tagonzo wrote:These are results from several days at the range with my chrono. I mention this because I did notice a little difference in average fps of the same load from different days. Probably due to temp and humidity differences, etc. All the above are averages from 5 shots.
Are you loading by weight or volume.? d:^) Schneeks..
JohnInNH wrote:What's the deal with the 1 in 10 twist?... Could be that is a 300 whisper chamber, and not a BLK one. This makes me doubt their data as being the latest and most accurate. Still excellent. Bbetter than nothing.
Thanks for posting this
Hmmm, good catch I did not see that in my haste to post it. I'll shoot him an e-mail and ask for a clarification on the barrel twist.
For the purpses of load data, I don't see how twist rate is relavent. Afterall, the powder company is only concernend with the SAAMI specs of the cartridge and making sure the powders tested do not exceed maximum allowable chamber pressures. Accuracy and stability of the bullet tested is no concern for them.
They likely just chambered whatever barrel blank they had available at the time and went with that.
2bad4u2 wrote:For the purpses of load data, I don't see how twist rate is relavent. Afterall, the powder company is only concernend with the SAAMI specs of the cartridge and making sure the powders tested do not exceed maximum allowable chamber pressures. Accuracy and stability of the bullet tested is no concern for them.
They likely just chambered whatever barrel blank they had available at the time and went with that.
I for one wonder how well the 230's shot? Lyman will list best "target" loads it's not just ED and SD that they use but real groups. Same with Sierra.
So they shot subsonic 230 gr bullets in a 1:10 at paper or was it just in a backstop and only looking at FPS and Pressure ..
I also think it's on the verge of irresponsible to publish data that will possibly cause damage to a silencer with loads that are specific to silencer usage. You KNOW some clown will think his 1:10 is OK to run these loads safely in his 8" SBR he just made with a 1:10 barrel he had set back and re-chambered. Really not knowing that a 1:8 should be used.
It's obvious it's back from the 300 WHISPER days when people were using 1:10 for supers and moderate Subs Unless they re-cut (used a BLK reamer) the pressures are not 100% accurate.
What chamber was their test data derived from. Not that it's BAD it's just not 100% correct.
Long distance, the next best thing to being there!
If they do it right you can be sure the data is correct, even if the twist is not the same.
The barrel will be at minimum and the chamber will be at minimum. There is special ammo made for pressure testing reference, so they can check the pressure reading of known pressure ammo in the new test barrel.
There is plenty of good data for 223 REM 70+ gr bullet loads that are shot for pressure in 12 twist test barrel.
-k- wrote:If they do it right you can be sure the data is correct, even if the twist is not the same.
The barrel will be at minimum and the chamber will be at minimum. There is special ammo made for pressure testing reference, so they can check the pressure reading of known pressure ammo in the new test barrel.
There is plenty of good data for 223 REM 70+ gr bullet loads that are shot for pressure in 12 twist test barrel.
Todd, I honestly do not think the pressure data is a problem because of the twist. It does look a bit pessimistic (low fps) whick makes me think they may have used a 300 Whisper chambered test barrel. It also could be a BLK chamber no way to tell on this end other than to speculate. Load data with a 26" barrel would still be safe as it has nothing to do with pressure either. At least it's 16"
The reason is because a lot of old wisper load data is with 1:10 barrels, and is why it triggered my reaction. I have a collection of it.
Long distance, the next best thing to being there!
JohnInNH wrote: The reason is because a lot of old wisper load data is with 1:10 barrels
It's probably for the same reason, they had the special minimum sized 1 in 10" twist barrels on hand while a 1 in 8" twist would be special order. I don't think they would use the wrong chamber, it should also be special and cut at the absolute minimum. The 300W is proprietary so you can't just call up a reamer manufacturer and ask for a minimum 300W reamer for a pressure test barrel.
I'm a lot more interested in the Hodgdon data showing CUP for pressure. From what I understand there is no direct way to convert psi and CUP, and there should be no standard for CUP as psi is the standard for modern cartridges.
My DSA upper is on its way so I have been collecting load date on the powder I'll be using, Lil'Gun. I've pulled the following together from a bunch of sources, including this board:
Last edited by lauyerman on Fri Feb 24, 2012 3:29 am, edited 1 time in total.
d:^) Schneeks..Could be that is a 300 whisper chamber, and not a BLK one. This makes me doubt their data as being the latest and most accurate. Still excellent. Bbetter than nothing.
