Not enough neck tension?

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SC_Dave

SC_Dave

Member
Joined
Nov 20, 2012
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437
Location
Hickory, NC
9mm
Hornady dies
115 gr FMJ RN

I can "set back" the bullet by pressing the finished round between my thumb and forefinger. Granted it takes a good deal of pressure but I can do it. I don't think this is ideal. Sized case ID is .352. Bullet OD is .355. Is .003 enough to give good neck tension?
David
 
.003" is plenty. The problem is very likely either : (A) Because it's a FMJ you are able to press extremely hard against the bench without deforming the bullet, or (B) You are over crimping the case, thus decreasing neck tension due to pushing the mouth back or buckling the mouth.

It doesn't take much over crimp to decrease neck tension. And when this happens it can be such that, identifying the issue even with calipers is extremely difficult to see the variance, as it can effect a very small region of the mouth and neck.

Try taking a resized case and chamfer the inside of the mouth nice and even and seat a bullet without belling or crimping. This will produce maximum obtainable neck tension which will give you a base line to compare to. If you can still push the bullet back after seating in this manner, then you either have a brass issue, or you are seriously capable of producing some major foot lbs. of pressure by hand.

As to the seating method I described above that eliminates belling and crimping the case, I have been seating bullets like this for many years with excellent results, and it saves a little time by not having to adjust for crimp or belling. This mehtod works great with jacketed bullets, but I doubt it will work with non jacketed bullets due to shaving issues.

GS
 
I bell my case but you can't tell by looking at it. You can barely feel it. Just enough for the bullet to set in. Crimp is just as easy. Just enough to ensure the mouth isn't sticking out.
 
I'm using all brands of cases mixed with my 9mm and don't sort them. I have my flaring die backed out so far I don't know if it's even doing anything and with all the brands of brass, so maybe I''ve been lucky, but I don't seem to have any neck tension issues with jacketed bullets. Some definately seat easier then others but I can't move any of them even pushing them against a bench. You can't really have to much neck tension so that's not a concern.
 
Never heard of the bathroom scale push test, is their an acceptable amount of pressure/pounds on the scales that if the bullet doesn't set back you're ok?
David
 
I don't know the "pounds" but if you can do it with your bare hand without leaving a bruse, it isn't near enough.

Check your taper crimp setting.
A finished round should measure no less, and no more then .376" at the case mouth.

Then, see if the loose bullets are only in one brand of brass.
If it is, chuck them!

rc
 
I just tried some of mine on my bathroom scale, I now have an imprint of a 9mm in the heal of my hand. OUCH!. (I couldn't resist)

I got 55lbs with several head stamps before it hickover sideways and no set back. I think a cheap arbor press would be in order for testing this.

I don't know what the pounds considered safe would be either but with fingers, yea, definately not enough neck tension.

My thin cases resize at .369 and neck size at .372, but mine have been shot so many times that they are work hardened to the point they don't stretch as easy as soft brass does. My bullets also mic between .355-356, mostly .356.

Your sizing die may be a little over sized also that would account for why it isn't catching the thin stuff or mine is undersized and works better with the crap brass their selling today, mine mics at .382, or your running your flaring die to deep and undoing what the resizing die just did. I don't know what a resizing die is supposed to mic at inside, maybe someone else could tell you that.

I'd like to know what the 9mm resizing die is supposed to mic at inside, if mine is undersized, I need to stop replying to posts like this as my situation won't be the same as most everyone elses.
 
How did you measure the ID? Calipers don't work well for that.

Either the sizer is too big, or the expander is too big, or both. Will a bullet seated in a sized but not belled case stay put? If so, the expander is the culprit.
 
@ Gamestalker, I did as you suggested and di get a better result but I am still having trouble as you will see in the short video.

@rcmodel, I measured about 6 and they all measure .376 at the case mouth of a completed round.

@walkalong, I measured just inside of the case mouth after sizing.

To all, here is a short video. Same head stamp. I sized only, no flare, no crimp which as Gamestalker mentioned should give me the greatest possible neck tension.

http://s282.beta.photobucket.com/user/SC_Dave/media/27C197CA-A059-44CC-81B3-A23C8DD7C735-14221-000022414754FACD.mp4.html
 
I wish you lived closer to me, I'd love to have try that with my resizing die to see if it is the problem. I'm using an RCBS carbide die, do you know anyone around you that has another resizing die that you can try?
Check the shell plate on your press to see if it is loose, it will cause a lot of deflection and irratic neck tension from not pushing the case into the die far enough. If it isn't loose, it's either the brass or the die, I'm betting on the die.
I'm also using a LNL-AP for my 9mms.
 
Just remembered I measured some 9mm Win sized cases for somebody the other day.

My old RCBS die makes the case mouth O.D .372".

Then, the expander just kisses the case as it measures only .350".
I just bell enough to set bullets in charged cases without them falling off.

Then seat & crimp to .376".

rc
 
If it is only loose with the Federal brass?

It's the Federal brass causing it.

It may be thinner, or harder and spring back more after sizing.

rc
 
Sounds like either an expander plug problem, or, brass issue. Of all the brands of brass I've ever used for 9mm, Federal and Rem. have been the only one's I've experienced any degree of an issue with.

I loaded some once fired .40 cal. Federal brass last year that had some consistent set back issues. And the only other bad neck tension experience I can recall was with some old (30+ yrs.) 38 spcl. Rem brass. But other than those two incidents all other brass has been pretty good to me.

If your experiencing set back during live fire then deffinitely toss that brass. Just check the remaining rounds in the magazine after each shot fired to remain safe during testing.

GS
 
Checking rounds in the magazine after every shot will not do any good if the round sets back during feeding when it hits the feed ramp.

Thats where the problem occurs, not in the magazine.

rc
 
Well I think I may have solved the problem. I borrowed a friends RCBS sizing/decaping die. That's the only thing I changed. I pulled all the ones I had trouble with and re-sized them using the RCBS die. Of the ones I tried, I could not push them back into the case. I loaded 40 rounds and will try them at the range tomorrow and report back.

Just for reference ran a piece of brass through the Hornady sizing die and measured the OD at .375 at the case mouth. Changed to the RCBS die and ran the same case through and it measure .373 at the case mouth.

I let you know how it goes tomorrow.
David
 
Here's a tool for that.

tightgroup tiger said:
I just tried some of mine on my bathroom scale, I now have an imprint of a 9mm in the heal of my hand. OUCH!. (I couldn't resist)

I got 55lbs with several head stamps before it hickover sideways and no set back. I think a cheap arbor press would be in order for testing this.

I don't know what the pounds considered safe would be either but with fingers, yea, definately not enough neck tension.
Click to expand...
Iowegan built a tool to measure that. See post #3 in this rhread.

http://rugerforum.net/reloading/65863-lee-fcd-pistol-not-rifle-virtue-vice.html

The text of #3 and #5 are also illuminating.

Lost Sheep
 
I had problems with neck tension in 9mm and 40 s&w. It was not as bad as yours, but still dangerous since it was not every round. I had to check every round I loaded, and you can imagine how sore it made my hands. The one thing that I hate worse than spilling powder or dropping a primer, is to have to throw away brass that can be made serviceable (SAFELY). I will even go to the trouble of decrimping the primer pocket on 9mm military brass.
After several tests like yours in the video, led me to believe that it was the thickness of the brass that caused my problems. The thinner brass had less neck tension. I ended up getting a lee UNDERSIZED sizing die. My process is to run my cases through the LNL with my regular sizing die. Then I tumble and store my brass. When I load jacketed I compare the brass and bullet to get an idea of where the base of the bullet ends in the case. I then set my undersized sizing die so that it will only size the case a little past this point. I dont size the whole case with it, and I dont use it with cast bullets, they are .358. Midway usa and lee carries the undersized dies.
 
My RCBS carbide dies seem to resize any 9mm brass that I get without problems, and I get some real crap from the range brass that I buy. I would think any good quality die should do this if setup correctly. I've learned to feel the difference of a thin, "easy to resize'' case on my AP even through the bullet seating process and pull them out before going any further. When I feel something different I pull the one in resizing die and the one that just came out of the bullet seating die. I don't find a lot, but the ones I pull out get a pretty good checking over. If the one I resized checks out (no splits or problems) I throw it back in the case feeder and check the completed round for setback against the bench.
I check all brass that comes in my door for length especially 9mm. I set my dies to work with brass that mic's from .742 to .750. I've noticed that the brass that is shorter don't hold neck tension as good as the longer stuff. As Gamestocker and RC Model pointed out, you only need .003" press fit to hold tension. You take 1 or 2 thousands away and well you know what happens.
If the brass (like the ones I pull out only mic .735) it would make sense to me that they aren't long enough to go into the tapered resizing die far enough to get the .003"press that you need. I would think they would show as oversized even if your die is in spec, as I suspected your wasn't, and thin cases just complicate this. Maybe I'm way off base with this analegy of my loading process but I think it's why I don't seem to have resizing problems with my 9mm anymore. I have found brass from .735 being the shortest to .755 being the longest and my dies seem to work best in a .010"range. I throw the short stuff in a seperate container and trim anything longer then .753 back to .750. This also helps with setting the taper crimp die to get a more consistent crimp.

I only have to do this one time for the life of the brass so it's not that much of a hardship and provides a good time to inspect your brass anyways. My dies have made really good neck tension since I started doing this. From what RC and others have said, mine may be a little undersized but I don't think much.
I've never had a problem with neck tension in straight wall cases only the 9mm that's why I started loading the way I do and I haven't had a problem since, but am always checking.

Hope some of this helps
 
This post is full of good information!

I took the ones I reloaded with the RCBS die out to the range today. Had no problems with setback at all. In fact the accuracy was great. No problems at all. I ordered a set of RCBS dies today.

Tightgroup, I never thought much about length but what you say makes sense. I gonna go measure some case lengths.
David
 
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