Kimber Hunter Build & Stock Mods

[PathFinder]

Picked up a used Kimber Hunter in 6.5 CM at Scheels. The goal for this rifle is to be ~6.5lbs scoped, and maintain a 1k effective range. The 6 UM Tikka I've been hunting with weighs 11.5 lbs, this rifle is part of a plan to cut nearly 10 lbs from my base pack weight.
Eventually it will become a 6CM or 22CM, but the plan is to hunt with the 6.5 barrel for a while to prove out the concept and make sure it works.
The first order of business was to get everything assembled properly and make some usable geometry out of the stock. It's also undergoing ice testing to determine reliability of the Kimber trigger. Assembly will include a full bonded 1913 rail, rings, CF reinforced full length bedding, and proper installation of everything.

First up is the stock. Kimber seems to have gotten confused and designed a stock for a shotgun rather than a precision rifle. This method is similar to what I did on a Manners EHT that is on a Tikka 6UM. It gives Rokstok type geometry including a vertical grip, short trigger reach, flat toe, and higher negative comb. Not sure how this will end up for weight. Including the gel out of the stock it should be about 10 oz lighter than factory before adding the foam and CF. The process is as follows:

1. Make cuts. Leave material attached to use as pivot points where possible.
2. Cut the forend and hog all the extra material out of the barrel channel.
3. Set geometry where desired and tape in place
   1. Trigger reach and grip angle
   2. Comb height and slope
   3. Flat toe, just above flush with the bottom of the grip.
4. Fill with foam to provide UL structure. Loctite Titefoam works really well. Make sure that everything gets filled as uniformly as possible, go back and fill later if needed. This includes the extra space in the barrel channel.
5. Apply carbon fiber, 2 layers
   1. Rough up material with 60 or 80 grit
   2. Apply first coat of epoxy, let it get tacky
   3. Apply first layer of CF fabric
   4. Apply coat of epoxy to outside of CF fabric.
   5. Apply peel ply and wrap tightly with shrink wrap
   6. Use a dowel etc to form the barrel channel.
   7. Repeat for 2nd layer, sanding in between.

More pictures to come, here's the progress so far:

 

[HuntWyld]

Legit

 

[HNTR918]

I can't wait to see how this turns out.
Please be detailed, as I might copy this!

 

[RWT]

Very very interested.

 

[PathFinder]

Foam is trimmed, and the stock is all prepped for the first coat of epoxy. This kit was a sketchy one off Amazon so who knows how long it will take for the epoxy to tack up, should be able to get the first layer of CF on tonight. The barrel channel is channeled to a 1" diameter, and a 1" NPS PVC pipe will be used for the structure to shape the CF in that channel.

Rokstok type geometry taking shape. Feels really good so far.


Barrel channel:



Roughed everything up with 60 grit to help the first layer adhere to the plastic. That extra cut in the top of the stock is from my finding out that there's a solid plastic cylinder running the entire length from the buttpad screw to above the grip. That could be cut out to save weight but I was lazy and left it in.

 

[jakeohe]

Super impressive!! Thanks for sharing. I'm working on a tikka project but wont be quite as light

 

[BLJ]

Interested in finished weight.

 

[PathFinder]

Lots of progress made since the last post, it should be ready to shoot sometime tomorrow. There were some issues getting the CF to lay up smoothly over the larger foam sections, so that's going to require some attention to smooth out. There should be some extra MarineTex/CF mix from bedding, so I'll use that to fix those imperfections. Overall it is turning out pretty nicely though. Not sure what the finished weight will be, but it feels really light. The final coat of epoxy is curing today, it will be ready to remove the peel ply this afternoon.


This is with the peel ply on.


Plastic wrap to add tension after peel ply. Electric tape would be good to add additional compression, maybe below and on top of the plastic wrap. The PVC is there to form the radius in the barrel channel.


Epoxy applied after the first layer of CF fabric, getting ready for the second layer. I'll use a sander to transition the edges to the factory plastic after the final epoxy coat cures.



Dropped the barreled action in prior to adding the last epoxy coat this morning. The geometry feels good. Definitely some imperfections to iron out cosmetically but I'll do that while bedding it tonight. The full rail and rings could be ~3 oz lighter, but I'll leave it as is for now. Barreled action with scope (SWFA 12x) and mounts is almost exactly 5 lbs. Rail is a Talley, the rings are some Amazon ones that look promising at least. They're going to get some thorough drop testing to prove everything out. Should be able to get the rail bonded and everything mounted up for load dev. tonight. Hopefully the fore end is stiffer now, but even if it flexes there's no chance of it touching the barrel.


Still to do:

• Install Cervatelli Microcell recoil pad. Should arrive Monday
• Test magazine. Also arriving Monday
• Full length bedding
• Bolt handle
• Final carbon fiber finish
• Rattle can paint job
• Permanent optic. Probably a SWFA 3-9
• Zero retention testing
• Load development and trajectory validation
  • Starting with 1st gen Alpha brass, 145 Barnes MB, and RL16
• Ice testing completely dry, then probably with Interflon lubricant

 

[AZ_Hunter]

Tag for future awesome reading.

 

[RWT]

This has been amazing to follow. Very interesting with the changes you made.

 

[Stocky]

May have missed it what what the idea with the foreend?

 

[PathFinder]

Reduced weight and a ton of free float. These stocks flex a lot so I wanted it well away from the barrel, and shaved some weight in the process. Others have cut them much further but I wanted it full length still to have more options for front rests in the field.

The bedding is curing now. It's got too much chopped CF in the Marinetex so it was an absolute nightmare but the end result should be ok. Going to get the scope mounting finished too.

Filled some of the big cavities with foam, then forced bedding compound down into them. Drilled some holes and relieved material to give the bedding compound more to grab and fill. Hopefully it turns out ok, there's probably double the chopped CF in there that there should have been.

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[Philotheos777]

Great work

 

[PathFinder]

More progress over the weekend:

Loctite 380/Blackmax to bond the rail:


Not sure what to make of the group quite yet. This was 41 gr of RL17 and a 145 BMB. I'm inclined to think that the upper two are going to be the result of a bit of contact under the shank part of the barrel. I got that cleared out this morning. This load was pretty hot for some reason, significant swipes on the brass and pretty good click at the top of bolt lift. Additionally, I haven't found RL17 to be particularly consistent. Ten more are loaded up at 40 gr 4350 to try tonight. Hopefully that bottom cluster is more representative of what it will do.


Bedding turned out ok. It wasn't supposed to cover the tops of the pillars, but it will probably be ok. The recoil lug slot turned out great. The area in front of it was sanded down after this picture.


The rear part is sure rough looking after attempting to use the leftover Marinetex and chopped CF to fill the wavy areas. At this point I don't much care and will proceed with paint this week. A grind to fit recoil pad is showing up today too. Weight as it sits now is 6.6 lbs. Swapping to a SWFA 3-9 would get it down to the target of 6.5 lbs. Despite the light weight, the shape of the stock allow it to stay on target in the 12x scope at 100 yards. It should be a right on the money in a 6mm or 22 at some point.



Going to try the other powder charge next, then some 147 ELD-M. Rl16 will probably be the final powder if this barrel will shoot. The goal is to finish load development, paint, and some trajectory validation in time for a bear hunting trip this weekend...It's a tight timeline, but I'd really rather carry this rifle on this trip.

 

[HuntWyld]

More progress over the weekend:

Loctite 380/Blackmax to bond the rail:
View attachment 878932

Not sure what to make of the group quite yet. This was 41 gr of RL17 and a 145 BMB. I'm inclined to think that the upper two are going to be the result of a bit of contact under the shank part of the barrel. I got that cleared out this morning. This load was pretty hot for some reason, significant swipes on the brass and pretty good click at the top of bolt lift. Additionally, I haven't found RL17 to be particularly consistent. Ten more are loaded up at 40 gr 4350 to try tonight. Hopefully that bottom cluster is more representative of what it will do.
View attachment 878933

Bedding turned out ok. It wasn't supposed to cover the tops of the pillars, but it will probably be ok. The recoil lug slot turned out great. The area in front of it was sanded down after this picture.
View attachment 878934View attachment 878935

The rear part is sure rough looking after attempting to use the leftover Marinetex and chopped CF to fill the wavy areas. At this point I don't much care and will proceed with paint this week. A grind to fit recoil pad is showing up today too. Weight as it sits now is 6.6 lbs. Swapping to a SWFA 3-9 would get it down to the target of 6.5 lbs. Despite the light weight, the shape of the stock allow it to stay on target in the 12x scope at 100 yards. It should be a right on the money in a 6mm or 22 at some point.
View attachment 878936


Going to try the other powder charge next, then some 147 ELD-M. Rl16 will probably be the final powder if this barrel will shoot. The goal is to finish load development, paint, and some trajectory validation in time for a bear hunting trip this weekend...It's a tight timeline, but I'd really rather carry this rifle on this trip.

I know some smiths are a fan of bedding the chamber to the stock but I had a carbon stock made for my 84m and it shot like hell afterwards until I removed all bedding material in front of the recoil lug.

 

[PathFinder]

I know some smiths are a fan of bedding the chamber to the stock but I had a carbon stock made for my 84m and it shot like hell afterwards until I removed all bedding material in front of the recoil lug.

I had a similar experience on my Tikka 6 UM. Bedding material flowed under the chamber and bedded it, so I left it to test. It shot pretty badly and strung out vertically. After removing that, it went back to shooting nice round groups that were about .75 MOA smaller.

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[RepeatPete]

Great work so far!
Just another data point, not sure what is right/wrong - my 84m is bedded all the way up to the taper in the barrel and it shoots 1.5 MOA all day, and better if I focus. It also really seems to like the 143’s, though I haven’t tried any other quality bullets.

 

[PathFinder]

Things aren't looking so good for this barrel. Top group (excluding the ones up by the dot in the very top) is four rounds of 145 BMB with 40 gr H4350. The four above the bottom dot are factory 140 ELD M I had laying around. Even the least accurate of my three previous 6.5 CM (a CA) shot that load 1.5 MOA, and this group from the Kimber is 3 MOA +. I'm going to give 147s a shot over 40 gr 4350 today, if that doesn't work this barrel is getting pulled. It's probably not too surprising that playing Kimber roulette on the used rack didn't turn out. The throat in this thing is insanely long too. The 145s have a long nose, but they're jumping .150" at magazine length. If the 147s don't spray all over the target I'll measure how far they're jumping.

 

[Stocky]

Things aren't looking so good for this barrel. Top group (excluding the ones up by the dot in the very top) is four rounds of 145 BMB with 40 gr H4350. The four above the bottom dot are factory 140 ELD M I had laying around. Even the least accurate of my three previous 6.5 CM (a CA) shot that load 1.5 MOA, and this group from the Kimber is 3 MOA +. I'm going to give 147s a shot over 40 gr 4350 today, if that doesn't work this barrel is getting pulled. It's probably not too surprising that playing Kimber roulette on the used rack didn't turn out. The throat in this thing is insanely long too. The 145s have a long nose, but they're jumping .150" at magazine length. If the 147s don't spray all over the target I'll measure how far they're jumping. View attachment 879523

I've not had a kimber of recent build that wasn't accurate. Have you checked action screws and scope screw aren't touching the barrel tenon it used to be common. I had one that was similar to yours that once fixed is easily a 1.5 moa 10 shot group rifle with most options. Also what letter is stamped on the barrel? Being a creedmoor I'd assume it's a B from more recent manufacture.

 

[PathFinder]

I've not had a kimber of recent build that wasn't accurate. Have you checked action screws and scope screw aren't touching the barrel tenon it used to be common. I had one that was similar to yours that once fixed is easily a 1.5 moa 10 shot group rifle with most options. Also what letter is stamped on the barrel? Being a creedmoor I'd assume it's a B from more recent manufacture.

Thanks for the suggestion, I'll double check all of that tonight. I believe it does have a B stamped on it.