question about load pressure
#1
question about load pressure
I'm shooting a Thompson center Triumph .50Cal, Barnes spitfire 285gr sabot with 120gr charge of blackhorn 209 powder. When I chronographed this load the velocity was between 2,230 and 2,254 fps. Which seems really fast for this load. I shot 9 different strings through the chrono. Can this be caused by how hard it is to load the Barnes bullets with the yellow sabots? I already bent the ramrod. And can this cause dangerous excessive pressure when fired? This is a great load combination that groups 3/4" at 100yds and 2 inches at 200yds. Thanks...
#2
Yes if you bent your ram rod there could be a issues did you mark your ram rod to make sure you have the same depth everytime?
Everyone on here that has a Triumph has stated they ended up JB the bore for easier loading.
http://www.huntingnet.com/forum/blac...c-triumph.html
Everyone on here that has a Triumph has stated they ended up JB the bore for easier loading.
http://www.huntingnet.com/forum/blac...c-triumph.html
Last edited by donjose; 11-06-2011 at 04:27 AM.
#3
Nontypical Buck
Join Date: Aug 2008
Location: Rapid City, South Dakota
Posts: 3,732
.............................the velocity was between 2,230 and 2,254 fps. Which seems really fast for this load. I shot 9 different strings through the chrono. Can this be caused by how hard it is to load the Barnes bullets with the yellow sabots?......................
#5
All I would say is.. if the load is so hard to get down the barrel that you bent a ramrod.. this might not make a good hunting load. If you want to continue shooting this load, I would look for a better ramrod. When I loaded Barnes MZ Expanders in the red sabot in my Black Diamond they were "stiff" to load, but not impossible. And their accuracy was exceptional. Although I was not pushing them any where near what you are. Perhaps see what other sabots are out there and what effect they have on your bullet load.
The other side of the coin is.. if the velocity is even close to being true, (and with no first hand knowledge and experience I have no reason to doubt) and the accuracy you are getting is that good.. I can see why you're hesitant to switch. I mean, you are in center fire rifle area numbers, with a monster bullet. That would make an excellent hunting round. I mean, what could stand up to a bullet of that weight and that velocity, along with Barnes quality?
Does the second round load easier then the first round?
The other side of the coin is.. if the velocity is even close to being true, (and with no first hand knowledge and experience I have no reason to doubt) and the accuracy you are getting is that good.. I can see why you're hesitant to switch. I mean, you are in center fire rifle area numbers, with a monster bullet. That would make an excellent hunting round. I mean, what could stand up to a bullet of that weight and that velocity, along with Barnes quality?
Does the second round load easier then the first round?
#6
Giant Nontypical
Join Date: Nov 2005
Posts: 6,585
Kopfjaeger
First off Blackhorn is a progressive burning powder. This means that the higher the pressure the faster it burns and produces more pressure.
Second to answer your questions. It is quite possible to get these velocities with Blackhorn by loading it extremely tight. Since the normal pressure for 120 gr of Blackhorn is 15 % below the normal pressure of 777 and it gets the velocity it achieves by burns longer at peak pressure it is probable that your load does not exceed safe limits this can not be told for sure with out pressure testing.
Because a load that causes bent ramrods is not convenient for normal use I suggest you try a slightly thinner sabot or polish your barrel with 100 full length strokes of JB Bore Paste, this should relieve the loading problem as polishing tends to make things slide easier.
First off Blackhorn is a progressive burning powder. This means that the higher the pressure the faster it burns and produces more pressure.
Second to answer your questions. It is quite possible to get these velocities with Blackhorn by loading it extremely tight. Since the normal pressure for 120 gr of Blackhorn is 15 % below the normal pressure of 777 and it gets the velocity it achieves by burns longer at peak pressure it is probable that your load does not exceed safe limits this can not be told for sure with out pressure testing.
Because a load that causes bent ramrods is not convenient for normal use I suggest you try a slightly thinner sabot or polish your barrel with 100 full length strokes of JB Bore Paste, this should relieve the loading problem as polishing tends to make things slide easier.
#7
Thanks everyone. the 285gr bullets are easier to load now that I've put close to 100 rounds through it. Still need to get a new ramrod. when using this bullet and 150gr of 777 pellets and 777 primers I was getting around 2,043 fps, then when I went back to the Blackhorn 209 and cci primer using a barnes 250gr spitfire came out a blazing 2,275 fps. I was thinking about backing down the powder some due to the recoil and having a shallow eye relief on my scope could be painful, just can't keep the groups as tight.
#8
Giant Nontypical
Join Date: Nov 2005
Posts: 6,585
The next time you are looking at scopes take a look at the Nikon Omega it has 5 inches of eye relief, some do not like the circles for the longer distance shooting but I find them very convenient as they give 3 reference point per circle.
#9
I looked at the nikon 300bdc, and the leupold saber. I didn't like there reticule patterns seemed too cluttered and their narrow field of view. I ended up buying the vortex diamondback 3-9x40 bdc very nice scope just too small of an eye relief.
#10
Fork Horn
Join Date: Jan 2010
Location: Ontario, Canada
Posts: 414
I'm shooting a Thompson center Triumph .50Cal, Barnes spitfire 285gr sabot with 120gr charge of blackhorn 209 powder. When I chronographed this load the velocity was between 2,230 and 2,254 fps. Which seems really fast for this load. I shot 9 different strings through the chrono. Can this be caused by how hard it is to load the Barnes bullets with the yellow sabots? I already bent the ramrod. And can this cause dangerous excessive pressure when fired? This is a great load combination that groups 3/4" at 100yds and 2 inches at 200yds. Thanks...