Project Appleseed

Looking in both the Lee and Lyman reloading manuals, the trim-to length for 7.62x39 is 1.528"
I have a bunch of once-fired Winchester and Fiocchi cases, and now that they've been processed, I am ready to start loading them.  (by processed, I mean cleaned, deprimed, sized, tumbled, and primed again)
For consistency's sake, I decided to measure case length, and sort them based on case length and weight.  Here's the rub: roughly 90% of these cases are SHORTER than the trim-to size listed.
Not by just a few thousandths, either- many of them are in the 1.514-1.519 range.

Do I discard these cases? 

Do I trim them all to the lowest common denominator, and work up a load for that length?

Need some advice here-  Thanks in Advance!

Don't discard for too short, those are all safe and good.  It's not problematic to be  a bit under length, even less than MIN length, you just don't want to exceed MAX length.

I'd adjust the trimmer to 0.005" to 0.010" less than MAX length, and trim the batch.
Since you have many extra short cases, you can pre screen the shorties with a micrometer. 
With blasting grade ammo, as 7.62x39 is likely to be, wouldn't worry about having EVERY case the same length.  Only ensure that no cases exceed max length.

Factory brass shorter than the specified "trim to" length isn't uncommon.  But what to do about it?

Uniform case lengths are important for cartridges where the bullets are to be roll crimped.  If the cases are of different lengths, it'll be impossible to set your dies to get a uniform amount of crimp.  Some might get none at all, some a moderate (correct) amount, and some over-crimped so the neck will wrinkle or buckle and the round won't chamber.

If you're not crimping bullets in the necks, it's no biggie at all.  Just tension-seat the bullets and blast away.  You probably won't be able to tell any difference at all.

But there is a caveat, many self-loaders will shove bullets further down the cartridge neck during chambering, or recoil pounding of the rounds in the magazine will shove the bullets deeper into the necks.  If so, then all bets are off.  The then-under-length rounds might not want to chamber dependably, and firing such rounds could lead to a significant over-pressure situation.  Anybody know if this is likely to be a problem, and in which rifles?  I'd sure want to check it out thoroughly before I made anything un-crimped as my regular, ops-normal, load.

If you are intending to crimp bullets, rather than discarding some brass (Oh!   The horror!    ), or trimming them all to be the same length as the shortest, you might be able to MEASURE what you've got prepped with a caliper.  I'd betcha a thousand primers that the great bulk of them will be within .003" or so of each other.  Then, for your crimped loads, you can maybe trim those longer ones to that length.  Adjust your seating die to get a consistent crimp, whatever the length, and save the shorter ones for uncrimped loads.

Those with benchrest-grade AR's, SKS's, and Mini 30's should trim cases to within .001" for maximum uniformity of the crimp and bullet pull force, weigh every powder charge individually, and check every round on a run-out gauge to keep those groups under .300 MOA and stay competitive.  Sorry.  I couldn't resist.

I'm of the opinion that if I'm going to take the time to reload ammunition, I will do it to the best possible standard that I can, taking no shortcuts, and endeavoring to ensure maximum consistency from round to round. 


90% of the measured cases fall in the 1.514-1.519" length, while some of them measure to 1.534 or higher.

My take from the advice given so far is to trim them all to the 1.514" length, sort them all by weight, then develop a load for the most common weight cartridge.  Correct?

The first load that I created for my SKS utilized once fired Winchester brass, trimmed to 1.528, loaded with 20.4 grains of Accurate 1680, a Privi Partizan .311 diameter 150gr FMT-BT seated to an OAL of 2.200".  This load was exceptionally consistent, with a 5 shot cloverleaf at 25m (no bench, just rifle, sling and me), and extreme deviation of 11 fps.  I had tried powder weights from 20.0 - 20.6, working up in .2 grain increments- the 20.4 loading was by far the most consistent, in both accuracy and muzzle velocity. 

If I trim all of my cases to the 1.514" that seems to be most prevalent among my brass, how should I expect that to change my recipe? 

I don't think the short cases will change your recipe. Most bottle neck cases use the shoulder for sizing the chamber. I think thats what I wanted to say. Just in case.

I one thing I have a problem with you've already re-primed them. My trimmer, Lyman, cannot have the primer in the case to use.

Sort them into a length range and adjust the crimp as you go to the next range. Probably won't be the best, but it beats trying to remove live primers for trimming.

Just a thought.

Odd, my trimmer, also a Lyman, seems to have no difficulties with primed brass. 
Requires an extra bit of caution, but nothing disastrous has happened yet. (knock on wood)

Quote from: ItsanSKS on September 07, 2009, 05:07:31 PM
I'm of the opinion that if I'm going to take the time to reload ammunition, I will do it to the best possible standard that I can, taking no shortcuts, and endeavoring to ensure maximum consistency from round to round. 


90% of the measured cases fall in the 1.514-1.519" length, while some of them measure to 1.534 or higher.

My take from the advice given so far is to trim them all to the 1.514" length, sort them all by weight, then develop a load for the most common weight cartridge.  Correct?

The first load that I created for my SKS utilized once fired Winchester brass, trimmed to 1.528, loaded with 20.4 grains of Accurate 1680, a Privi Partizan .311 diameter 150gr FMT-BT seated to an OAL of 2.200".  This load was exceptionally consistent, with a 5 shot cloverleaf at 25m (no bench, just rifle, sling and me), and extreme deviation of 11 fps.  I had tried powder weights from 20.0 - 20.6, working up in .2 grain increments- the 20.4 loading was by far the most consistent, in both accuracy and muzzle velocity. 

If I trim all of my cases to the 1.514" that seems to be most prevalent among my brass, how should I expect that to change my recipe? 

Unless you are loading for match use, I can't imagine trimming or even worrying about brass that is a hundreth of an inch or so less than the trim-to length.  It won't affect your accuracy in any measure able way.  Just shoot it and don't worry.  Won't change your recipe a bit.  If this was for the 600-yard stage in highpower, you might drop a couple points using well-rigged service rifle and an excellent shooter.  Other than that, doesn't matter.  At maximum, having non-uniform trim lengths on brass might cost you a quarter to a half minute and you'll never notice that out of any SKS or factory battle rifle with Irons.

-David
Edgewood, NM

I admit that it is probably overkill, but I went ahead and trimmed my cases to 1.520", +- .001"
Seems like a happy medium- only had to set aside 7 cases out of 50 to be loaded as 'plinking' ammo. 

People (I included) long believed that the SKS was an inherently inaccurate platform, and that no amount of tinkering would make it better.  After purchasing one myself, and testing it with a plethora of factory loaded ammo, I was sure that it was plagued by something else- inconsistent ammunition. Even factory fresh wolf/barnaul/sellier&bellott/et al couldn't seem to provide reliable groups at 25m, let alone 400.  Even Winchester and Remington had consistency problems, with extreme deviation well over 100 FPS.

What I'm hoping to gain from the extra time invested, is a heartier round that will stay consistent at longer ranges than can usually be expected out of an SKS. 
Once I have my load fully configured, I'll post back with my results.

Quote from: ItsanSKS on September 07, 2009, 07:19:34 PM
I was sure that it was plagued by something else- inconsistent ammunition.
 
Once I have my load fully configured, I'll post back with my results.

ItsanSKS-

     Sounds like a very worthwhile experiment.  You might well be right, that the bad rep 7.62x39's have is due to indifferent ammo, and the fact that EastBloc rifles often had a pretty wide range of bore/groove diameters.  And pretty difficult-to-use sights.  And nobody seems to know why Mini-14's and Mini-30's tend to have such lackluster accuracy, just that they seem to ...

     So I'd like to know, too, what kind of accuracy a well-made SKS or AK will produce, given not necessarily match quality, just solidly, carefully assembled ammo made with quality components.  So best of luck!!   

I've never crimped my ammo intended for the M1A, the M1 Garand, the ARs, the mini14 or the Rem. 742.  No issues yet.

Don't know how many reloadings you'll get from that brass but every time you resize it you'll find it gets a little bit longer.  I'd suggest trimming to the minimum length (the ones that are long) and let the rest "grow" until they need trimming.

Brass (necks) too short shouldn't be a safety issue.  Brass (necks) too long can result in high chamber pressures if it's long enough to jamb into the end of the chamber and pinch the bullet or keep the bolt from fully locking up.

If you really want to see if there's any effect of various length brass....measure it, sort it by length into 3 or 4 groups, ID the brass in each group with a sharpie on the base of the case, load it with the same primers, powder, powder amount and bullets, shoot it by groups and check your group size.  Be sure to seat it to the same overall length so the pressure is more consistent.

Be safe, have fun, let us know what you learn.

edited to add (necks) in two places, as a case that is too short can be a problem

I suggest a brass catcher - SKS and AK's toss far forward; I was loosing 20% of my brass to the toad army in the tall grass.

(Often wondered if I could dremel the angle on my ejector and push it sideways.)

Chambers on these rifles (and AK's) tend to be generous - neck sizing die may help in consistancy and certainly in brass life - if you can keep the brass to the rifle.

I had luck with H4895 - I think a slower burning powder worked better on the SKS than the shorter AK, but I can't find the details.

Accuracy in x39 is a nobel endevor, though I have to admit I gave it up for now, figuring I should be reloading more expensive rounds with the limits of time and budget.

Well, I've run into another snag in the operation- after meticulously setting up my bullet seating die for 2.200" OAL, I run 10 rounds through and check to see how well its holding.  Well, it isn't.  Not even close- I have rounds as long as 2.220" and as short as 2.200"..  and everything in between.  

The die isn't backing out, the bullet depth adjuster hasn't moved (I scribed it).  
Are Lee dies really that inconsistent?

I thought I'd be able to dial it in, lock it down, and be done with it.

and that is one of the reasons I've been switching over to a different brand of dies where possible.

Quote from: ItsanSKS on September 07, 2009, 09:22:57 PM
Well, I've run into another snag in the operation- after meticulously setting up my bullet seating die for 2.200" OAL, I run 10 rounds through and check to see how well its holding.  Well, it isn't.  Not even close- I have rounds as long as 2.220" and as short as 2.200"..  and everything in between.  

The die isn't backing out, the bullet depth adjuster hasn't moved (I scribed it).  
Are Lee dies really that inconsistent?

I thought I'd be able to dial it in, lock it down, and be done with it.

There's nothing wrong with the dies.  Nothing wrong with your technique.  You CANNOT chase an overall length.  Dies don't seat bullets using the tip.  They seat bullets using the ogive (a part of the curve on the bullet).  The nature of jacketed, swaged bullets make them vary slightly in length.  THIS IS NORMAL.  Even our 1000-yard 50 BMG match bullets vary a bit in length (Hdy) A-max but if you seat them all with the same die settings, they are capable of 0.5 MOA accuracy at 1000 yards.

Relax.

-David
Edgewood, NM

Yeah, you can't chase that OAL. He is right. I see this when I load .223. Measure your bullet lengths and you will see that sort of variation in them.

The .762X39 is a fine cartdrige, capable of excellent accuracy. Inexpensive plinking ammo like wolf, brown bear and the others are made to less than exacting standards.
A few years back I purchased a bolt gun in .762x39. Mounted a scope on it and went to the range with 4 diffrent kinds of cheap ammo.
Bought a set of dies on the way home. No problem getting to 1 1/4 min at 100 yards with reloads from bench. The cheap ammo varied from 4-8 minutes.
About the trim length, trim about .010 less than max length and let the short ones grow. The bullet seating depth regulates case capacity.

Quote from: didactic on September 07, 2009, 04:54:19 PM


Those with benchrest-grade AR's, SKS's, and Mini 30's should trim cases to within .001" for maximum uniformity of the crimp and bullet pull force, weigh every powder charge individually, and check every round on a run-out gauge to keep those groups under .300 MOA and stay competitive. 

Well, I'm an ex-BR competitor myself, and though I would trim the cases so they were the same length (Forster trimmer in a drill press, for speed), I didn't crimp (wrong bullets anyways), didn't worry about bullet pull force (we turned the necks, tight chamber), never weighed each powder charge and only used a run out gage (we called it spinning them) on the bullets. I've shot some mighty small groups, one of the more memorable ones was a .204 at 200 meters.

Most BR competitors use a really good measure, and call it good. They don't have the TIME to weigh each charge, as they're reloading at the event, usually with Wilson hand dies. They reuse the same cases over and over.

Lots of good comments here. The one thing holkding an SKS back is surely the ammo.

I've heard Fred say he knows an SKS CAN shoot a Rifleman score, and he's proven it himself.

RE: the OAL issue- my experience reloading 7.62x51 and .30-06 is identical.  With pulled M80 ball, pulled M2 ball and pulled unidentified 150 gr. FMJ the OAL wanders.  I have started gauging with a micrometer at my desired OAL, adjusting the seater to give about 1/3-1/4 passing with the first seating run (passing being OAL or just under).  Tighten the seater, run them through again, gauge again, with the objective of each time passing around 1/3 of the lot.  This might actually be more trouble than warranted given the comments in this thread.

RE:  brass lengths-- best thing since sliced bread for non-OCD reloaders is the Lee Factory crimp die.  I have used range pickup that is shorter than min, I just trim to recommended length on any longer ones, load my standard load for the caliber and crimp with FCD.  It handles inconsistent neck lengths with no problem.

The rifle you referenced shooting 5 shot cloverleafs from prone, what make is it?

Any mods to sights or trigger?

How did you decide to attach the sling?

Reason I ask, I have used (stock) SKS' for AQTs, and have a love/hate relationship.  I know the rifle is mechanically capable of shooting like I want, yet have never been able to break 200 with one.  I love it because it is a GREAT trainer rifle, yet would also like to be able to give it to my son for some (relatively) cheap AQT shooting.  That won't work unless there is a reasonable chance of him getting a rifleman score....

Interested in seeing how your experiment turns out.  I have on my to-do list getting into reloading for the 7.62x39, seems it might be even more important than realized.

SoM

SoM- PM inbound regarding SKS.

After reading everyone's comments regarding COAL, I decided to just set the length for one bullet, then start cranking them out.  Only problem with this, is the fact that the 2.200" OAL I was shooting for is the magazine size- any longer, and they won't load properly, any shorter and I run the risk of over-compressing the powder.

Nearly every single round I loaded ended up being longer than the 2.2" I set the die for with the first case.  Being as I'm running a compressed load as it is, I *need* to have consistent bullet seating depth.  Is there a die out there that will do what I need, or do all of them use the bullet ogive for reference?

Compressed powder charges are not necessarily a bad thing.

For example, it's difficult to put enough IMR 4350 or IMR 4831 in a .308 or 30.06 case to get desired velocities without compressing the powder, and yet the chamber pressures are well under maximum for most bullets (check out the reloading manuals).

Now there's probably not nearly as much experience or info on the 7.62X39 but the case is so small you have to use faster powders than with bigger cartridges/cases.

There's lots of reloading info available on line:
http://www.alliantpowder.com/reloaders/recipedetail.aspx?gtypeid=2&weight=123&shellid=144&bulletid=145
http://data.hodgdon.com/cartridge_load.asp

powder burn rate chart

http://www.hodgdon.com/burn-rate.html

Be sure to read the safety section of these sites about reducing initial/starting powder charges, the signs of high pressure, etc.

Good luck, have fun working up some good loads.

Quote from: ItsanSKS on September 08, 2009, 05:19:11 PM
SoM- PM inbound regarding SKS.

After reading everyone's comments regarding COAL, I decided to just set the length for one bullet, then start cranking them out.  Only problem with this, is the fact that the 2.200" OAL I was shooting for is the magazine size- any longer, and they won't load properly, any shorter and I run the risk of over-compressing the powder.

Nearly every single round I loaded ended up being longer than the 2.2" I set the die for with the first case.  Being as I'm running a compressed load as it is, I *need* to have consistent bullet seating depth.  Is there a die out there that will do what I need, or do all of them use the bullet ogive for reference?

All rifle dies seat off the ogive unless you are shooting cast bullets.  It won't hurt a thing to bump all those bullets back a couple hundredths of an inch.  That much powder compression won't do much unless you were already running them too hot or if you shoot what was a safe load at 70 deg F in Phoenix when it's 120 deg F.

-David

OD-
Excellent resources, sir.  Greatly appreciated.  They have been added to my "Reloading Resources" tab in favorites.

The load that I am concocting is not a typical load for the SKS.  Popular doctrine dictates the use of bullets in the 120-130 weight.  As you may or may not know, the bullets found in factory ammunition are short- 0.875" to be exact.  The bullets that I am loading (.311 diameter, 150gr FMJ-BT) are 1.115"    

Too heavy, too long, at least according to what the factory loads for the 7.62x39...

The load data that I started from was listed in the "Modern Reloading- Second Edition" Lee manual.  
This load is for a 150 gr jacketed bullet, but one that I'm sure is more in line with the .875" bullets that are typically loaded.  Starting load called for 20.3gr of Accurate 1680, which should produce a MV of 1808 FPS.  I started a bit shy of that, at 20gr even, and was already seeing MV 75-80 fps higher than that.  Working up from there in .2gr increments, I found that 20.4grs was the most consistent (with 11fps extreme deviation) right at 2005 FPS.  
By the book, this load shouldn't be a compressed load- not with a bullet "properly" sized to the cartridge; but with the longer bullet that I am loading, there is a slight compression of powder in the case.   No signs of over-pressure on even my hottest load (20.8gr) but consistency/accuracy had gone out the window at that point, so I decided to stick with the 20.4 load that seemed so promising.  Have yet to test it at ranges longer than 25m, but hope to at least get some 100yd time in a week or so.  


When I first started with this load, I hadn't been aware of how much the COAL of my cartridges had been, as I had not measured them, aside from the first round created while setting up the bullet seating die.  Guess I started thinking too much...

Unless I'm mistaken, one sign of low pressure is a blackend neck/shoulder area where the pressure is a little less than required to expand the neck and seal off the gas.  I see that on my M1 with commercial cases loaded with the same amount of IMR 4895 used to load the military cases (commercial cases have thinner case walls =  larger internal volume = less pressure with the same powder).  Another is the primer is still really rounded on the outside edges were it butts up against the primer pocket (I see this also on my M1 loads in commercial cases).  Another is supposed to be the primer trying to slighly back out of the primer pocket (I see this on some of my above mentioned loads).

That tells you you're low on pressure.

Working up from there the signs of high pressure I pay the most attention to is that same outside edge of the primer.  That nice rounded "corner" will begin to disappear as the pressure forces the metal of the primer cup to expand outwards to the side of the primer pocket in the case.  Sometimes you'll also see the metal around the firing pin indentation begin to "raise" up making it look like a small crater.  This is from the pressure forcing the primer cup material to expand back into the gap between the firing pin and the firing pin hole in the bolt face.  Sometimes this one can fool you a little if the hole in the bolt face is worn or expanded above what is "normal" or as manufactured.

I've never really done any case measuring.  Brass is different (brand to brand), different based on how hard it gets from repeated firing and resizing and different when fired in one rifle vs. another.  I just stick with the primers and from experience it seems my most accurate loads are always under the max load velocity wise (and pressure wise).  The only "gun" I've got that seems to eat and shoot "hot" loads well is my old Ruger Super Blackhawk.  It shoots everything in tight groups.

One of the things I've learned from reloading is the more manuals I have and read the more I learn as some cover things ignored in others.

Good luck.