Originally Posted by leifalweapon
Can you elaborate on your friends gun and loads, I havent heard of anyone with a long range non lead setup! Thanks
The rifle is a Christensen Arms Carbon Custon in 300RUM, Thumbhole stock. 26" barrel. Pretty much standard as the options like set trigger are not his thing.
The gun came with 2 boxes of 'tuned' copper loads as my buddy specified it must shoot TTSX.
We used the provided ammo to break in the barrel and cron the load in multiple sessions.
The load provided came out at 3241. A COAL of 3.615.
We kept one round back for me to dissect and took 5 fired cases to measure H2O volume.
- Projectile: Barnes TTSX 180
- Brass: Remington
- Primer: Federal GM 215M
- Powder: IMR 7828, the load was from a 'boutique' ammo company so probably not a blended powder.
- Load: Sorry, I'm not saying as it is very very scary hot. However there is no sticky bolt. There is an ejector mark and cases last 2 to 3 firings but most get 3 to 4 at the most on Rem RUM brass anyway.
- Accuracy/Precision: Met the stated 1/2 MOA guarantee from Christensen Arms
- Velocity: 3241
How did I determine what the powder was?
I have a very large selection of powders that would work with this class of projectile/chambering.
I examined the extracted powder to make sure it was not a blend. It was an extruded powder (stick), all the kernels were the same length/diameter. Color was consistent for all kernels in the case.
I measured the length diameter of enough kernels to be sure of the dimensions.
I weighed collections 50 kernels on my Gempro 250 to determine the kernel weight.
Now time to compare to powders in my collection. Obviously ball powders were not even compared. Some of the stick powders were so obviously not the same dimensions they were easy to eliminate. I got down to I think 3 powders before bothering with the mic. Retumbo and H1000 color was 'close' but were just 'wrong' when mic-ed. Leaving IMR 7828. Color was very very close, put the powder on a piece of 'computer' paper. Dimensions were dead on. All that was left was to weight some lots of 50 with my Gempro 250. Yup, 7828. Not what I expected and a little 'hot' for me but it is what was provided.
Of course I checked the Hodgdon data and Barnes loading data. Yup much hotter, however when I plugged it all into QuickLoad with the extended COAL it made sense and the QL prediction was exact, actual at 3241 vs QL at 3243.
For the technology/QuickLoad haters. Go away
. Please don't pick a fight with me on this as it serves no purpose.
Yes I know the legal issues of loading for anyone else. I know that it's not my buddy that will sue me but his family/survivors. I shoot the firearm as well so there has to be some proof of malice, negligence or other for the suit to prevail. Yes it will cost me money to defend the suit, oh well.
Load work up. I discussed with my buddy about how hot this was. The options were to redevelop with a slower powder, lower the FPS or go with it as provided by the manufacturer, with or without with my 'improvements'.
Jimmy opted to go with what was provided with my improvements of primer pocket uniforming, flash hole deburing, concentric neck mouth and neck turning and for me the most important, HBN coating the projectiles.
For me HBN adds consistency to precision and also protects from 'bullet weld'. I have experienced this when I load a batch with non-coated bullets and they wind up sitting on the shelf. The velocity goes up and of course pressure goes up. For most of my loads this is an annoyance, for this load it could be life threatening.
So the brass was prepped, bullets were coated, dates were set for meeting at the range.
Starting at slightly above the book minimum to compensate for the extra capacity from shallower seating and in 1grs increments.
Shot, check brass, shot, check brass...
The Magnetospeed chronograph
tells the details. As each powder increment was shot we got closer to the provided rounds velocity. All increments were predictable except discordant nodes which showed odd changes and were off precision (can you tell I'm reading Brian Litz's book). The others were in a line working slowly up.
BTW: There was no intention to exceed the load provided.
When we hit the same load as provided, velocity was dead on. Ejector marks and brass condition was the same as the provided load. So it was duplicated.
With one exception: My loads were closer to 1/4 MOA. Just standard accurizing brass techniques.
He ordered custom turrets for yardage.
Fouled cold bore is very very close on this firearm.
Antelope: 915 yards
Mullie: 725, 10mph
Pig: 980, 15mph
Pig: 835, 6mph
Pig: 1035 but don't remember.