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I've had some batches of safety ladders worked up using CFE to get an idea of where my carbine stands with regard to velocity and consistency with Hodgdon's CFE223.
123gr A-MAX First
I had a suspicion that Hornady's data in the 9th Edition for 120-123gr pills could be based on the least common denominator of the projectile with the most drag in bore and start pressure sensitivity, which is the 120gr GMX solid copper unit.
Two things that steered me in that direction were the data meticulously recorded by Bwild97 here, and Hornady's CFE data for the 129gr SST, which is .5gr higher for the max load compared to the 120-123gr pills.
I already know that my Grendel handles 31.0gr of CFE well behind the 123gr A-MAX, so I wanted to run more extensive testing to see where the charge weight starts to spike.
I loaded 10 incremental charges, with 2 batches of each 10-round sequence. I used the longest COL I could get away with in my chamber and mags, which was
* 2.272"-2.277"
* once-fired Lapua brass
* Remington 7.5 primers
* 123gr A-MAX
* CFE223
Here's where you need to check yourself when viewing this data, because I literally expected to hit bad pressure signs much earlier. Thoroughly examine your experience with hand-loading before considering using any of the below data, especially since I set out to depart from published max loads.
A Chrony Beta Master was used for velocity readings as a potential indicator of pressure spikes, erratic deviations from a trend, or consistent charge weight to velocity increase. The Chronograph was at least 15ft from the muzzle. Temperature was 60 F measured on-site with a thermometer out of the sunlight, next to the shooting position.
Brass was measured before and after shooting, at the case web just above the extractor groove, using dial calipers in order to inspect for case web expansion (serious pressure sign). Before, measurements were consistently .441"-.442" at this location. After each round was fired, the chronograph reading was observed, recorded, and brass inspected visually and with the calipers.
31.1gr 2489 fps case web .441" dia., no ejector swipes, no primer abnormalities
31.4gr 2520 fps same, velocity increase was 31fps
31.7gr 2532 fps same, 12fps increase
32.0gr 2553 fps same, 21fps
32.3gr 2572 fps same, 19fps
At this point, I stopped and double-checked everything, since I was into some unusually fast velocities for a 16" Grendel with a 123gr A-MAX. I had not seen any significant jumps in velocity outside of 31fps at this point, which is consistent with .3gr increments in this case and other powder/projo combos.
I decided to seek the point of departure by pressing forward cautiously.
32.6gr 2598 fps no dimensional change in the web, primer GTG, 26fps increase
32.9gr 2612 fps same, 14fps
33.2gr 2640 fps primer starting to crater, 28fps increase
33.5gr 2698 fps slight cratering again, 58fps spike
At this point, I had found what I was looking for, which was a clear departure from the trend, confirmed with slightly cratered primers. I had to have been well above Grendel SAAMI Maximum Average Operating Pressure by then for certain. The question is, when did I exceed that point, and what is a safe load for me?
2698 fps from a 16" Grendel carbine pushing a 123gr A-MAX is some bad ju-ju, and you won't find any industry-tested data from a 24" gun to-date over 2650fps that I'm aware of.
Either way, CFE appears to be some very forgiving powder as to building pressure ideally in the Grendel. I chose not to fire the last round of 33.8gr, because I knew I would have even more of a cratered primer or worse, and I had already exceeded MAOP much earlier.
107gr SMK
I then moved on to my 107gr loads with CFE.
107gr SMK
CFE223
Lapua 1 x fired brass
Rem 7.5 Primer
2.275" COL
Everything went haywire at this point. I could not correlate one charge weight with a sensible velocity at all. I don't know if the Chrony went to lunch, the sun angle made readings skewed, or what. First time I have seen it with this chronograph.
31.5gr 2708 fps no pressure signs on brass or primers, velocity reading WTH?
31.8gr 2522 fps
32.3gr 2526 fps
32.7gr 2658 fps
33.0gr 2750 fps
33.3gr 2575
33.6gr 2672
33.8gr 2668
34.0gr 2757
I don't know if the cartridges were rearranged in my case, or got somehow out of sequence, but the brass was all fine, no cratered primers, nothing other than a mystery with the numbers, especially since the first and last loads were so close, as well as the middle????
Questions
I started wondering if my digital scale had been subjected to RF interference during the loading session at my bench, and other sanity checks, as this is the first time I have seen this type of behavior with the Grendel. I was definitely scratching my head.
It could also be that my COL is so long, that I'm spiking the pressure from the start with the ogive jammed into the lands. Dimensional variation in the projectiles can account for different jump and jam depths, even with the same raw COLs, so I think I need to consider reducing the COL.
Experiences in the past with TAC and the 100gr NBT showed pressure signs right where one would expect them when I exceeded published velocities for max loads with that combination, to include blatant ejector extrusion, cratered primers, and velocity excursions from the safe trendline. Today, I didn't see one single instance of ejector extrusion or even a hint of ejector shadow on either of the load batches.
Conclusions
CFE is a very forgiving powder in my Grendel at 60 F with the above loads. I need to reevaluate my bench, look at COLs again, and double-up Chronographs next trip. I'm still at a loss on the 107gr SMK's. I suspect a mistake somewhere on my part. Either way, many of the velocities were above max book value for 24" Grendels, which is a major red flag I think, but I also suspect that CFE will safely deliver noticeably higher velocities than any of the other powders I have worked with, and not spike.
Even at ~ max listed book data of 31.1gr under the 123gr A-MAX, I'm within 11fps of an 18" Grendel. What this day did for me was establish a set of known parameters where I can look for accuracy nodes in the future with my set-up.
BTW, every one of these loads was shot at 500yds on a large rock formation, with nice impacts. We video'd it through a spotting scope when I shot on IPSC steel as well.
123gr A-MAX First
I had a suspicion that Hornady's data in the 9th Edition for 120-123gr pills could be based on the least common denominator of the projectile with the most drag in bore and start pressure sensitivity, which is the 120gr GMX solid copper unit.
Two things that steered me in that direction were the data meticulously recorded by Bwild97 here, and Hornady's CFE data for the 129gr SST, which is .5gr higher for the max load compared to the 120-123gr pills.
I already know that my Grendel handles 31.0gr of CFE well behind the 123gr A-MAX, so I wanted to run more extensive testing to see where the charge weight starts to spike.
I loaded 10 incremental charges, with 2 batches of each 10-round sequence. I used the longest COL I could get away with in my chamber and mags, which was
* 2.272"-2.277"
* once-fired Lapua brass
* Remington 7.5 primers
* 123gr A-MAX
* CFE223
Here's where you need to check yourself when viewing this data, because I literally expected to hit bad pressure signs much earlier. Thoroughly examine your experience with hand-loading before considering using any of the below data, especially since I set out to depart from published max loads.
A Chrony Beta Master was used for velocity readings as a potential indicator of pressure spikes, erratic deviations from a trend, or consistent charge weight to velocity increase. The Chronograph was at least 15ft from the muzzle. Temperature was 60 F measured on-site with a thermometer out of the sunlight, next to the shooting position.
Brass was measured before and after shooting, at the case web just above the extractor groove, using dial calipers in order to inspect for case web expansion (serious pressure sign). Before, measurements were consistently .441"-.442" at this location. After each round was fired, the chronograph reading was observed, recorded, and brass inspected visually and with the calipers.
31.1gr 2489 fps case web .441" dia., no ejector swipes, no primer abnormalities
31.4gr 2520 fps same, velocity increase was 31fps
31.7gr 2532 fps same, 12fps increase
32.0gr 2553 fps same, 21fps
32.3gr 2572 fps same, 19fps
At this point, I stopped and double-checked everything, since I was into some unusually fast velocities for a 16" Grendel with a 123gr A-MAX. I had not seen any significant jumps in velocity outside of 31fps at this point, which is consistent with .3gr increments in this case and other powder/projo combos.
I decided to seek the point of departure by pressing forward cautiously.
32.6gr 2598 fps no dimensional change in the web, primer GTG, 26fps increase
32.9gr 2612 fps same, 14fps
33.2gr 2640 fps primer starting to crater, 28fps increase
33.5gr 2698 fps slight cratering again, 58fps spike
At this point, I had found what I was looking for, which was a clear departure from the trend, confirmed with slightly cratered primers. I had to have been well above Grendel SAAMI Maximum Average Operating Pressure by then for certain. The question is, when did I exceed that point, and what is a safe load for me?
2698 fps from a 16" Grendel carbine pushing a 123gr A-MAX is some bad ju-ju, and you won't find any industry-tested data from a 24" gun to-date over 2650fps that I'm aware of.
Either way, CFE appears to be some very forgiving powder as to building pressure ideally in the Grendel. I chose not to fire the last round of 33.8gr, because I knew I would have even more of a cratered primer or worse, and I had already exceeded MAOP much earlier.
107gr SMK
I then moved on to my 107gr loads with CFE.
107gr SMK
CFE223
Lapua 1 x fired brass
Rem 7.5 Primer
2.275" COL
Everything went haywire at this point. I could not correlate one charge weight with a sensible velocity at all. I don't know if the Chrony went to lunch, the sun angle made readings skewed, or what. First time I have seen it with this chronograph.
31.5gr 2708 fps no pressure signs on brass or primers, velocity reading WTH?
31.8gr 2522 fps
32.3gr 2526 fps
32.7gr 2658 fps
33.0gr 2750 fps
33.3gr 2575
33.6gr 2672
33.8gr 2668
34.0gr 2757
I don't know if the cartridges were rearranged in my case, or got somehow out of sequence, but the brass was all fine, no cratered primers, nothing other than a mystery with the numbers, especially since the first and last loads were so close, as well as the middle????
Questions
I started wondering if my digital scale had been subjected to RF interference during the loading session at my bench, and other sanity checks, as this is the first time I have seen this type of behavior with the Grendel. I was definitely scratching my head.
It could also be that my COL is so long, that I'm spiking the pressure from the start with the ogive jammed into the lands. Dimensional variation in the projectiles can account for different jump and jam depths, even with the same raw COLs, so I think I need to consider reducing the COL.
Experiences in the past with TAC and the 100gr NBT showed pressure signs right where one would expect them when I exceeded published velocities for max loads with that combination, to include blatant ejector extrusion, cratered primers, and velocity excursions from the safe trendline. Today, I didn't see one single instance of ejector extrusion or even a hint of ejector shadow on either of the load batches.
Conclusions
CFE is a very forgiving powder in my Grendel at 60 F with the above loads. I need to reevaluate my bench, look at COLs again, and double-up Chronographs next trip. I'm still at a loss on the 107gr SMK's. I suspect a mistake somewhere on my part. Either way, many of the velocities were above max book value for 24" Grendels, which is a major red flag I think, but I also suspect that CFE will safely deliver noticeably higher velocities than any of the other powders I have worked with, and not spike.
Even at ~ max listed book data of 31.1gr under the 123gr A-MAX, I'm within 11fps of an 18" Grendel. What this day did for me was establish a set of known parameters where I can look for accuracy nodes in the future with my set-up.
BTW, every one of these loads was shot at 500yds on a large rock formation, with nice impacts. We video'd it through a spotting scope when I shot on IPSC steel as well.
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