MarshallDodge... good advice and will do, Thanks!
I have not had any issues, including light strike. The gun shoots great! Having said that, it only has about 300 rounds through it at this point.
- Thread starter GunnyUSMC
- Start date
MarshallDodge... good advice and will do, Thanks!
I have not had any issues, including light strike. The gun shoots great! Having said that, it only has about 300 rounds through it at this point.
You are setting the shoulder back too far, causing the case to stretch and thin. Here are 2 commercial cartridge gauges one 308 and one 6 5 Creedmoor with a go gauge inserted to see how they compare to the chamber and the reamer that actually cut the chamber....notice the cartridge gauges are off +.002" and the other -.002" for .004" difference...some will be closer. But when using gauges to drop the cartridges in ya gotta know where it is in comparison to the chamber.
Reamers and go & no go gauges are usually CNC ground these days so they are what they say and all have a reamer print to check dimensions against, neck dia options and wildcats still have a print available, to measure.
I sometimes make the cartridge gauge with the reamer I cut the chamber with.
Back in the Presision Shooting days 308 Lapua was run 40 reloads by me before discarding, no annealing, no case prep, like primer pocket uniforming, just load with a Redding neck bushing die and a Redding bump shoulder die every 3 firings, firing hot loads, to 1000yds and beyond.
But one guy who annealed set a record with Lapua 308 brass loaded 58 times and he annealed his brass... so I wouldn't discount it but I don't anneal unless heavy case forming & wildcats. But here quit setting the shoulder back so far and your cases will last much longer.
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I ran 23.5 XBR with the 75 eld-m loaded at 2.525in. It is a very hot load and requires a custom chamber with at least 100FB.
Anything above 24gr would be > 60 PSI
A Berger 80 vld even at these long coal, would be above 65K psi at 24gr
Anything above 24gr would be > 60 PSI
A Berger 80 vld even at these long coal, would be above 65K psi at 24gr
Once again, OP - I would strongly recommend you check the overall case length of any cases that you have fired and wish to reload. You have been shooting very hot loads and knocking the shoulder back repeatedly, in a rifle that may not have the headspace set correctly. As you are aware, this has thinned the brass out, and the repeated resizings have moved the brass material out of the case sides and into the shoulder and neck, lengthening the case overall length. (You do not mention checking and trimming case length as part of your reloading regimen.) If you were not getting serious pressure signs with this same load on prior loadings, yet separated a case, I would strongly suspect, as mentioned above, that you have pinched a bullet and case neck into the area of your chamber that has not been cut for the full neck diameter. As well as checking case lengths, it might also be useful to chamber your longest empty case and look at where the end of the neck is positioned in the chamber with a borescope. I do not mean to disparage your reloading methods or talk down to you, but checking case length after each firing, especially with hot loads, is a mundane and boring exercise, but can be critically important and can prevent serious issues.
Decap the primers and look at the sides.
Over pressure signs:
- Hourglass from middle of primer to top
- Burnt powder residue creeping up the sides
- Decapped without resistance. ***
- Anvil falls out or is disintegrated
***Primer pocket is enlarged. Enlarged primer pocket after 1-3 firings is showing overpressure. That growth should only occur after many more firings.
If you're talking about a Berger 75 VLD, according to Quickload that combo is only 53337 PSI. Just at the upper edge of recomendable load. WAY milder than what he's loading.
Quickload is turning out to be a worthwhile investment. I was hesitant about spending the money but if it keeps me from having a rifle blow up in my face, its money well spent. And it allows me to play around with COAL and CBTO and know I'm in a decent range for velocity without wasting time and materials
Pressure is different discussion for a different thread because it has zero or next to zero to do with the CHS half way up the case. All this heehawing about his loads being too hot is only serving to clutter thread and obscure any attempt to help with the actual problem.
I have had CHS in 5 loads before. I had a chamber that would swallow a field gauge +.003, and I was bumping brass .008-.01.
Pressure matters . This OP's brass may still be in one piece if loaded at a lower pressure . Pressure may not be the culprit, but it sure helped find an issue .
Thought experiment: imagine that new cases are exactly chamber size in all dimensions. You load 'em up and shoot. Suppose your load is very hot - high pressure. The pressure will push forward on the chamber shoulder and back on the case head and stretch the chamber. At most shooting pressures, the brass is soft like butter so when the chamber under pressure gets longer, the case stretches a little, usually at the weakest spot somewhere in the middle of the case wall. When the pressure drops the case is forced back to "cold" size. That thin-crush cycle creates an unstable area in the case wall - kind of a crunched ring. If you fire that case several times the case will eventually fail at that ring.
Now take the same case and push the shoulder back ten thou. When the firing pin hits the primer it shoves the brass forward until the case shoulder hits the chamber shoulder then the primer fires and the powder flashes. The case walls grab onto the chamber walls but the pressure is also pushing the case base toward the bolt face. The base moves ten thou - the length that you bumped the shoulder. And that thin spot gets a lot thinner. When you size the case, you shove the base and shoulder back together - wrap a sheet of paper around a can, wrap your hands around ends of the can then push your hands together. The brass will behave a little like that. Note we didn't need to overcharge the ammo, just excessive shoulder bump. High pressure creates more stretch so makes it worse.
The point of minimal shoulder bump is to reduce the thin-crush cycle and, thereby, increase brass life. You can probably bump shoulders by fifteen thou and load them really hot - the military does something like that. But after one firing the brass is damaged. You have the evidence in your hand. Deep shoulder bump makes the brass tolerate a dirty environment better - more room for crud. Imagine you are getting shot at, I don't know about you but I'm not digging around for my brass so I don't care if I get only shot. But if that brass was expensive and you are picking it up and giving it tender loving care, minimize the shoulder bump. It will still fail eventually but you get to use it longer.
The max COAL for 85gr Berger is 2.542 in my chamber. I am loading to 2.535
I dont have the FB specs available right now for this barrel but will get it from the manufacturer. It is what they call the .223 Rem Match which does provide a longer FB over normal.
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I do spot check my cases as part of normal reloading. To be sure, i just checked my fresh fired cases in a case gauge and they fit fine in every way. I will check again for length once they are resized.
I agree, went for years without using a comparator. The first time I tried one, I never went back.
So a quick update... i received my comparator and took some measurements. I was really surprised at the results.
Lapua Cases for .223
new=1.413
fired=1.419
resized=1.408
IMI Cases for .223
fired=1.415
Bottom line is that with my resizing die configured to contact the case holder, headspace of the resized brass is shorter than fresh new brass. WOW! i would not have expected that.
I did an experiment and FL resize the LP brass to 1.419 and test fit in my chamber. There was slight resistance when closing the bolt and after removing my brass, i rechecked headspace and it read 1.417. I did not expect that so i repeated the experiment again and had the same results. So now i realize what the actual headspace of my chamber is.
Going forward, i am setting my headspace to .001 less than my chamber... which is 1.416.
This was a great exercise.
Lapua Cases for .223
new=1.413
fired=1.419
resized=1.408
IMI Cases for .223
fired=1.415
Bottom line is that with my resizing die configured to contact the case holder, headspace of the resized brass is shorter than fresh new brass. WOW! i would not have expected that.
I did an experiment and FL resize the LP brass to 1.419 and test fit in my chamber. There was slight resistance when closing the bolt and after removing my brass, i rechecked headspace and it read 1.417. I did not expect that so i repeated the experiment again and had the same results. So now i realize what the actual headspace of my chamber is.
Going forward, i am setting my headspace to .001 less than my chamber... which is 1.416.
This was a great exercise.
Gunny,
The SAAMI specs for 223 are not the best. They leave a 10 mil range for the chamber datum length, and the largest ammo may not fit the smallest chamber. For example, a 1.467 round will not clear a chamber at 1.464 without yielding, so brass and ammo tends to run shorter than the max to be on the safe side. As a result, it often has a long way to grow on factory chambers that may run as long as 1.474"
Just a suggestion.
If you like to run the sizer down against the shell holder to cam over, consider a set of these.
The SAAMI specs for 223 are not the best. They leave a 10 mil range for the chamber datum length, and the largest ammo may not fit the smallest chamber. For example, a 1.467 round will not clear a chamber at 1.464 without yielding, so brass and ammo tends to run shorter than the max to be on the safe side. As a result, it often has a long way to grow on factory chambers that may run as long as 1.474"
Just a suggestion.
If you like to run the sizer down against the shell holder to cam over, consider a set of these.
One problem with the Redding solution, you need a new set of shellholders for each case type.
This note is a variation on the competition shellholder idea:
Buy these shims. They cost $15 from Brownells.
Using your standard shellholder, set up your die so it contacts the shellholder. Lock the lock ring in place. Using a new Lapua case and your comparator, verify that headspace is 1.408 -- as above.
You fixed the lock ring on the die. Unscrew the die while keeping the lock ring fixed in position on the die. Position the .010 shim between the press and the lock ring, screw the die back into the press. Size another case. It should measure 1.418. That is, with the ten thou shim the case should be ten thou longer than without the shim and one thou shorter than the fired case length.
Suppose you want headspace to be two thou shorter than fired length, use a .009 shim or use a .004 and .005 shim. Want three thou shorter? Use the .008 shim. Less shim means more headspace.
Suppose that you are sizing IMI cases, find the right shim for IMI and use that.
If you anneal after each firing, the shim required to get a specific headspace will stay the same. If you don't anneal, the brass gets harder and you need a different setting in order to get the same headspace. This technique makes it easy to adjust in .001 increments without having to re-setup your die.
Things that can go wrong ... If you size a lot of cases, the die could work loose and the headspace will get longer. [solution: put a witness mark on the lock ring and on the press. While sizing, periodically check the marks. This problem exists whether or not you use shims] The lock ring gets loose, then there is no telling what happens to headspace. [solution: before each use, make sure the lock ring set screw is tight].
Those are the big issues. There are a few other things like getting lube on the shims or lock ring (lube has dimension), getting crud on the shims or lock ring, having two or more presses.
This works for me. Not every solution works for every person.
I was
I was just about to ask how old, or rather what round count your rifle has?
I have heard from others who “are” in the competition circuit (which I am not), that new barrels have lower pressure until the burrs and imperfections are smoothed away. And, that once broken in and smooth, your barrel will have built up some pressure from where it was new and rough, to where it is now smooth.
Assuming this is in fact true it could make sense that you have developed a load for this rifle or used a trusted load from other rifles that are on the hotter side of published charge weights, and based on the pressure signs you got when your barrel was brand new (lower pressure) all signs looked good and load seemed totally fine despite being a hot charge.
So you got your charge weight up there and they were probably fine at first, but now your seeing issues.
Just another element to look into or at least consider in your troubleshooting process. Definitely check head space and your brass sizing set up as well.
This is a new rifle with about 280 rounds through it.
Nice job OP. And some good posts above about the use of shims, etc from Bax.One comment
I will make here in general based on my (limited) experience with .223 + lapua brass. Consider to Aim for a shoulder bump of like 2 - 3 thou if you do field shooting as opposed to BR.
I don't want to side track your progress. Just remember your tools are only as accurate as the weak link, and anyhting using a caliper is only "within a thou, plus or minus a thou", its measured accurately...to the .001.
So if you gooing for .001 over min, you should really aim for .002 and you will get .001 to .003 with alot of them closer to .002 that either extreme. The key thing here is avoid a bunch of .000 from your likely distribution.
This is kind of a debate topic, and others have different views....but just want to at least raise the issue for consideration.
AFAIK...Lapua brass can handle a 2-3 thou bump and still give you great brass life.
Thanks... great advice!
Good job. Identified the problem and found a solution. I am like masmith. I like to lean closer to .003 than .001. I don't like tight clambering rounds or galled bolt lugs. Also in my experience when some chamber tight and some chamber smooth, they never seem to shoot well.
For what it's worth ...
Suppose the shoulder is annealed before sizing (as opposed to only annealing the neck). If you take a headspace measurement following sizing, the measurements have a smaller range.
With annealed shoulders, the range is usually plus or minus one thou - so, if the target is 2, you will see mostly 2 with a few 1 or 3.
If you do not anneal shoulders, the range will probably be plus or minus 2 (maybe a little more) so - if the target is 2, you will see a wider distribution - by the way, with more on the long side. I think this happens because the work-hardened brass deforms less so sizing may push it smaller but it springs back. Annealed brass permanently deforms more easily, work-hardened brass permanently deforms less easily.
Suppose the shoulder is annealed before sizing (as opposed to only annealing the neck). If you take a headspace measurement following sizing, the measurements have a smaller range.
With annealed shoulders, the range is usually plus or minus one thou - so, if the target is 2, you will see mostly 2 with a few 1 or 3.
If you do not anneal shoulders, the range will probably be plus or minus 2 (maybe a little more) so - if the target is 2, you will see a wider distribution - by the way, with more on the long side. I think this happens because the work-hardened brass deforms less so sizing may push it smaller but it springs back. Annealed brass permanently deforms more easily, work-hardened brass permanently deforms less easily.
