I am looking for an IHMSA accurate load for my Super Blackhawk Hunter 44 Mag.
The accuracy of this gun was not very promising when I bought it many years ago. Jacketed bullets fell through cylinder throats which led me to suspect throats to be too large.
Now I finally purchased a set of pin gauges and I found out that a 0.432" gauge goes in the throats and a 0.433" does not, meaning the throat diameter is somewhere between 0.432" and 0.433". To verify the results I measured two Smith & Wesson 629s and got 0.429"-0.430" on both. Which confirms the Ruger has oversized throats. The motivation for this may be to lower peak pressures when shooting +P 300 gr hunting ammo.
This revelation gave me the idea to try larger diameter cast bullets, which I do not have so far, or driving jacketed 0.4295" bullets so hard that they hopefully obturate to fill the throat.
In the past couple of weeks I have experimented with Sierra 250 FPJ 0.4295" bullets in front of Vihtavuori N-110, Winchester Large Pistol primers. After two rounds of tests a charge of 19.4 grains seems promising. The next step is to make a larger batch of that load and start shooting in earnest, hopefully lessening the effect of shooter error.
These are the 25 meter (27ish yards) results today, in sub freezing 17 F temperatures.
3.5" (after this group I adjusted the sights to the right)
2.6"
2.3"
3.5" (maybe inconsistent hold and shooter fatigue caused the vertical spread?)
To be reasonably effective in IHMSA the gun should shoot 1"-1.5" groups at 25 yards. So the search and practice continues.
If someone sees a negative throat cutter that adds material instead of removing, please let me know. I would like to add a couple of thousandths of metal to make the throats smaller.
The accuracy of this gun was not very promising when I bought it many years ago. Jacketed bullets fell through cylinder throats which led me to suspect throats to be too large.
Now I finally purchased a set of pin gauges and I found out that a 0.432" gauge goes in the throats and a 0.433" does not, meaning the throat diameter is somewhere between 0.432" and 0.433". To verify the results I measured two Smith & Wesson 629s and got 0.429"-0.430" on both. Which confirms the Ruger has oversized throats. The motivation for this may be to lower peak pressures when shooting +P 300 gr hunting ammo.
This revelation gave me the idea to try larger diameter cast bullets, which I do not have so far, or driving jacketed 0.4295" bullets so hard that they hopefully obturate to fill the throat.
In the past couple of weeks I have experimented with Sierra 250 FPJ 0.4295" bullets in front of Vihtavuori N-110, Winchester Large Pistol primers. After two rounds of tests a charge of 19.4 grains seems promising. The next step is to make a larger batch of that load and start shooting in earnest, hopefully lessening the effect of shooter error.
These are the 25 meter (27ish yards) results today, in sub freezing 17 F temperatures.
3.5" (after this group I adjusted the sights to the right)
2.6"
2.3"
3.5" (maybe inconsistent hold and shooter fatigue caused the vertical spread?)
To be reasonably effective in IHMSA the gun should shoot 1"-1.5" groups at 25 yards. So the search and practice continues.
If someone sees a negative throat cutter that adds material instead of removing, please let me know. I would like to add a couple of thousandths of metal to make the throats smaller.
