Compressed Load?

[jsthntn247]

I am trying to figure out if my 257 Weatherby load is compressed or not. I asked this question on another forum and havn't got a response yet. I loaded a 100gr barnes Tipped TSX bullet to 3.170 Coal ranging from 75.5 to 78.0gr and started to hear powder crunching at 77.5 and 78.0 grains of H-1000. Hodgdon list 78.0 as book max, but they are using a different bullet and a COAL of 3.20. I am just trying to figure out if this a compressed load or not. I went home and did some figuring and this is what I came up with..... Was this done correctly

So, I got home and did a little calculating. I filled the case with water and it weighed 85.5 grains which is consistent with other findings. I then filled the case with water and inserted a bullet to my seating depth which should tell me my case capacity. The water left in the case after removing the bullet weighed 80.7 grains. So my case capacity after seating a bullet should be 94.4% of the original capacity. I then filled the case with H-1000 and it weighed 83.0 grains. Multiplying that by .944 gives me 78.35. Am I correct in thinking that this is my true case capacity after bullet seating and a load at 78.0, although it crunches powder, is not really a compressed load????

 

[MT4XFore]

Check out Barnes' data: http://www.barnesbullets.com/wp-content/uploads/2008/03/257WeatherbyMagnumWeb2.pdf

 

[BuckSnort]

Get a drop tube for the powder..

As far as measuring a cases capacity by filling with water then seating a bullet and measuring ..It may be a flawed process because water doesn't compress therefor it may be changing case dementions when seating bullet?... This is just my opinion and I may be completely wrong...

 

[backwoods83]

At 3.17 78grns of H-1000 is compressed and doesn't sound very safe, I use 75.5grns of RE25 and that will break 3800fps depending on the rifle. Compressing H-1000 doesn't seem safe.

 

[Gunpoor]

I don't think you should use H1000 if you are going to compress it. I ran a compressed load of it in my 270win and the compressed loads develope ignition trouble after sitting for a time. I pulled some bullets and the powder charge was one solid chunk.

 

[jsthntn247]

I am glad I asked this question before I just looked at Hodgdon's website and went blasting away. I have looked at two Barnes manuals, one said 76.0 grains as max and the other said 75.5. I emailed Barnes, and this is the response I got. "
I just talked to the guys that shoot the data. I hope I can say this aseloquent as they put it. They said from BRM#3 to BRM#4 the entire way that they shot data changed. For BRM#3 they used to shoot a charge then measure the head stamp for expansion. For BRM#4 they used a strain gage to measure barrel expansion, which was a more accurate reading. For BRM#5 they are
using a conformal transducer that can read internal chamber pressures which is more accurate still. Each time they get more accurate reading on
pressure combined with the different bullets, different barrel, different powder lot#'s and other components all add up to drastic changes.

72 to 76 grains seems like allot of variance. I just ordered a chronograph and am going to wait to shoot it through there. Once I get around 3600, if my groups are decent, I'm gonna call it good.