Brass pressure problems in Mauser build

[vzerone]

This----^

High pressure is evidenced by the speed the load chronographed at and the neck of the cartridge is coned in as if it had formed against the leade. As the go/no go gauges have no case neck, they wouldn't have picked this up. Perhaps the reamer was of the sort that needs following up with a throating reamer to machine truly custom chambers?

Out of curiosity, what does the neck of a loaded hornady round measure?

If it was catching the end of the chamber, in other words the case is too long, he's have LOTS of pressure because the case mouth wouldn't expand enough to release the bullet and the feel there would be a more obvious ring around the case mouth. But his cases are the right length and he used the headspace gages to measure when he reamed the chamber so it has to be the right length too.

[swheeler]

This----^

High pressure is evidenced by the speed the load chronographed at and the neck of the cartridge is coned in as if it had formed against the leade. As the go/no go gauges have no case neck, they wouldn't have picked this up. Perhaps the reamer was of the sort that needs following up with a throating reamer to machine truly custom chambers?

Out of curiosity, what does the neck of a loaded hornady round measure?

Should be easy enough to tell, size about 1/16th of the neck, insert a flat based bullet backwards(nose inside the neck) and seat it with the bolt then carefully withdraw the dummy from the chamber. Or you can buy a chamber length button from many places including NOE, might have to sacrifice a case though. Anything is possible but remember not too many years ago the starting load from Alliant with 250 grain was 54.0 grs. of RL15. I know, I know new ways of testing chamber pressure, blah-blah-blah, mostly I just think new attorneys! AND WE ALL LOVE ATTORNEYS

[vzerone]

If he flared the case mouth on empty case and chambered easy and slow he could tell if it catches the end of the chamber. Most chamber ends (right in front of where the case mouth set...I know you trim your cases shorter) have an abrupt shoulder. The 6.5 Japs don't as those buggers go right into the throad and then leade in. I sectioned a chamber on a take off barrel and was shocked to see that. Then I examined more 6.5 Japs and they were the same. Don't have to worry about case length LOL

As said his cases are the correct length so I don't think that is it.

I think he needs to bump up his load swheeler, believe you mentioned that too.

[kfd518]

This----^

High pressure is evidenced by the speed the load chronographed at and the neck of the cartridge is coned in as if it had formed against the leade. As the go/no go gauges have no case neck, they wouldn't have picked this up. Perhaps the reamer was of the sort that needs following up with a throating reamer to machine truly custom chambers?

Out of curiosity, what does the neck of a loaded hornady round measure?

I don't have one available at the moment but I did identify a substantial taper crimp on the hornady rounds. When I posted this originally I didn't recall that much crimp. I need to cast the chamber before I go back to load testing. But elk ridge states on their web page that it is a Saami spec. 35 whelen finish reamer.

https://www.reamerrentals.com/Produc...tCode=35Wh%2Ef

[kfd518]

Should be easy enough to tell, size about 1/16th of the neck, insert a flat based bullet backwards(nose inside the neck) and seat it with the bolt then carefully withdraw the dummy from the chamber. Or you can buy a chamber length button from many places including NOE, might have to sacrifice a case though. Anything is possible but remember not too many years ago the starting load from Alliant with 250 grain was 54.0 grs. of RL15. I know, I know new ways of testing chamber pressure, blah-blah-blah, mostly I just think new attorneys! AND WE ALL LOVE ATTORNEYS

They didn't seem to like it when I questioned a change of ownership at close to the time of the data being changed!

[kfd518]

If he flared the case mouth on empty case and chambered easy and slow he could tell if it catches the end of the chamber. Most chamber ends (right in front of where the case mouth set...I know you trim your cases shorter) have an abrupt shoulder. The 6.5 Japs don't as those buggers go right into the throad and then leade in. I sectioned a chamber on a take off barrel and was shocked to see that. Then I examined more 6.5 Japs and they were the same. Don't have to worry about case length LOL

As said his cases are the correct length so I don't think that is it.

I think he needs to bump up his load swheeler, believe you mentioned that too.

the Saami whelen drawing below shows a tapered chamber end I will tell you by feeling with a long chisel edged matchstick that I can feel this taper. There are no sharp stops in that chamber.

I plan to go back to the 52 gr load as a starting point when I get back to load development.

[vzerone]

the Saami whelen drawing below shows a tapered chamber end I will tell you by feeling with a long chisel edged matchstick that I can feel this taper. There are no sharp stops in that chamber.

I plan to go back to the 52 gr load as a starting point when I get back to load development.

Most, not all, bottleneck cartridge chambers have a tapered neck. That's normal. Military calibers definately do. Don't believe that has anything to do with your problem. You should at least load one or two rounds up with a new bumped up load and test them first before going to the trouble to do a chamber cast. If you use Cerosafe you have to mic it within a certain time period. A pound cast you don't.

[runfiverun]

48.5 grs of RL-19 and a 250gr bullet gives me about the same velocity [2325 or so] as your getting.
only I'm using a 358 win and a cast bullet.

the reason I mention the case mouth catching is I am thinking your driving the round forward with the firing pin.
it's basically stopping about when the ejector grabs it,,,, but... that's also when it's hitting the end of the chamber.

[kfd518]

This----^

High pressure is evidenced by the speed the load chronographed at and the neck of the cartridge is coned in as if it had formed against the leade. As the go/no go gauges have no case neck, they wouldn't have picked this up. Perhaps the reamer was of the sort that needs following up with a throating reamer to machine truly custom chambers?

Out of curiosity, what does the neck of a loaded hornady round measure?

.3760

In doing more research and measuring the hornady brass head to shoulder length fired vs unfired is the same length within .0005
Neck length grows approx .0040 but is still within max length @ 2.4935

Those re formed that were sized in full length lee sizer have not had the shoulder touched at all. This as well as being freshly anealed I believe may be allowing the forward movement either from primer pressure or firing pin strike. The formed cases before firing are 1.9775 to the shoulder. The fired are 1.9660 to the shoulder

Bushing size used to measure is .420

[kfd518]

Most, not all, bottleneck cartridge chambers have a tapered neck. That's normal. Military calibers definately do. Don't believe that has anything to do with your problem. You should at least load one or two rounds up with a new bumped up load and test them first before going to the trouble to do a chamber cast. If you use Cerosafe you have to mic it within a certain time period. A pound cast you don't.

My reference wasn't to the neck itself but the end of the chambe showing a 30* angle instead of a 90* at the end of the chamber.

Belled case mouth brass a.390 trimmed to 2.494 gives no sign of increased resistance closing the bolt.

[vzerone]

There's nothing wrong with that 30 degree angle. Eventually a 90 degree angle is going to get rounded from powder erosion.
Do you think that maybe your firing pin spring is a little too strong? Most military rifles have strong firing pin springs. I believe you said your action is a Mauser...military Mauser?

[swheeler]

Measure the 00 52.0 gr case for shoulder position after firing, is it set back .011" like the rest, the picture of it looks like a flush seated primer after firing? What about the Hornady ammo, shoulder would be farther forward I'd guess after firing(since the ammo will be sized to min spec to fit all chambers). If you have a die with .375 expander run 5 cases through it to create a false shoulder, size just enough in your 35 Whelen dies to get the bolt to close with a slight interference fit, load at 49-50-51-52-53, fire and measure location of shoulder again, 53 stayed where it should be?
I believe the 98 mauser was supposed to have an 18-19 pound mainspring, All mine are 22# Wolfe(including the Whelen) except one 308 that has a 30# and you can tell it when you lift the handle to cock.

[swheeler]

48.5 grs of RL-19 and a 250gr bullet gives me about the same velocity [2325 or so] as your getting.
only I'm using a 358 win and a cast bullet.

the reason I mention the case mouth catching is I am thinking your driving the round forward with the firing pin.
it's basically stopping about when the ejector grabs it,,,, but... that's also when it's hitting the end of the chamber.

The ejector doesn't grab anything, it pushes on the case head the last 1/16" of bolt travel to the rear.

[swheeler]

I don't remember if it has been mentioned above but use you calipers as a depth gauge and measure pin protrusion, .060" should be fine.

[kfd518]

Measure the 00 52.0 gr case for shoulder position after firing, is it set back .011" like the rest, the picture of it looks like a flush seated primer after firing? What about the Hornady ammo, shoulder would be farther forward I'd guess after firing(since the ammo will be sized to min spec to fit all chambers). If you have a die with .375 expander run 5 cases through it to create a false shoulder, size just enough in your 35 Whelen dies to get the bolt to close with a slight interference fit, load at 49-50-51-52-53, fire and measure location of shoulder again, 53 stayed where it should be?
I believe the 98 mauser was supposed to have an 18-19 pound mainspring, All mine are 22# Wolfe(including the Whelen) except one 308 that has a 30# and you can tell it when you lift the handle to cock.

Well I reloaded at 52 gr and at the request of another lightly oiled the cartridge before firing. Results were a case of my previous lot after firing shoulder to head length of 1.9815. No pinch mark at case mouth. Primer is still seated. .0025 increase over the hornady length.

I have not fiddled with the spring at all but it does appear in pretty good shape for an 87 year old spring.....

Don't recall what I measure pin protrusion at but it was good.

[swheeler]

.3760

In doing more research and measuring the hornady brass head to shoulder length fired vs unfired is the same length within .0005
Neck length grows approx .0040 but is still within max length @ 2.4935

Those re formed that were sized in full length lee sizer have not had the shoulder touched at all. This as well as being freshly anealed I believe may be allowing the forward movement either from primer pressure or firing pin strike. The formed cases before firing are 1.9775 to the shoulder. The fired are 1.9660 to the shoulder

Bushing size used to measure is .420

Sorry missed that on the Hornady fired brass. So here's the way to find the problem...........
1-Resize the Hornady OF brass-MAKING SURE TO NOT TOUCH THE SHOULDER-if you do touch it call .001 good
2-load as you did before with 49.0 gr RL15-fire
3-If the shoulder is shoved back you know it is a light load, if the shoulder is in original position you know to dump the reformed 270 brass.

The explosive force of the primer acting against the bottom of the pocket is always trying to shove the brass forward, smaller the shoulder to stop it more it moves it(35 Whelen) unless the cartridge develops enough pressure to push the brass back reseating the primer.

[kfd518]

Sorry missed that on the Hornady fired brass. So here's the way to find the problem...........
1-Resize the Hornady OF brass-MAKING SURE TO NOT TOUCH THE SHOULDER-if you do touch it call .001 good
2-load as you did before with 49.0 gr RL15-fire
3-If the shoulder is shoved back you know it is a light load, if the shoulder is in original position you know to dump the reformed 270 brass.

The explosive force of the primer acting against the bottom of the pocket is always trying to shove the brass forward, smaller the shoulder to stop it more it moves it(35 Whelen) unless the cartridge develops enough pressure to push the brass back reseating the primer.

I believe I created a bit of confusion those cartridges that I had resized were all the rp 270 brass and those are the ones that didn't have the shoulder touched.
POST#55 was also rp 270

[swheeler]

Well I reloaded at 52 gr and at the request of another lightly oiled the cartridge before firing. Results were a case of my previous lot after firing shoulder to head length of 1.9815. No pinch mark at case mouth. Primer is still seated. .0025 increase over the hornady length.

I have not fiddled with the spring at all but it does appear in pretty good shape for an 87 year old spring.....

Don't recall what I measure pin protrusion at but it was good.

Sounds like you got it, go to 53. and ditch the oil, too light a load.

[vzerone]

Sounds like you got it, go to 53. and ditch the oil, too light a load.

The lightly oiled light charge was by request of me. I felt he was initially loading a light charge and the firing pin was driving the case forward and it obturated in that forward position and backed the primer out. Lightly oiled prevented the case from obturating and expand to fill the chamber, a method that many use in fireforming cases with a filler, not a bullet. We both are very aware of cases are to be oil free along with the chamber upon firing them.

You know that runfiverun meant the extractor claw not the ejector.

[kfd518]

Gentlemen thank you for all your assistance, now to get the rest of these formed up. Will keep everyone up to date on the final conclusions after formed and performance level determined.
From my conversation with hornady they did not seem to worried about the extra velocity and they have to be aware that this stuff is being used it over the hill actions. The rep did say they actually figure on getting I believe 85 fps faster than what they label as. Kind of curious to see what it's leverevolution clocks in my 30-30.