Post by GLSHOOTER on Feb 24, 2018 13:49:25 GMT -8
This is the second report on the Consistent Crimp tools. I think the applications from this test will be interesting to those so inclined.
This test was different in that I selected a Remington 700 BDL in 243. This is a standard sporter with a 21" barrel as opposed to the varmint weight 223 with a 26" barrel in the first test. I bought this rifle at Cabelas in the summer of 2007. It was bought on a whim as I was picking up a 204 SPS Varmint and happened to see this one on the used rack.
If I read the dating on the barrel right it was manufactured about 1975. It came with a old Weaver 3X9 variable in Leupold mounts. My goal was to build a custom rifle on the action and since the price was only $300 I felt it was worth it. The bolt appeared to show little use as the bluing did not look worn. The stock has few dings but is in good shape with some pretty figure in spots. The overall bluing was in bad shape with lots of surface rust. The barrel looked OK but that never really tells the tale of future performance. All told I believe I would name this one my, "Corner Gun" as it looks like it was set up in the corner of a shed that was not very dry and basically left. It is the quintessential sows ear in my battery of rifles.
Here are a couple of pics of the rifle I decided to use that could come out of any house in the US:
I had never fired this rifle and figured that I actually might want to use it as a walking varminter so the test subject was picked. I went ahead and pulled the action and tweaked the trigger. Removed the Weaver and mounted up a 24 X Leupold target scope. I wanted everything going for the testing of the ammunition crimping tools and wanted as little me variation in play to skew the results.
I went through my manuals and the internet info from the powder company for a charge weight. I had already selected the 70 grain Hornady TNT bullet so now it was a matter of seeing what I had on the shelves for powder. IMR 4895 looked like a good one for top velocity and I had a supply of Federal LR primers. I also happened to have a large batch of once fired FC 243 brass that I bought back about 20 years ago that I had sized previously. I started looking and decided to trim the cases to the same length per spec and spent a pleasant afternoon trimming and deburring.
The next day I sat down and loaded up 110 rounds of test ammunition using a charge of 42.6 grains of IMR 4895. I used a PACT electronic powder dispenser and scale. All loads were weighed. I selected cartridges from the pile at random and started applying the Consistent Crimp with fifteen rounds loaded with ZERO crimp, and ten each at 5 ft/lb increments up to 45 ft/lbs with the final five rounds being done at 50 ft/lbs.
All done and then I waited for the weekend. Temps the first weekend were in the early spring level of 98-101. I'm glad it was cooling off. Range was 100 yards with the rifle set up on a front pedestal and rear bean bags filled with plastic pellets. The first five rounds were to zero the rifle then on to the test.
My procedure was to fire a five shot string taking barrel temperatures after each shot. The wind was gusting on all test days so there were times that some barrel cooling did occur between shots but it was negligible amount. I recorded the velocities using a CED Millennium chronograph and the targets were a freebie download from MY TARGETSthat provided me with an excellent set of reference points for the cross hairs on my scope. The Leupold hairs laid perfectly on the dark reference lines and were a tremendous aid in avoiding a cant and really allowed in the observation of issues with drift off center. After I shot the first five shot string I waited for the barrel to cool to ambient air temperature and repeated the shot string at that crimp pressure. Targets shown are the best of the two groups at each level.
Below are the targets shot across three separate weekend days. The first two sessions saw temperatures from 98-102 on Day #1 and 100 - 103 on Day #2 with Day #3 being a balmy 89 - 91. The chronograph/temp data with a compiled group size is shown in the last three pictures. Notice the variation in the muzzle velocity between the 89 degree days vs the 102 degree day. Also note the SD's and Extreme Velocity spreads for the strings realizing that all charges were thrown, weighed and bullets seated on the same day. The three biggest spread strings turned in the best groups if I am interpreting them correctly.
Complied Chronograph and Temperature Data
Now that you have my downrange results and the data compilation in front of you I'll give you my interpretation.
An overview of the targets laid out shows trending of group movement as the crimp pressure is altered. The Zero crimp target is the baseline that I established for the testing once I got it sighted in to place the rounds into an area that was easily observable with the spotting scope and scope combinations.
As the crimp pressure increased the rifle seemed to want to print more and more to the right from the reference impact point. Movement of center impact moved up to one inch from start to finish. Also of note was that the groups also started a very slight, yet detectable, drift lower in their centers. One half to three quarters of an inch vertical depression was noted with the largest margin being a full one inch.
Group shape on the reference target was a bit of an oval. The groups started varying in shape as the test progressed with 15 ft/lbs target being the one that we all like to see. A nice little cluster with most bullets touching if not all together. Lateral dispersion was noted in the rounds that were given pressures in the 25 and 35 ft/lb levels. The 25 ft/lb group was the smiley event for this run.
Looking a the targets I note that many have four relatively close holes with a single bullet popping out of the general area. Probably a shooter error in 75% of these but we all have limitations in our abilities at times. Even when one "got away" the group sizes were not so large as to make any of the loads unusable. Only three of the eleven record groups shot had measurements exceeding one inch. Taking the best four of these all put those groups firmly into the sub-MOA range. None would have missed a deer sized animal under 400 yards although some PD's would be laughing later at the big bees they dodged.
As mentioned earlier, I shot two groups at each pressure except the 50 ft/lb level was only one group. I felt the highest pressure was excessive and far more than I would ever put on a cartridge of this type. The actual "felt" experience of the crimp adjustment was very informative. I had never used the Lee Factory Crimp Die previous to these experiments and was pleasantly surprised by the results. Five ft/lbs of pressure was almost unnoticeable as compared to zero crimp. As the pressure increased it became more and more obvious that something was happening up inside that die. The press handle was much more firm and the torque wrench arrangement made it quite repeatable for felt effort. As stated, fifty ft/lbs is a bunch of pressure and I was having to lean on it a bit.
I have recorded the results of both groups in my data sheet. The majority of the "big" groups not pictured were obviously the guy at the bench on that pass. Even with operator error the only group exceeding 1 1/2 inches was on the 25 ft/lb crimp pressure and was the second group shot for record at that level. The learning curve of a reworked trigger probably had something to do with this one as the previous group was about 45% smaller.
Back to back group sizes that really indicate consistent shooting and performance of the crimping tool was demonstrated at all levels. Only three group pairs varied in overall size by more than 0.2 inches. Extrapolating for best scene scenario that would mean a variation only one inch at 500 yards. Who knows if I got caught by a wind change or just plain flinched but the indications for use are there.
I like the best four evaluating tool for my own personal use. I always suspect that it is just a very minor technique failure when one bullet drifts out of the group. Hence the re-shooting for verification of a "good" load at the next range trip. Obviously a bullet that ends up two inches out is more than likely a complete breakdown in the shooting platform if we are talking 3/4 inch four shot clusters.
Overall my pick for the pressure level for this bullet set up for this rifle with these components would be the application of 15 ft/lbs of crimp. The average group size at this setting was 0.48 with the best four shot combined average group size of 0.347. Second choice would be the 5 ft/lb crimp level. Average group size was 0.799 with a four shot combined average of 0.554
Using a baseline of 1.064 with Zero crimp shows some comparisons that are promising. Ten more groups fired yielded two that exceeded the baseline with an overall average of the ten groups with crimp being 0.868. This equates to a group decrease in size of approximately 20 %. Smallest group vs baseline shows a 60 % decrease in group size.
Looking at only the best four shots in the ten groups shot with a crimp using a baseline of 0.83 shows and overall crimped average group of 0.638. This equates to a decrease of approximately 24 %. Smallest four shot group vs baseline four shot group shows a 70 % decrease in size.
Data that allows interpretation in several areas was obtained and based on my assessment of my experience with this rifle and load I know that it does respond positively to a crimp pressure of 15 ft/lbs with two groups at that level showing, too me, definitive evidence for that conclusion.
The issue of barrel temperature didn't seem to enter in to the results to any degree in this test. Group size did not appear to vary much as I shot one group to the next. Bullet impact did not trend up or down, as is often seen in a heated barrel. The speed of the shooting, along with the cool down periods, placed little stress on the platform. What I found was that the most the barrel ever heated up near the chamber area following a five shot string only encompassed less than a 12 degree spread. The effect of merely leaving the rifle out in the sun here in Arizona for fifteen minutes would far exceed this. I don't wear Nomex gloves when I shoot so I prefer to keep the direct sun off the rifle. I have experienced the pain of picking up an Arizona sun pre-heated rifle during a match and it is something that I do not wish to experienced again in the near future.
One interesting note was that velocities did vary on the same day with the temperature varying by one or two degrees. Crimp must have has some play in this as the hot days of 98 to the days of 103 showed a change of 23 FPS. The drop to 90 degrees on Day #3 showed a velocity drop of 77 FPS between high and low. I also noted that published velocity for this load was 3558 , from Hodgdon, which was reflected on the last group of 50 FT/lbs on the last day at 92 degrees? Coincidence? I think not. The effect of heat here in Arizona on many powders is so obvious that it throws an extra challenge at the reloader and he/she must take into account that velocities will tend to be higher across the board when we push the 100+ envelope. Normal reloading data is done at, I believe, 70 degrees so an increase of 2 % in velocity is not unheard of. My testing showed this anecdotally and while the velocities are higher a 2% increase is well with in the range of expected variation of even factory ammunition.
One other statistic that is always fascinating to me is the Standard Deviation numbers. All loads were weighed and all loaded on the same day yet SD varied from 9.02 to 30.59. Hand in hand with SD is the Extreme Spread. Excluding the coolest day of testing I observed an ES 115 FPS from lowest to highest shots fired. The crimp level with the highest SD, 30.59 and the highest ES, 102, turned in the second best group series. The best group series showed a middle of the road SD, 20.7, while it had the fourth highest ES of 72
I spent about 14 hours on the range doing this work up. I got some great trigger time with a "new" old rifle that has been rode hard and put up wet. Looking at it on the rack all I could see was a donor rifle for a tube gun action. I may well be looking at a 30-06 BDL for that now. I was able to evaluate the Consistent Crimp tools and the Thermometer system. The benefits of the system spoke volumes to me when I sat down and really looked at the data. I was impressed with the crimp process and what effect it had on the ultimate performance of the rifle.
I'm very glad that I have the tool available in my reloading room and will be using it again in the near future. This test was on a standard weight 243 that lots of us have tucked away for deer season until we can buy that 6.8 or the laws get changed. I'll be doing a test on a run of the mill AR later as I have ammo all loaded and crimped and ready to go for that one. I know that after the first test with may 223 Varmint that I bought an RCBS Rockchucker Supreme so I would have a platform to use the tool on.
Thank you all for reading the review and please comment. If you have questions about the test method or any difficulties I had just sing out. If you think that the test was not valid please share what you would have done differently.
Greg
This test was different in that I selected a Remington 700 BDL in 243. This is a standard sporter with a 21" barrel as opposed to the varmint weight 223 with a 26" barrel in the first test. I bought this rifle at Cabelas in the summer of 2007. It was bought on a whim as I was picking up a 204 SPS Varmint and happened to see this one on the used rack.
If I read the dating on the barrel right it was manufactured about 1975. It came with a old Weaver 3X9 variable in Leupold mounts. My goal was to build a custom rifle on the action and since the price was only $300 I felt it was worth it. The bolt appeared to show little use as the bluing did not look worn. The stock has few dings but is in good shape with some pretty figure in spots. The overall bluing was in bad shape with lots of surface rust. The barrel looked OK but that never really tells the tale of future performance. All told I believe I would name this one my, "Corner Gun" as it looks like it was set up in the corner of a shed that was not very dry and basically left. It is the quintessential sows ear in my battery of rifles.
Here are a couple of pics of the rifle I decided to use that could come out of any house in the US:
I had never fired this rifle and figured that I actually might want to use it as a walking varminter so the test subject was picked. I went ahead and pulled the action and tweaked the trigger. Removed the Weaver and mounted up a 24 X Leupold target scope. I wanted everything going for the testing of the ammunition crimping tools and wanted as little me variation in play to skew the results.
I went through my manuals and the internet info from the powder company for a charge weight. I had already selected the 70 grain Hornady TNT bullet so now it was a matter of seeing what I had on the shelves for powder. IMR 4895 looked like a good one for top velocity and I had a supply of Federal LR primers. I also happened to have a large batch of once fired FC 243 brass that I bought back about 20 years ago that I had sized previously. I started looking and decided to trim the cases to the same length per spec and spent a pleasant afternoon trimming and deburring.
The next day I sat down and loaded up 110 rounds of test ammunition using a charge of 42.6 grains of IMR 4895. I used a PACT electronic powder dispenser and scale. All loads were weighed. I selected cartridges from the pile at random and started applying the Consistent Crimp with fifteen rounds loaded with ZERO crimp, and ten each at 5 ft/lb increments up to 45 ft/lbs with the final five rounds being done at 50 ft/lbs.
All done and then I waited for the weekend. Temps the first weekend were in the early spring level of 98-101. I'm glad it was cooling off. Range was 100 yards with the rifle set up on a front pedestal and rear bean bags filled with plastic pellets. The first five rounds were to zero the rifle then on to the test.
My procedure was to fire a five shot string taking barrel temperatures after each shot. The wind was gusting on all test days so there were times that some barrel cooling did occur between shots but it was negligible amount. I recorded the velocities using a CED Millennium chronograph and the targets were a freebie download from MY TARGETSthat provided me with an excellent set of reference points for the cross hairs on my scope. The Leupold hairs laid perfectly on the dark reference lines and were a tremendous aid in avoiding a cant and really allowed in the observation of issues with drift off center. After I shot the first five shot string I waited for the barrel to cool to ambient air temperature and repeated the shot string at that crimp pressure. Targets shown are the best of the two groups at each level.
Below are the targets shot across three separate weekend days. The first two sessions saw temperatures from 98-102 on Day #1 and 100 - 103 on Day #2 with Day #3 being a balmy 89 - 91. The chronograph/temp data with a compiled group size is shown in the last three pictures. Notice the variation in the muzzle velocity between the 89 degree days vs the 102 degree day. Also note the SD's and Extreme Velocity spreads for the strings realizing that all charges were thrown, weighed and bullets seated on the same day. The three biggest spread strings turned in the best groups if I am interpreting them correctly.
Complied Chronograph and Temperature Data
Now that you have my downrange results and the data compilation in front of you I'll give you my interpretation.
An overview of the targets laid out shows trending of group movement as the crimp pressure is altered. The Zero crimp target is the baseline that I established for the testing once I got it sighted in to place the rounds into an area that was easily observable with the spotting scope and scope combinations.
As the crimp pressure increased the rifle seemed to want to print more and more to the right from the reference impact point. Movement of center impact moved up to one inch from start to finish. Also of note was that the groups also started a very slight, yet detectable, drift lower in their centers. One half to three quarters of an inch vertical depression was noted with the largest margin being a full one inch.
Group shape on the reference target was a bit of an oval. The groups started varying in shape as the test progressed with 15 ft/lbs target being the one that we all like to see. A nice little cluster with most bullets touching if not all together. Lateral dispersion was noted in the rounds that were given pressures in the 25 and 35 ft/lb levels. The 25 ft/lb group was the smiley event for this run.
Looking a the targets I note that many have four relatively close holes with a single bullet popping out of the general area. Probably a shooter error in 75% of these but we all have limitations in our abilities at times. Even when one "got away" the group sizes were not so large as to make any of the loads unusable. Only three of the eleven record groups shot had measurements exceeding one inch. Taking the best four of these all put those groups firmly into the sub-MOA range. None would have missed a deer sized animal under 400 yards although some PD's would be laughing later at the big bees they dodged.
As mentioned earlier, I shot two groups at each pressure except the 50 ft/lb level was only one group. I felt the highest pressure was excessive and far more than I would ever put on a cartridge of this type. The actual "felt" experience of the crimp adjustment was very informative. I had never used the Lee Factory Crimp Die previous to these experiments and was pleasantly surprised by the results. Five ft/lbs of pressure was almost unnoticeable as compared to zero crimp. As the pressure increased it became more and more obvious that something was happening up inside that die. The press handle was much more firm and the torque wrench arrangement made it quite repeatable for felt effort. As stated, fifty ft/lbs is a bunch of pressure and I was having to lean on it a bit.
I have recorded the results of both groups in my data sheet. The majority of the "big" groups not pictured were obviously the guy at the bench on that pass. Even with operator error the only group exceeding 1 1/2 inches was on the 25 ft/lb crimp pressure and was the second group shot for record at that level. The learning curve of a reworked trigger probably had something to do with this one as the previous group was about 45% smaller.
Back to back group sizes that really indicate consistent shooting and performance of the crimping tool was demonstrated at all levels. Only three group pairs varied in overall size by more than 0.2 inches. Extrapolating for best scene scenario that would mean a variation only one inch at 500 yards. Who knows if I got caught by a wind change or just plain flinched but the indications for use are there.
I like the best four evaluating tool for my own personal use. I always suspect that it is just a very minor technique failure when one bullet drifts out of the group. Hence the re-shooting for verification of a "good" load at the next range trip. Obviously a bullet that ends up two inches out is more than likely a complete breakdown in the shooting platform if we are talking 3/4 inch four shot clusters.
Overall my pick for the pressure level for this bullet set up for this rifle with these components would be the application of 15 ft/lbs of crimp. The average group size at this setting was 0.48 with the best four shot combined average group size of 0.347. Second choice would be the 5 ft/lb crimp level. Average group size was 0.799 with a four shot combined average of 0.554
Using a baseline of 1.064 with Zero crimp shows some comparisons that are promising. Ten more groups fired yielded two that exceeded the baseline with an overall average of the ten groups with crimp being 0.868. This equates to a group decrease in size of approximately 20 %. Smallest group vs baseline shows a 60 % decrease in group size.
Looking at only the best four shots in the ten groups shot with a crimp using a baseline of 0.83 shows and overall crimped average group of 0.638. This equates to a decrease of approximately 24 %. Smallest four shot group vs baseline four shot group shows a 70 % decrease in size.
Data that allows interpretation in several areas was obtained and based on my assessment of my experience with this rifle and load I know that it does respond positively to a crimp pressure of 15 ft/lbs with two groups at that level showing, too me, definitive evidence for that conclusion.
The issue of barrel temperature didn't seem to enter in to the results to any degree in this test. Group size did not appear to vary much as I shot one group to the next. Bullet impact did not trend up or down, as is often seen in a heated barrel. The speed of the shooting, along with the cool down periods, placed little stress on the platform. What I found was that the most the barrel ever heated up near the chamber area following a five shot string only encompassed less than a 12 degree spread. The effect of merely leaving the rifle out in the sun here in Arizona for fifteen minutes would far exceed this. I don't wear Nomex gloves when I shoot so I prefer to keep the direct sun off the rifle. I have experienced the pain of picking up an Arizona sun pre-heated rifle during a match and it is something that I do not wish to experienced again in the near future.
One interesting note was that velocities did vary on the same day with the temperature varying by one or two degrees. Crimp must have has some play in this as the hot days of 98 to the days of 103 showed a change of 23 FPS. The drop to 90 degrees on Day #3 showed a velocity drop of 77 FPS between high and low. I also noted that published velocity for this load was 3558 , from Hodgdon, which was reflected on the last group of 50 FT/lbs on the last day at 92 degrees? Coincidence? I think not. The effect of heat here in Arizona on many powders is so obvious that it throws an extra challenge at the reloader and he/she must take into account that velocities will tend to be higher across the board when we push the 100+ envelope. Normal reloading data is done at, I believe, 70 degrees so an increase of 2 % in velocity is not unheard of. My testing showed this anecdotally and while the velocities are higher a 2% increase is well with in the range of expected variation of even factory ammunition.
One other statistic that is always fascinating to me is the Standard Deviation numbers. All loads were weighed and all loaded on the same day yet SD varied from 9.02 to 30.59. Hand in hand with SD is the Extreme Spread. Excluding the coolest day of testing I observed an ES 115 FPS from lowest to highest shots fired. The crimp level with the highest SD, 30.59 and the highest ES, 102, turned in the second best group series. The best group series showed a middle of the road SD, 20.7, while it had the fourth highest ES of 72
I spent about 14 hours on the range doing this work up. I got some great trigger time with a "new" old rifle that has been rode hard and put up wet. Looking at it on the rack all I could see was a donor rifle for a tube gun action. I may well be looking at a 30-06 BDL for that now. I was able to evaluate the Consistent Crimp tools and the Thermometer system. The benefits of the system spoke volumes to me when I sat down and really looked at the data. I was impressed with the crimp process and what effect it had on the ultimate performance of the rifle.
I'm very glad that I have the tool available in my reloading room and will be using it again in the near future. This test was on a standard weight 243 that lots of us have tucked away for deer season until we can buy that 6.8 or the laws get changed. I'll be doing a test on a run of the mill AR later as I have ammo all loaded and crimped and ready to go for that one. I know that after the first test with may 223 Varmint that I bought an RCBS Rockchucker Supreme so I would have a platform to use the tool on.
Thank you all for reading the review and please comment. If you have questions about the test method or any difficulties I had just sing out. If you think that the test was not valid please share what you would have done differently.
Greg