Crooked bullet seating with Lee 7.62 x 40 WT dies - need help

[dimaprok]

So I decided to get Lee dies against going with more expensive Hornady from Wilson Combat where my barrel was purchased. After making about 185 pieces of brass from LC 223 brass I proceed to load "carbine" 110gr bullets and was quite shocked how crooked the bullets were seated, they were tilted and could be seen clearly with naked eye. So I happen to read at same time one starline review where guy said he had same problem with different 30 cal brass because the necks came from factory too tight .305 for .308 bullet, it was about same for me and he talked about fixing with custom expander so I machined one that looked like NOE with bottom section at .306 and step up section at .309 so it flared the neck about 1/3 to aid going in straight and it seemed like it solved my problem. BTW I called Lee earlier and they blamed this on bullet seating stem not working well with round nose bullets. I told them I'll try spire point bullets. So I tried seating Lee 155gr and with longer bullets my gosh! They came up looking like bananas! I examined the the necks, not only they were crooked / tilting but half had shoulders that were more formed on one side than the other (shifted to one size and crooked). What in the world is going on? Is my FL die making them crooked? Now It's not noticeable until I seat the bullet. I also discovered the seating die has build in crimp functionality so you can't just screw in die until it touches shell holder, you run the case inside the die and you screw in until it touches the neck and lock it. So that's my problem and I am not sure what do about it, sending to Lee might result in dies sent back and a note that saying "everything is fine". I am thinking of making a dummy round and sending to them to see but before I send it out I want your input what I can try solve this problem. I have 2 sets of Lee 300 BLK dies too and wondering if can use 300 BLK seating die? Would a shorter die cause some undesirable freeplay?

Ok now here's the 2nd problem. Now I've read some articles that it's better to full length size and not use expander mandrell because it actually expands, contracts and expands again the case mouth and that just over works the brass. Better approach is to size without expander ball and open up neck with a separate die with custom mandrell and that's was my approach, he said that regular method stretches the brass and I found that to be true, I saw .002 growth in case where as 2nd method it didn't. So here's my problem, when I FL sized the case and went to measure the ID of the neck I was quite shocked! It was .293! Seems to me that is extreme reduction only to be expanded again, now I haven't measured how much 300 BLK die shrinks but don't you guys think this is excessive? Has anybody who has 7.62 x 40 WT Hornady dies tried this?

[Rcmaveric]

You said the seater has a crimp ring and that you had the die backed off to only seat the bullet and not crimp. The only thing i can think of is the the brass doesnt have the case and neck support during the seating proccess and that is why your bullets are crooked.

I looked it up and yes your seater die has the built in crimp. Try screw you die in more. It will remove the flare but thats fine we are just trying to suport more of the case during seating.

You could also take your seater die apart to see what the support of the case is like. You might try and find a seater die. Expanding the case necks will help releve some of the pressure of seating and reduce the chance of distortion. But until the case neck and shoulder is properly supported i think your going to have problems. Maybe a different seater die.

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[popper]

Is this a 300BO or actual 40WT die set? I use the Lee set for BO, no problems at all - jacketed or FN cast - even the half jacket plinkers. I don't expand the neck separately. RN boolits have a problem with normal seater stem. Start seating just a tad, then rotate 90 and do more. Continue until seated. You need to flare the case just a tad also - to get the boolit started straighter. Found this out loading RN 9mm. Don't think my Lee is a taper crimp but I use the Lee FCD that came with it. Only diff in 40WT & BO is case and neck lengths. The Lee expander does expand (but not much as it enters the neck before the neck sizing area - leaves after the neck size area), shrink and re-expand but even with my turned necks the PP goes before the neck fails. The comment about the expander in rifle is it pulls brass from the shoulder area into the neck and you can get a thicker 'donut' ring at the shoulder. IIRC my Lee plug is 0.297, just right for jacketed or 3085 cast.

[country gent]

Usually its in the die with bullets seated out of square or off center. Out of square shell holders can also have this effect but it will show in sized cases if you measure them. A press that's not concentric will give fits at times. If all your going to shoot is the 30 carbine round nose then you can fit the seater stem to it. Start by inking a few bullets when you seat them and see where they bear a little hand work fit some sandpaper and a dowel may help a lot. Or make if custom with epoxy.

If the dies is taking necks down to .293 if this is outside dimension of neck that's a lot Measure a loaded rounds neck dia and compare them. Loaded round neck dimension is probably in the .330 range with the bullet seated. ( .308 + .011 + .011 = .330). As long as the die is sizing down this small whether you expand up in the die or in a separate die its over working the brass. The thing to do is to polish up the neck in the die to where it sizes down the neck ,003 below bullet dia then lightly expand back up just the little bit. Right now your sizing the brass roughly .015 I would recommend working the die out to where this becomes .003-.004 or .304 - .305 ID

[bruce drake]

If you are cutting down the 7.62x40 brass from LC or other military cases, your necks may need to be thinned as well. If you are using ready-made from Wilson or other brass sellers than disregard.

[bruce drake]

country gent,

great points!

[Rcmaveric]

If you are cutting down the 7.62x40 brass from LC or other military cases, your necks may need to be thinned as well. If you are using ready-made from Wilson or other brass sellers than disregard.

Thats a good point. He is making it from LC 223 brass. May need neck turn those necks if you trimmed off 5mm of case length.

Case necks are thinner when compared to the case walls. Brass also work hardens. So after all that trimming, forming and expanding. An annealling may also help.

Also thicker case necks could be messing with your seater die and its crimp ring.

[jsizemore]

Anneal the case neck/shoulder and fireform without a bullet/boolit.

[EDG]

The LEE seater only has a short ring to guide the bullet. The seating punch can float around allowing short RN bullets to tilt. The 45-70 seater does the same thing with 300 RN and FN bullets. Lee is not a very good designer or design tester. Other companies don't have many problems like this because they have a long close fit bullet guide diameter in their seaters.
This is a major design defect in the design of LEE dies.

[popper]

Crimp and seat in the same operation doesn't work for me. Don't even see a Lee 40WT die on their web site. I've formed 40WT with BO die, don't know about seating.

[dimaprok]

Thanks guys for all the feedback, the situation has improved. I haven't got that many crooked rounds. Instead of using a separate expander I went back to using expanding mandrel that's inside the FL die that I machined for 300BO earlier it's slightly bigger at .306 not sure it this was solution though. Using this stretched my cases by 2.5 thousands on average and since I am not using any inside neck lube I could definitely feel resistance as neck is being expanded from .293 to .306! Perhaps if I used some kind of dry lubricant it wouldn't stretch.

Country gent - I don't think I can "polish" the die neck to open up from .293 to let's say .303 that's a lot of material to remove and it it's actually carbide ring in there you need diamond tool but this concerns me, not sure if it's by design or simply poor engineering on Lee part. P.S. I am talking about ID size of the neck when sized not actual dimensions of the die neck but I think you get my point.

Using LC brass to form brass with Lee FL die. First it was cut off with HF chop saw at neck than it was formed and trimmed, very little needed trimming about < .005, I modded my HF saw to make very precise cuts to +/- .001 simply by replacing the hinge rod with thicker one to remove play. I did anneal brass before forming. I didn't measure neck as I knew from experience LC works great for 300BLK so it should be fine for 7.62x40. I formed my brass on my Hornady progressive press and now I am wondering if perhaps there was flex in shellplate with just one die installed. The effort / force to form is less than forming 300 BLK, very easy. I might need to get some find of concentricity gauge, I ordered MEC single stage press to make sure it's not my press as it's highly rated. So that's my process and plan I might actually order Hornady dies as suspect lee dies is the culprit. I noticed even the seating stem leaves marks on my bullets from being rough machined.

Regarding seat/crimp I tried to use crimp feature but it just plain doesn't work! I don't know if my brass maybe was over annealed but the shoulders of the case would get pushed down instead and nothing was happening with case mouth even on hard lead bullets, I was expecting to see some kind of dent, like when you crimp .357 and edges of the case roll over. I readjusted to remove build in crimp and modified 300 factory crimp die to crimp and it works great, I am using only light crimp to get little bit more tension as the top of the neck has been expanded to accept bullet and has no tension.

I might need to get some find of concentricity gauge, I am thinking to rig up something similar to how Hornady concentricity gauge is working except on my lathe and using dial indicator. I ordered MEC single stage press to make sure it's not my press as it's highly rated. I might actually order Hornady dies as suspect lee dies is the culprit. I noticed even the seating bullet stem leaves marks on my bullets from being rough machined.

Popper - I thought you decided to stick to 300 BLK that was neck stretched to 38mm? or did you simply formed some for the heck of it? Can you actually form full 7.62x40 case with 300BO FL die?

Got short window of opportunity to go shoot my gun for the first time this weekend. Was very excited, it's my fist AR15 that I build it and I am using ammo that is totally custom made - brass formed, cartridges hand loaded and cast lead bullets! Got 1" group at 50 yards with NOE HTC 130 (actual 136.5gr) this was literally shots 5 through 10. This was my "starting" charge. No sign of pressure, good velocity, brass falling 4 o'clock.


And here's my AR15 before I mounted scope. Simple cheap build except premium barrel and nice 2 stage Geissele trigger (both were free to me)

[Rcmaveric]

Good job. Thats a good feeling you got there.

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[popper]

Can you actually form full 7.62x40 case with 300BO FL die? Yes, I was just playing but it does work - you just have to adjust the die correctly. I post a pic but I guess I'm over limit on something, get an error. I was looking at making the powder space larger but also leaving the neck longer (BO length) - but I just shoot BO. Kind a wildcat idea the worked but I never proceeded with it. Intent was to get closer to 30/30 performance with 150-180 gr cast. Went as far as I could without getting into the 223 shoulder area as it doesn't reform/cut very well. Tried expanding the 223 neck but it split every time. Basically 40WT case OAL with the shoulder back farther like the BO.