Integrated Mounting Block

Terry Cross

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I wanted to share some info on this project.
The M.A.C.S. project was being developed specifically to compete for certain types of business. One of the requirements is a "no bedding" system.

Last year, I shared some info about the development in another thread and you may remember this:
beddingblock-saoctober272009.jpg

Design on this project feature was started in June of 2008 but had been slowed by my lack of time to devote to it.
Since that time, we have steadily been playing and refining. Last November, I started serious testing with it and the results were good. I had a small run of the initial C.A.D. and installed the first production sample into a SENTINEL stock while the others went to anodizing. I shot that sample in the 2010 Snipers Hide Cup figuring that it would be a good addition to some realistic testing. After shooting each day, the rifle was removed from the stock and re-installed. Each day, the rifle retained zero.

It must be noted that the shooter must retain their brains in their head in order to get any meaningful data from the equipment and I forgot that on day 3. However the last rifle shot of the competition was a 1" dot at 100yds from prone. The rifle finished out well with a center hit on that shot.

Basically the rifle did a very good job of retaining POI/POA during the entire event. As some of you have seen, I don't baby my gear and usually throw the rifle down (with bolt back and mag out) to get to my handgun during the run&gun stages.

The overall results were good enough for me to decide that it should become an option on the SENTINEL stocks as well as the M.A.C.S. and I now have the first 16 rifles out on the street with the I.M.B.

Below, you can see that the stocks have been inletted to allow a very nice integration of the block. One of my key goals was to obtain a lot of receiver contact and support all the way up to the waterline of the stock and still get good cosmetics. This is a shot of one of the live installs that went out a few months ago.
2182010007.jpg


More information is available on this update page:

. . .<span style="color: #000099"> go to this page and scroll down to the slide show pictures</span>.


CAD work for the Long Action version and the XL-CIP version is 99% done. Badger M2008 std and magnum versions should also be completed by end of year.

While the M.A.C.S. is still not in full test mode yet, this is a major component of it and these results bode well for how that project should run once let out of the gate.

Thanks to everyone associated with helping this project along and being brave enough to test it and chance its failure.

Everyone have a safe Memorial Day Holiday.
Let us remember our brothers and sisters in our country's service as well as those that served in the past. I very much appreciate all of you no matter how small a part you think you play.

Best,
Terry
 

Jeff808

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Re: Integrated Mounting Block

Awesome work Terry! I've been checking on your site for a while now, do you have any ETA when more sentinel stocks will be available?
 

Terry Cross

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Re: Integrated Mounting Block

Thanks Jeff.

I am compiling some extra SENTINELS for sale but am totally out of the dedicated DBM systems. Should have the short action bottoms in around 3 weeks and can start figuring out what colors and inlets I have to offer.

At first, most of the SENTINELs with the I.M.B. will be committed to complete rifle builds but I should have some stand alone stocks available with that option by late summer/fall.
 

FequalsMA

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Re: Integrated Mounting Block

Thanks for all the hard work you put in to improve and refine the equipment available. That mounting block gives a extreemly clean look. I can't wait until my stock is done!
 

DesertMonkey

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Re: Integrated Mounting Block

As always Terry your work is top notch! Looking forward to a chance at testing one out. (Dreaming)

And I want to say thanks to all our troops for there hard work and sacrifice!

L.
 

mattmcg

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Re: Integrated Mounting Block

Terry,

So I have a few questions about this setup.

1. With the bedding block in place, can you simply drop in your action and bolt it to a specified torque spec to combine the stock and action? Are there any other complications that require attention?

2. How does this system ensure a "bedded" fit to a specific action if there happen to be variances between action production lots? Is this a concern at all?

3. How is the bedding block physically connected to the stock itself? What sort of material do you use to create a strong interaction?

Looks like a great project. Definitely interested in hearing more.
 

Terry Cross

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Re: Integrated Mounting Block

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mattmcg</div><div class="ubbcode-body">
I have a few questions about this setup.

1. With the bedding block in place, can you simply drop in your action and bolt it to a specified torque spec to combine the stock and action? Are there any other complications that require attention?

<span style="color: #000099">Yes. It is designed to be a drop in per the requirements I was building it for.

While I am convinced that a properly done pillar bedding job is THE closest to perfection, I was tasked with making a system that would approach that as close as I could and still not require any skim bedding, lapping or grinding. The whole reason for that requirement is so that any rifle stock rendered unserviceable in the field would just be shit canned, another pulled from inventory, bolted on and carry on. Nobody wants to send a rifle back to the rear to be bedded into a new stock. Too much logistics and the rifle is out of service for a longer period of time.

Since I had to do this, I tried to address all the things that I don't like in other bolt on chassis/block systems. Only time will tell if these improvements pan out as expected.

As far as "other complications", I am sure that in spite of my homework and efforts, I may have missed something. I hope not but we shall see. I tried to design this particular mounting block to accomodate R700SA type actions as well as most customs with similar receiver diameter, bolt handles and side bolt stops. </span>

2. How does this system ensure a "bedded" fit to a specific action if there happen to be variances between action production lots? Is this a concern at all?
<span style="color: #000099">
It doesn't.
I have not figured out a way and I have not seen any other system that can take a rigid material (7075-T6 in this instance) and make it have a "bedded" fit to variable production surfaces on all actions. By definition "bedding" is a custom layer of material between the solid stock form and irregular surface of the receiver. This layer has to be semi-fluid (up to and including clay like consistency) at some point in order to conform to the surface before transitioning to a hardened, stable, solvent resistant, UV resistant, temp resistant, dimensionally stable solid.

So. . . . Yes, it is a concern but cannot be totally avoided and still meet the requirements.
My approach was to avoid a "V" block. After doing both, I decided to go with a round profile with a radius that is slightly undersize on most actions. Stock bolts pull the two together. Most production actions will have irregular exteriors but I felt that this approach still gave me the most surface to surface contact and consistency. Any of the custom actions mounted into this system approach perfection as they all have true and smooth exteriors that match wonderfully to the CNC machined mounting block.

Look at any V based system and you will only see a few spots of contact. Additionally, NONE of those systems support the action very far up the sides. I do not like the idea of any action to block shift if the rifle incurs any impact or bump from the side. The stock bolts physically are limited in just how much they alone can hold the parts in position when abused from different directions.

That being said, the existing systems already out there do an excellent job. I just wanted to insure that mine performed at least as well and hopefully better.

This block is definitely more expensive to manufacture than a smaller V-block but I think it is superior.</span>

3. How is the bedding block physically connected to the stock itself? What sort of material do you use to create a strong interaction?
<span style="color: #000099">
The stocks are CNC inletted by McMillan to a very close tolerance fit. I have a positioning fixture that acts as a pseudo barreled action that the I.M.B. is bolted to. This fixture makes sure that the I.M.B. is in perfect position with the X and Y axis of the stock and barrel channel when it is in place.

This I.M.B. also has a ton of exterior surface available to mate to the interior stock material. Again, more expensive to produce but I thought that it was the best way.

The sides of the I.M.B. have the typical glue ribs for extra grab. Epoxies are used to seal it permanently into position. The DBM system being bolted up from the bottom justs adds to the already solid anchor. BTW, I did bolt up a trashed action and barrel into one of the early raw I.M.B.s and proceeded to try to tear it back out of the stock by swinging the setup against a 6x6 post. Holding it by the stock and having the bottom of the barrel impact the post gave maximum impact leverage to the I.M.B. installation and it held up just fine. I do not believe that I need any additional cross bolts or pins to anchor it.</span>


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