What COAL are you folks loading ARC / BR / Dasher? Need design input

[pods8 (Rugged Stitching)]

In working on the Tikka ARC mag it has become apparent that the cartridge length matters, IE too short of a cartridge in a mag that allows a longer COAL causes a problem. So the length association needs to be more optimized compared to the cartridges that have longer case bodies. This may mean the mags need to be in more than one length depending on the needs of the users.

I'd like the following input from folks.
-Cartridge (arc / br / dasher)
-What length do you commonly load to?
-Realistic minimum length you'd use / load to?
-Realistic maximum length you'd use / load to?


@Jake Leibke @Plague @Carl Ross @sndmn11 @Lawnboi @waspocrew @gbflyer @ACHILLES @hereinaz

Tag others that use this cartridge if you know someone.

 

[KyleR1985]

6ARC will be 2.15-2.35 for probably 99% of loads. Maybe the 115’s and 116’s (maybe 112’s too) stretch - but the point of the cartridge is fitting in an AR. Almost all will be under 2.3”.

Dasher will be 2.3-2.6 for majority. Most will be 2.4-2.5”

 

[waspocrew]

Good question - I’ll get some measurements with my Tikka this evening.

 

[pods8 (Rugged Stitching)]

6ARC will be 2.15-2.35 for probably 99% of loads. Maybe the 115’s and 116’s (maybe 112’s too) stretch - but the point of the cartridge is fitting in an AR. Almost all will be under 2.3”.

Dasher will be 2.3-2.6 for majority. Most will be 2.4-2.5”

Thanks for the summary. Being these are for a tikka and folks might throat their rifles differently I need a feel for the extremes also, ie if someone is throating an ARC long for 115s for instance. Or loading a BR/Dasher really short.

I haven't tried to calculate the numbers yet but it will probably be something like max mag length minus something in the ~0.2" range could be covered. IE the initial prototype I made that was something like 2.57" could handle 2.44" rounds just fine but 2.3" rounds were too short. So trying to get a feel for the best optimization of lengths.

 

[Lawnboi]

I’m not home to measure for you. But one thing to keep in mind with the dasher is the lack of case taper like most other cartridges. Not much taper means feed lips sometimes need some geometry to make sure those rounds dont nose down.

 

[pods8 (Rugged Stitching)]

I’m not home to measure for you. But one thing to keep in mind with the dasher is the lack of case taper like most other cartridges. Not much taper means feed lips sometimes need some geometry to make sure those rounds dont nose down.

I bet that is more a function of short case bodies in too long of a mag than the case taper. If the case bodies are still stacked when the bullet tip starts riding up the feed ramp it should have a chance to nose dive.

 

[KyleR1985]

New 116 TMK is 1.375” long, 6ARC case 1.49”. Assuming you loaded boat tail at shoulder neck junction you’re looking at 2.44” as a max. Is there a longer 6mm bullet someone would load in 6ARC?

Same bullet in dasher you’re just adding .060 for extra case length, so 2.5” is probably safe here.

I couldn’t speak to bullets longer than the 116 TMK’s.


As far as minimums for 6ARC, the shortest in the Hornady load data with really light bullets (58gr Vmax) is 2.085”. I doubt this is a market you’re capturing, but maybe? Again, add .060” for the dasher case - so minimum length 2.15”.

 

[pods8 (Rugged Stitching)]

As far as minimums for 6ARC, the shortest in the Hornady load data with really light bullets (58gr Vmax) is 2.085”. I doubt this is a market you’re capturing, but maybe? Again, add .060” for the dasher case - so minimum length 2.15”.

I'm just trying to make whatever is useful to folks and understand better what that is since something that accomodates 2.5" can't accomodate 2.15" for example. I doubt folks are loading the 58vmax in a tikka but figure its better to ask and understand vs assuming about a cartridge I don't shoot.

Keep in mind we aren't just talking the 6s here, folks are necking these down to 22 often for instance.

 

[KyleR1985]

I'm just trying to make whatever is useful to folks and understand better what that is since something that accomodates 2.5" can't accomodate 2.15" for example. I doubt folks are loading the 58vmax in a tikka but figure its better to ask and understand vs assuming about a cartridge I don't shoot.

Keep in mind we aren't just talking the 6s here, folks are necking these down to 22 often for instance.

Got it.

How many mag length ranges are you trying to have, given the .2” max range of OAL

 

[pods8 (Rugged Stitching)]

Got it.

How many mag length ranges are you trying to have, given the .2” max range of OAL

I don't truly know its .2" range yet, I just tossed that number out there but it'll be something of that nature. Obviously less variations are easier to coordinate but if there needs to be numerous I don't care either but they may be made as requested versus premade items. Step 1 is figuring out what folks here are typically using and the extremes they are using (keeping in mind the other caliber variants also).

 

[KyleR1985]

87vmax
90eldx
95tmk
103eldx
108eldm

None of them had the boat tail below shoulder neck junction at 2.4” in 6dasher.
2.3-2.5 would capture this bullet class perfectly. Hopefully someone else can fill in blanks for you on the heavy heavies.