Ok, so I brought the grendel out to shoot long range today for the first time in a 'LONG' time. I loaded two ten round mag about 6 months ago, shot 5, and had the rest left to shoot today. Out of the 15 rounds I had, only 4 chambered. The rest didn't allow the bolt to go in to battery. After looking at the rounds, I didn't see any markings on the bullet, as if it had engaged the rifling. The only thing I could tell is that there was a little marring on the shoulder, like maybe it wasn't set back enough.
They are Lapua 7.62x39 cases sized with the Redding dies, 100 gr Nosler BT's. I also had some rounds made up with 80 gr Sierras. Several of those had the same problems. I've been using this setup for three years now and never had this issue before. I'm wanting to punch out a bunch more, but I don't want a lot of duds. I have to drive almost two hours to shoot, so it's a little dissapointing when they don't go bang.
Any suggestions?
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06-05-2011, 04:36 AM
(This post was last modified: 06-05-2011, 03:11 PM by bwaites.)
Welcome back!
Well, this is almost always a shoulder set back issue. I'm assuming that these haven't yet been fireformed, and I'm not a 7.62x39 fireforming fan, so I'll be interested when a few others chime in also.
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt
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Oobray Wrote:Ok, so I brought the grendel out to shoot long range today for the first time in a 'LONG' time. I loaded two ten round mag about 6 months ago, shot 5, and had the rest left to shoot today. Out of the 15 rounds I had, only 4 chambered. The rest didn't allow the bolt to go in to battery. After looking at the rounds, I didn't see any markings on the bullet, as if it had engaged the rifling. The only thing I could tell is that there was a little marring on the shoulder, like maybe it wasn't set back enough.
They are Lapua 7.62x39 cases sized with the Redding dies, 100 gr Nosler BT's. I also had some rounds made up with 80 gr Sierras. Several of those had the same problems. I've been using this setup for three years now and never had this issue before. I'm wanting to punch out a bunch more, but I don't want a lot of duds. I have to drive almost two hours to shoot, so it's a little dissapointing when they don't go bang.
Any suggestions?
OOB:
Did you try to chamber a couple of pieces of your brass to see if you had bumped the necks enough, before you loaded them? Just to see if your die was set correctly?
LR1955
I had to recently pull out of a competition because of this exact problem. Upon investigation, I found that 4 of my rounds did not have the shoulder bumped back enough. I bump my fired brass back .003. These were only .001. I have also found, at least on my G's, that they are not very forgiving about the shoulder not being back enough. I use AA and Hornady 6.5 brass and always full length size my new brass. I do not shoot fire-formed 7.62x39, but the shoulder issue should be similar.
Thanks bwaites, I'm glad we got the forum back. Although the new user interface is taking some getting used to.
The way I set the dies is for the shell holder to just barely make contact with the die at full upstroke. I'm sure there's a better way. I have now thought about chambering the brass before reloading, but that seems very long and tedious. I seem to recall there was some sort of "gauge" the brass could be set in and get a "go" "no go" indication.
I think we are all correct that this is a shoulder set back issue. I just needed some assurance from the grendel community.
Thanks guys!! I'll report back after next range day. Although I don't think I have anymore 7.62 brass. It's all been shot/formed except the ones in question.
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06-05-2011, 05:31 PM
(This post was last modified: 06-05-2011, 06:34 PM by bwaites.)
Oobray,
This advice comes with the caveat that you try it at your own risk. Because I have done it does not make it safe!
Pull your decapping pin unit out of your dies and very carefully screw the die down a quarter turn past where you are, then take one of the cartridges and and gently reset the shoulder. See if it chambers, if not, repeat until it does.
Be careful, thats a loaded cartridge! I had to do this with about a dozen cartridges loaded with Wolf brass a while back.
You seek escape from pain. We seek the achievement of happiness. You exist for the sake of avoiding punishment. We exist for the sake of earning rewards. Threats will not make us function; fear is not our incentive. It is not death that we wish to avoid, but life that we wish to live. - John Galt
Oobray Wrote:Thanks bwaites, I'm glad we got the forum back. Although the new user interface is taking some getting used to.
The way I set the dies is for the shell holder to just barely make contact with the die at full upstroke. I'm sure there's a better way. I have now thought about chambering the brass before reloading, but that seems very long and tedious. I seem to recall there was some sort of "gauge" the brass could be set in and get a "go" "no go" indication.
I think we are all correct that this is a shoulder set back issue. I just needed some assurance from the grendel community.
Thanks guys!! I'll report back after next range day. Although I don't think I have anymore 7.62 brass. It's all been shot/formed except the ones in question.
This one works well....
http://www.midwayusa.com/viewproduct/?pr...ber=277624
bwaites Wrote:Oobray,
This advice comes with the caveat that you try it at your own risk. Because I have done it does not make it safe!
Pull your decapping pin unit out of your dies and very carefully screw the die down a quarter turn past where you are, then take one of the cartridges and and gently reset the shoulder. See if it chambers, if not, repeat until it does.
Be careful, thats a loaded cartridge! I had to do this with about a dozen cartridges loaded with Wolf brass a while back.
Also dump the powder and get all powder residue off the machine and in closed containers, keep your face away and wear safety glasses.
I intentionally set off a magnum primer once, it was quite loud with concrete walls!
I loaded 500 rounds of Grendel in wolf brass for this weekend without a hitch except that some of the primers (6) went in cockeyed, what the hell?
Dillon 650 as well, I use Redding dies and I am very happy with them.
I had that problem long ago..Was ALWAYS the shoulder not set back far enough.
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Oobray Wrote:I have now thought about chambering the brass before reloading, but that seems very long and tedious.
OOB:
You don't chamber every single piece of brass. Screw the die down more like Bill recommended then size three or four pieces and run each through your chamber. If all of them chamber and extract easily, the die is set and go to town. I doubt you will have any more problems.
I always chamber a couple of pieces of brass after sizing just to make sure it cycles. This includes fired brass, bolt rifles, etc. It takes a few seconds and is a good check to make sure nothing has changed.
LR1955
I can attest to this, I had a with just a few rounds that would not chamber, it was so close you would swear the bolt was closed.
A sloppier carrier would have slammed them into tolerance but out of all that I loaded I got maybe 30 or so that were just barely long at the shoulder.
Which reminds me that I also need a case trimming tool for Grendel
You will find this pretty cool, I have a micro mill that is not good enough for true precision machining, however I made a bar of aluminum with milled recesses the size of each caliber's case head on it.
I labeled each one and when I trim I can just set the stop according to the digital micrometer attached.
It makes this very fast.
I also cut the shank off a primer pocket cleaner and put it into my drill press, I then hold the case and bump it then it is clean.
I only had the problem when doing the fire-forming of the 7.62x39 brass.
I had a similar problem but it was with a new rifle. I could single load a cartridge by hand but not from a magazine. Ended up that the finish on the ejector was a little proud. I removed and polished the ejector. Also, I touched it once or twice to my belt sander to shorten it just a hair. Polished it all up and it solved my issue. Doesn't sound like it will fix your problem but I thought I'd share.
I have a strange question, I was working with a fired piece of brass last night and it would not chamber easily, and when I could get it to chamber I just about had to use a mallet on the charging handle to get it back out. Is that normal to do that??
Thanks,
Greg
Greg,
That's a sure way to jam your chamber up. The reason is that fired brass has expanded with tens of thousands of PSI to literally form it to your chamber-not just the perceived shape of your chamber, but all the microscopic crevices along the chamber surface as well. When this expansion occurs, after the peak is reached, and as the pressure curve spikes back downwards, the molecular memory of the brass attempts to re-orient itself to its position before being expanded, but only contracts a little since that memory has been almost entirely erased by the intensity of 50,000 + PSI.
When the brass is still hot and contracting on a semi-auto, it is easier to be extracted, which is where dwell time comes into play for gas-operated weapons, and delayed blowback on others. It is also why military rifles and machineguns have a chrome-lined chamber, to provide more Rockwell hardness and a smooth texture to facilitate the extraction. (They also help prevent corrosion from the elements.)
Taking a cold piece of fired brass and forcing it into your chamber will get it stuck nice and good, usually requiring removal with significant force, even if your extractor is strong enough to handle the task.
In short, I don't recommend doing it. Sized brass will drop in just fine, provided your chamber and sizing die like each other-at least this has been my experience.
LRRPF52
Ditto LRRPF52..
you force unsized brass back in there, not good on rifle or the brass.
Thanks guys, it just didn't make sense to me why it was tight, I know on my bolt guns they fit back fine so I was confused why it did it on here. My Grendel is the only semi-auto weapon I own and it has been an interesting learning curve I can say.
Thanks,
Greg
Your bolt gun is different in that you are camming that case in with force. 2nd, that bolt gun's spent case has more time to cool down before you pull it out compared to the AR(or any semi or full auto)rifle. Those cases come out so hot and fairly violent that the case is pulled/stretched more than the cooler case coming from a bolt gun or lever gun etc. That's why you can get by with just neck sizing in a bolt gun.
GregP42 Wrote:Thanks guys, it just didn't make sense to me why it was tight, I know on my bolt guns they fit back fine so I was confused why it did it on here. My Grendel is the only semi-auto weapon I own and it has been an interesting learning curve I can say.
Thanks,
Greg
And a side note..I saw your avatar in concert, 31Dec 1974 IIRC(and I use IIRC loosely, it was a Zappa concert afterall) at the Forum in LA..
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