April 12 – The Pillars and a free floated barrel

April 12 – The Pillars and a free floated barrel

So in our quest to build a more accurate rifle we have a snug fitting bolt with polished locking lugs, a smoothed out action to make the bolt throw more precise, an improved 2.5 lbs.  trigger, and now we are going to mount this whole contraption on a chunk of wood and hope that everything works out!

Well…maybe not.

Remember in my past updates I mentioned that the curse of accuracy is uncontrolled vibration?  Well,..we can minimize it even further…and here is where things get rather messy.  Not in theory…. Literally messy….you may want to put on some rubber gloves for this part.

Ok…the barreled action is designed to sit on the stock and be held fast with two (sometimes three…but in this case two) “action screws”.  These screws enter holes in the bottom of the stock and attach to holes drilled into the bottom of the action.   The problem is that the material creating tension against the screws is wood.  Wood is a cellulose structure that can change geometry over time through tension, or exposure to the elements.  So…what we are going to do is take the wood out of the equation, and we are going to do it with aluminum pillars.

 These are the pillars. Notice the holes in the center?  They are where the action screws will sit.  These pillars will be embedded in the stock permanently and create a stable platform for the receiver. 

I’m going bore out two 5/8 inch holes where the action screws would have gone to accept the new dimensions of the pillars.  They are adjustable to a point, but more then likely will have to be filled down to fit lengthwise perfectly.  Once they have been dry fit I will need to check the space allowance between the barrel and the wood barrel channel on the stock.

 Thank God for drill presses!  This wicked looking counter bore will open up the stock and create channels for the pillars to fit into.

Here is where we come to the “free floated barrel”.  This really improves accuracy.  When you shoot a firearm the barrel actually “whips” as the projectile travels down it.  Believe it or not that is good…as long as it “whips” the same way each time and is predictable.  When the sights are set (in my case the scope that I will be mounting on it) the whipping action will be accounted for in the scope settings. 

What we don’t want is pieces of wood getting in the way of that barrel movement during the firing process.  So I’m going to carve out the barrel channel deep enough so that when the barreled action is mounted in the stock a dollar bill can be slipped under the barrel and travel freely all the way the “fatter” chamber portion of the barrel, back by the receiver….don’t worry if this doesn’t make complete sense…I’ll post of picture of it after the whole process is finished. 

Ok...so the carving and hole drilling is done. Now it is time to mix up some special glass bedding compound….a mixture that is essentially an epoxy and makes a mess!

The epoxy will dry and hold the pillars in place and also provide a perfect fit floor for the action to rest on.  It will also line the barrel channel and prevent any of the elements from entering the stock from below the barrel and possibly altering the shape of the wood over time. 

Like I said, this is messy.  From having to coat literally everything made of metal with release agent, to stressing out whether or not I’m going to break my stock once the epoxy dries when I go to remove the barreled action, this is definitely not the most fun part of the program. 

But it is something that needs to be done!  With everything in place, the excess glass bedding scraped off and the bedding screws tightened it’s time to turn out the lights and let it cure for 24 hours. 

 Messy!  Here the barreled action has been placed in the stock over the bedding compound.  All of the junk you see on top of the barrel and the receiver is release agent.  When it is all done I will need acetone and steel wool to clean it up.

 Looks like it fits nicely!  That beige stuff you see in the back of the receiver is actually modeling clay.  I use it to "plug" all the holes during this process.  It should all come out relatively easy during the clean up process.

 The bedding compound is starting to set!  See that bead of chocolate pudding stuff along the barrel?  That is the glass bedding, still soft to the touch.  It is the same material that is going to dry hard and hold the pillars in place too.

If everything works out the long process removing the “flash” of the epoxy with a file and using sand paper to “clean up” the stock will consume my shop time for the next couple of days!