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6mm ARC - Practical Reloading

Gentlemen. ( Moved from general reloading)

Looking for some information from you experienced ( RSGs) Real Smart Guys. :)

Have loaded mag length pistol and rifle rounds before, have the loading manuals, and always attempt to stay on the safe side of pressures. Now my first attempt at long loading rifle rounds to single feed , my question is, any information in any of the loading manuals in regards to powder charge ? Where does one find such information, I am limited to 52,000 lbs in a gas gun, I am getting older ( not old) and would like to shoot a few more years with my son, so therefore I ask questions.

When you dont know what you dont know, you get in trouble.

Gentlemen I originally posted this question in the general reloading section. It seems to be getting off base there.

Let me state the situation
When using a Bob sled type mag to single feed a round into the chamber of a gas operated weapon, that has the bullet seated out past the loading manuals OAL , I am trying to find out how to safely determine safe powder charge. I know the manuals all state. MIN/ MAX for the specified length. With the bullet now seated further out, the operating pressure should now be reduced, to my way of reasoning. With the bullet now seated closer to the lands I would think maybe about a pressure spike.

I am looking to shoot the heavier, longer 6 MM bullets in my 6 ARC gas gun, for ELR shooting.
If I cant go past MAX powder charges and do it safely ( staying within the 52,000 lb) range is it worth trying to utilize the Bob sled mag and load to longer over all length.

Hopefully I have worded my question sufficiently. I know I am trying to get the little round to do a big task, but I also enjoy a challenge.

Thank you.
 
Retired shooter said:
Gentlemen. ( Moved from general reloading)

Looking for some information from you experienced ( RSGs) Real Smart Guys. :)

Have loaded mag length pistol and rifle rounds before, have the loading manuals, and always attempt to stay on the safe side of pressures. Now my first attempt at long loading rifle rounds to single feed , my question is, any information in any of the loading manuals in regards to powder charge ? Where does one find such information, I am limited to 52,000 lbs in a gas gun, I am getting older ( not old) and would like to shoot a few more years with my son, so therefore I ask questions.

When you dont know what you dont know, you get in trouble.

Gentlemen I originally posted this question in the general reloading section. It seems to be getting off base there.

Let me state the situation
When using a Bob sled type mag to single feed a round into the chamber of a gas operated weapon, that has the bullet seated out past the loading manuals OAL , I am trying to find out how to safely determine safe powder charge. I know the manuals all state. MIN/ MAX for the specified length. With the bullet now seated further out, the operating pressure should now be reduced, to my way of reasoning. With the bullet now seated closer to the lands I would think maybe about a pressure spike.

I am looking to shoot the heavier, longer 6 MM bullets in my 6 ARC gas gun, for ELR shooting.
If I cant go past MAX powder charges and do it safely ( staying within the 52,000 lb) range is it worth trying to utilize the Bob sled mag and load to longer over all length.

Hopefully I have worded my question sufficiently. I know I am trying to get the little round to do a big task, but I also enjoy a challenge.

Thank you.
Click to expand...
first determine how long you can load...
when you increase case volume( by loading longer than the book) with a given load, pressure basically goes down and vel follows.
you can add more powder a little at a time and watch what happens.
it really depends on how much more you can add..
the other side of the coin, near the lands is normally near the best accuracy
 
Thank you

So no hard and fast set formula. SWAG method add powder in minimal amounts ( maybe 2 tenths of a grain )looking for over pressure then backoff.!
 
Frankm said:
I too am wondering about H380 as I have 2-3 pds. It’s right next to zLever evolution on burn rate charts. Not sure if it ll work well at 60k psi but probably worth a try on heavy 6 ARC loads.

Will follow this post for any definitive responses on H380!
Thx
Click to expand...

Diffrent burn rate charts can & do show considerable differences relative positioning.

Hodgdon burn rate chart has LVR at 118 & H380 at 119

Whereas the Ballistic assistant places LVR at 382, IMR4350 at 433 & H380 at 439.
 
Retired Shooter, I've recently started shooting the 6 ARC with 107 Sierras with encouraging results so far, I started with Lever Revolution and 450's .003-.005 off the lands with a Bob Sled, using reformed PPU and Nosler Grendel brass both shot just above 1/2", I haven't got velocity yet.
I pulled Hornady 103 ELD precision hunter bullets (very flat primer) and seated 85 sierras and 90 Bergers, The Sierra 85's not good, the Berger 90's very good.
Next time out I'll put a Chono on the loads.
 
Good evening all.
Many of you know about the new upper assy. that Paul Craddock and his team assembled for me. Great guy to deal with, and an awesome group of guys in the machine shop. Thank you Paul & your team.:);):)

I have not fired a rifle or pistol for about a year now. I know this upper assy will do better than my first time out with it. Here is the proof. Please do not judge this upper from my lack of shooting in the last year.

Pictures are self explanatory , velocity by magneto speed.

100 yard sight in. HORNADY 6 ARC. 108 grain ELD Match
20230408_211944.jpg20230408_211956.jpg20230408_212258.jpg
 
I am moving my response to this thread from HERE because this one seems to get more traffic.

I wanted to experiment with 6 ARC and IMR 4320 in my 20 inch CMMG Endeavor. Not expecting to get earth shattering results, just trying to get a usable load using up components I have on hand. I loaded ladder with 4320 and 85 grain Speer boat tails in .2 grain increments (Fiocchi primers, Hornady brass). Starting charge was 25.7 ending was 28.7. Maximum velocity was 2729. All charges were relatively mild based on case/ primer condition. The shots grouped about 6 inches at 200 yds and did not show any real pattern until I got to the last three shots. I'm going to load another ladder starting at about 28 grains and go up to 29.5 or so and try again. I was hoping to break 2900 FPS but I doubt I will get there. As a side note I also did a ladder with LVR and 87 grain Bergers and busted 2900 and the total group was about 3 inches. I'll say I am cautiously pessimistic about 4320.


https://forum.accurateshooter.com/t...ly-well-in-the-6mm-arc.4058857/#post-38633507

6arc_4320.jpg
 
Last edited:
CSL grandpa said:
Retired Shooter, I've recently started shooting the 6 ARC with 107 Sierras with encouraging results so far, I started with Lever Revolution and 450's .003-.005 off the lands with a Bob Sled, using reformed PPU and Nosler Grendel brass both shot just above 1/2", I haven't got velocity yet.
I pulled Hornady 103 ELD precision hunter bullets (very flat primer) and seated 85 sierras and 90 Bergers, The Sierra 85's not good, the Berger 90's very good.
Next time out I'll put a Chono on the loads.
Click to expand...
I just tried some 90gr Bergers and shot my best groups yet. I only loaded 10 rounds, 5 with lever and 5 with varget and both groups were under .5". I have some more loaded up to try a seating depth test using Lever. I usually get .6"- .8" groups with Hornady 105s.
I'm hoping better groups at higher velocities will do better than higher BC out to 600 yards.
 
Squirtgun, looks like your headed in the right direction, I’ve only loaded with H-LevRev so far/Sierra 107’s besides replacing the factory 103’s with Sierra 85’s and Berger 90’s all with decent results.
I did a seating depth test with the 107’s yesterday and was surprised I expected all to be under .5” most were .6” one stood out as 4 shots were .24”.
Velocity With the Berger 90’s in the Factory case/primer/powder was high according the the Hornady gas gun data, 2873 average, primer pockets were still good, got some shiny marks on some, using a Magneto speed-5 shots.
I‘ve enjoyed the 6ARC so far, I don’t like leaving it home.
CSL grandpa
 
I got 2847fps using 29.8gr of Lever. SD was not great though SD 21. No pressure signs at all, and I usually get small swipes with light loads using 105-108s.
I ran the load on a ballistic calculator and it's way flatter and half the wind deflection out to 600 yards compared to 105s. Down side is it shows it will go transonic a little over 800 yards. But the longest range near me is 600, so I think they'll work out good.
 
Interesting that most of you are trying to get the 107 to 112 or the "Heavies" to shoot for you. I honestly think the 6ARC is ideally suited for the 80 to 90gr bullets. I believe it gives you the best of both worlds. Great for LR steel, Deer, coyotes, or whatever. I have a load with 90s that shoot under half MOA out to 600yds and that is for 5 shot groups!! I have shot 1.1 to 1.2" 5 shot groups at 300yds. Three shot groups at 600yds were 2.75 and 3.5" with my 18" AR. What is not to love!!! Give them a try with LVR or CFE. I found those two give the best results with the best velocity.....
 
If I am going to drop down to 80 or 90 grain bullet in the 6mm ARC for Deer, I will opt for a all copper bullet. Last fall I did just that & a 87 grain Absolute hunter did not disappoint on two healthy whitetail doe's.

Then the previous year I did go cup & core & happened to score on the largest whitetail buck I have taken yet. Never weighed the deer though I would have guessed live weight near 300lbs give or take 20 lbs. 108 grain Elite Hunter, placed in a high shoulder location made for a very short tracking job. Buck was at 254 yards. He simply collapsed at the shot DRT.

More than one way to get the job done, though proper shot placement is first priority after selecting a properly constructed bullet.

L
 
My main question being is pressure signs. Zero ejector hole marks and no ejector scratch? Work up to the slightest indication of either and back off .5 grain?
 
rickt300 said:
Well we all know book data is very useful but every rifle doesn't have the same length throat or barrel twist, some barrels are bored tight others not so much.
Click to expand...
My post was in reply to where you mentioned specific pressure signs that, in a bolt gun, don't typically appear until you are well above the pressures that the AR15 is intended to handle, so has nothing to do with tight bores or freebores, etc..but your stated pressure indications. Specifically, bolt thrust is the enemy of the ar design and particularly with larger id cartridges than it was designed for because they generate more bolt thrust at equal pressure as opposed to say a 5.56 based cartridge. That's why the max pressures are relatively lower for the ARC, Grendel etc cases in that gun vs a strong bolt rifle. Just trying to be helpful. I have been wildcatting Grendel based cartridges fo a number of years. The ARC is very similar and shares the same bolt head and nominal case ID.
 
My particular rifle is chambered in 6 Predator so I have a bit more capacity than the average 6 ARC. That said it is a tackdriver but with brand new brass and loads using ARC data I get very mild ejector hole and extractor marks. Could this be the product of fireforming the case to the chamber for the first shot? Not all cases show this maybe 5 out of 15. Trying to fireform some 500 cases.
 
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