OAL question, and sorry I haven't posted...

[armoredman]

...on the nice boolits this great new mold makes, but circumstances beyond my control have kept me off the range for a while. I SHOULD be able to get it together next week, hope and pray, so I started to get the press running to get some testers loaded up...and ran into something interesting.

For those who are new to the story, I have been using the Lee 160grain boolit for 7.62x39mm, and getting so so results. Enter in a great guy who sells me this nifty 5 cavity NOE mold, which after I was schooled on proper pre heating of molds, :wink:turns out a really nice boolit!

So here we are, got the standard empty dummy case to experiment/set up the seater, and lo and behold, the crimp groove appears to be a bit high.
Please forgive the horrible pictures, my son destroyed my camera, so I am using the nasty phone camera.

http://i16.photobucket.com/albums/b13/armoredman/casting%20stuff/shortboolit2.jpg

It's standing next to a Wolf HP for comparison. That is an OAL of 2.16, BTW, the manual suggests 2.18 with a 129 grain j-word bullet. Now, please, understand, I am not mad or upset about this development, just wondering, and excited to try something differant.

1) If I seat this to the crimp groove, with the lighter charges we use in cast loads, I shouldn't have to worry about pressure spikes? Or should I crimp in this lube groove at this OAL?

2) The mags seem to hold by case neck, so the round shouldn't slam itself against the front of the magazine and shorten themselves, I think?

3) Some boolits a really good guy sent me, Lyman 311359, has the crimp groove even farther forward, same questions? Nifty little pill, looking forward to trying it out, as well.:D

I am going to load some 18 grain testers with the boolit seated to the crimp groove, and try it out, just wondering what the board thinks.

[noylj]

If your dummy fits your magazine and feeds and chambers, you should be good to go.
You may want to make a couple more dummies and cycle them a couple of times in your gun. If bullet set back is marginal (i.e., your eye says it still looks the same), you should not have any problem. If you load up 10 rounds at the range, you should drop the magazine and check for bullet extension for rounds 8.9, and 10. Those bullets have a lot of inertia and don't want to move when the rifle and magazine recoil backwards.
One problem with so many molds is the crimp groove is not where your rifle wants it. If you find you need to crimp, at least the rounds will still fit in your magazine and all.

[lwknight]

I think that bullet was not designed for the 7.62X39.
You do not always have to crimp in the groove.
That one looks like you might have to.

Question 1.: Have you tried it in the chamber?

I always start with the OAL long enough to get rifling marks then start seating deeper till they go away. Then go 1/32 deeper.

Question 2.
The picture looks like the boolit may be shorter than the one next to it because the taper is a lot wider. Did you calculate just how much is in the case and compare to the other bullet?

[armoredman]

The boolit is roughly the same length as a Jword bullet I have on hand. I loaded up some to try out, down to the crimp groove. I might load some more with the same charge to the first lubegroove, and might give a gentle nudge with the Lee FCD to keep it in place.
I don't have the rifle at this moment, a buddy does, getting it back next week.
The taper on the ogive is a LOT wider than the others, and I think that alone may decide the shorter OAL, when I get to drop test in the chamber.
Thanks for the replies!

[lwknight]

I would say that if your load data does not give directions for that particulat boolit that you should back your load down by 3 grains or so and work up.
You may indeed have less case capacity than was presumed by the data reference.

The 7.62X39 is not a real small case but , its not all that roomy either. A deeper seating bullet will have more affect than say a 30-06

[armoredman]

I started at the lightest load data I had, 16 grains of AA#1680, very light load with the 160 grain boolit. Loaded testers at 16 and 17 grains, figured that was a safe zone for starting - find out next week!

[geargnasher]

How about rolling a crimp to just barely bite into the driving band there where you have it seated? It shouldn't take much to keep the boolit from driving back into the case under recoil, remember that it's really just the static mass of the case and primer driving against the boolit under recoil. If you only have a taper-crimp die, seat and crimp in one operation and the case mouth will dig its own crimp groove.

Gear

[armoredman]

Loaded some testers at 2.18 COAL, used the Lee FCD die to barely kiss the brass into the driving band. We'll see!

[JIMinPHX]

It's a lead boolit. You can crimp anywhere that you want to. You don't need to be in a groove.

In an auto feeder, I'd be a little concerned about the boolit getting knocked sideways if the amount of the boolit in the case neck is too much less than 1 diameter deep.

Just my $0.02