We have many "new" cartridges that have high (65K+). They "outperform" older cartridges that have lower limits. As an example - .25 Creedmoor and .257 Roberts. If I build a rifle on a bolt action (which can typically used for either cartridge), why can't I load to the higher pressure? The 6mm Remington is loaded to much higher pressure but uses the same base case as .257 Roberts, so this would seem reasonable. It seems to me that the lack of data (loading details) would be a major issue. If QuickLoad good enough for such an endeavor?
Pressure Limits
- Thread starter Huntslow
- Start date
MagnumManiac
Well-Known Member
For 257 Roberts upgraded to 65,000psi load data, you simply look up +P 257 Roberts. It is all their to be found.
I use the max +P data as my start load in my 257 AI cartridge. Never had an issue doing so with Winchester 'white/yellow' boxed head stamped as 'ww-super'.
It is a fair step up from anaemic factory loads.
Cheers.
I use the max +P data as my start load in my 257 AI cartridge. Never had an issue doing so with Winchester 'white/yellow' boxed head stamped as 'ww-super'.
It is a fair step up from anaemic factory loads.
Cheers.
MagnumManiac
Well-Known Member
I use my Pressure Trace and increase to 63,000psi-65,000psi. This is usually an additional 2-3 grains of most stick powders in the correct burn rate.
Cheers.
lancetkenyon
Well-Known Member
Only YOUR rifle and brass can tell you the limits.
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And either one is idiot proof, and Murphy does not discriminate.
Rabid Fish
Well-Known Member
I wondered the same thing.
30-06 is limited to 60K psi
270 ha a 65K psi limit.
If you have 2 similar rifles, both chambered in either cartridge, would it be safe to boost the 30-06 pressure to the 270 pressure limit ?
Obviously both rifles were manufactured after 1925.
30-06 is limited to 60K psi
270 ha a 65K psi limit.
If you have 2 similar rifles, both chambered in either cartridge, would it be safe to boost the 30-06 pressure to the 270 pressure limit ?
Obviously both rifles were manufactured after 1925.
I have .270 Win/AI, .30-06/.30 Gibbs; I cannot measure actual pressures, so instead, I monitor the pressure signs, as @lancetkenyon noted.
MagnumManiac
Well-Known Member
Problem there is that you won't know the pressure, whether the original load is at max pressure already, or if your guesstimate at a powder increase is at 5000psi or more.
This is why I invested in the Pressure Trace, unfortunately, the strain gauges are extremely difficult to get now. When I remove them, 50% of them never work again no matter how careful I am. It's a pity, I had a chance of buying 50 at one time, but, I just thought when I needed more, I could just buy however many I needed. Oh well…
Cheers.
Mikecr
Well-Known Member
Part of limitations you run across are due to specific SAAMI testing conditions and requests.
SAAMI is right about their declared SAAMI max -with a specific chamber (usually SAAMI), and specific brass.
Dig & see if the chambers and brass compared are actually the same.
QL load data doesn't care. It lists SAAMI max, and assumes your conditions correlate. A lot of times it does.
But only local testing will tell you.
You can run 'what ifs' in QL while setting any max pressure you wish.
SAAMI is right about their declared SAAMI max -with a specific chamber (usually SAAMI), and specific brass.
Dig & see if the chambers and brass compared are actually the same.
QL load data doesn't care. It lists SAAMI max, and assumes your conditions correlate. A lot of times it does.
But only local testing will tell you.
You can run 'what ifs' in QL while setting any max pressure you wish.
Brass life, whatever kind you run, will tell tale the tale on acceptable or excessive pressure.
Most cartridges give pressure signs as a visible warning to reduce the charge weight but not all.
Bore diameter, condition, chamber dimension, many factors differ from gun to gun and make a difference when you run close to the edge. But I gotta know where it is…
Most cartridges give pressure signs as a visible warning to reduce the charge weight but not all.
Bore diameter, condition, chamber dimension, many factors differ from gun to gun and make a difference when you run close to the edge. But I gotta know where it is…
MagnumManiac
Well-Known Member
Biggest factor for me running the Pressure Trace is brass head hardness.
Some brands will show excessive pressure signs well below max pressure because the brass is soft. Federal brass and Hornady brass are the worst for this.
Cheers.
Some brands will show excessive pressure signs well below max pressure because the brass is soft. Federal brass and Hornady brass are the worst for this.
Cheers.
Seabeeken
Well-Known Member
The 250 savage ackley improved and 25 creedmoor are virtually identical aside from 40° and 30° shoulder respectively and different pmax. Hornady has been reinventing things for some time now. I ran my 250ai at 22-250 pressures with no issues.
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MagnumManiac
Well-Known Member
Not sure which year it was, but, when SAAMI stepped into the same realm as CIP in changing max pressure limits from average numbers to absolute max pressure, things changed significantly in many reloading manuals, maximums were reduced because it took only ONE powder charge to exceed max pressure, not an average of 10, to then be governed as safe by reducing the maximum charge listed where no load exceeded max pressure.
I don't know why this change came about, but, even reference ammo was altered due to this. Fudge factors were also changed so that if any load tested exceeded the pressure according to the fudge factor limit, it was deemed unsafe…
Cheers.
