Mausingfield M7 Pressure Signs

[Hawk in WY]

I'm about to start a load workup for a Mausingfield M7 action.

My standard procedure is to start low and move higher watching for signs of pressure and load below that maximum.

Will this work with the Mausingfield bolt head and ejector design?

No ejector marks to look for obviously and I'm wondering if the bolt head design might make stiff bolt lift not a good pressure sign.

 

[Hawk in WY]

No one developing loads for a Mausingfield?

 

[ForgeValley]

Just switched my MF to 7 SAUM, and going to push some loads until I get pressure signs of some type (I hope). I plan to look for primer crater and flattening, and I think you would see some flow into this area:

 

[Another Casual]

Should get ejector marks (but more subtle) through the opening above. I don't have an MF, but my big horn gets it there if I push too hard.

 

[ForgeValley]

Just googled mechanical ejector pressure signs. Good info there, some hits to threads here as well.

 

[Hawk in WY]

There's more out there than I realized. Thank you.

Primers flattened but otherwise not remarkable.

No marks on the case head.

Bolt lift normal.

Two problems: I'm at 10% higher velocity than I expected and they go into one hole at 100 yards with low single-digit standard deviations.

Probably over SAAMI max pressure or so QuickLOAD tells me based on velocity, but in a hunting rifle in 300 Norma Mag which probably gets shot ten times a year, I'm tempted to stay where I am.

For other rifles where I burn out barrels yearly, I would back down.

This is a cold-weather rifle so I'm not worried about pressure spikes due to temperature.

I actually do not "need" the extra velocity for elk but I built this rifle with a 28-inch barrel for that purpose.

Am I missing anything?

 

[Steel head]

You’ll see flow into the ejector slot if you getting into nuclear territory but you’ll probably feel a bit more bolt resistance first.

If you load is hot high temps or wet conditions could bite you on an important shot.

 

[Hawk in WY]

I checked again and the primers look like all other primers and there is not even a hint of flow into the ejector slot. The bolt lift has been normal.

Wet conditions could be a concern although I suspect a chambered, dry round and those in the BDL magazine should stay dry.

I suspect the next step should be to back down and see how they do wet.

Thank you for the input.

 

[KnowNothing256]

Two problems: I'm at 10% higher velocity than I expected and they go into one hole at 100 yards with low single-digit standard deviations.

Not gonna lie, I wish I had "problems" like yours lol

 

[Hawk in WY]

Not gonna lie, I wish I had "problems" like yours lol

That's how I feel.

Hot loads make me nervous having been bitten in the past.

This one may be too good to pass on.

 

[KnowNothing256]

That's how I feel.

Hot loads make me nervous having been bitten in the past.

This one may be too good to pass on.

10% over book seems like a lot, but if I wasn't seeing pressure signs and wasn't gonna shoot it in hot weather, I'd burn a sacrifice to the gun gods and load it up!

 

[BCX]

Every barrel, chamber etc. is a little different. Some data seems conservative. I have been know to push well over book to pressure sign than back down and work a load...

 

[Hawk in WY]

Every barrel, chamber etc. is a little different. Some data seems conservative. I have been know to push well over book to pressure sign than back down and work a load...

I do the same but there are no published data for the combination I am using.

I too load increasing powder charges and stop and back down when I see pressure.

The challenge here is I was seeing no pressure signs well over what QuickLOAD is telling me is maximum pressure.

I don't doubt I have a hot load but for my purposes, I think I'm good.

Thanks everyone for the help.

 

[BCX]

I run all improved cartridges so i know your pain lol.

 

[Wyo_Jo]

Might want to have plenty of brass on hand or keep the reload count to a minimum if you keep it hot. Did the same for some heavy bullets for the caliber, about 5% over any and all published info. Shot good groups, had very good velocity numbers. No case pressure signs but by the 3rd firing was blowing primers out the pockets. Almost botched a hunt as i found this problem out when i went to send a follow up shot and couldnt close the bolt because a blown primer fell in the way.

 

[Hawk in WY]

Might want to have plenty of brass on hand or keep the reload count to a minimum if you keep it hot. Did the same for some heavy bullets for the caliber, about 5% over any and all published info. Shot good groups, had very good velocity numbers. No case pressure signs but by the 3rd firing was blowing primers out the pockets. Almost botched a hunt as i found this problem out when i went to send a follow up shot and couldnt close the bolt because a blown primer fell in the way.

This is good advice.

If this was a range gun, I certainly would back off velocity.

Since this is a once-per-year, purpose built hunting rifle, I think I am good.

What I will do is run two lots of brass. One for load development and long-range dope validation and one for rounds for serious purposes.

 

[Barelstroker]

Pressure Trace ran some testing on "over pressure" signs commonly used by reloaders.
They found that true pressure readings were not reliably indicated by flattened primers or web expansion &, most book max values are just that......MAX VALUES. Although they found a general correlation between the common overpressure signs & true overpressure, the correlations were very poor indicators of the extent of the overpressure there was. In the case of web growth, some pressure values were up into 85,000 Lbs with very little expansion measured while considerable expansion measurement yielded less pressure.
Pressure Trace concluded that the standard overpressure signs used by shooters are not reliable indicators as to the extent of the pressure spikes generated.
For those who believe loading a little over max book isn't a big deal, think again. Different powders react very differently & the pressure rise times are not usually linear or intuitive. Pressures can & do spike far more dramatically than we realise, making any perceived benefit a considerable risk, not to mention the elevated wear & tear on the action.

 

[Hawk in WY]

Thank you for that vote for sanity.

I agree the usual pressure signs are not reliable.

Time to find a lower node.

 

[918v]

Just switched my MF to 7 SAUM, and going to push some loads until I get pressure signs of some type (I hope). I plan to look for primer crater and flattening, and I think you would see some flow into this area:

View attachment 7592167

I agree. You will experience stiff bolt lift and brass flow into holes in the bolt face just like other bolt designs but case extraction will be easy.