line up with the extractor much better than they did. The same rounds before would drop in and most needed a tiny bit of convincing to line up right. Now they drop right in with a lovely little thunk and line up just right on their own.

With all of this it sounds to me like I'm making the right adjustments but like I said, I'm brand new to this. Let me know if you see any holes in my logic. If my thought process on seating depth is off and the depth I was using and the setback I was getting is fine let me know. I just thought I'd provide a little more data in this post to help you guys understand more where I was and how I got to where I am so maybe you can better help me. I wish I could work up from a existing load like you mention @gamestalker but I've yet to build one that works :(

Thanks again for the help so far, it's greatly appreciated

Sent from my Galaxy Nexus using Tapatalk 2

January 25, 2013, 12:07 AM
You keep saying the same incorrect things. First off you should be getting no bullet setback. Secondly, seating the bullet deeper will do nothing to prevent or cure bullet setback. Only neck tension keeps the bullet in place and for the most part, crimping is mostly to remove any bell or flair you apply to aid in seating the bullet.

You also said "the minimum OAL listed in the Lyman manual" but the OAL listed for each bullet isn't the minimum OAL, it's the OAL they used when loading that round. If you're trying to duplicate the round they produced you should be using the OAL they used. Also, the OAL they used is only valid if you use the same bullet they used. Your round is much longer than the 95gr bullet round they loaded.

You are probably getting setback because you are not seating the bullet deep enough for the brass to grab onto the bullet but like I said above, seating the bullet deeper doesn't usually make the neck tension better. But that also usually assumes you are seating the bullet deep enough so that the neck tension can be effective with enough bullet to hold on to. Again, the OAL in the Lyman manual is not the minimum but what you should be seating to if the bullet you are using is the same or very similar to the one they are using. Being .070" away from their OAL is not a good thing since the bullet is barely in the case.

January 25, 2013, 09:55 AM
crap, I'm glad you guys are here to help this newbie out. Thanks for your patience.

I'm going to try to restate some of this in my own words to make sure I understand it. Let me know if/where I'm still wrong.

I know crimping is just to remove the bell and over crimping can actually reduce neck tension. Also, over expanding (bigger bell) can also reduce neck tension. It sounds to me like all crimping will really do is possibly help the round chamber better but if the bell isn't very big in the first place it possibly isn't even necessary.

Neck tension is what holds the bullet in place. Neck tension is a factor of a couple things. 1) the brass itself. As a case is used and reused the properties of the brass change which can affect it's ability to provide the needed neck tension 2) bullet seating itself doesn't determine neck tension but, if you don't have the bullet seated deep enough you can't get the proper neck tension in the first place. (So is it true then that if you have a deep enough seating, seating it deeper won't affect the neck tension (but could increase pressure)? When I have the proper neck tension, my bullet setback issues should go away and I should only see perhaps a couple thousandths change in OAL if any.)

The OAL I thought was the min OAL for the 95 grain round in the manual is really just the OAL for that round with that particular bullet as they tested it. my bullet may be different depending on how similar it's dimensions are to the one they used. I assumed however, that since they're both 95 grain jacketed rounds the dimensions are similar (shape is a little different, the sierra round they used has a flatter nose while mine is more rounded and therefore probably a little longer).

When you guys first develop a load do you load a dummy, slowly increasing seating depth until you get to a point where it no longer experiences setback?

Thanks again for you help and patience. I really want to get good at this and I recognize I have a lot to learn.

January 25, 2013, 02:01 PM
When you guys first develop a load do you load a dummy, slowly increasing seating depth until you get to a point where it no longer experiences setback?

Some loading manuals give the O.A.L. some do not. So how long should they be? Starting out I measured how long a factory round was and just made them that long. This may not be optimum, but it usually worked just fine. They need to chamber, and work in the magazine and action.

Yes, with taper crimped bullets, you can seat them a little deeper if needed. Not an option with a roll crimped bullet that is crimped in the crimp ring.

Look at this link (http://donce.lofthouse.com/jamaica/crimping.html)

January 25, 2013, 02:34 PM
Try a method I've been using for many years with jacketed bullets. Do a light and even chamfer of the inside mouth of a resized case, don't bell it. Now set a bullet on the mouth and seat it, don't any crimp at all, Your done. You now have as much neck tension as can be attained.

I load those 95 grain bullets and they are a bit short, so seating depth will make them a bit shorter in OAL than a 115 gr. bullet. But to properly determine OAL they need to clear the lands in the barrel, and they need to fit the magazine, and always work up from minimum charges once your've determined the seating depth you'll be using. This is because every time you change seating depth, you change pressures for that powder charge.


January 25, 2013, 09:47 PM
Got it. Thanks guys.

It's a great community here. :)

Sent from my Galaxy Nexus using Tapatalk 2

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