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I first built my Grendel 8-9 years ago. This rifle was the first AR I had built, so everything was a learning experience. And politcs being what they were at the time (the more things change . . .), rifle parts were somewhat in short supply. You could find things, but you coulnd't necessarily find exactly what you wanted. Anyway, I originally wanted an 18" barrel, but I settled for a 16" lightweight stainless fluted barrel purchased directly from Alexander Arms. The original idea behind the gun was to be a deer, hog, and coyote hunting rifle, and that barrel fit that task perhaps better than I knew it did at the time.
I learned a ton about reloading and about ARs in general from that barrel/rifle. I'll hazard a guess to say I've shot that rifle more over the last 8 years than I've shot any other rifle I own. But, intended uses and preferences change. I hunt hogs a lot less than I thought I might, and I often find myself reaching more for a bolt action when headed to hunt deer. These days, I'm much more likely to shoot my Grendel in one of the various matches my local gun club hosts for ARs each month. For the last couple of years, I shot my lightweight AA barrel in those matches. It did fine, and I learned a lot and got better as a shooter, but reloading for and shooting in those matches left me wanting a different barrel.
The main reason was that I came to believe that AA barrel had very tight/short throat. I do not have the tools, skills, or expertise to say whether it was or was not within SAAMI specifications, but when I measured 123 grain Hornady match bullets (BTHP or later ELD-Ms), those bullets were jammed into the lands as measured with my Hornady tool at about the COAL listed in Hornady's manual and at which I've seen Hornady factory ammo to be loaded to. I never had trouble with Hornady factory ammo in that barrel, and I always loaded my handloads a bit under that to ensure no issues there, but it's something that made me a bit nervous/curious. Because I had to seat the bullet so deep in the case to stay off the lands, I didn't have any room to play with the COAL.
The second reason I wanted a new barrel was because accuracy out of the AA barrel was just okay. In general, I considered that barrel to be a 1.5" inch barrel on average and over time. I shot some groups smaller than that, of course, but I also shot larger groups; so, in general that rifle was an average 1.5 MOA rifle. And, that skinny barrel sure did heat up when shooting a 20-round string in competition. Just fine for hunting, and not bad overall for a gas gun in my experience. But . . . what if a custom barrel could do better?
So, last fall I began researching AR Grendel barrels for the first time since I built the rifle. A couple of posts on this forum were incredibly helpful, even though I didn't ultimately listen. I learned of X-Caliber from one of the members of my local gun club who shoots at a very high level, and I ultimately went with them. I was debating between X-Caliber and a Criterion chambered by Precsions Firearms, and I let X-Caliber's early December 20% off sale and slightly shorter advertised lead time decide the issue. I ordered a stainless 18" SPR contour barrel with a rifle-length gas system; 1:8 twist with 5R rifling. I know that a 20" heavy barrel wold fit the match application better, but I just can't give up on the idea of this being a dual purpose rifle, which is part of the reason I stuck with the Grendel instead of going to a 6mm.
The barrel was delivered in early January, a few weeks ahead of schedule. One of the first things I did was measure for COAL using the same lot of ELD-Ms I had last loaded for the old AA barrel. The new X-Caliber barrel gained 0.020" maximum COAL, which means I can seat those bullets out magazine length and not be into the rifling. Check one. Check two was shooting some factory Hornady ammo through it to make sure everything was working correctly and to tune the gas block. The first four 5-shot groups out of the gun probably averaged 1.25" and all were under 1.5." Since I was playing with the gas system and otherwise just breaking the barrel in, I didn't get too hung up over groups. The rifle works and didn't just vomit all over the target with factory ammo the first time out.
Check three came on something I wasn't looking for but think may actually be kinda important now. When I went to measure the fired cases with a headspace comparator to adjust my reloading dies to the new barrel, I learned that they only stretched about .003" - .004" over unfired factory brass. Cases fired in my old AA barrel were stretching 0.010" in a single firing. Whether this translates into longer case life or not remains to be seen, but I would think it might. In any event, I view gettng a tighter chamber with a longer throat to be a plus.
Next to initial load devlopment. My old AA barrel shot basically every 123 grain Hornady bullet at about 2450 fps into about 1.5" to about the same point of aim when loaded over 31 grains of CFE 223. As a result, I have a fair amount of CFE 223 sitting around. So, I decided to load up several ladders with 123 ELD-Ms and that powder for initial load devlopment. I didn't even try alternative bullets or powdes on this first trip to the range. The results were underwhelming. Only one of my 5-shot groups was under 1.5" at 100 yards. The largest was over 2.5." Yikes! I know the barrel likes the ELD-M bullet okay because the factory ammo shot decent, so for now I'm blaming the powder. Which is a bummer becasue CFE 223 was my go-to powder in the old barrel and I have several pounds of it. (I also use for loading 223, but I don't shoot 223 very often).
Back to the drawing board. Second effort was to test 123 Lapua Scenars and 123 ELD-Ms with Benchmark and AR-COMP powders. One 10-shot ladder string, in .3 grain powder increments, for each bullet-powder combo, shot over a chronograph. The Benchmark-ELDM combo put 10 rounds within just ove an inch at 100 yards when there was over 150 fps in velocity spread between the top of the ladder and the bottom. The Benchmark-Scenar ladder measued about 1.2, whereas both AR-COMP ladders measured right at 1.5" for 10 shots. So, Benchmark is showing some promise. Unfortunately, Benchmark is topping out at about 2400 fps with the 123s. AR-COMP got me up to 2500 fps, but it's pretty hard to find rght now and very expensive when one does.
After range trip #2, I loaded up a few 5-shot ladders of 123 ELDMs and Benchmark with seveal powder charges near the top-end of published data. I also loaded some 5-shot ladders of Scenars with AR-COMP to test again as well becasue the velocity was great and I wanted to see how they shot when all shots in the group had the same powder charge. The goal here is to find a match load I can use this season, at least until I get some other powders and bullets tested. Unfortunately, the first match was this past Sunday and I hadn't had a chance to do my testing yet. So, I just loaded up a bunch of ammo using 27 grains of Benchmark and 123 ELD-Ms, and shot the match with those.
The match is called an "AR Tactical" match, but there's not much "tactical" about it. It's a short range, 300 yard match shot slow-fire prone. Target is an MR-63 with a 2.85" X-ring and 5.85" 10-ring. For equipment, you can use a field style bipod and rear bag without ears, and scopes can go up to 16 power. I use a magpul bipod, basic can-style rear bag from Midway, and a Vortex Viper HST 4-16x44. There was a fair bit of wind (10-20), and it was fishtailing all afternoon. Wind was predominantly from the southwest but blew everywhere from straigth out of the west to from the southeast. I shot a 577-16X, which is about as well as I've shot in that match. I had five 8s on the day; most of them were wind changes I missed, but there were a couple I can't explain. Winner shot a 587-21X, also with a Grendel. I've attached screenshots from my shotmarker targets.
So far, I'm generall pleased with the new barrel, though the verdict is still out until I complete load devlopment. I'm cautiously optimistic I'll find be able to find a good load with decent velocity. I plan to update this as I continue to shoot and learn the new barrel.
I learned a ton about reloading and about ARs in general from that barrel/rifle. I'll hazard a guess to say I've shot that rifle more over the last 8 years than I've shot any other rifle I own. But, intended uses and preferences change. I hunt hogs a lot less than I thought I might, and I often find myself reaching more for a bolt action when headed to hunt deer. These days, I'm much more likely to shoot my Grendel in one of the various matches my local gun club hosts for ARs each month. For the last couple of years, I shot my lightweight AA barrel in those matches. It did fine, and I learned a lot and got better as a shooter, but reloading for and shooting in those matches left me wanting a different barrel.
The main reason was that I came to believe that AA barrel had very tight/short throat. I do not have the tools, skills, or expertise to say whether it was or was not within SAAMI specifications, but when I measured 123 grain Hornady match bullets (BTHP or later ELD-Ms), those bullets were jammed into the lands as measured with my Hornady tool at about the COAL listed in Hornady's manual and at which I've seen Hornady factory ammo to be loaded to. I never had trouble with Hornady factory ammo in that barrel, and I always loaded my handloads a bit under that to ensure no issues there, but it's something that made me a bit nervous/curious. Because I had to seat the bullet so deep in the case to stay off the lands, I didn't have any room to play with the COAL.
The second reason I wanted a new barrel was because accuracy out of the AA barrel was just okay. In general, I considered that barrel to be a 1.5" inch barrel on average and over time. I shot some groups smaller than that, of course, but I also shot larger groups; so, in general that rifle was an average 1.5 MOA rifle. And, that skinny barrel sure did heat up when shooting a 20-round string in competition. Just fine for hunting, and not bad overall for a gas gun in my experience. But . . . what if a custom barrel could do better?
So, last fall I began researching AR Grendel barrels for the first time since I built the rifle. A couple of posts on this forum were incredibly helpful, even though I didn't ultimately listen. I learned of X-Caliber from one of the members of my local gun club who shoots at a very high level, and I ultimately went with them. I was debating between X-Caliber and a Criterion chambered by Precsions Firearms, and I let X-Caliber's early December 20% off sale and slightly shorter advertised lead time decide the issue. I ordered a stainless 18" SPR contour barrel with a rifle-length gas system; 1:8 twist with 5R rifling. I know that a 20" heavy barrel wold fit the match application better, but I just can't give up on the idea of this being a dual purpose rifle, which is part of the reason I stuck with the Grendel instead of going to a 6mm.
The barrel was delivered in early January, a few weeks ahead of schedule. One of the first things I did was measure for COAL using the same lot of ELD-Ms I had last loaded for the old AA barrel. The new X-Caliber barrel gained 0.020" maximum COAL, which means I can seat those bullets out magazine length and not be into the rifling. Check one. Check two was shooting some factory Hornady ammo through it to make sure everything was working correctly and to tune the gas block. The first four 5-shot groups out of the gun probably averaged 1.25" and all were under 1.5." Since I was playing with the gas system and otherwise just breaking the barrel in, I didn't get too hung up over groups. The rifle works and didn't just vomit all over the target with factory ammo the first time out.
Check three came on something I wasn't looking for but think may actually be kinda important now. When I went to measure the fired cases with a headspace comparator to adjust my reloading dies to the new barrel, I learned that they only stretched about .003" - .004" over unfired factory brass. Cases fired in my old AA barrel were stretching 0.010" in a single firing. Whether this translates into longer case life or not remains to be seen, but I would think it might. In any event, I view gettng a tighter chamber with a longer throat to be a plus.
Next to initial load devlopment. My old AA barrel shot basically every 123 grain Hornady bullet at about 2450 fps into about 1.5" to about the same point of aim when loaded over 31 grains of CFE 223. As a result, I have a fair amount of CFE 223 sitting around. So, I decided to load up several ladders with 123 ELD-Ms and that powder for initial load devlopment. I didn't even try alternative bullets or powdes on this first trip to the range. The results were underwhelming. Only one of my 5-shot groups was under 1.5" at 100 yards. The largest was over 2.5." Yikes! I know the barrel likes the ELD-M bullet okay because the factory ammo shot decent, so for now I'm blaming the powder. Which is a bummer becasue CFE 223 was my go-to powder in the old barrel and I have several pounds of it. (I also use for loading 223, but I don't shoot 223 very often).
Back to the drawing board. Second effort was to test 123 Lapua Scenars and 123 ELD-Ms with Benchmark and AR-COMP powders. One 10-shot ladder string, in .3 grain powder increments, for each bullet-powder combo, shot over a chronograph. The Benchmark-ELDM combo put 10 rounds within just ove an inch at 100 yards when there was over 150 fps in velocity spread between the top of the ladder and the bottom. The Benchmark-Scenar ladder measued about 1.2, whereas both AR-COMP ladders measured right at 1.5" for 10 shots. So, Benchmark is showing some promise. Unfortunately, Benchmark is topping out at about 2400 fps with the 123s. AR-COMP got me up to 2500 fps, but it's pretty hard to find rght now and very expensive when one does.
After range trip #2, I loaded up a few 5-shot ladders of 123 ELDMs and Benchmark with seveal powder charges near the top-end of published data. I also loaded some 5-shot ladders of Scenars with AR-COMP to test again as well becasue the velocity was great and I wanted to see how they shot when all shots in the group had the same powder charge. The goal here is to find a match load I can use this season, at least until I get some other powders and bullets tested. Unfortunately, the first match was this past Sunday and I hadn't had a chance to do my testing yet. So, I just loaded up a bunch of ammo using 27 grains of Benchmark and 123 ELD-Ms, and shot the match with those.
The match is called an "AR Tactical" match, but there's not much "tactical" about it. It's a short range, 300 yard match shot slow-fire prone. Target is an MR-63 with a 2.85" X-ring and 5.85" 10-ring. For equipment, you can use a field style bipod and rear bag without ears, and scopes can go up to 16 power. I use a magpul bipod, basic can-style rear bag from Midway, and a Vortex Viper HST 4-16x44. There was a fair bit of wind (10-20), and it was fishtailing all afternoon. Wind was predominantly from the southwest but blew everywhere from straigth out of the west to from the southeast. I shot a 577-16X, which is about as well as I've shot in that match. I had five 8s on the day; most of them were wind changes I missed, but there were a couple I can't explain. Winner shot a 587-21X, also with a Grendel. I've attached screenshots from my shotmarker targets.
So far, I'm generall pleased with the new barrel, though the verdict is still out until I complete load devlopment. I'm cautiously optimistic I'll find be able to find a good load with decent velocity. I plan to update this as I continue to shoot and learn the new barrel.
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