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Heavy Grendel powder - kiwi shooter - 04-25-2023
[ATTACH=CONFIG]19693[/ATTACH]
got round to loading some up today
used starline brass
cci 400 primers
and lever revolution
loaded 5 rounds each of 27.0,27.5,28.0.
according to GRT 27.0 will produce 38283psi and around 2134fps from the 20" barrel.
28.0 will produce 43302psi and around 2221fps.
considering 6.5g has a max psi of 58000 psi this should be a good safe place to start.
Heavy Grendel powder - LR1955 - 04-25-2023
kiwi shooter Wrote:[ATTACH=CONFIG]19693[/ATTACH]
got round to loading some up today
used starline brass
cci 400 primers
and lever revolution
loaded 5 rounds each of 27.0,27.5,28.0.
according to GRT 27.0 will produce 38283psi and around 2134fps from the 20" barrel.
28.0 will produce 43302psi and around 2221fps.
considering 6.5g has a max psi of 58000 psi this should be a good safe place to start.
KS:
Really long OAL. Are those bullets 'bore riders'?
LR-55
Heavy Grendel powder - JASmith - 04-25-2023
kiwi shooter Wrote:[ATTACH=CONFIG]19693[/ATTACH]
considering 6.5g has a max psi of 58000 psi this should be a good safe place to start.
Please verify whether the GRT pressures you are using refer to the CIP standard or the SAAMI standard.
You are likely referring to the CIP standard (Pmax = 4050 bar) for the pressure limit.
CIP pressures are measured differently than the SAAMI standard (52,000 psin "Maximum Average Pressure").
This means that if one grabs a "number" from the CIP standard for the max and then compares the results from either software or actual testing done via SAAM methods, then the loads can be 6,000 higher than desired.
Heavy Grendel powder - kiwi shooter - 04-25-2023
LR1955 Wrote:KS:
Really long OAL. Are those bullets 'bore riders'?
LR-55
Yes they are
The first part of baring surface is only just above the case mouth
They are just loaded to mag length in the howa could be longer if I wanted to single feed them
Heavy Grendel powder - kiwi shooter - 04-25-2023
JASmith Wrote:Please verify whether the GRT pressures you are using refer to the CIP standard or the SAAMI standard.Yes correct
You are likely referring to the CIP standard (Pmax = 4050 bar) for the pressure limit.
CIP pressures are measured differently than the SAAMI standard (52,000 psin "Maximum Average Pressure").
This means that if one grabs a "number" from the CIP standard for the max and then compares the results from either software or actual testing done via SAAM methods, then the loads can be 6,000 higher than desired.
I have converted the units in grt to what i am used to you can do that in settings so its in psi not bar 4050bar= 58740.28 psi
Heavy Grendel powder - JASmith - 04-25-2023
kiwi shooter Wrote:Yes correct
I have converted the units in grt to what i am used to you can do that in settings so its in psi not bar 4050bar= 58740.28 psi
The apparent difference in pressure standard between CIP and SAAMI is confusing. I know that the 52000 psi number in the SAAMI standard is based on a statistical model that minimizes the chances of getting dangerous pressures when using standard load data.
I also know that the pressure test procedure with CIP is different that the procedure one follows when complying with SAAMI standards.
What I don't know is whether a load producing 52,000 PSI under the SAAMI standard actually produces a measurement of 58,000 psi when tests are done while following CIP procedures.
Does the user information for GRT expand on this?
Heavy Grendel powder - kiwi shooter - 04-26-2023
JASmith Wrote:The apparent difference in pressure standard between CIP and SAAMI is confusing. I know that the 52000 psi number in the SAAMI standard is based on a statistical model that minimizes the chances of getting dangerous pressures when using standard load data.
I also know that the pressure test procedure with CIP is different that the procedure one follows when complying with SAAMI standards.
What I don't know is whether a load producing 52,000 PSI under the SAAMI standard actually produces a measurement of 58,000 psi when tests are done while following CIP procedures.
Does the user information for GRT expand on this?
not sure buddy cip is 58000psi sammi is 52000 psi
my starting load should be just under 39000 so i should be well safe well under both cip and Sammi max.
i have a good mate that uses grt all the time and his suggestion was to start at 40000psi or the closest 0.5gn to it
looking at cip all of the specs are metric so i wonder if it's based on bolt actions. many countries including mine don't allow any semis. so, I wonder if it's as simple as cip assuming a bolt action which handles a lot more pressure than say an AR15.
Heavy Grendel powder - kiwi shooter - 04-30-2023
So a went to my brothers house for dinner last night
He lives on a small block of land and has a safe spot to fire a couple of rounds
It was heavy rain and wind so I only fired one round of each charge to check pressure
No accuracy or velocity yet but at least we know that they are safe
Heres a photo of the brass from the highest charge
28.0gn of lever revolution
[ATTACH=CONFIG]19709[/ATTACH]
As you can see it looks perfect so atlest we have a starting point