Wildalaska
member
OK here is the scenario.
I want to duplicate the Hirtenberger match 308 load with the 190 grain match king. This is the load that my Swarovski scope is cammed for, and supposedly is optimized for the SSG.
Hitenberger gives a lot of info about the load. It is running 730m/s which translates out to about 2400 fps. OAL is 2.799. The powder they use is Bofors NP3, uunavialable in the US, but several powders are close to the burning rate and I chose RL 15 becasue it is available up here. The other 2 powders at the same buring rate that I can get up here are IMR4064 and maybe Vitavouri N140
Dont know what type of rifle they used to shoot to derive there velocity
So I will use Win 1x fired cases, 190 MKs and RL 15 and Fed 210M and work from there.
The sierra manual uses a 26 in bbl Savage 1-10, probaly close enough to the SSG. they list 38.8 grains to acheive 2400. They max it out at 40.4 for 2500 fps. Interestingly, N140 in the maanual requires 39.6 grains and maxes out at 41.3 for 2500 fps. IMR 4064 has data going up to 2600.
So I shot today, very sunny, wind blowing straight in my face. The chrony is a POS range chrony and probably is 40 fps error +/- although when I chronied my Swede it seemed dead on. Of course I dont have any Hirtenber factory ammo to chrony to see how it performs out of the SSG..
38.8 gave me an average of 2257 with an ES of 29.3. 39 grains gave me an average of 2262 with an ES of 51.6. These were fired wiith a warm, dirty barrel. Both grouped about 3/4 inch. Interestingly,l plugging in my specific numbers into Quickload predicts 2388 at 39.8 and 2400 at 39, difference of 123 fps and 138 respectively
Primers are not flat, recoil isnt bad, no noticeable case problems althio I did not measure expansion ring.
Now the issue is..
If I increase to 39.5 and then 40, it seems that at best I will achieve, at 40 will be per quickload 2455, if I take off 125 for the appaenrent difference btween observed velocities and Quickload predictions (and I have my bbl legnth and all other parmaeters plugged in) I am at 2325 which is consistent with the velocity steps I have been observing ( about 30fps per .5 grain)...if i run to 40.4 I would probably observe velocites of about 2350...I want to be at 2399...or as close as possible...
Now Quickload predicts with 41 I am at 2510, which based on observed velosities would put me close to where I want to be..OF COURSE, keeping in mind that I have no factory 190 grain Hirtenber to chrony out of an SSG to establish a benchmark....this however, while normal pressure per Quickload of 49406, the load is still HIGHER r than called for in the Sierra manual..also the pressure is a bit higher than the hirtenberger load.
So bottom line...do I keep working up with RL 15 even if I have to EXCEED the manual figures (of course keeping my eye on pressure), or should I just ditch it and move to IMR...interesting per quickload, IMR 4064 is giving higher pressures for the same velocity as is N140....eVEN imr 4320 AND n540 show predicted higher pressures to acheive the same velocity as RL15..
Keep in mind this is Alaska...cant really get Norma or some of the exotics.,....
WildconfusedAlaska
I want to duplicate the Hirtenberger match 308 load with the 190 grain match king. This is the load that my Swarovski scope is cammed for, and supposedly is optimized for the SSG.
Hitenberger gives a lot of info about the load. It is running 730m/s which translates out to about 2400 fps. OAL is 2.799. The powder they use is Bofors NP3, uunavialable in the US, but several powders are close to the burning rate and I chose RL 15 becasue it is available up here. The other 2 powders at the same buring rate that I can get up here are IMR4064 and maybe Vitavouri N140
Dont know what type of rifle they used to shoot to derive there velocity
So I will use Win 1x fired cases, 190 MKs and RL 15 and Fed 210M and work from there.
The sierra manual uses a 26 in bbl Savage 1-10, probaly close enough to the SSG. they list 38.8 grains to acheive 2400. They max it out at 40.4 for 2500 fps. Interestingly, N140 in the maanual requires 39.6 grains and maxes out at 41.3 for 2500 fps. IMR 4064 has data going up to 2600.
So I shot today, very sunny, wind blowing straight in my face. The chrony is a POS range chrony and probably is 40 fps error +/- although when I chronied my Swede it seemed dead on. Of course I dont have any Hirtenber factory ammo to chrony to see how it performs out of the SSG..
38.8 gave me an average of 2257 with an ES of 29.3. 39 grains gave me an average of 2262 with an ES of 51.6. These were fired wiith a warm, dirty barrel. Both grouped about 3/4 inch. Interestingly,l plugging in my specific numbers into Quickload predicts 2388 at 39.8 and 2400 at 39, difference of 123 fps and 138 respectively
Primers are not flat, recoil isnt bad, no noticeable case problems althio I did not measure expansion ring.
Now the issue is..
If I increase to 39.5 and then 40, it seems that at best I will achieve, at 40 will be per quickload 2455, if I take off 125 for the appaenrent difference btween observed velocities and Quickload predictions (and I have my bbl legnth and all other parmaeters plugged in) I am at 2325 which is consistent with the velocity steps I have been observing ( about 30fps per .5 grain)...if i run to 40.4 I would probably observe velocites of about 2350...I want to be at 2399...or as close as possible...
Now Quickload predicts with 41 I am at 2510, which based on observed velosities would put me close to where I want to be..OF COURSE, keeping in mind that I have no factory 190 grain Hirtenber to chrony out of an SSG to establish a benchmark....this however, while normal pressure per Quickload of 49406, the load is still HIGHER r than called for in the Sierra manual..also the pressure is a bit higher than the hirtenberger load.
So bottom line...do I keep working up with RL 15 even if I have to EXCEED the manual figures (of course keeping my eye on pressure), or should I just ditch it and move to IMR...interesting per quickload, IMR 4064 is giving higher pressures for the same velocity as is N140....eVEN imr 4320 AND n540 show predicted higher pressures to acheive the same velocity as RL15..
Keep in mind this is Alaska...cant really get Norma or some of the exotics.,....
WildconfusedAlaska