Roy Weatherby made a living from long freebores and velocity.
6mm ARC - Practical Reloading
- Thread starter Henryrifle
- Start date
Hey Spotshooter:
Unfortunately, I am starting to think that -- I -- can't shoot an AR accurately. I have been as careful as I know to be without success but, let me relate this one experience to you: two weeks ago, I was thinking I had found the magic load. I was just sure it was the 108 ELD-M and 27 grains of Varget. I shot a 5-shot group at 100 yards and it shot a very acceptable (for this project) .52 MOA at 2554 FPS. I had 10 round left. I shot several at 700 yards on a 2.5 MOA (18") steel plate. With the remaining 4 shots I put 2 on the 800 yard gong and 2 on the 900 yard gong. Looking at the impacts through the scope, I estimated the hits to be 4" or less apart at both 800 and 900 yards. This is before additional testing and a lot of evidence that the combination of components listed above actually shoots much worse than that experience would indicate.
Maybe I need to stop testing at 100 yards and just go back to longer distance but the point I am trying to make -not arguing- is that if the rifle shoots in the .5s, 1000 yards should be very achievable on wind-calm days.
Henryrifle
Unfortunately, I am starting to think that -- I -- can't shoot an AR accurately. I have been as careful as I know to be without success but, let me relate this one experience to you: two weeks ago, I was thinking I had found the magic load. I was just sure it was the 108 ELD-M and 27 grains of Varget. I shot a 5-shot group at 100 yards and it shot a very acceptable (for this project) .52 MOA at 2554 FPS. I had 10 round left. I shot several at 700 yards on a 2.5 MOA (18") steel plate. With the remaining 4 shots I put 2 on the 800 yard gong and 2 on the 900 yard gong. Looking at the impacts through the scope, I estimated the hits to be 4" or less apart at both 800 and 900 yards. This is before additional testing and a lot of evidence that the combination of components listed above actually shoots much worse than that experience would indicate.
Maybe I need to stop testing at 100 yards and just go back to longer distance but the point I am trying to make -not arguing- is that if the rifle shoots in the .5s, 1000 yards should be very achievable on wind-calm days.
Henryrifle
I didn't necessarily mean that the long freebore was a negative but, how did Roy's long freebore, high velocity chambers shoot? I think the answer might be okay but not great? Is that close to right?
Henryrifle
Henryrifle,
Thanks for all your work. You’ve sent a bunch of rounds, time and $ downrange on this quest.
Yes, I’d send the bbl back.
I’d lean towards the ELD as far more jump tolerant than the Berger, at least in my experience. I too would stay away from 115 class bullets.
I applaud your efforts and desire. I do view the ARC as quite appropriate for your LR AR efforts and, on paper, it should excel in that role.
I’m looking forward to the end of this COVID induced financial funk. I will join you on the ARC quest, though likely in 20” Encore form.
Thanks for all your work. You’ve sent a bunch of rounds, time and $ downrange on this quest.
Yes, I’d send the bbl back.
I’d lean towards the ELD as far more jump tolerant than the Berger, at least in my experience. I too would stay away from 115 class bullets.
I applaud your efforts and desire. I do view the ARC as quite appropriate for your LR AR efforts and, on paper, it should excel in that role.
I’m looking forward to the end of this COVID induced financial funk. I will join you on the ARC quest, though likely in 20” Encore form.
Henryrifle,
I thought a Ruger RPR 6mm CM I had was a dud.
Once I tried very deliberate, different grips (as in hand pressure/finger placement), I found on that worked consistently and BINGO, precision and consistency were outstanding, especially for a production rifle.
I find the AR architecture to be trick, but learnable.
You might be on to something here but don’t give up quite yet. Anything you can do to maintain consistent cheek weld and separate your muscles into those that maintain and those few that squeeze the trigger will likely show up on target.
I thought a Ruger RPR 6mm CM I had was a dud.
Once I tried very deliberate, different grips (as in hand pressure/finger placement), I found on that worked consistently and BINGO, precision and consistency were outstanding, especially for a production rifle.
I find the AR architecture to be trick, but learnable.
You might be on to something here but don’t give up quite yet. Anything you can do to maintain consistent cheek weld and separate your muscles into those that maintain and those few that squeeze the trigger will likely show up on target.
Yes, I think that's a fair assessment. As with any factory rifle, results can vary a good bit, from gun to gun...and, one man's junk is another man's treasure. Fine guns with better than needed accuracy for the guy deer hunting in a tree. Some of them shoot surprisingly well but I've always considered the majority to be average, at best.
I'm not a fan of longer than needed freebores but my point was that he got good speeds without over pressuring things by using excessively long freebores. He marketed "speed"
G&G: I know you are right and appreciate the benefits of a longer throat.
lb-ft: Thank you for the advice. I recognize it as solid guidance. I believe that I am a good bolt gun trigger puller and know that I need to work on my AR skills. Not giving up but would like a second opinion on the barrel. I do have a new premium bolt that should arrive today or tomorrow. I do want to give that a try and bring along a shooting buddy who is a better AR driver than me!
Henryrifle
lb-ft: Thank you for the advice. I recognize it as solid guidance. I believe that I am a good bolt gun trigger puller and know that I need to work on my AR skills. Not giving up but would like a second opinion on the barrel. I do have a new premium bolt that should arrive today or tomorrow. I do want to give that a try and bring along a shooting buddy who is a better AR driver than me!
Henryrifle
Thanks and fwiw, I find AR's to often shoot best from a bench with the front rest right in front of the mag well and a firm hold on the gun. Hope that helps. I think you just have to test and see what works best on each gun. A long, heavy bbl will like a different hold and maybe moving the gun back on the front rest some vs a short barrel...think gun balance. The other thing is that the upper receiver is REALLY not very stiff on typical mil spec stuff...That's where the bbl is attached, so a little flex here can make a big difference.
I like the question, how did Roy's long freebore shoot? The real question is how well do they have to shoot?
Bench rest repeatability is not always the best for varmint shooting or other hunting. Roy's concept was reduced time of flight and secondary wound channel not bench rest rifles. For the most part but not all of Roy's cartridges for for medium to heavy game.
I have two examples but one will suffice. My Howa 1500 in 223 Remington loaded to fit the box magazine at 300 yards with a 55 grain projectile on low wind days could print a 1" group. However to get that result I was down to 3,175 average FPS. As the wind picked up just a bit that group spread to over 3". Enough to miss a chucks head, not good enough for field work.
So with a 1 in 12 twist heavier projectiles were not an option and of course the freebore was increased with lighter projectiles.
I ended up with a 40 grain load that prints 1 1/8" groups at 300 yards but now at 3,900 FPS an increase of 725 FPS and a flatter trajectory. Yes it's not my best 300 yard group but the reduced time of flight keeps the group spread in moderate wind to about 2" and shooting flatter is a plus. Making this rifle cartridge combination a reasonable 350 chuck gun, about the limit for a 1 shot 1 kill rifle 223 rifle.
So the answer for my case was accurate enough to head shoot a chuck in moderate wind at 300 yards. The result was not my best low or no wind group but a significant improvement in field accuracy in varied conditions.
An AR is in my opinion can be a duck the does not swim in the same pond with the other ducks. Some custom made AR platform rifles are as easy to shoot off the bench as bolt guns, but make rather poor field rifles. You'll see smaller magazines, longer barrels and sleeker rifles.
I find the basic AR, M4 and M16 handle very well as field rifles however they require dedicated practice if you use them as target rifles.
Just for fun or something like that I shot some 115 DTACs today. They were the rebated boat tail version. Quickload estimated 28.3 grains of CFE-223 would give a MV of 2524 FPS. That is enough speed to keep the projectile supersonic out to 1000 yards most summer days here in hot and humid Georgia. I measured a MV of 2509 FPS a difference of 15 FPS with the Labradar with an SD of 9.8. Not awesome but not terrible either. This shot goups of .97, 1.1 and 1.2 MOA at 100 yards. I can tell my standards are slipping [rapidly] but that is an average of 1.09 MOA. There most be some shooter error in there too right?
I have not tried it but I also happen to have an unused kit of David Tubb's Final Finish system. If I decide not to send the barrel back I'll run them but, I won't if I do send it back. I searched the web last night for any other available 6 ARC barrel--there wasn't a single one that I could find. I also called PTG to inquire about the wait time for their 6mm ARC reamers. It is not stocked, and, therefore, at least a 6-week or longer wait.
Interesting spot to be in. It looks like the OBT note for the DTACs is slower than I am shooting, around 2440 FPS. That would keep the projectile supersonic to 900 yards but not 1000. Might be worth a try to slow down that round.
On an interesting note, shooting the DTACs feels great. There is one solid thwack with each shot. The rifle feels extremely solid and you can't tell that there are several moving parts. That part, I really like. I shot these at mag length and have not measured what that jump is as of this writing.
Well, testing continues...
Hope y'all all have a great weekend.
Henryrifle
I have not tried it but I also happen to have an unused kit of David Tubb's Final Finish system. If I decide not to send the barrel back I'll run them but, I won't if I do send it back. I searched the web last night for any other available 6 ARC barrel--there wasn't a single one that I could find. I also called PTG to inquire about the wait time for their 6mm ARC reamers. It is not stocked, and, therefore, at least a 6-week or longer wait.
Interesting spot to be in. It looks like the OBT note for the DTACs is slower than I am shooting, around 2440 FPS. That would keep the projectile supersonic to 900 yards but not 1000. Might be worth a try to slow down that round.
On an interesting note, shooting the DTACs feels great. There is one solid thwack with each shot. The rifle feels extremely solid and you can't tell that there are several moving parts. That part, I really like. I shot these at mag length and have not measured what that jump is as of this writing.
Well, testing continues...
Hope y'all all have a great weekend.
Henryrifle
Lkwebb
Gold $$ Contributor
Www.dpgunworks.com
Resuming testing with a new barrel:
New barrel is finished, installed and ready for testing! It is the first AR barrel I have ever profiled, chambered, threaded and drilled. It is a Wilson match grade SS cut to 21 & 3/4” with a 7.7 twist. The profile is heavier than I want the finished rifle to be but, it will be good for testing the cartridge. It was chambered with a PTG 6mm ARC SAAMI standard reamer.
It has taken a while to assemble all the parts. The reamer was the longest wait but it is not easy to find barrel extensions or barrel extension pins at the moment. I used a .875” Superlative Arms adjustable gas block, Bravo Company extension and Thunderbeast CB muzzle brake. I am also using a JP Rifles bolt. The rest of the rifle is the same as the original with, VLTOR upper and lower, SSA-E trigger, Magpul STR stock and Ergo original grip with a free float hand guard.
I put together 20 break-in rounds using the Hornady 108 ELD-Ms and and 26.8 grains of Varget. I did the shoot and clean routine for 20 rounds. The first 5 rounds out of the barrel shot a .98 at 100 yards. Already better than the old barrel. Speeds were in the 2614 FPS range with single digit SDs.
After 25 shots of break-in I upped the load 2/10ths to 27.0 grains of Varget as that is were I had the most success with the old barrel. Results were mixed over three 5-shot groups: .9, .75 and .33 MOA. SDs were in the 4 to 5 FPS range. Speed was in the 2625 FPS range. I did try two 5-shot groups at 27.2. Noting very interesting there at 1.2 and .82 MOA.
I did also shoot two 5-shot groups of 105 Hornady Black factory ammo. That shot about as poorly as it did in the last barrel at 1.4 and 1.1 MOA. Average speed for both groups was 2700 FPS. SDs were 12 FPS.
Next steps are to get this data into a spreadsheet and match Quickload to it to plan the next testing charges.
Would have loved to see several .5 or better groups but this is not a bad start. On a personal note, I was relived that the rifle operated normally, fed from the magazine and ejected correctly without any failures.
Planning next steps…
Henryrifle
New barrel is finished, installed and ready for testing! It is the first AR barrel I have ever profiled, chambered, threaded and drilled. It is a Wilson match grade SS cut to 21 & 3/4” with a 7.7 twist. The profile is heavier than I want the finished rifle to be but, it will be good for testing the cartridge. It was chambered with a PTG 6mm ARC SAAMI standard reamer.
It has taken a while to assemble all the parts. The reamer was the longest wait but it is not easy to find barrel extensions or barrel extension pins at the moment. I used a .875” Superlative Arms adjustable gas block, Bravo Company extension and Thunderbeast CB muzzle brake. I am also using a JP Rifles bolt. The rest of the rifle is the same as the original with, VLTOR upper and lower, SSA-E trigger, Magpul STR stock and Ergo original grip with a free float hand guard.
I put together 20 break-in rounds using the Hornady 108 ELD-Ms and and 26.8 grains of Varget. I did the shoot and clean routine for 20 rounds. The first 5 rounds out of the barrel shot a .98 at 100 yards. Already better than the old barrel. Speeds were in the 2614 FPS range with single digit SDs.
After 25 shots of break-in I upped the load 2/10ths to 27.0 grains of Varget as that is were I had the most success with the old barrel. Results were mixed over three 5-shot groups: .9, .75 and .33 MOA. SDs were in the 4 to 5 FPS range. Speed was in the 2625 FPS range. I did try two 5-shot groups at 27.2. Noting very interesting there at 1.2 and .82 MOA.
I did also shoot two 5-shot groups of 105 Hornady Black factory ammo. That shot about as poorly as it did in the last barrel at 1.4 and 1.1 MOA. Average speed for both groups was 2700 FPS. SDs were 12 FPS.
Next steps are to get this data into a spreadsheet and match Quickload to it to plan the next testing charges.
Would have loved to see several .5 or better groups but this is not a bad start. On a personal note, I was relived that the rifle operated normally, fed from the magazine and ejected correctly without any failures.
Planning next steps…
Henryrifle
Do you have any more H4895 or XBR8208? They may not be the fastest, but people have seen good groups with them. I know you had mediocre groups with the other barrel and H4895 but might be worth a re-test. LeverEvolution is supposed to be the cat’s meow for velocity but I don’t like how temperature sensitive it is, but might be worth trying if you have some.
Big fan of H4895 for heavy .223 but not super enthusiastic about it for 6mm ARC. It gives a little more velocity than Varget but with a corresponding pressure increase. I will still give it a try. CFE223 gives great velocity results but generally with double digit SDs. That is probably okay for this application. Would like to try some LeverEvolution and have ordered a few pounds.
I am getting concerned that I can't find any of the powders that I'd like to be using for this cartridge for sale and am using existing supplies. Would like to find a good [great] baseline load with Varget or maybe Reloader 15 and then start experimenting with other powders for more speed. The truth is, any velocity above 2550 FPS with the 108 ELD-M meets my needs.
I have not seen any other links to actual load data and results. My Google fu must be weakening...
I am getting concerned that I can't find any of the powders that I'd like to be using for this cartridge for sale and am using existing supplies. Would like to find a good [great] baseline load with Varget or maybe Reloader 15 and then start experimenting with other powders for more speed. The truth is, any velocity above 2550 FPS with the 108 ELD-M meets my needs.
I have not seen any other links to actual load data and results. My Google fu must be weakening...
108-110gr Gas gun (52kpsi) in an 18” barrel.https://www.hornady.com/assets/site/hornady/files/load-data/6mm-ARC-gas-108-110gr-data.pdf
Lighter gas gun data: https://www.hornady.com/assets/site/hornady/files/load-data/6mm-arc-gas-58-105gr-data.pdf
Here is bolt gun data (rifle info in page headers): https://www.hornady.com/assets/site/hornady/files/load-data/6mm-arc-bolt.pdf
I’m actually interested to try AR-Comp, which is unfortunately not in any of the book data.
Lighter gas gun data: https://www.hornady.com/assets/site/hornady/files/load-data/6mm-arc-gas-58-105gr-data.pdf
Here is bolt gun data (rifle info in page headers): https://www.hornady.com/assets/site/hornady/files/load-data/6mm-arc-bolt.pdf
I’m actually interested to try AR-Comp, which is unfortunately not in any of the book data.
Spent some time at the range today testing Hornady's 108 ELD-M with both Varget and CFE223 and observed some better results with the new barrel. The purpose of the test was to calibrate Quickload to this barrel and to plumb around the minimum speed range that will work for my objectives.
All of the below are 5-shot groups at 100 yards shot from prone with an F-Class bipod and rear bag, Nightforce 5.5-22X50 optics and a COAL of 2.260 and an accu-wedge.
I tested Varget from 25.8 grains up to 26.4 grains in .2 grain increments. The most interesting groups came from:
26.0 grains 1.04 MOA @ 2558 FPS
26.2 grains .826 MOA @ 2574 FPS
26.4 grains .635 MOA @ 2599 FPS
If the above represents a trend, 26.6 and 26.8 grains would be interesting to test.
I tested CFE223 from 28.4 grains up to 29.2 grains in .2 grain increments. Below is the series:
28.4 grains .514 @ 2586 FPS
28.6 grains .662 @ 2603 FPS
28.8 grains .987 @ 2636 FPS
29.0 grains .989 @ 2649 FPS
29.2 grains .663 @ 2669 FPS
That looks like a series that might just be between two nodes, or, said differently, centered on a scatter node. The 29.2 grain group was shot in heavy rain and I may have shot a lucky group as the target was not crystal clear. Speed is great for my purposes with this powder. Perhaps on impulse I did buy a pound of LeverEvolution to try but based on the above, I want to finish this testing before adding a new variable.
Next steps are to test Varget at higher charge rates. At a minimum, I'll test 26.6 and 26.8 to see if the trend continues. For the CFE223 loads, I will test 28.0 and 28.2 as well as the other end at 29.4 and 29.6 even though that is likely a little above 52K PSI. Will also retest some of the better loads to see what, if anything, repeats.
Finally it is starting to get interesting...
Henryrifle
All of the below are 5-shot groups at 100 yards shot from prone with an F-Class bipod and rear bag, Nightforce 5.5-22X50 optics and a COAL of 2.260 and an accu-wedge.
I tested Varget from 25.8 grains up to 26.4 grains in .2 grain increments. The most interesting groups came from:
26.0 grains 1.04 MOA @ 2558 FPS
26.2 grains .826 MOA @ 2574 FPS
26.4 grains .635 MOA @ 2599 FPS
If the above represents a trend, 26.6 and 26.8 grains would be interesting to test.
I tested CFE223 from 28.4 grains up to 29.2 grains in .2 grain increments. Below is the series:
28.4 grains .514 @ 2586 FPS
28.6 grains .662 @ 2603 FPS
28.8 grains .987 @ 2636 FPS
29.0 grains .989 @ 2649 FPS
29.2 grains .663 @ 2669 FPS
That looks like a series that might just be between two nodes, or, said differently, centered on a scatter node. The 29.2 grain group was shot in heavy rain and I may have shot a lucky group as the target was not crystal clear. Speed is great for my purposes with this powder. Perhaps on impulse I did buy a pound of LeverEvolution to try but based on the above, I want to finish this testing before adding a new variable.
Next steps are to test Varget at higher charge rates. At a minimum, I'll test 26.6 and 26.8 to see if the trend continues. For the CFE223 loads, I will test 28.0 and 28.2 as well as the other end at 29.4 and 29.6 even though that is likely a little above 52K PSI. Will also retest some of the better loads to see what, if anything, repeats.
Finally it is starting to get interesting...
Henryrifle
XRing seems to like his 6 ARC bolt gun.
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