That’s why I like a .40S&W case. It acts like a blade against the shoulder of the case. All the Hornady comparators suck.
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Hornady brass explosion
- Thread starter Pilotscrappy
- Start date
I don’t think it matters what you use, but comparing numbers will always be a general thing unless everyone is using the same tool. A sized vs fired 40s&w case will give very different readings, as you know.
Edit: My only gripe with the hornady tool is they’re not made out of steel.
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The datum on a creedmoor case is at .400. You’re using a smaller diameter comparator, which is why your headspace numbers appear long. That doesn’t mean your cases are long.
The standard hornady set
A creedmoor go gauge with a .400 comparator
Same gauge with a .375 comparator.
That’s the problem. Due to the length of the comparator you’ll get misalignment between it and the case. You will get different readings every time you measure.
Yeah, just checked and it is the .375. I didn't know there were different ones.
What's the purpose of making a .375 and a .400?
Just to accommodate different cartridges. Hornady actually recommends the .375 for the creedmoor, which is a little strange.
Same
A quick spin and it aligns itself nicely.
That’s exactly what I do.
I wonder if 918v wasn’t closing the caliper jaws on the comparator to square everything before he tightened the screw?
I’ve only seen case head separations from a few situations.
1-gross headspace on first shot(two milsurp rifles come to mind)
2-a big growth on first shot(many factory chambers) and then reloading that brass a few times with a moderate set back. Usually 4-7 loadings.
3-grossly over sizing every time about the same 4-7 loadings.
I personally compare my go gauge to the brass I’m using to make sure they jive.
I then set my chamber to allow no more than .002 of growth on the first shot.
I then never size the brass over .002.
I have a set of 200 Winchester cases that have killed two 260 barrels and are now starting a third.
a good start and moderate sizing with realistic loads makes brass last a long time.
1-gross headspace on first shot(two milsurp rifles come to mind)
2-a big growth on first shot(many factory chambers) and then reloading that brass a few times with a moderate set back. Usually 4-7 loadings.
3-grossly over sizing every time about the same 4-7 loadings.
I personally compare my go gauge to the brass I’m using to make sure they jive.
I then set my chamber to allow no more than .002 of growth on the first shot.
I then never size the brass over .002.
I have a set of 200 Winchester cases that have killed two 260 barrels and are now starting a third.
a good start and moderate sizing with realistic loads makes brass last a long time.
If you have some new brass left from the same lot you can just neck size and shoot for 3-5 times to see if the issue is with your resizing or measuring.
Unfortunately I didn't measure the brass before I fired it.
I will definitely get this measurement next time I get some new brass
I have to wonder how you check saami specs with a comparator. The shoulder is based on a reference line and each person has a different reading according to his collets. I try to get close to the datum line, but it is arbitrary for each fire-formed chamber to die formed brass. As far as I know, you have to compare the fired and formed brass on the same comparator and check the difference to get head space A case gage can give you an idea of saami spec length to shoulder.
First of all, I would like to have the source of this study to know who did it and to see their credentials and data for arriving at this conclusion. I don't know what headspace you use, but I strive for .001". Because of this, I size for each rifle. Even if they start out at the same headspace, after some amount of rounds, chamber length will change slightly. Once I discovered salt bath annealing and built a PID controlled annealer that maintains the temp within less than one degree of set point, there was no other choice for me. Annealing the neck and shoulder of a case does two things, it helps prevent neck splits, and it softens the shoulder to lessen springback. Without this process, you cannot hold the tolerances that I have become used to. Please forward the study on salt bath annealing as soon as possible as I am anxious to find the error of my ways.
I suppose you dont really measure it rather than compare it to something that is saami spec. case guages, go guages, and such. or create your own saami spec case.
I sometimes check my comparator against my go gauges and then against a fire formed case. A little math gives a good reference to saami. This also works with factory loads and fresh brass. I size my brass to - .001" compared to the fire formed case. I seldom need a true saami comparison, because I set the headspace on the barrels with a saami go/no go gauge. There are several thousandths of tolerance there and I load closer than that. Look at a saami spec drawing and notice what the tolerance is on the chamber and cartridge dimensions and figure the worst case cumulative error. That's why you load to the gun and not the spec for accuracy. Repeatability is the name of the game.
I am well aware of what annealing does. It is not the subject of the thread. A simple google search of "salt bath annealing does not work" is all you need to do.
The subject was Hornady brass separation. It is caused by case stretch because of sizing the shoulder too far back. Annealing, salt bath in my case, allows for an accurate sizing without spring back. Only a few years ago I thought all you had to do was push the shell holder up to the die and tighten it down till you got a good cam over. I hadn't heard of a comparator. A lot of things such as jump, more accurate powder scales, better bullets, better quality control etc, ad nauseum. A lot of "unnecessary" things have been added to reloading, but many people don't consider it necessary. That's why they have primitive weapon's hunts. As for me, I think I will keep advancing when I feel it's worthwhile.
Another question guys, I just ran the bore scope down my chamber and it appears i have a carbon ring in their. It doesnt look like its out of control yet but there is defintely a ring forming inside. Could this have possibly casued the brass to fail? Weird thing is if the carbon ring did cause a huge pressure spike wouldnt it have blown the primer out or at least showed signs on the primer or pressure?
Here are some pics of the chamber i just scoped.
Here are some pics of the chamber i just scoped.
Also, i had some once fired brass set to the side and i just chambered it and it chambers with ease. So should i just neck size it and not use the full length for a couple firings?
Numbers even when using two D .400" Hornady inserts will not be the same. The inserts have a chamfer on the inner edge. That chamfer can vary a bit. I have two D .400"inserts. One will measure a 1.630" 308 headspace gauge @ 1.622" (.008"chamfer) the other measures @ 1.611" (.019" chamfer).
They are both accurately measuring the 1.630" 308 Go gauge, but the numbers are different.
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Bingo... Your brass sprung back after stretching all the way on the first firing and you bumped it back again when you reloaded it. Always check the brass safer the first firing to see if it Chambers easily. If it does you don't want to push the shoulder back any until after the second firing.
Do you have access to hs guages?
D
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Doesn't matter which comparator he is using as long as he uses the same one.
I agree, which is why I go all batty when people are worrying about specs and numbers matching.
Very much doubt that the chamber is off, but worth checking anyway.
1.537” on the Hornady 400 comparator: So i have exactly the same dimension for my fire formed brass from my MPA in 6.5 CM. [Of course your gauge can be expected to be slightly different from mine.]
MPA cuts a “match chamber” (see section in your manual), and their reamer has tighter dimensions than the typical standard SAAMI reamer. Fire formed brass from my Remington or Savage does not fit in the MPA.
I bump the shoulders 0.002”. Never had a head seperation, touch wood, but i am very careful how i fire form the brass the first time: Load a cheap soft lead core bullet long with max neck tension and make sure it has a hard jam, so the ejector pin is pushed back into the bolt. Some folks remove the ejector pin. Round will be hard to close due to the hard jam. Reduce powder charge at least 2 grains to prevent a pressure spike in 6.5 CM, but don’t load too low either. [Other larger calibers will need a bigger reduction.]
May i suggest that you unload all the unfired cases, and then cut one or two cases through the middle (section it longitudinally), and check for a thinning ring in the brass on the inside close to the web. If a reloaded case that has not been fired in this batch already had weakness (thinning) close to the web, then it is likely cumulative damamge incurred over multiple firings due to over sizing. Most common reason is usually bumping the shoulder way too much each time, or the first time the case was fired (presume from factory ammo?), the case was very short, and headspace was way too much. Btw: When i started using the AMP annealer, which makes the neck shoulder junction softer, i had to adjust my FL sizer die. Previously used gas flame annealing.
Something is likely off on your measurements. Recheck everything. Try to get good calipers, i-gauging or Mitutoyo makes good ones. Remove primers.
And start with a new batch of brass. I know a lot of folks who shoot really well with Hornady brass, and i don’t mean to offend anybody, but Lapua brass is stronger. Of course, then you need to deal with the complication of small rifle primers and a small flash hole. [Folks joke that you can “drive Lapua like you stole it”... and they do have a point.] Of course, excessive head spacing can cause Lapua or any other make of brass to suffer head separation too.
If your original batch of virgin never fired Hornady brass was very short, it would also explain the head separation. The first time you fire form virgin brass, it is crucial to do it right.
If you have a bad (well developed) carbon ring that is severely pinching the bullet, pressures could spike a lot, enough to cause the big increase in recoil you reported, and of course over pressure the case.
Best advice is to stop shooting the rifle and ask a gunsmith with a high quality borescope to inspect it. Also inspect the action. He can check headspace with a go and a no-go guage while you are at it, just to be on the safe side.
Let us know how you resolve the issue. Always eager to learn.
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Thanks for this reply, I'm thinking I totally have been overworking the brass since I have been full length sizing after every firing and clearly it's been springing back.
I do not have headspace gauges but I live in Southern Oregon, I'm minutes away from pacific tool and gauge, I think I'll stop by and see if I can snag a couple gauges. I have been meaning to pick some up anyways.
I'm using the d400 hornady Comperator, luckily it's the only one I have, so my measurements are consistent.
Does all your once fired measure exactly the same?
Still curious as to what measurements you get after checking the actual headspace as described in the video and posts above.
Ive had good luck reloadung my Hornady American gunner brass. It starts out only .001 under.
You really just need a go guage and some scotch tape. I think your chamber might be closer to the long side which is fine you just need to be aware that your brass won't be fully fire formed to your chamber until after the second firing.
What kind of dies are you using?
You just need to set your sizer up to just size the neck and body on the 1st firing. After the second firing if the brass is tough to close on a fired case, you are set to screw the die in a tad more to bump the shoulder in a thou or two
Do yourself a favor and get any headspace gauge other than PTG.
Manson, or Forster are more likely to actually be in-spec. PTG QA has been ass for a while now.
Just a point of clarification, there is no issue with full length sizing every time. How you use the FL die is what’s important. It’s this very thing that brought about the “you must neck size only for accuracy and brass life” wives tale that just won’t die.
Maybe that’s what you meant, but just want to be sure you’re not drawing the wrong conclusion.
One other technique that works well is to remove the striker from your bolt, leave the ejector in, and test fit cases. The ejector pushes off the case head creating space between it and the bolt face. Now just thrust the bolt forward. Very easy to tell if you have space. .001 is easily discernible, and .005 feels like a mile.
I have a few observations and welcome corrections to poor judgement, thick skin.
I'll base these on 308 and 223 since my grendel is new and 300 blk subs are different from normal.
#1 factory rounds for 223 and 308 routinely run 0.006 - 0.008 below go gauge dimensions.
#2 those rounds normally measure within 0.0005 of go gauge on first firing. No matter the brand.
#3 I have measured all my family's chambers and hundreds of clean range brass from unknown guns. It's all the same with a few exceptions that get culled.
Observations:
Brass grows full chamber first shot in a clean gun every gun I have measured.
Not necessarily neck length.
Running virgin brass, sizing it will probably only set neck tension as you wish since everything I get is short in the shoulder, and damn sure check trim length.
My pos hornady comparitor set is within 0.0005 in 4 different gauge sizes using go gauge dimensions. Lucky me, I've been told.
Any manufacturer can have a bad lott of brass / ammo get out. The lott#'s of that hornady brass probably match and if they do should be reported.
I'll base these on 308 and 223 since my grendel is new and 300 blk subs are different from normal.
#1 factory rounds for 223 and 308 routinely run 0.006 - 0.008 below go gauge dimensions.
#2 those rounds normally measure within 0.0005 of go gauge on first firing. No matter the brand.
#3 I have measured all my family's chambers and hundreds of clean range brass from unknown guns. It's all the same with a few exceptions that get culled.
Observations:
Brass grows full chamber first shot in a clean gun every gun I have measured.
Not necessarily neck length.
Running virgin brass, sizing it will probably only set neck tension as you wish since everything I get is short in the shoulder, and damn sure check trim length.
My pos hornady comparitor set is within 0.0005 in 4 different gauge sizes using go gauge dimensions. Lucky me, I've been told.
Any manufacturer can have a bad lott of brass / ammo get out. The lott#'s of that hornady brass probably match and if they do should be reported.
perfect...for that once fired brass that has not been resized, write down what the average of a few are with your HS comparator and then screw your die in but dont screw it in to touch the shell holder. Leave a small gap. I would start with a gap that a dime would fit in.
Size a piece of brass and see if it pushed your shoulder back...It shouldn't. Then check if it squeezed the neck down to accept a bullet. If it did great your done size the rest of your once fired brass and go shoot again.
On the next firing if the 2nd fired brass struggles to close, screw your die in a tad at a time until you only push the shoulder back one thou and then check to see if it chambers easily. If it doesn't screw the die in a tad more and recheck. I like my brass to chamber freely so it ends up being for most of my rifles 2 thou bump with my sizer.
This is a weak point for me. I use the ghetto socket in the drill method. And on this lot of brass that failed I didn't use tempilaq.
I turned lights real low and stopped when they just started to glow. I know it's far from the correct way,I just haven't been able to get a annealer yet. I annealed them on the 3rd firing (4th loading of brass) . The brass just failed was on the 6th firing ,I just checked my notes.
OP: I just reread your original post, and worry about your observation that recoil was 2x higher than normal. Indicate high pressure. A typical instance of head separation will not do that.
Worth rechecking the trim length as well, as stated before. If the brass grew too long, the neck will get pinched as the bolt closes, even if there is only a minor carbon ring, or no carbon ring, as effectively the end of the chamber is now crimping the round (hard), pinching the bullet, and pressure can spike very significantly. That will bump up speed and recoil a lot.
Scrub out that carbon ring (whether real or not, it is worth being sure that issue is not present).
Get a good gunsmith to inspect the rifle. Money well spent in this scenario.
Also, in my experience, the MPA chamber is tight and my max load has come down by 1.3 plus grains compared to the Savage LRP with the Shilen barrel. Max speed is down by 60-70 fps. Accuracy is way up.
Presume you did not measure speed while firing these rounds? MagnetoSpeed is cheap and accurate. Worth getting one. That would have been definitive proof of high pressure.
Worth rechecking the trim length as well, as stated before. If the brass grew too long, the neck will get pinched as the bolt closes, even if there is only a minor carbon ring, or no carbon ring, as effectively the end of the chamber is now crimping the round (hard), pinching the bullet, and pressure can spike very significantly. That will bump up speed and recoil a lot.
Scrub out that carbon ring (whether real or not, it is worth being sure that issue is not present).
Get a good gunsmith to inspect the rifle. Money well spent in this scenario.
Also, in my experience, the MPA chamber is tight and my max load has come down by 1.3 plus grains compared to the Savage LRP with the Shilen barrel. Max speed is down by 60-70 fps. Accuracy is way up.
Presume you did not measure speed while firing these rounds? MagnetoSpeed is cheap and accurate. Worth getting one. That would have been definitive proof of high pressure.
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I have recived virgin brass that was not trimmed or trimmed properly.
At least 2 brands.
I run virgin brass through my entire process including a brief tumble to deposit some wax on the case.
Evidently the phrase (fully prepped) used by manufacturers is subjective.
If the brass is sized gtg then it doesn't work it any if not it needed it.
At least 2 brands.
I run virgin brass through my entire process including a brief tumble to deposit some wax on the case.
Evidently the phrase (fully prepped) used by manufacturers is subjective.
If the brass is sized gtg then it doesn't work it any if not it needed it.
Just a stupid question. Are you measuring your shoulder length with a fired primer in the case? This can lead to false readings due to primer cratering. You should be measuring a deprimed fired case. See if that gives you any better numbers (consistent).
