Reduced Load for fireforming 300WM

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DanK3Pos

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My goal is to fireform new Peterson brass so that I am starting load development with brass headspacing off the shoulder, not the belt.

I know I can use a reduced load with H4895 (https://hodgdon.com/wp-content/uploads/2016/11/h4895-reduced-rifle-loads.pdf). Is that a reliable way to fireform the brass, or will the reduced load and reduced PSI not fully fireform the case to the chamber?

I know the best way to answer my question is to load a normal charge weight and a reduced load, then fire both and measure the cartridges. The rifle won't be here until next week, though, and I wanted to get a head start on loading, so I'm calling on the collected wisdom of THR reloading community.
 
I have always used near max/max loads to fire form straight forward changes like that. I use the bullet seated into the lands to help hold the case back when forming a new shoulder forward of the old one. Very lightly lubricated cases can also help the case stay back against the breech. At least slick, like tumbled in corn cob with polish. Others do it differently.
 
Walkalong said:
I have always used near max/max loads to fire form straight forward changes like that. I use the bullet seated into the lands to help hold the case back when forming a new shoulder forward of the old one. Very lightly lubricated cases can also help the case stay back against the breech. At least slick, like tumbled in corn cob with polish. Others do it differently.
Click to expand...
Okay, if I want to load to the lands I will have to wait for the rifle to arrive, so that answers my question. I hadn't thought of loading to the lands, but that makes all the sense in the world. I will use Hornady One Shot to lube the cases.

Thank you very much for the speedy and excellent input!
 
DanK3Pos said:
Okay, if I want to load to the lands I will have to wait for the rifle to arrive, so that answers my question. I hadn't thought of loading to the lands, but that makes all the sense in the world. I will use Hornady One Shot to lube the cases.

Thank you very much for the speedy and excellent input!
Click to expand...
The two major options are loading jam or creating a false shoulder.
 
I usually seat the bullet to about .015 jam and use the starting load for the fastest powder the manual calls for.When I fire form my 300WM brass,I usually use a starting load of IMR 4350.Headspacing to the shoulder will make your brass last longer and it usually helps accuracy.
 
Seeing as it is a belted cartridge, is seating into the lands really accomplishing anything other than putting you in uncharted territory (pressure wise) with your first loading for a new rifle? The case is going to fill up the chamber either way.
 
Laphroaig said:
The case is going to fill up the chamber either way.
Click to expand...

Yes, but we want to keep from stretching the case near the web, which means we want to case head back against the breech face. Seating say .030 into the lands with a near max load will be ok. I used 1 Gr less powder to fire form Dasher cases than I use in matches. For .220 Russian to 6 PPC I used a max load, but we seated into the lands for everything anyway.
 
Walkalong said:
Yes, but we want to keep from stretching the case near the web, which means we want to case head back against the breech face.
Click to expand...

I've always assumed that the belt was designed to do exactly that. My understanding of the OP's question was he wanted to set up his dies to headspace on the shoulder for subsequent firings, a great idea. Its not like he's moving the shoulder ahead or anything drastic where headspace in the initial firing is an issue. By this logic, any non-belted once fired brass is deficient in some way.

I will say that a near max, or even a starting, 300WM load jammed into the lands scares me more than having a new case stretch a few thousandths on the first firing. That just might loosen up the primer pocket enough to reduce the case life more than a potential case separation would from that one firing.

Be careful out there!
 
Load them with a full charge, coat the outside of the case in a lubricant, and fire them. The lubricant will prevent the front of the case from grabbing the chamber. A lubricated case will slide to the bolt face, the shoulders will fold out in front, and at the end of the event you will have a stress free, perfectly fireformed case. And that is particularly important with belted magnums where the base to shoulder distance is not standardized. From there, use case guages to figure out the base to shoulder distance, and bump the shoulder back 0.003" for the next firing.

Lightly greased, this hair gel is vasoline with beeswax as a thickner. And it has a pleasing smell. Just smear the lube on the outside of the case, particularly making sure to coat the neck and shoulder.

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this is not a reduced load!

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Walkalong said:
Yes, but we want to keep from stretching the case near the web, which means we want to case head back against the breech face. Seating say .030 into the lands with a near max load will be ok. I used 1 Gr less powder to fire form Dasher cases than I use in matches. For .220 Russian to 6 PPC I used a max load, but we seated into the lands for everything anyway.
Click to expand...

Laphroaig said:
I've always assumed that the belt was designed to do exactly that. My understanding of the OP's question was he wanted to set up his dies to headspace on the shoulder for subsequent firings, a great idea. Its not like he's moving the shoulder ahead or anything drastic where headspace in the initial firing is an issue. By this logic, any non-belted once fired brass is deficient in some way.

I will say that a near max, or even a starting, 300WM load jammed into the lands scares me more than having a new case stretch a few thousandths on the first firing. That just might loosen up the primer pocket enough to reduce the case life more than a potential case separation would from that one firing.

Be careful out there!
Click to expand...
I should have mentioned that this is Peterson 300 WM Long. Here is their explanation of that cartridge where they discuss the dimensions involved.
https://www.petersoncartridge.com/t...terson-cartridge-introduces-300-win-mag-long/
I like the way they think and I like giving my business to a family owned American company.

I also appreciate everyone's input on this. I learned a long time ago I don't have to re-invent the wheel and forums like this allow me to learn from everyone else's experience.
 
Designed to yes, but it often does it poorly, and the issue there is moving the shoulder too much and causing case separations because we are headspacing on the belt and our shoulder is unknowingly getting moved too far back, and we get away with it because the belt holds it and it fires, despite excess head clearance because we moved the shoulder too far because we don't measure it, just screw the die down, and let the belt "work". This leads to separations. So a lot of people simply measure carefully and use the shoulder to "headspace" the round instead of the shoulder, it can be more consistent than the belt, and then we know we are not moving the shoulder enough to cause potential case head separations.

Hope that made sense, not 100% awake and my head hurts on top of that. :)
 
Laphroaig said:
I will say that a near max, or even a starting, 300WM load jammed into the lands scares me more than having a new case stretch a few thousandths on the first firing. That just might loosen up the primer pocket enough to reduce the case life more than a potential case separation would from that one firing.

Be careful out there!
Click to expand...
I get that, and I don't know how far the shoulder needs to move, but if it is more than .003/.004 I want my case head against the breech when it happens.

Uncomfortable with jam? Load the bullet to jump and grease the case. Uncomfortable with that? Dunno, just load them and shoot them, then set up the sizer to only move the shoulder .002, and keep doing that. Chances are very good that we didn't stretch the web enough to worry with if we keep moving the shoulder minimally.
 
Use near maximum loads to fire form. Reduced loads of 4895 may make the head to datum shorter, as the case body expands outward.

In a large chamber, head spacing off the shoulder may cause the area in front of the belt, to become unsupported. After a few loadings, resized rounds may not chamber. More so with neck sized only brass.

https://www.larrywillis.com/ Die maybe needed?
 
I do not use reduced loads for fire forming brass. Did that for years, but learned different from three PHD Ballistics Engineers working the Gau 8 Ammo project. Our range was used by the project engineers to shoot on during their off times. We had Lockheed, GE and Honeywell folks about during that project.
 
Armorer 101 said:
I do not use reduced loads for fire forming brass. Did that for years, but learned different from three PHD Ballistics Engineers working the Gau 8 Ammo project. Our range was used by the project engineers to shoot on during their off times. We had Lockheed, GE and Honeywell folks about during that project.
Click to expand...
It is a shame I don't have any Lockheed engineers around to consult with on this project :)
 
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