Feeding large caliber bullets into Tikka action

[rharbaugh]

I'm in the process of building a 458 socom on a tikka action and have ran into a hiccup with getting large, flat nose bullets to feed into the action. What happens is the bolt pushes the cartridge forward, and the middle of the large, flat nose bullet jams into the action feed ramp and won't chamber. I'm going to order a different style of bullet to see if that helps, but in the meantime would appreciate some tips and tricks from others if they have had this issue or have any creative solutions.

Picture of 300gr RNFP loaded in MDT metal 6BR AICS mag


Magazine inserted into KRG Bravo with bolt to the rear


Pushing bolt forward and bullet about to jam on feed ramp


Bullet jammed on feed ramp



Tinkering a little last night trying to see how much of a "ramp" I need to get the nose of the bullet up enough, I cut a popsicle stick that goes from the back of the magazine follower and just flush with the front edge of the magazine body

Cartridge loaded on top of popsicle stick



magazine inserted and bolt to the rear


bullet at the feed ramp


bullet going up the feed ramp



The popsicle stick solution only works for one round.

Two ideas that i've come up with so far:
1) modify the magazine follower so that all the bullets in the magazine are angled upward and will feed onto the ramp, but i'm concerned raising the front of the cartridge too much will lower the rear, and the bolt will glide over the case head and not pick up a round
2) fabricate and attach a small ramp to the front of the magazine that doesn't move with the follower. it'd have to be tall enough to line up with the action feed ramp and short enough that it wouldn't interfere with the cartridges in the magazine.

Ideas and suggestions are appreciated.

Thanks all,

RH

 

[waspocrew]

Can you tweak the front of the mag lips a bit to see if opening it allows the cartridge to ride up?

PS- this build looks awesome!

 

[rharbaugh]

Can you tweak the front of the mag lips a bit to see if opening it allows the cartridge to ride up?

PS- this build looks awesome!

I'll give that a try and report back.
Thank you! I plan on running subs through it and using it for IA and NE deer.

 

[Bluefish]

I'll give that a try and report back.
Thank you! I plan on running subs through it and using it for IA and NE deer.

45 cal subs are great on deer.

On the feed issue, I would try bending feed lips and maybe 3d print a new follower.

 

[rharbaugh]

45 cal subs are great on deer.

On the feed issue, I would try bending feed lips and maybe 3d print a new follower.

I'm going to bend the lips and try sanding them as well tomorrow. 3D printing isn't an option for me unfortunately.

 

[wyosam]

I’d just file and polish a short ramp into that lip.


Sent from my iPhone using Tapatalk

 

[Kurts86]

I would buy a 458 follower for an AR mag and stuff it in there as a baseline. You could also try a magazine without a back spacer so the cartridge sits further back and has a shallower feed angle.

It looks like someone on Reddit pull an aics 458 mag off with 3D printed parts. If I had to solve this problem it would likely involved tweaking the magazine feed lips wider in the front, greater lift on the front of the magazine follower before I polished a feedramp.

 

[SloppyJ]

Id try adjusting the magazine first to get the nose up. Last resort is to do some work on that feed ramp. Looks like that little bit of lip is what's killing you.

 

[rharbaugh]

I would buy a 458 follower for an AR mag and stuff it in there as a baseline. You could also try a magazine without a back spacer so the cartridge sits further back and has a shallower feed angle.

It looks like someone on Reddit pull an aics 458 mag off with 3D printed parts. If I had to solve this problem it would likely involved tweaking the magazine feed lips wider in the front, greater lift on the front of the magazine follower before I polished a feedramp.

i've had decent luck manipulating the magazine lips. i get it to feed about 90% of the time now, and occasionally will have a round "nose dive". not sure if the malfunction is being caused by the slop between the magazine and bottom metal, not enough spring pressure on the follower, or from the rounds sliding forward in the magazine while cycling the bolt.

I tried a 300wsm/6.5prc mdt magazine as well (read "magazine without a back spacer"), and the cartridges would "nose dive" even worse than the 6br. i believe this was cause by there being too much distance between the magazine lips and the feedramp.

i'm going to see if i can find a different magazine follower before i modify the one i have

 

[rharbaugh]

There was considerable slop between the magazine and bravo bottom metal. after some internet searches, i found out that the bravo has an adjustable trigger guard, so i moved the trigger guard all the way forward, and this helped tighten things up and improved feeding a little. Still some play in the magazine.

I was able to get rounds to feed consistently for about 95% of the time, but kept having trouble with the second to last round from feeding. it would regularly nose dive and jam in to the action feed ramp still. rounds 5, 4, and 3 would feed just fine, round 2 would jam, and round 1 would feed fine. this told me that rounds 5, 4, and 3 had enough spring pressure on the follower to push them high enough, and round 1 was riding the follower in. not a perfect solution, but one that works, I cut a 1/2" chunk of wood and put it in the bottom magazine under the spring to create more/consistent spring pressure on all the rounds. this limits me to only 4 rounds now, but every single one feeds consistently.