Mountain Rifle - Kimber 84M Proof Research .308 Win

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MCMXI

MCMXI

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@<*(((>< started a thread in December of last year about his Winchester Model 70 Proof build.

https://www.thehighroad.org/index.php?threads/mountain-rifle-win-m70-280ai-proof-research.859865/

I've done something similar with a Kimber 84M and picked up the barreled action from Proof yesterday. The rifle as shown with an empty 5-round AICS magazine weighs 8lb 2oz and with an empty 10-round AICS magazine weighs 8lb 5oz. Those weights include everything listed below. The rifle is a bit of a Frankenstein at this stage but I'll either be painting or dipping the stock and possibly the scope, exposed stainless and some other parts to make the overall package more cohesive. That's a ways out though since I want to work up loads, and possibly do some bedding of the recoil lug and perhaps the action. Here are the build details:

Kimber 84M action
Proof Research CF wrapped 24" .308 Win barrel 1:10 twist
AG Composites CF stock
CDI Precision bottom metal
TriggerTech trigger
Talley one-piece rings
Zeiss Conquest HD5 3-15x42mm RZ800 optic
SilencerCo Harvester suppressor
TAB Gear suppressor cover
Area419 Hellfire adapter 5/8-24
Area419 Hellfire suppressor mount 1.375-24
AICS 5-round and 10-round magazines

The plan is to work up two loads, one using a Barnes 175gr LRX bullet for hunting, and another using a Hornady 178gr A-MAX "match" load. Both will use Lapua brass, Federal primers and probably Varget. If the weather is decent this weekend I plan to shoot some groups using good factory ammunition to get the scope zeroed and get some idea as to baseline performance. I'm looking for as much velocity as I can get with acceptable accuracy/precision.

Shown with 10-round AICS magazine - "tactical" configuration

84m_proof_agc_zeiss_10rnd.jpg

Shown with 5-round AICS magazine - hunting configuration

84m_proof_agc_zeiss_5rnd.jpg
 
troy fairweather said:
How long can you load in those mags.
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2.86" is the max if I remember correctly. You can remove the steel stiffener plate from inside the magazine to get more length but I won't be doing that. Proof uses a proprietary reamer on the .308 Win chamber but I'll know soon enough what kind of jump the bullets will see. I've always been able to work up good loads even with significant jump so I'm not concerned .... yet. :D

I haven't looked at MAGPUL's AICS type magazine but that's an option too.

roy fairweather said:
If I remember right this was a hunter?
Click to expand...

Yes. I sold the stock/magazine and trigger for a total of $200 and would have sold the barrel but the threads were messed up.

I have the option to swap this barrel out for a 22" version if necessary, but at this stage I'm planning on sticking with the 24".
 
Ok cool, one day I hope to build a rifle with a carbon barrel, it will 100% be a crf action. I'd guess the ss golled the barrel coming off. I wonder if there enuff to tread it for a 6.5 jap action there a pretty small shank.
 
I bedded the recoil lug late last week, and despite it being very cold I managed to put a few rounds through the rifle yesterday afternoon. I'm getting lazy in my old age so didn't bother to bore sight. The first three shots using Federal GMM 168gr ammunition resulted in a clover leaf nowhere near the point of aim. :D A good start for sure but since it was less than 20F the mirage was brutal after the first three shots. I made a scope correction and sent three more rounds downrange despite the mirage (right target) . Yep, this is going to be a shooter for sure but I'm definitely going to switch out the scope for load development. The RZ800 reticle is great for hunting but is way too heavy for fine work with the targets that I have. I was shooting suppressed and recoil is very soft with the Harvester screwed on the muzzle.

fgmm_168gr.jpg
 
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Was the mirage from your barrel or the can? I usually have to use a mirage cover for my suppressors when doing load development, but never use one when hunting, the oz or so doesn't seem to make a difference with load preference. I believe CF conducts heat quite well, do you see more barrel mirage during a string than with a stainless barrel?
 
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I was out for surgery yesterday and am recovering at home today so my apologies for the delay in responding.

troy fairweather said:
Any velocity numbers yet.
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I had the LabRadar set up but forgot to add the microphone so didn't get a velocity for any of the shots. :mad: That Harvester suppressor is quite effective so the sound wasn't enough to trip the unit.

LoonWulf said:
that does look like it's gonna be a real shooter!
Click to expand...

For sure! If it weren't for the mirage I think the second group would have been a lot smaller. Regardless, given the performance of the first six rounds I'm sure I can work up 175gr and 178gr loads that will put 5 shots inside 1/2 moa, maybe even a 10-shot group.

Gtscotty said:
Was the mirage from your barrel or the can? I usually have to use a mirage cover for my suppressors when doing load development, but never use one when hunting, the oz or so doesn't seem to make a difference with load preference. I believe CF conducts heat quite well, do you see more barrel mirage during a string than with a stainless barrel?
Click to expand...

The mirage was most likely from the can. I had a TAB Gear cover on it but the can has an integral brake on the end which I leave uncovered. It was very cold when shooting (less than 20F), and the mirage could have been due to gas slowly escaping the can or heat from the can. Seriously, after the first three shots and a scope adjustment, the mirage was ridiculous. Typically it'll dissipate fast enough to get a good sight picture within 30 to 45 seconds but it wasn't going away. I don't like shooting on very cold days for this reason.

I won't be shooting for a few weeks due to the surgery but I'm looking forward to trying a couple of other factory loads and then doing some load development.

Here's the bedding job on the recoil lug. It came out quite well and the barreled action feels very solid in the stock. Once I've got everything where I want it I'll paint the barrel channel with Cerakote and touch up the stock using a stencil. I'm thinking about sending the bolt and receiver out to get it salt nitrided but I haven't looked too hard into that yet. Ted of American Rifle Company mentioned something about salt nitride causing strength issues so I'll have to look for that info. I just want to smooth up the action as much as possible.

recoil_lug_bedding.jpg
 
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Nature Boy said:
Get well and get back to updating us on this build!
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I probably shouldn't be doing too much this week given the three puncture wounds in my abdomen but I was restless this morning. I decided to swap out the Zeiss for a Vortex Viper PST and then shoot a few rounds at 100 yards to get the scope zeroed. I found a partial box of Black Hills 175gr SMK so used that. I mistook a staple on one of the targets for a very small group so made a scope correction which by dumb luck was really close for horizontal but 1.6 mils too low for elevation. :D A few more shots and I figured out what was going on. I ended up shooting a 5-shot group which was ok but the diagonal stringing indicates that it's not an ideal load for this setup. I'm going to rest up now and take some pain meds .... urghhh!

bh_175gr.jpg
 
TexasPatriot.308 said:
Im a .308 person, have a few hunting rifles in .308 plus some
AR10s and an M1A.....just bought another bolt action .308
Click to expand...

I am too! I have rifles chambered in 6.5 Creedmoor and 6.5x47 Lapua but I still find myself coming back to the .308 Win and certainly prefer it over the 6.5 CM for hunting, in large part due to my preference for solid copper bullets. I've had quite a few rifles chambered in .308 Win/7.62 over the years including an Accuracy International AW, Springfield M1A, DSA FAL, custom Remington 700 with Krieger barrel, POF P308, Kimber 84M and Kimber 8400. I sold the M1A and FAL when I realized that the POF was better suited to my needs, and sold the custom Remington 700 soon after I bought the AI. I have multiple barrels for the Kimber 8400 so can change it back to .308 Win if I want/need. I sold the first 84M quite a few years ago because I prefer the 8400 action, and if I could build the package shown here off the 8400 WSM receiver I'd be a lot happier.

So as far as .308 Win is concerned, I'm down to the AI with .308 Win/6.5 CM barrels, the POF P308, the 8400 WSM with 300 WSM/.308 Win/6.5 PRC barrels and this 84M with the Proof barrel. This rifle is going to be a great shooter but I do need to work on the a couple of functional aspects such as feeding. This is a custom rifle in every sense of the word since Kimber doesn't offer an 84M that uses an AICS magazine. I've been "playing" with the magazine feedlips to improve feeding and will get there in the end (I hope).
 
I've had good luck with just mili 308 brass mostly lc and wcc. Last time out I shot two almost I e hole groups with my 700 308 I built. Funny thing it was just a quick load of imr 4895 using Lee dippers with the 165 Sierra gkhp.

$65 for lapua is a great price tho.
 
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