Kimber 84M Montana .308 Win hunting load development

[MCMXI]

I bought my girlfriend a Kimber 84M Montana in .308 Win earlier in the year for her to use for deer and elk up here in Montana and last week I started load development for it. The general rifle season opens tomorrow so I think I have a great load worked up just in time. It didn't take long or use up much in the way of components to get here. I thought 45.8gr was the sweet spot but 45.5gr might be better since 46.1gr didn't do as well. I will eventually test 45.2gr to make sure that the 45.5gr load is nicely bracketed. Anyway, here's the load data, rifle and some targets from today. The RZ600 reticle means that the rifle needs be zeroed for 200 yards so I'm about 2.0" high at 100 yards which is close to where it should be. I'll have my girlfriend shoot the rifle/load tomorrow to make sure that it's zereod for her and then we're off to the races.

Barnes 165gr TTSX
Varget 45.5gr (and 45.8gr)
Federal GM210M primer
Lapua case (shoulder bumped back to SAAMI minimum chamber and neck sized)
OAL = 2.810"
MV = 2,750 fps

Kimber 84M Montana in .308 Win with a Zeiss Conquest 3-9x40mm with RZ600 reticle



A couple of custom features with the Adirondack bolt handle and Mountain Ascent lightweight extractor and Mountain Ascent thread protector



First 3-shot group using 45.8gr load



First 3 shots using 45.5gr



... followed by two more shots that opened the group up a little, but still very acceptable for a lightweight rifle and hunting load.



Great little rifle and a nice load. Hope she gets an elk and deer this year!

 

[lobo9er]

nice groups would love to go after some Elk someday

 

[Orcon]

Omg Lapua and Barnes and Varget and Kimber all in one package! I hope you got some 5.11 on. I hope you're ready for opening weekend!

I used to hunt, fish and hike everything from the Yaak to the Bob. I'll be your way in a few weeks, excitement! Tell everybody to save me one please.

 

[jmr40]

Those little rifles can be amazingly accurate. If the shooter is good enough to shoot a rifle that light.

 

[LoonWulf]

sweet looking rig, nice shooting too.

 

[murf]

did the 46.1 group string vertically, horizontally, or randomly?

murf

 

[MCMXI]

did the 46.1 group string vertically, horizontally, or randomly?

Randomly around the point of aim with one shot (on the left) that was most likely my fault. Here's a 5-shot group with the 46.1gr load. Three of the shots are within 0.322", and four of the shots are within 0.698".

 

[Lloyd Smale]

wish my 308 montana shot that well. It seems to only like 125s and 130s and shoots anything else into 2 inch or more.

 

[stringnut]

Any of those groups would be good enough to knock the stuffing out of any deer or elk that ever lived. As far as your group size really changing with a .3 grain change that is probably unlikely. You would have to shoot many groups with each load to see any statistical difference. Also, .3 grain, is only about .6 percent of your total powder charge. Other variables in cases and bullets will count for more than that. When I loaded 22 hornet any noticeable difference always came with a change of around a grain. With a case that small thats around 10 percent. Anymore, if the rifle groups 1.5 or less , I just load up and go hunting.

 

[OldBrownDog]

Just out of curiosity, why did you decide on 165 gr TTSX? My experience is that TTSX work best when driven fast, so I would think 130s or 150s from a .308 would be perfect, but I'm curious if I'm missing something.

 

[MCMXI]

Just out of curiosity, why did you decide on 165 gr TTSX? My experience is that TTSX work best when driven fast, so I would think 130s or 150s from a .308 would be perfect, but I'm curious if I'm missing something.

If I'm going to shoot a 130gr bullet it'll be from my 6.5 Creedmoor but I'm not a fan of elk hunting with the Creedmoor or even mule deer much beyond 300 yards. To me, 150gr to 168gr is the sweet spot for the .308 Win and hunting loads. The original TSX bullets were far more velocity dependent compared to the newer TTSX bullets. Regardless, any TTSX bullet needs to have an appropriate velocity to perform well and 2,700 fps for a 165gr .308 cal bullet is just that. Federal's outstanding Trophy Copper 165gr .308 Win load which uses a very similar monolithic copper bullet leaves the muzzle at 2,750 fps out of my AI AW and it works very well on mule deer and elk.

 

[MCMXI]

Just out of curiosity, why did you decide on 165 gr TTSX? My experience is that TTSX work best when driven fast, so I would think 130s or 150s from a .308 would be perfect, but I'm curious if I'm missing something.

According to Barnes these are the optimal velocity "windows" for the .30 cal bullets. Going with a MV of 2,750 fps and the 1,800 fps minimum, the 165gr should be effective in terms of expansion from 0 to at least 550 yards which is about as far as I'd want to shoot an elk or deer with a .308 Win.

.30 cal 150gr TTSX 2,000 fps > 3,000 fps
.30 cal 165gr TTSX 1,800 fps > 3,000 fps
.30 cal 180gr TTSX 1,500 fps > not tested

 

[Steve S.]

I have the 84M CC in .308; they are great little rifles - it looks like you have mastered the light weight technique (it took me about 60 rounds or so to get the feel). My rifle groups about the same with WW PP 150 grain; I will be testing handloads when the weather warms. You are a good shooter with that light rifle - you will love the light carry - good luck.

 

[Another_Kelley]

150tsx into a water barrel at 2700 - 2100 - 1800

 

[Casefull]

I hunt with a Montana and a Mt. ascent in 308. 150 grain TTSX with RL15 powder gives me 2950 ft./s and under 1 inch groups with both rifles. I have killed a couple of elk with each rifle. They are great Guns. I have to grip the fore arm tightly with these light rifles to get them to group off the bench.

 

[MCMXI]

Steve S. I bought the rifle for my girlfriend and in November she shot a whitetail buck with a broken front right leg about 130 yards from the house using the load above. According to the butcher, she put two bullets in the same hole and both through the heart. The deer didn't move after the first shot and my gf thought she'd missed so shot him again. This was a mercy killing but we got about 50lb of meat from him. We have two mule deer and one whitetail in the freezer this winter thanks to Kimber rifles.

Another_Kelley, those bullets seem consistent with the data from Barnes.

I have to grip the fore arm tightly with these light rifles to get them to group off the bench.

In my experience with numerous Kimber rifles they certainly don't shoot well in free recoil off a bench and will humble many shooters used to heavy rifles.

CORRECTION: I just realized that shots 4 and 5 shown in my first post were in the middle of the group and didn't open up the group at all. Must be my measuring error in OnTarget.

 

[Akspudus]

I hunt with a Montana and a Mt. ascent in 308. 150 grain TTSX with RL15 powder gives me 2950 ft./s and under 1 inch groups with both rifles. I have killed a couple of elk with each rifle. They are great Guns. I have to grip the fore arm tightly with these light rifles to get them to group off the bench.

I’m curious. I’m in the process of working up a load for a Mt. Ascent. What are the specifics of your RL15 load? I’m at book max for the 150ttsx and still not to 2900fps. Quickload says I can go higher and plan to as I have no indications of pressure.

 

[MCMXI]

I'd forgotten about this thread but here's a 5-shot group using the rifle shown above and Hornady's Superperformance 150gr SST factory load. I shot this last November and it's fairly respectable for a production rifle that with the scope only weighs around 6lb 2oz. My gf had no problem carrying this rifle on 7 to 8 mile hunting trips last November in deep snow and with 2,000 ft elevation change.

 

[mshootnit]

Here is a load that is shooting sub moa in my 308 M&P 10 rifle:
Hornady 150 gr. SST
44.7 gr. H4895
CCI BR2 Win brass
2.740" Crimped.

 

[mshootnit]

...So apparently the new threaded barrels are shooting well!

 

[Casefull]

I’m curious. I’m in the process of working up a load for a Mt. Ascent. What are the specifics of your RL15 load? I’m at book max for the 150ttsx and still not to 2900fps. Quickload says I can go higher and plan to as I have no indications of pressure.

I’m curious. I’m in the process of working up a load for a Mt. Ascent. What are the specifics of your RL15 load? I’m at book max for the 150ttsx and still not to 2900fps. Quickload says I can go higher and plan to as I have no indications of pressure.

47g. RL15 gives 100 to 150 fps over varget in my rifle with similar accuracy.

 

[mshootnit]

Do you think a Kimber in 25-06 would be worth a look? What about the Kimber "Hunter" models?

 

[flyguyskt]

I've been loading the .308 for some time now for a semi custom 700 vtr. my .75moa loads will not work in the Kimber 84m...too long. I load them close to the lands but the box in the Kimber is waaaay to short for that. Hope I can use your measurements of a short, stubby 2.810" - 2.840"(max mag well length) will shoot well. My past experience makes me worry about this amount of jump.

Do any of you hard core reloaders think this could be part of the accuracy issues so many people experience with the 84's? I found in my VTR 308 that they need to be at 2.865 OAL for it to shoot tight. Also my model 70 243 and rem 721 300 H&H both need very little jump to achieve sub moa accuracy.

 

[MCMXI]

flyguyskt, there's no question that there are numerous sweet spots for a cartridge in terms of overall length and bullet jump. A bullet doesn't have to be close to the lands to shoot well. Bullet jump is related to barrel time which is related to when the bullet exits the muzzle and where the muzzle is in its vibration cycle. Berger has a good article on bullet jump on their website that talks about the VLD but applies to any bullet. The article infers that the sweet spot might be .120" to .130" off the lands .... or more!

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

Here's the important part.

"Trying to find the COAL that puts you in the sweet spot by moving .002 to .010 will take so long the barrel may be worn out by the time you sort it out if you don’t give up first. Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot.

Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
1. .010 into (touching) the lands (jam) 6 rounds
2. .040 off the lands (jump) 6 rounds
3. .080 off the lands (jump) 6 rounds
4. .120 off the lands (jump) 6 rounds

Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
1. .010 off the lands (jump) 6 rounds
2. .050 off the lands (jump) 6 rounds
3. .090 off the lands (jump) 6 rounds
4. .130 off the lands (jump) 6 rounds

Shoot 2 (separate) 3 shot groups in fair conditions to see how they group. The remarkable reality of this test is that one of these 4 COALs will outperform the other three by a considerable margin. Once you know which one of these 4 COAL shoots best then you can tweak the COAL +/- .002 or .005. Taking the time to set this test up will pay off when you find that your rifle is capable of shooting the VLD bullets very well (even at 100 yards)."

 

[Nature Boy]

I have a great load for .308 using Sierra 180g matchkings that is very jump tolerant. Bullet geometry has a lot to do with that (tangent vs secant ogive)

You give up some BC with the tangent ogive but you get seating depth flexibility for loading for short throat chambers and magazines.