Result of a little heat and.............
Jan 15, 2009 9:57:16 GMT -5
Post by Richard on Jan 15, 2009 9:57:16 GMT -5
high pressure.
ON Tuesday, I was back on the range along with Herman and our other "regular" shooting buddy Bill. I was only planning on a little muzzle loading along with shooting two of my varmint rifles. I really wanted to get scope settings on the custom .204 Ruger I built, by brought the right ammo with the wrong rifle. (.204 Ruger does not work in a .22BR) But did fire a few shots from a .17 MKIV I put together on a Sako action.
So, about the heat and high pressure. (the accompanying sheet has the stats) On group one, note the first shot out of a clean, dry, cold barrel.......This shot loaded Extremely hard. Two hands on the power rod and me on my knees getting it down the barrel. Duplex 22/48 - N110/322 First shot 2614. Then I used my cleaning regiment of one patch with 4 drops of Rem. bore cleaner in/out and one dry patch in/out. DID NOT use cool rod as the barrel still felt cold. This shot loaded normally for me and produced a normal 2574 fps velocity. First two shots pretty close. So here is the kicker: The barrel still felt relatively cold so I did not use the cool rod The resulting third shot did not recoil as much, I believe I observed some flash coming out the muzzle and when I checked the target, could not locate the shot? Looked at the chrono and 2257 fps velocity! Bingo, blown sabot. Proceeded to use cool rod for the last two shots and velocity returned to normal. Group not great!
So, my thought was this. The barrel was actually warmer on the inside (YES EDGE, you are correct ), the load was one of high pressure and the mmp short black sabots have given me several blown shots in the past. Always with high pressure loads.
This sabot works great and gives a good tight fit, but if the load is one of high pressure, there goes the sabot.
The second group was shot with the same charge, but using the Red Crush sabot. This combo loads easier, even though the diameter is the same.... .508" due to, I'm assuming, the ribs on the sides. It also reflects the slight lower velocity: 2579 vs. 2546 fps. Again, not a great group, but definitely capable of getting a critter at reasonable distances. Here again, this same combination on other other occasions has shot 1" to 2" groups? Consistently inconsistent but still accurate enough for hunting.
The third group had a reasonably decent extreme spread and the velocity was good (you can see the difference in POI) however shot three seemed to disappear? (same short black sabot but lower pressure load) The velocity was not out of line? When I actually picked up the target, all four holes appeared to be round?
But.......when I got home, I noticed a hole 9" to the left in the margin? So, was this actually the third shot? or, was it the disappeared third shot from the blown sabot in #1? And did I in fact have an exact double in that group........hmmmmmmmmm. Most likely, it was that third shot, but why? It felt good, I immediately looked at the target after the shot and fully expected it to be in the group?? Or is it just that Savage barrel thing.
So, provided your loads are not high pressure and you use the crush rib sabots, a" little extra heat" should not be a big problem. If it feels slightly warm on the outside, it is much warmer on the interior.
These are some of the things that caused me to order my Pac-Nor.
Richard
Yeah, that little .17 Mk IV (with a cheap BSA scope) even the flyers are close enough to produce minute of groundhog "eyeball"
Richard
ON Tuesday, I was back on the range along with Herman and our other "regular" shooting buddy Bill. I was only planning on a little muzzle loading along with shooting two of my varmint rifles. I really wanted to get scope settings on the custom .204 Ruger I built, by brought the right ammo with the wrong rifle. (.204 Ruger does not work in a .22BR) But did fire a few shots from a .17 MKIV I put together on a Sako action.
So, about the heat and high pressure. (the accompanying sheet has the stats) On group one, note the first shot out of a clean, dry, cold barrel.......This shot loaded Extremely hard. Two hands on the power rod and me on my knees getting it down the barrel. Duplex 22/48 - N110/322 First shot 2614. Then I used my cleaning regiment of one patch with 4 drops of Rem. bore cleaner in/out and one dry patch in/out. DID NOT use cool rod as the barrel still felt cold. This shot loaded normally for me and produced a normal 2574 fps velocity. First two shots pretty close. So here is the kicker: The barrel still felt relatively cold so I did not use the cool rod The resulting third shot did not recoil as much, I believe I observed some flash coming out the muzzle and when I checked the target, could not locate the shot? Looked at the chrono and 2257 fps velocity! Bingo, blown sabot. Proceeded to use cool rod for the last two shots and velocity returned to normal. Group not great!
So, my thought was this. The barrel was actually warmer on the inside (YES EDGE, you are correct ), the load was one of high pressure and the mmp short black sabots have given me several blown shots in the past. Always with high pressure loads.
This sabot works great and gives a good tight fit, but if the load is one of high pressure, there goes the sabot.
The second group was shot with the same charge, but using the Red Crush sabot. This combo loads easier, even though the diameter is the same.... .508" due to, I'm assuming, the ribs on the sides. It also reflects the slight lower velocity: 2579 vs. 2546 fps. Again, not a great group, but definitely capable of getting a critter at reasonable distances. Here again, this same combination on other other occasions has shot 1" to 2" groups? Consistently inconsistent but still accurate enough for hunting.
The third group had a reasonably decent extreme spread and the velocity was good (you can see the difference in POI) however shot three seemed to disappear? (same short black sabot but lower pressure load) The velocity was not out of line? When I actually picked up the target, all four holes appeared to be round?
But.......when I got home, I noticed a hole 9" to the left in the margin? So, was this actually the third shot? or, was it the disappeared third shot from the blown sabot in #1? And did I in fact have an exact double in that group........hmmmmmmmmm. Most likely, it was that third shot, but why? It felt good, I immediately looked at the target after the shot and fully expected it to be in the group?? Or is it just that Savage barrel thing.
So, provided your loads are not high pressure and you use the crush rib sabots, a" little extra heat" should not be a big problem. If it feels slightly warm on the outside, it is much warmer on the interior.
These are some of the things that caused me to order my Pac-Nor.
Richard
Yeah, that little .17 Mk IV (with a cheap BSA scope) even the flyers are close enough to produce minute of groundhog "eyeball"
Richard