Well I thought I would share an observation tht came about today for me.
Yesterday I decided to pull out my Rem 700 6BR with a 10 twist and fire a few reloads down range. It had not been fired since August 30.
The load at that time was 30.8 grs of H4895 and a 95 gr Sierra Match King coming out of the 26" barrel at around 3100 + or -. It was jammed 10 thou into the lands. The temp that day was not known as I did not mark it down.
I would assume that it must have been in the low 20's celcius that day. I know there was not a lot of wind when I fired that group. The 95 gr SMK had no problem stabilizing at 1000 yards. My best target was 4 out of 5 shots into a group just under 6". I was tickled as hell for only my second time shooting at that distance.
The holes in the target at that distance were perfect little round 6mm holes.
The rest of the story.
Yesterday I loaded up JUST 7 rounds to confirm the load was still pretty good despite the more than 40 deg temp swing.
Set a target out at 100 and proceeded to shoot the 7 rounds and not hit the paper. I adjusted the scope thinking I had not rezeroed after shooting at 1000 yards but could not confirm as I only had 7 rounds.
The only thing that I had done since it was last shot was strip the barreled action out of the stock and give a thorough wipe of oil to prevent rust and reassemble. It went into the locker until just yesterday.
When I got home I checked to make sure nothing was loose. All seemed 100%. Decided to clean the bore thoroughly and make more loads to check the gun at 100 yards today.
Made 16 rounds of the exact same load as yesterday. The only difference was going up to 31.0 grs from 30.8.
Headed to the range, stapled a target at 25 yards, set up on rest and fired. There was no hole in the paper. Totally baffled I was. Since I played with the turrets yesterday I figured it must be low so I aimed at the top of the target and fired again. Finally, a hole but about 5" to low. I adjusted and fired again. That was better, but something was wrong. The hole looked mighty big for a 6mm hole. I proceeded to the target only to find that the 95gr SMK's were no longer stabilizing they were keyholing. Went back fired once more and another keyhole. Now I was starting to think, why?
I began to draw some conclusions and some of which I was pretty sure of the answers.
I thought I would share what I figure is the culprit. What could be a good or what one thinks is a good load one day and the next not worth sh++.
In reality when I built my 10 twist it was built around shooting the 95gr Berger. This was re an article I read from another site. I chose the 10 twist and the 95gr Berger because on paper at 1000 yards balistically the 95 gr Berger gave BETTER downrange ballistics than the 107 SMK's. I did not know iif I would ever shoot at 1000 so I was not concerned whether or not I could shoot to that distance. The 95gr Bergers proved to stabilize so I was happy but I thought I would try the then new 95gr SMK. They appeared to work and work well out to 1000 in August.
In theory the 10 twist is marginal for stabilization of the 95gr Berger or SMK but they appear to have worked for me until the last couple of days. What happened?
The only logical explanation I can find is the lack of muzzle velocity required to stabilize the 95gr SMK out of the 10 twist barrel. It was the velocity that helped stabilize those bullets and not the twist alone. The bullets needed that velocity to stabilize them which in Aug was around 3100 fps in say a +20deg temp. Today it was more than 40 degrees colder trying to shoot the same load just .02 grs more powder. It is not enough extra powder to make up the lack in velocity to stabilize the bullets.
Make sense? I think that is the explanation.
Tommorrow I will load up the same 31 grs but this time with the 95 gr Berger bullets which have approximately 55 thou shorter bearing surface than the 95gr SMK's and see whether or not they stabilize at 100 yards.
I have not played with the Bergers and H4895 as of yet but I will give it a shot tommorrow and see what comes of it.
I will not pull the current loads but will put them away until it warms up in the summer and try them again to see what happens at that time. I would like to think they will be okay?????????????????
I will take my chronograph and fire a round over it with the 95GR SMK's and see what they are coming out of the muzzle at. I would think there will be a substantial loss of velocity. I may try and bring the velocity up to make up the difference and see what happens as long as the pressure signs stay within limits.
Any thoughts from the PRO's out there?????????????????? Make sense?
Calvin
Yesterday I decided to pull out my Rem 700 6BR with a 10 twist and fire a few reloads down range. It had not been fired since August 30.
The load at that time was 30.8 grs of H4895 and a 95 gr Sierra Match King coming out of the 26" barrel at around 3100 + or -. It was jammed 10 thou into the lands. The temp that day was not known as I did not mark it down.
I would assume that it must have been in the low 20's celcius that day. I know there was not a lot of wind when I fired that group. The 95 gr SMK had no problem stabilizing at 1000 yards. My best target was 4 out of 5 shots into a group just under 6". I was tickled as hell for only my second time shooting at that distance.
The holes in the target at that distance were perfect little round 6mm holes.
The rest of the story.
Yesterday I loaded up JUST 7 rounds to confirm the load was still pretty good despite the more than 40 deg temp swing.
Set a target out at 100 and proceeded to shoot the 7 rounds and not hit the paper. I adjusted the scope thinking I had not rezeroed after shooting at 1000 yards but could not confirm as I only had 7 rounds.
The only thing that I had done since it was last shot was strip the barreled action out of the stock and give a thorough wipe of oil to prevent rust and reassemble. It went into the locker until just yesterday.
When I got home I checked to make sure nothing was loose. All seemed 100%. Decided to clean the bore thoroughly and make more loads to check the gun at 100 yards today.
Made 16 rounds of the exact same load as yesterday. The only difference was going up to 31.0 grs from 30.8.
Headed to the range, stapled a target at 25 yards, set up on rest and fired. There was no hole in the paper. Totally baffled I was. Since I played with the turrets yesterday I figured it must be low so I aimed at the top of the target and fired again. Finally, a hole but about 5" to low. I adjusted and fired again. That was better, but something was wrong. The hole looked mighty big for a 6mm hole. I proceeded to the target only to find that the 95gr SMK's were no longer stabilizing they were keyholing. Went back fired once more and another keyhole. Now I was starting to think, why?
I began to draw some conclusions and some of which I was pretty sure of the answers.
I thought I would share what I figure is the culprit. What could be a good or what one thinks is a good load one day and the next not worth sh++.
In reality when I built my 10 twist it was built around shooting the 95gr Berger. This was re an article I read from another site. I chose the 10 twist and the 95gr Berger because on paper at 1000 yards balistically the 95 gr Berger gave BETTER downrange ballistics than the 107 SMK's. I did not know iif I would ever shoot at 1000 so I was not concerned whether or not I could shoot to that distance. The 95gr Bergers proved to stabilize so I was happy but I thought I would try the then new 95gr SMK. They appeared to work and work well out to 1000 in August.
In theory the 10 twist is marginal for stabilization of the 95gr Berger or SMK but they appear to have worked for me until the last couple of days. What happened?
The only logical explanation I can find is the lack of muzzle velocity required to stabilize the 95gr SMK out of the 10 twist barrel. It was the velocity that helped stabilize those bullets and not the twist alone. The bullets needed that velocity to stabilize them which in Aug was around 3100 fps in say a +20deg temp. Today it was more than 40 degrees colder trying to shoot the same load just .02 grs more powder. It is not enough extra powder to make up the lack in velocity to stabilize the bullets.
Make sense? I think that is the explanation.
Tommorrow I will load up the same 31 grs but this time with the 95 gr Berger bullets which have approximately 55 thou shorter bearing surface than the 95gr SMK's and see whether or not they stabilize at 100 yards.
I have not played with the Bergers and H4895 as of yet but I will give it a shot tommorrow and see what comes of it.
I will not pull the current loads but will put them away until it warms up in the summer and try them again to see what happens at that time. I would like to think they will be okay?????????????????
I will take my chronograph and fire a round over it with the 95GR SMK's and see what they are coming out of the muzzle at. I would think there will be a substantial loss of velocity. I may try and bring the velocity up to make up the difference and see what happens as long as the pressure signs stay within limits.
Any thoughts from the PRO's out there?????????????????? Make sense?
Calvin
