Doug Beach
Silver $$ Contributor
Excess pressure doesn’t split necks.
Had my First case failure from pressure today - updated
- Thread starter HuntClub
- Start date
I seem to be getting split necks in 223 LC brass much sooner than I used too. I still have some 70's, 80's and 90's with 10-20 loading and it's still going strong. early 2000's seem to only about 7-9 loadings and newer brass I'm lucky to get 3-5 loadings. I don"t anneal. Think its oversizing the case necks and oversize chamber necks.
Frank
Frank
The total amount of neck working involved in the firing / sizing / seating cycle for a factory chamber and using an off the shelf factory non-bushing die is horrendous. I did your exercise years ago for a 308 Win FN SPR (marksman type rifle made for LEA use), and the aggregate working was horrendous - can't remember the exact value, but over 40 thou' in total. It's not surprising necks split after a few firings without annealing, especially if the original factory annealing is poor.
R-P fireformed brass from a 'minimum SAAMI' 7-08 match chamber I had in an F-Class rifle a while back produced 56.4gn water overflow capacity. Only Lapua ran at 55gn; everything else had more capacity. So, I'd have thought 44gn N140 a stiff load but not excessive. (But maybe not even 'stiff' depending on how close to SAAMI spec Tikka makes its barrels and what the factory freebore runs at.)
As an aside, back in the days when I ran a UK spec (manually operated straight-pull; no gas-guns allowed here) custom-built AR-15 with a modified Wylde chamber cut by what was claimed to be one of the better US machine shops, I used Winchester brass (much better than today's some 25 years ago) sized and bullets seated with a standard Hornady 'New Dimension' set. Necks started to split on the 7th firing and were all scrap by 9 or 10. This was with very modest pressures as high pressure and straight-pull extraction don't mix well in the AR given its lack of cammed primary extraction. According to QuickLOAD, I'd start to see hard extraction with loads that got anywhere near 55,000 psi, so I was running at a fair bit less. (Conversely, European manufactured 5.56 NATO could be fired but needed a really hard tug on the heavy-duty side-operating handle to break the fired case fit in the chamber!) Neck splits are simply a fact of life in the absence of annealing when there are generous chamber clearances, standard reloading tools and techniques are employed - little or nothing to do with pressure as others have said in their posts.
I am no expert or gunsmith, but I've been told that AR chambers like most semi-auto rifles tend to expand cases to a greater degree. Thus, repeated firing and sizing would increase work hardening of the necks compared to the tighter chambers of bolt rifles.
All my Semi-Auto rifles preferred between 48,000 and 55,000 psi to cycle normally and make the brass last a long time. Anything over 55,000 psi (according to QL) trashed the brass and accuracy was not optimal either.
NorCalMikie
Gold $$ Contributor
Be surprised how thin necks perform when annealed often. The thinner they are, the easier they split.
Pierced primer? (headspace) Case too small for the chamber? (shoulder pushed back too far and you got movement) Brass problem, not chamber issue.
Soot on the necks? Neck couldn't expand enough if work hardened.
Pierced primer? (headspace) Case too small for the chamber? (shoulder pushed back too far and you got movement) Brass problem, not chamber issue.
Soot on the necks? Neck couldn't expand enough if work hardened.
dellet
Gold $$ Contributor
It’s not really the size of the chamber that is the problem. It’s the speed of extraction, basically a tuning problem.
You can set up an AR that it is easy enough on the brass to neck size only. I have also seen AR style rifles in large calibers so poorly tuned they pull case heads off.
Somewhere in between is where most people operate, but you can’t pull hot brass that is still stuck to the chamber wall out without some distortion. Even the fastest bolt action shooters just aren’t that fast and the brass is relatively cold coming out of the chamber.
Here’s a guess:
You can split a neck without loading a round.
Of course depending on the size of the neck expander, take a piece of brass and run it in and out of a die say say 50 or 100 times. No loading no firing. Just keep that brass in and out of the die. The only thing taking a stretch and contraction is the neck. I’ll say it will split. No pressure involved.
Like I said it’s a guess.
You can split a neck without loading a round.
Of course depending on the size of the neck expander, take a piece of brass and run it in and out of a die say say 50 or 100 times. No loading no firing. Just keep that brass in and out of the die. The only thing taking a stretch and contraction is the neck. I’ll say it will split. No pressure involved.
Like I said it’s a guess.
Thanks for the clarification. I haven't shot an AR since 70-72 while in the Army. Know less about reloading for them.
Neck tension alone on the bullet will split the neck over a long enough period in the absence of annealing. One of those little known facts about British 0.303 cordite loaded ammo is that the propellant was measured out into little tied bundles and each inserted into a partially formed case in the ordnance factory. That is the case was formed the by the usual drawing methods but lacked the final neck and shoulder form-step in order to be able insert the propellant bundle. Then and only then were the neck and shoulder formed. As the cordite charge was now inside the case, final heat annealing of the shoulder / neck was obviously impossible. It wasn't at all unusual for necks to split of their own accord after several years in storage purely from the tension of the seated bullet. I first learned of this when an old friend bought a large sealed case of military 303 Mk VII that was 30 plus years old. The cartridges were in excellent, bright condition, but around half had split necks.
Although a very special case, it illustrates how handloading practices / tools can also impact on case-neck life. Have a very high degree of neck tension as imparted by some standard size dies / expander balls and the neck brass is given a harder life simply from having a bullet pushed into it.
wildcat3d
Silver $$ Contributor
Excess pressure, hot day in Texas, Match day, hot load,hot barrel, to long in chamber.. scared the heck out of me,
Attachments
Old Navy
Gold $$ Contributor
Never saw one just like that. AR ?
wildcat3d
Silver $$ Contributor
6PPC
searcher
Gold $$ Contributor
Not necessarily. All brass stretches quite a bit on the first firing in most guns. It is the need to full-length resize them and push the shoulders back at least .003' to .004" which ensures semi-auto-fired case stretch over that of a bolt gun in which the brass was only pushed back, say .001" or .002" and which could be neck sized only. Also - some guys have very tight chambers in their semi-autos which actually require a short-base sizing die (especially if using fired military brass) - all of which add up to shorter case life. Usually nothing to do with the chambers (of modern firearms). Then, of course, there is the variance between dies.
searcher
Gold $$ Contributor
And that is a fact!
You split a neck. Did the primer pierce?
At the risk of sounding like a dick, I only neck size my 6MM and my 223 Remington, (varmint shooting). Years ago I bought so much brass for each and I'm such a lazy shit, I shoot them until the neck splits and toss them in the recycling tub.
The worse problem is that you're not noticing a different brand brass.
The worse problem is that you're not noticing a different brand brass.
searcher
Gold $$ Contributor
Yes - kind of like mixing 5x fired brass with 10x fired brass
It is interesting that your speeds "were increasing" up until that shot. A lot of guys brought up different topics - so I'll dwell on that one element of what you said. Let's say you were running a maximum load (I have no knowledge about that powder/charge in that caliber). And let's say you were using something like an older Chargemaster (like mine) or another scale that requires it to be on for at least 20 minutes before it "settles in". If I just turn on my scale and start weighing charges and filling cases (say I'm doing 100), I'll get about a third into the cases and my charge weights are at least 1/10th grain off from when I began. I have had to re-do many a portion of a batch until I finally either started weighing after waiting a half hour for the scale to warm up or just use one of my other trusted scales. I'd fire up your scale and weigh out five loads of powder. Wait a half hour then weigh five more and compare them with the first batch. You may be very surprised. Of course, if using a balance beam - this may be mute point.
Then - say you were shooting that batch of uneven charges on a day where the temperature were rising as you fired your loads. If the temp went from, say 60 degrees to 85, you are going to see an increase in speed. I once had a load I used in my .223 varmint rifle (used for years, but only shot in cold weather on a certain yearly hunt where temps might be 40 to 60 degrees). Then one day, I shot at my local hunting area on a day when the temp was 95. The first five shots exhibited a result of what your brass looks like in your photo). I ended up backing that load off a full two grains and no more issues. Thankfully, the load liked that powder so much (Rel 7), that it still shot as well, which was somewhat remarkable.
Seeing how your brass was mixed up (different brands), you are most likely going to get different speeds between the brands either because of case volume, flash hole size, differences in neck thickness, differences in neck annealing, etc.. Increasing speeds can also result from changes in friction in your bore. You didn't mention whether these speeds were increasing from shot to shot or from batch to batch. If the speeds increased since the last batch, doughnuts in your brass may becoming increasingly problematic on your load with each reloading. Likewise, your bore may be getting coppered up. All that said, I didn't catch how many firings you had on your brass. I saw someone mentioned 20. That would be an exceptional number of firings on Remington brass before failure. Even 10 warm loadings would be a high count in my experience with that brass, so I'd not write off your load if you had used it extensively before. I'd just get a batch of brass that is the same brand and lot, then ladder up all over again to the load you were shooting, then I'd go past it in 2/10 grain increments until you see signs of real pressure. I'd start by measuring the base of your brass, then stop increasing your loads once it expands .001", even if there are no other signs of pressure. If the load you are using is not a full 1 1/2 grains less than that, I'd consider lowering your powder charge from what you have been using, especially if it is not hot when you are doing your testing. Good luck!
searcher
Gold $$ Contributor
Yes - kind of like mixing 5x fired brass with 10x fired brass
I have used many thousands of pieces of Lake City in high-volume A/R varmint hunts over many years and I can say that having split necks after 4 to 5 loadings in an A/R is pretty much the norm. I anneal mine every other firing for twice+ the life, mainly because I skim turn the necks and don't want to have to replicate that process and the primer pocket reaming any more than necessary.
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