Tikka 6MM ARC / 6.5 Grendel

[nm.otter]

trim the feed lips back so they are just shorter than the shoulder of the case.

Here's a 6.5mm CM in a factory M+ mag:

 

[waspocrew]

@hereinaz and others -

I tried feeding 6 ARC ammo out of the following: Waters 223, Tikka 223 (S mag), and Tikka 22-250 (M mag). I tried to take pics of when the midfeeds happen, but pictures may not be the best quality.

Clear winner: Waters 223 mag
I loaded 3 rounds and they cycled perfectly. Repeated this for a total of 30 rounds and they fed flawlessly, even at slow speeds and quick cycles.


2nd place: Tikka 22-250 (M mag)
When loaded with 3 rounds, the first round wants to pop up and nose dive. The next two rounds will then feed fine. Not sure why this is the case, but when only loading with 1 or 2 rounds in the magazine, it's fine.



3rd place: Tikka 223 (S mag)
Would not feed when loaded with 1-3 rounds in the mag. The round will pop up and the cartridge will jam nose up. This will cause the round below it to nose dive in the mag. Cycling speed had no effect.





Here's a pic of the three magazines and the feed lip length relative to the shoulder.
L to R: Waters, S mag, M mag

 

[waspocrew]

The rifle is almost complete! I'll get my NX8 mounted in the next day or two, then hoping to hit the range this weekend. No clue when my Rokstok will be done (120 days lead time is coming up in a couple of weeks), but for now, the factory stock will function fine. This is the 18” Preferred Hybrid Lite from a pre-order from LS Wild Armory. Excited to get some rounds down range with it.

 

[hereinaz]

@hereinaz and others -

I tried feeding 6 ARC ammo out of the following: Waters 223, Tikka 223 (S mag), and Tikka 22-250 (M mag). I tried to take pics of when the midfeeds happen, but pictures may not be the best quality.

Clear winner: Waters 223 mag
I loaded 3 rounds and they cycled perfectly. Repeated this for a total of 30 rounds and they fed flawlessly, even at slow speeds and quick cycles.


2nd place: Tikka 22-250 (M mag)
When loaded with 3 rounds, the first round wants to pop up and nose dive. The next two rounds will then feed fine. Not sure why this is the case, but when only loading with 1 or 2 rounds in the magazine, it's fine.

View attachment 993031

3rd place: Tikka 223 (S mag)
Would not feed when loaded with 1-3 rounds in the mag. The round will pop up and the cartridge will jam nose up. This will cause the round below it to nose dive in the mag. Cycling speed had no effect.

View attachment 993029
View attachment 993030
View attachment 993033

Here's a pic of the three magazines and the feed lip length relative to the shoulder.
L to R: Waters, S mag, M mag
View attachment 993032

Good info.

I am gonna have to pick up some Waters mags. Separately, I will try some tweaks on the Tikka mags and sacrifice them for the cause.

@pods8 (Rugged Stitching) might have some info on 3d printed mags.

 

[hereinaz]

The rifle is almost complete! I'll get my NX8 mounted in the next day or two, then hoping to hit the range this weekend. No clue when my Rokstok will be done (120 days lead time is coming up in a couple of weeks), but for now, the factory stock will function fine. This is the 18” Preferred Hybrid Lite from a pre-order from LS Wild Armory. Excited to get some rounds down range with it.

View attachment 993045

That thing looks so good!

 

[nm.otter]

I will try some tweaks on the Tikka mags and sacrifice them for the cause.

Seems like a few minutes with a razorblade on a Tikka 'S' mag feed could mimic the geometry in my M+ photo.

 

[pods8 (Rugged Stitching)]

Good info.

I am gonna have to pick up some Waters mags. Separately, I will try some tweaks on the Tikka mags and sacrifice them for the cause.

@pods8 (Rugged Stitching) might have some info on 3d printed mags.

I am traveling for the holidays but can message you around with it when I get home. There was some chatter before about wondering about trying to optimize a COAL for arc and maybe BR or GT, would need to refresh my memory.

 

[hereinaz]

I am traveling for the holidays but can message you around with it when I get home. There was some chatter before about wondering about trying to optimize a COAL for arc and maybe BR or GT, would need to refresh my memory.

Enjoy the travels! Will revisit later.

 

[ACHILLES]

Good info.

I am gonna have to pick up some Waters mags. Separately, I will try some tweaks on the Tikka mags and sacrifice them for the cause.

@pods8 (Rugged Stitching) might have some info on 3d printed mags.

Tikka factory 223mags with the feed lips filed open slightly work great in my 22arc. I also have an 8rd Mag3d 223mag 2.55” for handloads with a longer COAL. I had to file the feed lips open slightly but only took 5min. I have the waters 223mags but didn’t try them, they are high quality but heavier than poly mags if that is of any concern.
I think the Ascension 6ARC mags will be a good option also but you have to use your own spring from a factory t3 mag

 

[hereinaz]

Tikka factory 223mags with the feed lips filed open slightly work great in my 22arc. I also have an 8rd Mag3d 223mag 2.55” for handloads with a longer COAL. I had to file the feed lips open slightly but only took 5min. I have the waters 223mags but didn’t try them, they are high quality but heavier than poly mags if that is of any concern.
I think the Ascension 6ARC mags will be a good option also but you have to use your own spring from a factory t3 mag

Sweet! Glad to hear.

I have always gotten mags to work by slowly filing the feed lips wider, taking equal strokes on each side. I compare how high the base of the cartridge is. That is the right start for how wide in the back. Then I watch for the length and width of the front. Sometimes it matters. A little can go a long way. A few passes with a file at first, then one or two each side as it gets close.

 

[ACHILLES]

Seems like you know how it’s done then. I have the front of the cartridge riding high as I could so that the plastic tips on the Hornady factory ammo just barely has to touch the feed ramp as it’s chambered. In the ruger gen 2 arcs I had alot of tips break off because they rode the feed ramp so hard and a few failures to go into battery from tips getting in the lugs. Also have had tips get stuck in the lugs once or twice out of 550rnds on my ar15 arc.
In 350rounds on my tikka arc with the tikka 223mag and Mag3d mags I’ve never had a tip come off or get damaged.