Sensible question about stretched cases in a 305.
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beavis_m305
Regular
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- New Zealand
The headspace can give false pressure signs so I've read. I wouldn't worry bro.
I don't see how you can measure 20 thou (from shoulder) or less accurately without using proper tools. You either need chamber gauge(s) or a cartridge gauge. I'd be cautious about reloading cases more than a couple of times without knowing how much they are being stretched, and keeping a close eye on them watching for case separation at the base.
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Just for sh!ts and giggles, measuring at the same point, what is the case diameter before and after firing? Cases should not shrink. All the forces exerted on a casing expand the case in every direction - not shrink it. The material casing is elastic as well, but should not shrink it. My unfired core lokt OAL measures 2.006". Most of the fired casing OAL are (on average) 2.010".
just having some fun
CGN Ultra frequent flyer
Its Very Common for this to happen .
Its not a match barrel headspace combo in the norinco
If you clean your brass and resize it it will be back to 2.005- or .010 and if do it all over it will shrink and resize
I have done what you are doing, trim to 2.005 load and fire them then then neck size 4or 5 times then aneal and full length resize and had the brass strech 0 or .001 or 2 trim and do it all overagain -- it depends on the chamber and the load combination
With a start of 2.007, after firing & resizing, mine stretch to a rough average of 2.010 as well. This is with Lapua brass.
LordEvilPepper
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um WTF?
OAL will not shrink when you resize it, infact the opposite will happen. not sure what your doing for reloading here but you just put in a bunch of extra steps and steps that require expensive equipment to do properly. Why would you even bother to aneal cheap brass for a gun that will beat the crap out of the cases long before you worry about case neck cracking and bullet retention issues?
its a semi... so full leangth size (use a headspace mic and set the die up to bump back 3 thousand of an inch so the brass will fit in the chamber no issues but its not getting exsesivly worked... it will extend case life and help reduce those wild elongations of the case), then trim and load. I would recomend triming to 2.010, which should get you at leaste 2 firings before you need to to trim again now that the brass is formed.
Kayser Sose
CGN Ultra frequent flyer
- Location
- Southern Van Isle
@Beavis;
I think the problem with primer inspection as a gauge of load pressure is that it's a subjective analysis. FWIW, op's primers look absolutely fine. But to him 'something looks wrong'.
In the stack of South African, upper left primer, obv. Now there's something to compare primers to! But then, how to know you're creeping up to dangerous pressures, with a sturdy batch of primers...
One day I'd really like to check my loads using a chronograph. I'd really like to know what my 42.5-42.7 IMR4895/FC brass/Hornady 150gr FMJ/2.800 COAL is doing up the spout. That's my accurate load for my specific rifle; sometimes it doesn't seem to be the bullet has much velocity. I wonder myself if the use of primer condition as my sole indicator of load pressure analysis has led to accurate but underpowered loads.
Thoughts? Thanks in advance.
edit:
So that load I posted, above? I got to that by loading up five rounds at each weight of powder, from 41.0 up in half grain increments. Sometimes I didn't fire all five off; this happened when I had clear signs of pressure issues, such as unexpanded brass (sooty), snappier recoil (and if in conjunction with flattened primers, definitely didn't feel the need to test that load further) and the ammo would get recycled. Love that bullet puller.
After collecting that data I seemed to zero in on the 42.5gr as snappy enough, with good accuracy and no primer abuse. I am also satisfied with 42.7gr, but that certainly 'feels' faster, accuracy is the same, and the primers are still acceptable.
But I'd still like to assess this using a chrony. Without, it's just not reliable 100% trustworthy data.
Happy to be able to cross-reference my experiences on CGN; take the time and read the threads before starting another. There's already lots of info here esp in the Reloading Forum.
I think the problem with primer inspection as a gauge of load pressure is that it's a subjective analysis. FWIW, op's primers look absolutely fine. But to him 'something looks wrong'.
In the stack of South African, upper left primer, obv. Now there's something to compare primers to! But then, how to know you're creeping up to dangerous pressures, with a sturdy batch of primers...
One day I'd really like to check my loads using a chronograph. I'd really like to know what my 42.5-42.7 IMR4895/FC brass/Hornady 150gr FMJ/2.800 COAL is doing up the spout. That's my accurate load for my specific rifle; sometimes it doesn't seem to be the bullet has much velocity. I wonder myself if the use of primer condition as my sole indicator of load pressure analysis has led to accurate but underpowered loads.
Thoughts? Thanks in advance.
edit:
So that load I posted, above? I got to that by loading up five rounds at each weight of powder, from 41.0 up in half grain increments. Sometimes I didn't fire all five off; this happened when I had clear signs of pressure issues, such as unexpanded brass (sooty), snappier recoil (and if in conjunction with flattened primers, definitely didn't feel the need to test that load further) and the ammo would get recycled. Love that bullet puller.
After collecting that data I seemed to zero in on the 42.5gr as snappy enough, with good accuracy and no primer abuse. I am also satisfied with 42.7gr, but that certainly 'feels' faster, accuracy is the same, and the primers are still acceptable.
But I'd still like to assess this using a chrony. Without, it's just not reliable 100% trustworthy data.
Happy to be able to cross-reference my experiences on CGN; take the time and read the threads before starting another. There's already lots of info here esp in the Reloading Forum.
I don't see anything abnormal about this. Every single piece or bottlenecked brass that has come out of my rifles after being shot has done so shorter than when it went in the chamber. The moment the case mouth expands to let go of the bullet the brass gets shorter. Yes, the shoulder is usually pushed forwards, but the brass still shrinks lengthwise. Once you resize it, it'll grow longer again, usually a bit more than it was before the first shooting. Although how much will depend on the type of brass and the type of resizing die being used.
Kayser Sose
CGN Ultra frequent flyer
- Location
- Southern Van Isle
...and then also consider; bags of raw unprimed from factory should be trimmed, as at times those lengths aren't bang on...
Perhaps the brass overall length wasn't 'bang on' from the factory?
Perhaps the brass overall length wasn't 'bang on' from the factory?
