What caused this???

[Halleywood]

What was your load??
I've only seen this with mild doses of slow burning powders if the pressure is too low or a big case with a light bullet load and a mild dose of powder that is rather fast for the case. The last time I had it was last winter burning up some 125 bt's in my 300win with 4895; gotta shoot what ya got these days and the 125's were gathering dust.

Load was 168 grain berger VLD with 76 gr R25 being ignited by cci magnum large rifle primers.

Berger book shows max load to be 75.3 grains in R25.

 

[Lefty7mmstw]

Load was 168 grain berger VLD with 76 gr R25 being ignited by cci magnum large rifle primers.

Berger book shows max load to be 75.3 grains in R25.

sounds about right, but I'd ditch the cci primers, imo. I was tossing some test ammo together a few minutes ago with 168 vld bullets for my 7stw. The recipe was 86-88 grains rl50 in reformed 375 h@h brass with a 215 lighting the fire.
Once you pass 160 grains in a stw they seem to respond better to 50bmg class powders. That said, I was using 75 grains rl25 with the 171 barnes lit by a 215 last year and the load was stable... the accuracy was squirrely though as the barnes seems to be built for lesser calibers.
It seems you may need to get your headspace straightened out and possibly anneal your brass to get a better seal. I personally would ditch the cci's, but others like them so that's your boggle. The 215 is a bit hotter primer so it'll help seal things up at the chamber end by getting the pressure up quicker.

 

[barnesuser28]

Halleywood, if you decide you want/need your brass annealed, pm me.

Riley

 

[Halleywood]

I loaded up the same load with federal 215M primers along with some more with cci 250 to see if there is a difference. I'm planning on going out tomorrow to see what it tells me.

I have shot around 180 rounds down this rifle various loads and all with cci 250 primers. The only thing that changed this time around was I used new RP brass.

Lefty, I may go pick up some 50bmg powder this weekends as it seems that is the only thing scheels has.

 

[Halleywood]

We'll I went and measured a fired case versus the new brass I have and the headspace difference is 20 thousandths! What can you do to new brass to fix that? That has to be all or part of the issue.

 

[AZShooter]

Is there a chance that the case in question had less powder than the others? If powder bridging happened in the funnel that would mean that another case has more powder. This happened to me when loading the 7 RUM with RL-25.

I would pull all loads and weigh them. Also as another poster suggested double check the powder scale.

 

[Lefty7mmstw]

We'll I went and measured a fired case versus the new brass I have and the headspace difference is 20 thousandths! What can you do to new brass to fix that? That has to be all or part of the issue.

I'd set your sizing die long and possibly run new brass over a 30 cal expander and bring your brass down again afterwards.... My current stw was reamed a bit long also. I think I'm in the ten to fifteen thou. long range... I'd have to check to be exactly sure but I've got a sheet of paper's gap between the sizing die and shell-holder when she's properly set. I've just let them go and run them through a properly set die for subsequent loadings, but with the brass availability today I think I'll likely be necking to provide a headspace point on the shoulder for any more new brass. I think I've got 100 loaded and squirreled away I need to do this with.
As to powder, I think rl25 would work, but 50bmg, rl50, retumbo, rl33, and a few of the slower Vit/ norma powders are better choices as they fill the case better than the mid-magnum powders do. Especially up here where it gets below zero you want to try for hot ignition and full cases for hunting loads.

 

[woods]

We'll I went and measured a fired case versus the new brass I have and the headspace difference is 20 thousandths! What can you do to new brass to fix that? That has to be all or part of the issue.

Forward movement of the case in the chamber is stopped by the belt which is really "headspace" but I assume you are talking about .020" gap at the shoulder from new to once fired. .020" is not that an unusual amount of shoulder gap for a belted case as I reload for several and they vary from .015" to .040".

There is nothing that you can do to keep the brass from expanding that much upon firing. Creating a false shoulder or seating bullet to lands with a firm crimp will not work as it would on an unbelted case. Hornady used to make a hydraulic die special order but I don't think they do anymore.

Like with any belted case there will be more thinning at the pressure ring with initial firing and it is important to push the shoulder back minimally after full expansion is reached (neck sizing only till crush fit develops)

 

[Lefty7mmstw]

There is nothing that you can do to keep the brass from expanding that much upon firing. Creating a false shoulder or seating bullet to lands with a firm crimp will not work as it would on an unbelted case. Hornady used to make a hydraulic die special order but I don't think they do anymore.

why won't a false shoulder work; he's looking to seal his chamber after all and I'm pretty sure everyone realizes you are getting to get a bit of stretch when you fire brass in a belted the first time?? I use a false shoulder all the time when reforming brass to stw from 375 h@h. I never let it use the belt as a headspace point. I get where you are going with the belt as a primary headspace but using the shoulder works just fine from what I've seen with the hundreds of casings I've done.

 

[Halleywood]

AZ- I don't think any cases weighed less in powder charge as I am in the habit of weighing all charges when doing load development. It is possible my scale was off but I check that regularly. Because it was for load development I don't have any rounds to pull.

So if I back off my sizer die a bit so the shoulder doesn't get bumped that will work for just neck sizing the now once fired brass correct? I don't have 30 cal dies for creating a false shoulder. Probably past my reloading expertise.

I have probably 20 rounds of the now once fired new brass. Should I just neck size now until it gets sticky in my chamber then bump back one or two thou?

I went and shot this morning with the same load, 6 with cci primers and 6 with fed 215m primers. The two cci groups each had two close with a flier. The fed groups were twin low .6's. I'm going to keep going with the federal primers. Amazing how just changing that made such a difference.
I have some retumbo that I will try as well as pick up some 50bmg.

Lefty- I have some 150 gr ABLR I am going to test. Are those light enough that the R25 will work with those in your experience?

Thanks for everyone's input. I really appreciate it!

 

[Lefty7mmstw]

Lefty- I have some 150 gr ABLR I am going to test. Are those light enough that the R25 will work with those in your experience?

Thanks for everyone's input. I really appreciate it!

should work fine. I have a box (20) of 150ablr's loaded with 80.0 rl25 and a 215. Work up to this of course.

As to sizing, I usually smoke the shoulder on the brass after lubing and bring the sizer die down a bit at a time until you see contact on the smoke. Confirm by chambering the empty that it will chamber fine; continue down a few thou. more until you get good chambering if needed.

 

[MagnumManiac]

AZ- I don't think any cases weighed less in powder charge as I am in the habit of weighing all charges when doing load development. It is possible my scale was off but I check that regularly. Because it was for load development I don't have any rounds to pull.

So if I back off my sizer die a bit so the shoulder doesn't get bumped that will work for just neck sizing the now once fired brass correct? I don't have 30 cal dies for creating a false shoulder. Probably past my reloading expertise.

I have probably 20 rounds of the now once fired new brass. Should I just neck size now until it gets sticky in my chamber then bump back one or two thou?

I went and shot this morning with the same load, 6 with cci primers and 6 with fed 215m primers. The two cci groups each had two close with a flier. The fed groups were twin low .6's. I'm going to keep going with the federal primers. Amazing how just changing that made such a difference.
I have some retumbo that I will try as well as pick up some 50bmg.

Lefty- I have some 150 gr ABLR I am going to test. Are those light enough that the R25 will work with those in your experience?

Thanks for everyone's input. I really appreciate it!

If your brass is fireformed to your chamber I would neck size them once, then bump the shoulders with your FL die .001"-.002" from then on.
I still think you were having ignition issues, hang fires aren't always a long delay between firing pin fall and ignition. It can often be so slight it's not noticed.
Anyway, stick with the Federal for now, but if you want an even hotter primer, the Winchester Magnum primers are the hottest on the market.
I don't feel the brass or the powder is your problem, the difference in head to shoulder measurement is normal, I've had 2 instances where a certain brand of brass in 300WM would be .062" short of the chamber shoulder, this brass would show signs of incipient head separation on the 3rd firing after being neck sized only.

Cheers.
gun)

Cheers.