- Thread starter KCORBIN
- Start date
Your probably at least 10 grains of powder too little for the h50bmg powder... 125 seems very very low. 125 is a good place to start with Retumbo..
Whats the story on that brass? What rifle? Headspacing good?
Whats the story on that brass? What rifle? Headspacing good?
Screen shot his post, where he is getting .006 shoulder movement. A couple of times at .006 would explain the case head separation.
Could explain the flat primers too.
Screen shot below.
Didn't see that earlier post. Your right, that could do it.
This is not good.
And not easy to diagnose over the internet.
How far away from you is the gunsmith ?
He needs to check some new from box brass against the headspace.
.006 jump is excessive. The headspace could be off and the brass could be off. Or both.
Either way, both need checking b4 u go further.
And not easy to diagnose over the internet.
How far away from you is the gunsmith ?
He needs to check some new from box brass against the headspace.
.006 jump is excessive. The headspace could be off and the brass could be off. Or both.
Either way, both need checking b4 u go further.
The brass could also be brittle. If it's too hard, improperly heat treated, and too short, it could completely be you have bad brass.
If you took new brass and ran it through the sizing die b4 you loaded it the first time, to uniform the necks, it might be possible you set the shoulder back unknowingly.
I have done that with a bad die following the manufacturers instructions. Another if.
Would be nice if you had some other brand brass to try or compare the Peterson to.
Best I can offer right now.
If you took new brass and ran it through the sizing die b4 you loaded it the first time, to uniform the necks, it might be possible you set the shoulder back unknowingly.
I have done that with a bad die following the manufacturers instructions. Another if.
Would be nice if you had some other brand brass to try or compare the Peterson to.
Best I can offer right now.
Ok thanks for helping
I’ve got some Bertram I could try but the shoulders are even further back on it. It seems thick but can’t prove it.
This is even more not good. Gunsmith time.
But. Take bertram brass and Peterson brass. Weigh them. Compare weights.
Put a fired primer in backwards.
Then with a 223 or pistol BALL powder, fill the cases completely. Bump pack it, fill until even with the mouth.
Then weigh the powder charges. That's the poor mans way to quick compare inside dimensions to weights and get an idea.
But, best safest idea is gunsmith.
@KCORBIN where are you located?
Your chamber doesn’t look great. Lots of reamer lines. Case head separation is caused by excessive headspace. I have yet to find a case that it’s been caused by anything else.
125gr of H50bmg is way too low.
Finally, I haven’t went back and read from the last time I was in here but, what is the neck diameter of your chamber? Peterson is a good .0015” thicker than Bertram. If your reamer is set up for bertram
And you are running Peterson, you could have an interface fit that is causing problems.
I have also seen wet chambers, and excessively low charges case false over pressure signs too.
Your chamber doesn’t look great. Lots of reamer lines. Case head separation is caused by excessive headspace. I have yet to find a case that it’s been caused by anything else.
125gr of H50bmg is way too low.
Finally, I haven’t went back and read from the last time I was in here but, what is the neck diameter of your chamber? Peterson is a good .0015” thicker than Bertram. If your reamer is set up for bertram
And you are running Peterson, you could have an interface fit that is causing problems.
I have also seen wet chambers, and excessively low charges case false over pressure signs too.
i live in rural Illinois. The guns machine work was done in Texas by a company called Mirage ULR. I don’t know what reamer they used. I spoke with the owner and sent him the virgin brass with the barrel blank. they used it to test fire it and sent it back. There was a heavy reamer groove in the fired brass. I sent it back and said that it wasn’t right they ”fixed it”and sent it back. I’ve always been suspicious of the chamber dimensions.I’ve asked the owner and he states he use to do the machine work for cheytac. Maybe they used a special reamer at the inception of the company I don’t know. I could invest in some go no go gauges and check it? I’m thinking this might be time to tear the barrel off and buy a longer tube and a smith that has a lot of experience with this caliber. Big suck
Not necessarily. A long chamber can still be make to work
I’m in central WI if you want an outside set of eyes on it.
Maybe after the beer bug lol thank you!
I do have this question: do I have the right bore?
I have a barline barrel from bugholes. .366 bore 375 caliber. I’ve seen other manufactures offer a .368 bore 375 caliber. Maybe I screwed up and bought something designed for H&H like cartridges? I’m still confused on the velocity why it’s so low on a 33” barrel.
I have a barline barrel from bugholes. .366 bore 375 caliber. I’ve seen other manufactures offer a .368 bore 375 caliber. Maybe I screwed up and bought something designed for H&H like cartridges? I’m still confused on the velocity why it’s so low on a 33” barrel.
You have too much else going on to answer the velocity question.
If you had some OTHER loaded ammo, new brass, 129 grains of retumbo, and a 350 Sierra for a control.....
That is our testing load for all new barrelled 375 ct rifles.
You are trying to find a velocity load with a sick rifle. And you are wasting your time.
Geno is a very good idea. He has knowledge of blowing out shoulders from Cheytac to Snipetac, and not separating case heads. He knows how to find that problem.
But, you have a rifle problem, that until you solve it, you are wasting your time trying to find a velocity load. Time and expensive components.
Best to you, very respectfully.
If you had some OTHER loaded ammo, new brass, 129 grains of retumbo, and a 350 Sierra for a control.....
That is our testing load for all new barrelled 375 ct rifles.
You are trying to find a velocity load with a sick rifle. And you are wasting your time.
Geno is a very good idea. He has knowledge of blowing out shoulders from Cheytac to Snipetac, and not separating case heads. He knows how to find that problem.
But, you have a rifle problem, that until you solve it, you are wasting your time trying to find a velocity load. Time and expensive components.
Best to you, very respectfully.
When i spoke with Peterson's case designer at Shot this year he told me that when you are sizing their brass as long as the case still chambers you should not bump the shoulder at all. I am using the AB .375 ct dies and have only had 1 case separation and that was on it 7 firing. Since i have gone to a zero bump i have cases with 9 firings and show no sign of separating. I am running 131.5 gr of N570 shooting the 400 lazer which gets me 2951 avg fps with an sd of 7. I can get 4 sometimes 5 firings before i bump .001. The they chamber like new.
One last question before I tear the rifle down. I did the scotch tape and masking tape head space check on a unfired cartridge with the ejector removed and it closes with just slight bit of effort. While I know this is no substitute for a real gauge.
Is it safe to say the headspace is jacked? Sorry for beating a dead horse but I’m still in denial.
Is it safe to say the headspace is jacked? Sorry for beating a dead horse but I’m still in denial.
I've been running peterson brass for the 33XC and so far have no case head separations after about 7 shots in my load workup brass. Some were pretty hot too. I can't see any ring forming inside or out either so I'm thinking its not peterson brass.
A good friend has been using the peterson brass for his 375 Cheytac in his Desert Tech HTI using the original factory barrel and the longer barrel I made using a 36" bartlein blank. Some of his cases have 8 or 9 firings so far and never a ring or indication of incipient case head separation.
So I'm guessing there is something up with the chamber in your rifle. If the neck is tight you can get high pressure which will blow primers and if the headspace isn't right case head seps. It might be worth investing in , borrowing or taking your rifle to someone who has good headspace guages. It could save you some cash. It might be possible to set your barrel back and ream it with a known proper reamer to bring it back into spec. If the barrel is good other than the chamber it might be the most cost effective way.
If the barrel is really tight bore it can cause some of those issues as well and if thats the case toss it and start over.
Thats my thoughts.
Frank
A good friend has been using the peterson brass for his 375 Cheytac in his Desert Tech HTI using the original factory barrel and the longer barrel I made using a 36" bartlein blank. Some of his cases have 8 or 9 firings so far and never a ring or indication of incipient case head separation.
So I'm guessing there is something up with the chamber in your rifle. If the neck is tight you can get high pressure which will blow primers and if the headspace isn't right case head seps. It might be worth investing in , borrowing or taking your rifle to someone who has good headspace guages. It could save you some cash. It might be possible to set your barrel back and ream it with a known proper reamer to bring it back into spec. If the barrel is good other than the chamber it might be the most cost effective way.
If the barrel is really tight bore it can cause some of those issues as well and if thats the case toss it and start over.
Thats my thoughts.
Frank
Today, I went to pick up 375#2... pic
#2 did not come home......
I sent my reamer. And go-no go gauges. Life should have been good.
I carried two boxes of boolitz with me. Both boxes were new Bartram unfired brass, loaded with retumbo and 350 sierras.
To prep the brass, besides weight sort and debur the flash holes, I neck sized it to true the necks and deburred them.
Then I checked datum line and oal. And sorted accordingly. And loaded select groups of all same same from new.
Now, good readers, these rounds fit just perfect in 375#1, and shoot ohhh so good.
Put #2 in vice and check rounds. Houston, we have a problem. 2% chambered fine. 96% chambered snug snug. 2% would have required seriously forcing the bolt.....
Each of these rounds were hand cycled through #1, with absolutely zero problem...
(Did jw say bad words, was he calm and collected, how did jw act ?)
There was a WTF moment and some discussion. Gunsmith took out his brass, new in the box and every single round chambered like a champ.
Like mine chamber like a champ in #1....
Gunsmiths brass is new peterson.
Mine is bartram. Obviously his is much smaller than mine. Ok, I can handle this.
Questioning further, since my reamer was cut off fired brass from #1, because I dont know Dave Viers reamer specs, and my dies were cut with Dave's reamers....
Fired brass from #1, resized brass fired in #1, resized in Dave's cut dies, and new bartram brass created my reamer.
This is a serious WTF moment. I'm like no f'ing way.....
A tiny bit further discussion. Tiny bit. Gunsmith cut the chamber with HIS reamer, not mine.
So, my options became.
375#1 eats bartram brass and gets resized with Dave's dies.
375#2 has to have Peterson brass AND new dies to with with HIS reamer dimensions. Gotta buy a bunch of stuff and start all over...
No f'ing way !!!!!
Hes going to re-pop the chamber with MY reamer.......
Will go back for #2 next weekend if the predicted bad weather this Sunday doesnt tornado me....
And, with calipers in hand, I'm going to seriously measure his Peterson brass and my bartram AND Jamison brass.....
Will record those numbers.
And at some point order some Peterson brass, and at some point, have reamer drawings of mine and his, and any other 375 reamer drawing I can find.
Hopefully this novelette will offer some insights to the readers who might have run into similar problems as OP KC.
This experience does not bother me, it's not the first one like it that I have had, BTDT in 308, 30.06, and 300wm.
Will report in as stuff happens.
Best to yall, vr
#2 did not come home......
I sent my reamer. And go-no go gauges. Life should have been good.
I carried two boxes of boolitz with me. Both boxes were new Bartram unfired brass, loaded with retumbo and 350 sierras.
To prep the brass, besides weight sort and debur the flash holes, I neck sized it to true the necks and deburred them.
Then I checked datum line and oal. And sorted accordingly. And loaded select groups of all same same from new.
Now, good readers, these rounds fit just perfect in 375#1, and shoot ohhh so good.
Put #2 in vice and check rounds. Houston, we have a problem. 2% chambered fine. 96% chambered snug snug. 2% would have required seriously forcing the bolt.....
Each of these rounds were hand cycled through #1, with absolutely zero problem...
(Did jw say bad words, was he calm and collected, how did jw act ?)
There was a WTF moment and some discussion. Gunsmith took out his brass, new in the box and every single round chambered like a champ.
Like mine chamber like a champ in #1....
Gunsmiths brass is new peterson.
Mine is bartram. Obviously his is much smaller than mine. Ok, I can handle this.
Questioning further, since my reamer was cut off fired brass from #1, because I dont know Dave Viers reamer specs, and my dies were cut with Dave's reamers....
Fired brass from #1, resized brass fired in #1, resized in Dave's cut dies, and new bartram brass created my reamer.
This is a serious WTF moment. I'm like no f'ing way.....
A tiny bit further discussion. Tiny bit. Gunsmith cut the chamber with HIS reamer, not mine.
So, my options became.
375#1 eats bartram brass and gets resized with Dave's dies.
375#2 has to have Peterson brass AND new dies to with with HIS reamer dimensions. Gotta buy a bunch of stuff and start all over...
No f'ing way !!!!!
Hes going to re-pop the chamber with MY reamer.......
Will go back for #2 next weekend if the predicted bad weather this Sunday doesnt tornado me....
And, with calipers in hand, I'm going to seriously measure his Peterson brass and my bartram AND Jamison brass.....
Will record those numbers.
And at some point order some Peterson brass, and at some point, have reamer drawings of mine and his, and any other 375 reamer drawing I can find.
Hopefully this novelette will offer some insights to the readers who might have run into similar problems as OP KC.
This experience does not bother me, it's not the first one like it that I have had, BTDT in 308, 30.06, and 300wm.
Will report in as stuff happens.
Best to yall, vr
[
Please dont take this wrong but I have had to do this before as well but I think you need to step back and look at your own practices before you tear down the rifle, I have heard nothiing but good things about Mirage and I bet the rifle is right . Check your own self and tools such as powder scale calibration ,check your headspace with masking tape, the bolt should not close forceably with one layer of standard masking tape, scotch tape is most likely thinner so use masking tape. Your first cases were under severe pressure and enough to fry them if you blew primers on them so use a 90 degree scribe and right where you saw the separation of the cases see if you feel a groove inside of the other cases that have been shot with your H1000 which was way over pressured so the cases that were shot with H1000 are most likely fried if they have grooves down inside near the base so they will separate on the next firing as a result of previous over pressure. Loading the H50 way below minimum charges can blow the bolt out the back of the gun.Also get some ioso gun bore polish and scrub the throat area real good to get rid of a carbon doughnut that can form really bad when case head separations or primers blow causing a rapid pressure drop. The H50 min load should normally been matched to RL 50 as they are almost identical burn rates . By under loading you can increase bolt force from 5000 lbs normal working pressure to 30, 000 psi or more in an instant and sheer the lugs off of the bolt. The reason being the case has to stick to the side wall of the chamber and only then is the bolt force reduced on the bolt to safe pressure with the majority of the chamber pressure held by the chamber walls it self.. If the case does not have enough pressure to stick to the chamber then the pressure has to go rearward against the bolt. Be safe and good luck
TiminTx
ok yeah I’ll go along with that. Just to give you an idea of what I’ve ive got and use: I’m using a charge master to throw and double check each load with an A&D fx120i. I’ve measure all Peterson brass using whidden shoulder bump gauge. All measure 2.540 from the shoulder to bass virgin cases. (Peterson has outstanding quality control FYI) Bertram is a different story 2.547-2.552 yes all over the place. I’ve sorted each piece. Masking tape method mine I have here measures .004 and I’ve got some scotch tape that measures .001. I can close @.005 and 2oclock lock at .008. Not an exact science but head space gauges are 6 weeks out from PTG. Back to todays work-Using the 2.549 (tightest on bolt closer) Bertram starting fresh giving the head space the benefit after firing shrinks to 2.546 under a load of H50 @115gr. .020 jump. Primers flat slightly and famous ring of starting to separate. I think the problem is with the cartridge is not standardized and people cut chamber and throats to what works best for them. Maybe that’s why Desert tech sells the ammo to go with the gun......
alright, we have a problem here. A snug close is one a headspace that is .009” longer than the great consistent Peterson brass. Your brass is screwed after the first firing.
Next, why on earth are you using a load of 115gr of H50?? That’s about 25gr below where you should be. Flat primes happen all the time with loads that are way too low.
How is your bolt lift resistance?
Next, why on earth are you using a load of 115gr of H50?? That’s about 25gr below where you should be. Flat primes happen all the time with loads that are way too low.
How is your bolt lift resistance?
I tried sending the Peterson brass with my barrel I feel like they will be around a little while and what I’ve read the Bertram brass is outside the US, supply could have been an issue. Just my reasoning. PTG makes a 9.5 x 77 reamer labeled Peterson. I would have to call and find out if it’s the same. Just not label Cheytac?
No this is on the Bertram brass I found a couple pieces that were at 2.549 and 2.550 they were tight on bolt closing taking the headspace up so I would not blow the shoulders any more forward on the smaller pieces of brass. FYI I checked this with the ejector out also. I’m thinking g the chamber is over bored and that’s why the brass shrinks to 2.546 after firing and I get a separation line. Bolt lift was good primers were less flat than what I’ve seen in the past charges. The Bertram brass didn’t show any ejector marks or extractor marks. The brass feels a little more heavy duty than Peterson but that’s purely an opinion.
Bartram is Australian. Rgr.
I have a "good" lot, and am aware the run after mine was pretty shitty.......
And, it sounds like you got in the run after mine. Sounds very much like it.
Now. Just fyi.
I had a 338Xtreme, and David Viers made a 338 snipetac.
Both can be formed by blowing out 375 cheytac brass, after it is necked to 338.
The amount of shoulder and body movement is pretty extreme.
Making a 375 Ackley type like the 338 edge is absolutely no problem blowing out shoulders.
Because you can do this with very relative ease, is what is making your experience a head scratcher. Blowing a shoulder out into a mercenary is same same.
You ABSOLUTELY should not be having this problem. If, and big if, your chamber is correct.
I've gotten with two of the gunsmiths I have used and we read your posts.
Now, up front, Mirage has a solid reputation and has put out some good rifles. Absolutely.
You said, the brass had a very "heavy reamer groove" on it when you first got it.
You said you sent it back and Mirage said, "This is wrong, we fix", and did something and returned it, repaired. (This is my paraphrase rather than your exact words.)
Geno pointed out the marks on your brass. This goes along with what you said about the heavy score mark.
My two gunsmiths looked at the pics, both believe removing the heavy score mark opened up the chamber too big and created the excess headspace you describe. It fits with several of our experiences.
A 'cerro-safe' chamber casting would give absolute proof. But, several of us with a bore scope could pretty much tell you the same thing along with your damaged brass.
The rifle, your damaged brass, and your dies need to go back to Mirage. They could easily trouble shoot your rifle and fix it. That is solution one. They would appreciate the opportunity to help you solve this problem and assure you and others of the quality of their service.
That would be my next move.
Again, very best to you.
Just for my curiosity,
What is the width at the body shoulder junction?
What is the width at the body shoulder junction?
.410 - .409 fired Pe
.403 virgin
I use neck bushings .402 Peterson
And .396 for Bertram
no fired measurement Bertram
I had to use the rounds that had the case head sep because I resized everything checking primers
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Here is a picture of the test fired brass that was returned to me . The pick is pointing to it. It was defined enough to where you could feel it. Like a hair was wrapped around it. Normally don’t get wound up about a damaged piece of brass but my concern was that when I got the rifle originally I put an empty unfired case in because I was told my action that was brand new from Stiller had a used extractor in it. Needless to say the extractor was bent and would not extract the empty unfired case. Feeling less than thrilled thinking that the case was fire forming to the chamber and bending the extractor when they extracted the spent round. (Rusty pitted chamber in service rifles have the same problem.) it was sent back they repaired it. Here we are today. Third times a charm? I’m all about second chances. And by all means I hate to be “that guy”. Lord knows the internet is full of them. Do I ask for them to short chamber it or cut my loses. I’m trying to stick to the facts with out bad mouthing a company. Everyone has a bad Monday.
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Been where you are, at least once. If there is any way u could go see Geno. No doubt in my mind you would know your next step b4 you parted company with him.
Any competent riflesmith with rifle in hand could find the problem in a very short time. As I said in an earlier post, you have a sick rifle, and will add, it needs a very good doctor.
bty, vr
That’s a chip weld. A chip welded itself to the reamer while they were chambering. As ugly as it is; it is not your problem
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