Home Forums Hunting & Shooting Hunting Rifles Kimber 84L mag spring swap-out

Last fall I noticed that my 270 Montana would miss a cartridge every once in awhile. The cartridges wouldn't push up far enough for the bolt to catch them.

I tried bending the spring to create more push but never could get it functioning 100% of the time. Thought I had it fixed but never fully trusted it.

Tried ordering a spring from Kimber but they were out of stock.

So I ordered a few springs from Brownell's.

A Remington ADL spring works great. Cycled a full mag-well about 8 or 9 times and it didn't fail to feed one time.

Brownell #767-170-280.



And before the anti-Kimber girls get all twisted up I had the exact same issue with a Sako 85 so it does happen.

Sam, I've had this issue with a few Win m70's as well as Montanas. The cheap fix is to bend feed lips on the mag box a scosh outward in the rear of the box.

Higbean, that's a great idea. I had thought about that but was too chicken to try.


Learning phase here!

You can occasionally "strengthen" a spring. Stretch it out so as to increase the preload, then stress relieve it for 1/2 an hour in an oven at 450°F. It may yield again the first time you load the mag full, but the spring will wind up being better than when you started.

I've used the trick many times over the years, on anything from pistols to classic cars, and it's always helped.

Sam, I wonder whether Kimber has finally used up its old supply of mag springs and started with a different one? Reason I ask is the "original" springs are super-stiff, tempered spring steel.

Was the spring in yours "soft"?

Glad you got it resolved.

Tex, maybe that's why I couldn't get the original spring to work.

It probably lost it's (after market)bend because it wasn't 'tempered'.

Anyone ever had feeding issues with the 84M?

None with either the 84 M's or L's... but all of mine have had the original tempered/spring-steel mag springs.

Again, I wonder if they've changed them?

Brad, I have no idea if they changed them. My 270 was purchased last spring(shiny trigger/aluminum trigger guard era).

I will say this, the 243(84M) feeds quite a bit better than the 270. The 270 takes a little effort on the bolt. Not even in the same league as my old ADL, that thing cycles cartridges like a dream. Of course it's also a longer action and no doubt that makes a big difference.

Blue tempered spring steel really isn't that expensive to buy, but forming some of the bends may have been problematic. I'm guessing they buy soft material and heat treat it. That should theoretically work, if heat treated correctly.

We've made a handful of them here, but all the bends have to be done by hand, and they wind up being relatively expensive. I'd be curious to know how they are made on a production basis.

The other thing to realize is that the strength of the spring depends a great deal on thickness. If you start at .015" thick, and go down only to .014" thick, the stiffness of the spring will decrease by about 23%. It's not uncommon that a springs is spec'd with .xxx thickness, and no one has it, so they just substitute .xxx-.002, not realizing it makes a big difference.

Sam,
I don't know for sure what was causing your feed problems, but my Montana (7mm-08) was a little sticky on feeding when I first got it. (bought at about the same time as yours). I opened up the back half of the feed lips by about .005" and then polished the inside edges with 400 grit. No problems since. However, sounds like you found another fix. May be better in the long run than what I did to mine.

Sam,

My 270 would occasionally cycle as you state though it did not keep me from killing an elk this past fall. The Remington spring is en route from Brownell's as I type. Appreciated.

Tex, possible spring thickness variance is a good point. That could very well have been what caused the issue.


Lastround, my rifle still doesn't feed quite as smmoth as I'd like but at least now it feeds. I think Brad also mentioned polishing the feed rails/lips(?) to smooth things up. Gonna tinker a little more on this thing.


Ed, curious to hear how it works out.

I have not noticed any feeding problems with my 7mm-08. I'm real happy to have it shooting straight

Thanks for the tip Sam.

My 84L did the same and I didn't trust it. I ordered the ADL spring and it works great. Definitely a stiffer spring. No malfunctions in cycling the mag 10 times.

Good deal Chiro, glad it worked!

Just saw this Sam. It worked fine. Thanks again.

I had the same thing happen on a Howa Mountain Alpine Rifle (.308). Only with the detachable mag though.

Is there a source for a stainless mag box for Kimber rifles?

I was thinking of asking my metal guy whether he could fab one out of aluminium.