Home Forums Hunting & Shooting Hunting Rifles Rebarreling Long Action Kimber Montana 84L to Short Action Cartridge

Pardon me if the subject has been discussed recently, but my search did not reveal what I was looking for. I have seen several people state that they prefer the short action 84M over the long action 84L in the Montanas. Not sure why that is, my 84L seems fairly light and trim, and reasonably manageable for recoil.

I have an 84L in 270 Win. that regularly shoots sub-MOA 3-shot groups with the right ammo and when I do my part. I have no plans to change this anytime soon. However, I thought I might like to rebarrel it to a 7mm-08 Rem. if I ever decided to re-barrel it.

What are the Pros and Cons of rebarreling an 84L to a short-action cartridge? Are there any benefits to using an 84L for seating higher BC bullets out long? Or would it just be better to use an 84M action if one wants a 7mm-08? Thanks.

My big question is why given your 270 is accurate? Performance wise they are fairly close with the edge going to the 270 inside 500 yards or so. 7-08 likely recoil a bit less.

I think one thing that gets lost in all these discussions are the real world results. High BC 0.284 bullets are more available than 0.277 bullets - but the 270 will start them at higher velocity which negates the higher BC at "normal" hunting ranges which I'm defining as inside 500 yards. Same goes for wind drift.

Then we move onto bullet integrity. As much as I'd like to shoot a bullet with an astromical BC, I'm affeared of them when elk and similar size animals get close. A more sedate velocity like the 7-08 with a high BC bullet mitigates thinnish jackets but I lean strongly toward less BC and more bullet integrity in almost all situations. As I've said numerous times before, for me, I've shot more elk at 50 yards and under than over.

Then comes ability to harness the higher BC bullet. Before high BC bullets, we all shot mid caliber magnums at fast velocity in order to get flatter trajectory. The 270 fits in this category as does the various 7mm and 30 cal magnums. Start a good bullet at 3000+ and learn holdover using your crosshairs and various gaps between reticle and edges or thicknesses. It worked but we can be way more precise today.

But wind is still wind, it still blows in not so constant velocities and directions, and can change from one side of a canyon to the other. Shooting from field positions in these conditions requires alot of skill. I'm not opposed to those that can do it but think way too many guys plunk steel off their bench under good conditions and think they are capable in the elk woods. I'm not one of them but don't need to be because I pass on those shots. Plus my hunting style is way more conducive to close and quick. I do sit openings, do range the edges, AND set myself up accordingly. Keeping the wind in my favor, I'll move/set up where all my shots will be within my comfortable shooting zone. Takes a bit of discipline to pass on shots outside of that comfort zone but have done it more than a few times.

After saying all that, if you want to build a 7-08 on a Kimber LA, go for it! I considered rebarreling my 280 AI to a 7x57 because I simply wanted to. I wised up and bought a 270 instead

I rebarreled a Montana L to 7x57 once. Worked beautifully. 150 partitions at 2850 and nice small groups. Should have kept that one, but circumstances at the time didn't allow it.

Teeder...I hate it when you have regrets after selling one.

Should work fine. I have an 84L rebarreled with a 55mm cartridge and it feeds. Check the feeding prior to rebarreling with the bullet you'd like to use and make sure things are acceptable. The Hunter models with their center feed have super slick feeding if there's any question.

Bwinters...
Thank you for your thoughtful response. I suppose my questions are somewhat of an academic exercise. Since I may ever only own one Montana, I would like to understand the versatility of the 84L action, and what my options are for future rebarrel. I certainly do not intend to rebarrel a perfectly functional Yonkers 270 that is accurate and cycles and feeds well, as some say those are hit-and-miss. I was originally looking for an 84M in 7mm-08 when I found a great deal on the 270, so I suppose I still have that chambering on the brain. The 7mm-08 would be on the short list of cartridges for a rebarrel in the future if I was gaining anything by taking advantage of the longer magazine box in the 84L.

I do realize that the light and handy Montana is not the
best candidate for a long range rifle and I have no intention of doing so. So perhaps the 270 is the easy button for good velocity within typical hunting ranges for that rifle, using 140-150gr bullets. Using handloaded 145 ELD-X, she smacks back pretty good, and I don't consider myself particularly recoil shy.

I try not to buy into all the hype, as the 270 has served quite effectively for taking deer and elk for many years. But the idea of an efficient 7-08 using high BC bullets has piqued my interest. Maybe I should be really looking at a fast-twist 270 if I ever rebarrel the 84L?

Prairie_goat...good to know. Did you rebarrel to a 6.5x55 Swede?

If recoil is an issue, the super high BC 7mm-08 is going to be fairly comparable to the 145 grain 270. Running the numbers, a 180 ELD out of a 7mm-08 vs. a 145 out of a 270 is within 1 ft. lb of recoil of one another.

A wildcat made from the 6.5x55 case.

Copy that. The recoil is near the upper end of what I might comfortably shoot in that rifle, despite having experience with several magnums that I've enjoyed shooting. The Montana stock was hitting me in the top of my clavicle when sighting in and load development from the prone position. But I rarely have opportunities to shoot prone while hunting the timber I tend to gravitate to, so I expect to be using more comfortable field positions.

I think an 84L in a 7x57, 6.5x55 (plain jane or improved) would be a wicked set up for todays bullets.

Of course there is always 6.5x284 😉

If you were to go full rifle looney, a 7x57 AI would be skookum. Be the best of both worlds - max case capacity in a mid length case, 0.284 high BC bullets, and enough mag space to capitalize on it. I seriously considered the 7x57 AI in my LA. I even loaded a few rounds at various overall lengths and bigger bullets to get an idea. They fed well. It is very feasible......

Thinking about it today, I would be curious how a 7-08 would perform in the 84L with high BC bullets. You could certainly seat them out a long ways. Twisted right it should have better long range capability than a plain Jane 270. But the ol' 270 do shoot pretty flat out to reasonably long range.

I don’t disagree.

Sometimes ya just gotta kick the tires on stuff

I don't want to get too looney, as I would prefer not to spend a bunch of time fireforming brass. But it would open up a new world for some of these old long action cartridges. My understanding was that 7x57 was similar performance to 7-08. But something tells me that making it an AI could turn some heads. 284 Win could be a lot of fun, but I'm not sure the availability of quality brass for it now that Lapua has decided to stop making it for now.

Along those lines, something I've wanted to build for a while is a fast twist 6.5x55 or 7x57 on a Kimber Classic, as a bit of a long range sleeper.

Hmmmm....your guys' "sickness" is much worse than mine😵‍💫🥴🤪

Headache said one couldn't rebarrel the 84M to .284 Winchester due to the wall thickness iirc.

Wondering if that applies to the 84L as well.

Inquiring minds want to know!

I'd think any short fat cartridge might go better on the 8400. But I've no idea the thickness of each action.

A 7-08 Montana shooting 180’s wouldn’t be the worst idea someone has had. And you aren’t going to do it out of a SA.

What is the maximum COAL I can use in 84L and 84M magazines?

A Montana ‘08 still has a pretty good jolt.

I’d look to 6.5 or 6 mms.

Or just find a reduced .270 load.

The 84L is just a stretched out version of the 84M, so yeah I bet it would.

I say the L is a modified M and not vice versa because the M was the first and only model for a few years.

Excellent question.

A few years back, I had some messages back and forth with MD about appropriate velocities for the 7x57 with modern pressures. He said with like bullet weights, the 7x57 can achieve 97% of what a .270 can do. So, if a .270 can do 2950 with a 150, the 7x57 can do 2862. That's a little increase over a 7-08. You'd have to figure how much of a gain the AI would give you.
In the Montana I had in 7x57, 50 grns of H-4350 got the 150 Partition to 2850.
If I were to do it again, I'd be tempted go the ai route and plan on 160's or so.
(I also want a 7mm-06 with a 30 deg shoulder) There, is that looney enough?

The 7x57 Improved would be everything the 284 Win is in capacity and would/should feed like crazy.

I think a Montana in the Improved would be a hammer especially if it is saddled with a 1-8 barrel and throated correct.

How about a 6.5x57AI?
That aught'a be kind of looney!

And it wouldn't do a single thing that the 270 couldn't. Other than the PIA of x57 and 284 brass etc.

Nope. Maybe not but we could go down the same road as the 270 wouldn’t do anything the 06 won’t do either.

Never stops a good idea fairy from building a rifle though.

I have a 6.5x55 Improved reamer that was made for 147 ELDs at 3.1”ish. That’d likely be a wicked one as well.

What fun would that be?

6mm I assume? I've long thought that cartridge checked a lot of boxes.


I know this to be the case. That said, IIRC, a poster (former) from here, think he lived in MT, had one rebarreled to 6-284 and I don't remember him blowing up the rifle. A search didn't turn anything up, but the search function here is far from good.

I think this would be the most for the least on the 84L while still leaving enough room in the mag box for longer bullets. As long as AI'ing didn't cause any feeding issues it would be my choice.

Haha...I love the way you guys think. We are in the deep end of the pool for me now...keep it coming!

6.5x55 (or AI) sounds fun if loaded to modern pressures, with available brass. However, I'm covered there for awhile with my 6.5CM. Besides 270, I'm also packing 223, 308, 30-06 and 300WSM (after selling another 6.5CM, 6.5 PRC and 7RM. I'm kinda jonesing for a 7mm, or even a 6mm...lol 😁

Well, I think this is likely a fools errand, but that has never stopped me before and I don't think it should stop you either. If you looking for a speed increase and wider selection of bullets to play with, you could also consider the 6.5 Weatherby RPM. That is a lengthened 284 case so I don't know if the wall thickness issue is true or not. Just want to throw something else in the mix for us rifle loons.

Definitely want to find out if .284 Win.-based cases are doable in the 84L. Fools errand? LIKELY. Probably have all that I need in the easy, cheap and available 270Win. But as many have said here...that's no fun😉

Since you mentioned a 6mm a 6-06 with a 1-7” would be pretty cool.

Having just rebarreled a Kimber 84M and loonyism not withstanding, I could have bought a couple of rifles for what it cost to rebarrel given that if you are going to rebarrel you might as well have the action trued, rebedded, etc. while you are at it. YMMV.

Correct. Using 112 Barnes Match Burners and 95 LRX these days.
One thing to keep in mind for those looking at a 6.5x55 or its derivatives on a Kimber is that the specs on the case rim are slightly different than a 270 or '06, which can lead to some minor extractor problems. The extractor either needs to be modified slightly with a file, or Winchester brass used, which uses the .473" dimensions (though that's not the greatest solution due to potential excess space at the case head).

I remember the rifle and poster you are referencing. He's still around, and suspect the rifle is as well.

Montanas are all about light weight and quick handling. If you're going with a short action cartridge, you might as well get it in a lighter, quicker handling short action rifle. Sure the difference isn't much in absolute terms, but in the world of light rifles a quarter pound is a lot.

If I had a Montana in a widely useful cartridge like 270 that shot sub-MOA I wouldn't dream of rebarreling it for any reason. Quit while you're ahead.


As explained above, if you want a 7mm-08, get an 84M. As far as putting a short action cartridge in a long action so you can seat the bullets out long, that may let you get the most out of the cartridge, but it doesn't get you the most out of the rifle. If you're going to have a longer heavier rifle, you might as well get the most out of it. This is a drawing of a 358 win cartridge vs a 35 Whelen, but the principle would be the same for a 7mm-08 and a 280:

If I had a long action & wanted a 7mm, the 280 Remington would be my huckleberry. Added horsepower & you haven't given up any action space to a lower performing cartridge. I love a 7-08 and have used them. But it is NOT a 280 Remington.

Amen.

In a Kimber long action I sure wouldn't rebarrel to a 280 or 280 AI when looking to use the long bullets, due to limited action length, as well as running into that somewhat nebulous recoil wall in a light rifle. It's not always about shoving the biggest motor into a car.

The sheer and utter CLUELESSNESS of Drooling Dumbfhuqks,NEVER disappoints in it's Magnificent Grandeur. Hint.

The 84L is VERY trite in COAL,for a "long" action. Hint.

For that reason,it's a Goat Fhuqk in 280 or 280AI. Hint.

Because bullets matter wayyyyyyyy more than headstamps,a shorter case with a better bullet,never comes in second place. Read that again. Now one more time. Hint.

A 84L 70Win is a steaming pile of fhuqking schit,that can't begin to keep pace with 264 Kreed Factory Fodder. Hint.

The ONLY things you gals "shoot" are your mouths and fhuqking Imaginations. Hint.

Fhuqking LAUGHING!................

Pardon wares that exist,as you Google Gals summons your Imagination and Pretend. Hint.



Fhuqking LAUGHING!................

Yep

You AMAZINGLY Inept clueless Fhuqks,couldn't summons a FIRST Fhuqking Clue,if your "life" depended on it. Fortunately,Imagination and Pretend are free,so even you Brokedicks can "afford" to "contribute". Hint.

1000 words and Google as you MUST,then nod pencil necks in unison,like you "understand". Hint.




Fhuqking LAUGHING!..............

OK Stick...
I think I did alright for an early Montana that shoots accurately. I have $650 invested in it after I sold the scheit scope that came with it. Not bad in a time when Montanas are fetching a premium right now. As I said...was originally looking for a 7mm-08. Sounds like you prefer the 84M and 8400.

In your opinion, how would you setup an 84L to maximize the potential of that action? Other than to sell the 84L and buy an 84M or 8400. Not trying to be confrontational...I really want to know. I realize that you have setup several Montanas to maximize what you can do with that platform.

The (3) things that matter most,are bullets,bullets and bullets. Hint.

The 84M is as maligned as the 84L,in that they are both very trite in COAL "latitude". The 8400 Whizzum's are THE cream of the crop,due COAL latitude,with the 7 Whizzum being The Belle of The Ball. They'll 180 out of the gate. Hint.



NO chambering,can be better than it's bullet. I would MUCH rather gun a 7-08 with .796 BC 180's,than a 280 squirting parachutes. My 280's are typically set up to kiss that 180 at 3.585" COAL. Same goes 7mm RemMags. Why? The cases are of like length and share the same box/follower in a 700 L/A,leaving room to chase lands. Hint.

With a 84L Donor on the table,I'd go 8" RPM 7 Mouser and throat 180 Smooches,from it's tiny in comparison box. Hint.

In a 84M,I'd go 284 Bleedmire,throated for same. Hint.



Bullets,bullets and bullets. Hint................

I've got 2 260's built on long action 700's . for the reason of seating long bullets. in ideal position to lands and still running through the magazine.
these 2 I shoot for the high power silhouettes get in the hunter class you have to run the ammo through the magazine... I built these long before the creedmoor was ever thought about...

Leave it as it is.

For me I've found the enjoyable upper recoil threshold with the 84M and 84L Montana's is the 308 Win in the M and 270 Win in the L. Add bore size and powder and things become too sporty (I've had something like 16+ Montana's).

If you don't like the 270, trade it for an 84M Montana.

700's are easy. Hint.

Simply go AICS binderless DBM and you are there. My 8" Hart 260AI loves 147 Smooches,fed from same. Hint.





Just sayin'. Hint..............

Brad...I think I will leave it as is. The juice just doesn't seem to be worth the squeeze, given my barrel is showing accuracy with me behind it. I was curious to see what I could do with a LA Kimber Montana.

Big Stick...thank you for answering my question and providing a "method to the madness" in trying to address optimizing an 84L. I'm picking up what you are putting down regarding choosing a high-BC projectile. I will be watching for an 8400 to turn up at a good price.

ALL...
I appreciate your input on the subject of rebarreling/chambering an 84L. Thank you for answering my questions. I will refer back to this thread as a template, should I ever get the itch to do something wild with my Kimber.