In my other thread I posted today, I showed the pleasing results I've achieved so far with my just finished Savage 223.  Unfortunately, it isn't all roses; I'm having feeding problems from my magazine.  This wasn't a disaster today for my inaugural range trip, I was perfectly happy to single load and continue shooting.

But I would like my feeding to work.  What's odd is that it worked fine when I tested at home with dummy rounds.  Fed and extracted smoothly.  I get to the range today, and there are problems.  When I push the bolt forward, the rear of the cartridge seems to leap up causing a misfeed.  This happens every time, except with the last cartridge in the magazine, which feeds correctly.  I took a video with my phone, which you can see at the link here: Feeding problem

I also noted that feed lips near the front of the mag didn't hold the cartridges as firmly.  If I dropped the mag halfway through a magazine full, it wasn't uncommon for the cartridges to be angled rather significantly upward.

So I get home and get inside.  I'm thinking maybe the dummy rounds I tested with were in spec, and maybe I made a mistake with my loading with my live rounds.  I took 5 live rounds and tried to feed them (keeping the muzzle pointed a safe direction, of course) and they feed fairly well.  Sometimes the nose of the bullet had a bit of a hitch but it wasn't bad.

It was rather warm today in my area, so my current theory is that it has something to do with temperature.  I'm using a polymer AICS magazine.  I'm wondering if this is a known issue, or if anyone else has encountered it before?  Can anyone recommend any alternative AICS compatible magazines I could try out?

Does it feed when the bolt isn't worked so slowly?

I havent noticed this with my 223 mags (AICS polymer) on the .300BLK R700. What does happen is if they are seated all the way to the rear it increases the odds of not picking up the round even on a full stroke.

No. And it does feed at home when worked that slowly as well.

Hard to see on the video, but the rounds seem to be popping up well before the end of the feed lips. I'd return the mags and try different mags, maybe metal.

That was my assessment as well. In the heat I did also notice the front of the feed lips weren't holding the cartridges much. They were starting to angle upward a lot.

Besides trying new mags, all I can think of to fix this one is to weaken the follower spring or try to bend the feed lips back into spec. Probably just try a new metal mag.

I  would try to adjust the feed lips I guess.

Different set up but when I got my HS-P mags for my 700 the included a slip with recommended feed lip spacing for different cartridges.

old picture but I am sure you can find similar. Looks like .320 front .350 rear maybe. But this is for HS-P mags. 

Not uncommon with Savages...and I say that owning a Savage 110 in 223AI that feeds from AI poly 223 magazines.

What was your solution?

My rifle is in a McMillan A5 inletted by CDI Precision for their Savage 110 LA/308 mag DBM.  It doesn't have rounds pop up-and-over the bolt like in the video...but I do frequently have the rear of the round jump enough that it 'binds' the bolt when chambering a round, requiring me to pull the bolt slightly back a bit so the rear of the round can fall then seating it home.  A similar type of issue can be seen at 0:15 in the film.

Interestingly, it happens less when I'm behind the rifle and run the bolt fast; that might be because I'm less inclined to exert a lever arm on the bolt (angled up/down/out/whatever) than when I'm standing with the rifle at my side doing things slowly.

I've had many many many Savages do this - long and short action, factory rifles and with aftermarket barrels installed, factory blind & detachable magazine & CDI DBM with AI and Accurate Pattern mags, when running 223, 223AI, 6.5 Creedmoor and 260.

Didn't stop me from shooting, but was aggravating enough that the only Savage I have now is my 110 223AI - never had these issues with a 700.

I have a feeling it is a combo of the action and the mags if they are in face AI branded mags.

I'm having trouble believing it's the action, because it feeds freaking perfectly on the last round.  The feed geometry seems correct in that sense, but only when the feed lips don't release the cartridge early.

It is an AI branded polymer 223 magazine.  Don't have a pic handy, unfortunately.

The AI brand 223 mags are junk

Oh  Well, that would explain it then.  How good is Accurate Mag?

they have served me well, and the MDT's aren't awful.  The accurate may need to have the spacer filed out some if you are seating long, but thats no big deal.

No they're aren't. The last run they did has some problems but I have two others that work flawlessly.

Did you swap out the bolt baffle? With my Savage 10 I had to swap the longer .223 bolt baffle for the shorter .308 baffle to cure feed issues I was having. I am using the MDT ploy mags here with no issues now.

MDT mags are way better than AI mags
You may want to try some

MDT had an issue a while back with their mags bulging when fully loaded - is this still the case ?

I did swap out my baffle, but not due to the feed issue in the video.  I swapped it because with the 223 baffle the bolt wouldn't come back far enough to strip a round from the top of the magazine.