Project: Custom Precision Rifle by Winchester_070

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### International said:
I haven't tried sticking a chambering reamer into a barrel while clamped in a barrel vise....at least not yet.

Your barrel vise is similar to mine except mine is 2" wide. Do you recall what torque you used and what chambering it was....
Click to expand...

The only reason I tried a reamer while in the barrel vice was because the headspace only needed to be increased about 2 thou... and I was going to do that right there by hand. I forget what the caliber was.... the vice was down tight with an 18 inch bar. Probably considerably tighter than any barrel block...

I think the glue in fit in a barrel block is just so much simpler to do with no torque problems...
 
I'd agree, modest torque with epoxy. I think Gary could try the suggestions I laid out earlier if he has time and thinks they will work...
 
So is the concensus epoxy over 620 loctite?

Since I use 620 all the time for locking gears, sleeves and bearings on shafts I'd have no problem putting my head behind an unshouldered barrel held in a sleeve with 620. I'm still interested in which one is better because I'm doing a build myself.
 
Epoxy is by far the most commonly used product.

I am concerned about using epoxy for two reasons: Heat and alignment.

Just about every clear epoxy I have used softens when heated to 60/70C. What a normal hairdryer will do and what your barrel temp will easily reach during a match. That softening will allow the action and barrel to move within the block. Not a good thing.

Simple test. Mix up a blob and let cure for a day or two. It will be hard enough that pressure from a screwdriver will leave no mark. heat up with a hairdryer for a few minutes or whatever you think it will see during a shooting string. Repeat the screwdriver test. I bet it dents now...

Then when the epoxy cools, it may solidify in another position. Not good. The rifle may start to walk within the block just like a scope in poorly fitting or loose scope rings.

If using epoxy, use the steel bedding compound. That should stand up to the heat (?????). Still softens but the metal content should help it retain rigidity. I would suggest steel shims be used to tighten up the fit and bedding used to hold in place. Best of course is to bore the block to a nice tight fit.

I would also consider pinning the barrel in the block just to be absolutely sure.

Now the second problem is during install. Because the hole is substantially bigger then the barrel, the barrel will likely not be centered in the middle of that hole unless alot of care is made in set up.

Imagine a 1" scope in 30mm rings. Exaggerated of course but you see what that looks like. The barrel sits on the bottom of the block with a cresent gap around the upper circumferance. Different amounts of epoxy, different rates of expansion. Could this lead to movement?

One solution is to mill the blocks mating surface so there is more of a gap. The barrel will now be clamped top and bottom with a gap around the sides. A circle in an elipse. Better but will it be stable enough over the long haul?

Also, will the barrel and block be true or will the barrel be cockeyed. Looking from the top, the block and barrel are not pointing in the same direction.

That misalignment, unlikely to cause any accuracy problems, will likely affect the apparent tracking of your scope IF the scope is mounted to the block. With elevation changes, the windage will be off. That is really going to give you grief if you need to shoot multiple distances.

My scope is still mounted to the action and of course the barrel is aligned with the action so even if the barrel is not true to the block, the scope will "see" correctly with relation to the bore.

The rule of thumb when shimming a scope is 1 thou of scope shim equals 1" at 100yds when a scope is mounted on a typical long action (5 to 6" ring spacing). The distance from the muzzle to the scope is how far??????

Affect at 300m, 600m, 900m?

I have been lucky that my block has been milled with an interferance fit with the barrel. No glue needed. Problem one solved.

With an action mounted scope, I don't expect to suffer from problem two either but LR shooting hasn't begun until I get more bullets. This my first blocked rifle.

Some things to keep in mind when making and using a block.

Jerry
 
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Epoxy seems to work fime as a bed within a barrel block and has been used by many for the purpose. It is impotant not to over-torque as it is possible to distort a bore. Having said that, most of the heavy guns I saw on the line at the 1000yd BR matches I attended, used a block system to attach those long heavy barrels to the stock. One of the neater ones used a carbon fiber block. Anyway, some bedded the barrel into the block with various epoxies, others used a machined fit. I never asked what torque was accepted practice. This would naturally vary depending upon the thread pitch and diameter of the fasteners being used. Art Bourne once fitted a barrel block using a shrink fit. He aimed for .001" of interference and probably achieved that since he was a pretty accomplished workman. When he installed the sleeve, or block, it was possible to feel the location of the block with a tight patch run through the barrel. This was on a 1.250 diameter Shilen barrel. So, he turned the block off and made another .002 over into which he glued the barrel using acraglas. This one stayed until the barrel was worn out. As I recall, the block was about 6 " long.
One guy you might want to contact regarding the setup of barrel blocks is Jay McMunn posting as Jay, Idaho on BR central. Jay has been fooling around building 1000yd BR rifles for quite some time and does some nice work both building and shooting them.
On your scope base. On the front, I would drill and tap your block from both sides and use opposed coned screws fitting into detents on the base. At the rear, a sliding wedge and locking screw arangement. You won't really have to move the base up and down too much in any case. Gary Geske ( the maker of Geske actions) showed me a pretty clever elevation adjustable base he had made up but the machining involved was a bit tricky for anyone less capable or experienced than he. Regards, Bill.
 
Bill, did you see any all aluminum heavy rifle stocks? These have the block, trigger guard, and the rest of the stock milled out of one honking big slab of alum.

If the block is within a thou or three over barrel diameter, epoxy would be an excellent product. When epoxy is used that thin, it has great shear strength.

What I mean is that many have bedded an action into a stock and you can be very generous with how much bedding compound you use and still have a very rigid set up.

So let's say someone has a 1.20" barrel and goes, hey 1 1/4" drill bit....that'll work. "I'll just bed it later". Nope, that will lead to the issues I made one post ago.

Apparently, boring a big diameter hole accurately down a long block is not the easiest thing in the world to do (or so my machinist has said).

Any tips to help the budding block builder would be helpful. Tools, set up, reamers/drills/boring bits, etc.

My block has 6 10-32 machine allen bolts to hold the top and bottom caps together. I tighten using the ##### cross pattern and try to keep the gap even around the block. I use firm hand pressure on a standard allen key (2.5" leg) after the bolts go firm. That is as tight as I go. Sorry, no torque reading but it is definitely not gorilla tight.

Removal requires firm pressure on the same allen key. No wrench required.

I just want to hold the barrel in place. Stretching the bolts or crushing the barrel is simply more force then I think is needed.

Jerry
 
Jerry,
Jay had one such stock which he had made (we didn't get into material costs). I haven't spoken to him for a couple of years so don't know what he is shooting now.
I have personally not been a fan of the barrel blocks just because I have always had good success with receiver bedding/glueing.
Boring a long hole is challenging for a couple of reasons. The first is chip clearance. It is difficult to clear the chips from the hole and their presence exacerbates the second problem which is bar deflection. The longer the bar, the worse the potential deflection problem. Shorten the bar though and you have to bore from both ends. Also tricky. I try to make sure the chip breaks well and clear the chips with compressed air. I figure on losing about 1/8 inch of length at each end which is off size due to bar deflection not having established itself. Boring from both ends can work out fine providing the final cut is the same depth in each case and providing tool wear does not rear it's ugly head. A perfect system is to leave the sleeve about .005 under and hone to size but most gunsmith shops don't have a cylinder hone so do the best they can with other methods. Honing also is as much an art as a science to avoid a taper.
It was once common practice to glue the barrel into the stock on BR rifles. This before gunsmiths decided gluing the receiver was better. A roughly 4" section of the barrel was bedded into the forend then prepped and glued in with epoxy. The receiver and evrything else, for that matter, floated. It worked out well enough but not as well as receiver bedding/ glueing which took over from there. Regards, Bill.
 
Bill, yep, those were the exact complaints from my machinist. He will no longer talk to me about making another block. Although, someone on this board has suggested he would. Time to go find some slabs of aluminum before he changes his mind.

You forgot to mention the action sleeve. But that is a nightmare for another time.

I think these concerns are what has driven the evolution of the BR rifle to use much larger custom actions. Hold up the barrel, everything is true and tight. No muss, no fuss and you pretty much know it will shoot once done.

Downsides are cost and enormous wait times.

However, just wanted to see what would happen when a block and a Savage were put together in a moderately heavy rifle. Works great.

Now here is something I saw that made me go NEAT. Barrel rings.

yep, they look just like great big scope rings. Now you are only dealing with something 3/4" thick (or whatever you dream up). That is easy to mill. My guess is that the two rings were made as a block then cut apart to ensure alignment.

Making an accurate hole in a 1.5 to 2" block would be pretty easy. Plus the weight savings would allow this set up to be used in light BR classes (could swiss cheese to hearts delight). You wouldn't have the heat sink benefits but in a light rifle, a block wouldn't work anyways.

Work great in long barreled LR hunting rifles.

A very simple evolution that I see having some serious merits. Support the barrel as well as a block, should still allow the use of a commercial action (if desired) or a lighter custom action (overal weight should be lower then a large custom action alone), pretty easy and less expensive to make.

Less weight in the action, more weight in the barrel. That's a good trade off.

The smiths that made this did well at their debut match so the concept seems to work.

Wonder what ideas will spin off that....? How about just one ring about 6" from the receiver and using the front action screw to hold it all in the stock, float everything else?

That would be light!

How about having that front ring on a rail and act as a barrel tuner?

Jerry

PS estimated cost for mondo alum heavy rifle stock $1795US. YIKES!!!! But then you also need the custom fitted front and rear rests for $$$$$$ More YIKES!!!!

All this and you get 10 to 15 shots at a registered match if you don't advance. F class for me...but that is some real nice machining.

Finally, found the link. Enjoy.

http://www.6mmbr.com/gunweek057.html
 
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Jerry
you were concerned bout barrel alingment "QUOTE"

"Now the second problem is during install. Because the hole is substantially bigger then the barrel, the barrel will likely not be centered in the middle of that hole unless alot of care is made in set up."

Actually even though i messed up when i drilled the hole i was able to save both ends and the gap is in center section of the block . What i mean is i bored the one end to size (barrel size ) i flipped it over found center based on the outside dimensions then bored that end to size luckily it cleaned up . So then both end were the same size as the barrel and also in the center running the lenth of the block. I then split the block lenthways with the bandsaw which gave me approx .060 opening on each side. But when lighlty clamped the ends still hold the barrel in alignment .As i mentioned to Dennis i think i will turn down the barrel maybe .020 or .030 from the reciever to the front of the block this will still allow the block to align the barrel but will act as an emergency recoil lug should i get a bit carried away and soften the epoxy if that should ever happen. :ar15:
I am probably not man enough to shoot a 338 Lapua long enough to even heat the barrel up, you may see a "for sale" post after a few shots . I hate the recoil on my 7STW and my 6# 30-338 is a bit nasty after 5 or 6 shots :) so i amagine this will be about the same as those on the bench even though it is heavy, i am working on a muzzle brake also that may help.....
Thanks Again Winchester
 
Great save. Would hate to have to toss that much alum. Where did you buy your raw material? Looking for some slab alum for another block or two.

definitely muzzle brake and lots of ballast. Here is a pic of my 300RUM. I launch 220gr MK at 3000fps using 97gr of H50BMG. Very similar recoil to your Lapua.

At 35lbs (15lbs of ballast bolted to the bottom of the stock-that black block) and that big port, recoil is slow and mild. The whole rifle moves less then 1" so a really gentle push.

That port reduced the recoil even when ballasted from 3" to 1". I was very impressed with how effective it is. 3/4" hole that's it. The barrel acts as a sail. If you put in two ports, it would be even more effective and you might get away with less ballast.

Noise on the other hand is quite exciting. So is the plumes of smoke out the sides. Looks just like artillery going off.

Hope this helps and let us know how it all comes together. Making that recoil lip is a great idea. I would also consider just putting a small allen bolt through the bolt and into the barrel to pin it in place so it can never rotate.

Jerry
 
Jerry ,
It is not aluminum it is steel , aluminum would have been much easier to machine . The gun weighs 41# as it sits right now i will be adding the scope and mount of some sort and probably some lead in the rear of the stock should finish up at around 60-70 #
Aluminum is around , i found a 30" piece of 5" round 6061 in Edmonton for $80.00 from the guy who sold me my milling machine .I wish he had more :(......
 
Jerry ,
1)What is the bore size of the bullet hole in your muzzle break, or asked another way how much clearance over bullet diameter , i get conflicting answers as to what it needs to be but it seems that .020 to .060 is acceptable by most people so i would like to know what yours is . 2) Also on the 3/4" hole is the most rearward part of the hole in line with the muzzle/crown? or behind or forward? and if the latter by how much ?
and 3) does it affect your accuracy at all ? and i might as well ask how much does it change your point of impact..
I am asking these questions just to try to confirm some thoughts , there is a great site on muzzle breaks but it is in German so a bit tough to read ,they do have a homemade tester to test the effectiveness of muzzle breaks .It would be fun to build if i had nothing to do but burn powder....well maybe :)
Let me know when ya get a chance
Winchester
 
Win070, if you get into that type of weight, you probably will not need a brake. That is right in there with heavy guns used in the US matches. I sincerely doubt they would risk recoil fatigue. Plus the style now is machine gunning which requires excellent recovery speeds.

Steel would be a tough thing to drill through. I think you don't give yourself enough credit for making that hole through that block. Sounds easy but everyone I have talked to says it requires good machining skills. Kudos...

The exit hole for a brake must be as small as possible without allowing the bullet to hit it. I have had brakes that would almost touch the bullet so clearance can best be described as tight. I wouldn't recommend that just in case...

The common diameter I use is 20thou over. With only a 3/4" port, you should be able to go tighter, at least 10thou just in case. The longer the brake, the larger the exit hole because you have to account for the longer time the bullet will be in the brake during recoil (rifle can move more). Ultimately, if it is bigger then it needed to be, you will just bleed exhaust gases forward and reduce your brake's effeciency. Not the end of the world.

What does matter is the overall size of the side ports. You want these as big a surface area as possible. Alot of 'theory' goes into locations and size and pattern of holes. Gas exiting at 4500fps at approx 35000psi, just doesn't care 1mm this way or that.

What it does care about is the path of least resistance. By making the area of holes as big as possible, it helps the gas change direction and exit sideways. This makes a brake more effective. I have taken a brake, enlarged the holes and the effect was dramatic. There was precious little metal between the holes and it worked much better. However, a fine balance has to be met between recoil reduction and brake life.

The gill brake (Micaluk, Holland, Armalite, howitzers) is by far more effective then the single expansion chamber with lots of holes around (KDF and Vias, etc). The front of each chamber acts as a sail that the gases hit and push before exiting. That transfer of energy drives the rifle forward reducing recoil.

This is similar to the forces in a spring powered air rifle so watch your scope. Some scopes, even very pricey ones, are not designed for that back and forth recoil force and will tear apart.

The single expansion brake only moves gas sideways. The front of these brakes are usually smaller reducing that 'sail' effect.

Venting the gases backwards makes it even more effective but horridly noisy. AR50 brake for one of the best and ugliest brakes in rifledom.

The wider the brake, the better as it increases the surface area of that 'sail' the gas can drive against.

With my 3/4" port, I wanted the hole to be centered on the boreline as viewed from the side. No milling maching, just a drill press so you can imagine it is not dead on but pretty darn close. The front edge of the port is 1/4" back from the 'muzzle' of the barrel. I wanted lots of metal as this area was going to take a pounding. Many brakes have 1/8" between the chambers/gills. I prefer more in these boomers as a crack here would be disasterous.

Crowning new muzzle was done carefully with a round ball and lapping compound. Just enough to take the sharp edge off the bore lip. No fancy angles. Seems to work just fine. The new muzzle is concave following the port contour.

As to accuracy, mechanically, brakes do not affect accuracy although you may have to adjust the load to account for different barrel harmonics. From a practical standpoint, not having my shoulder feel like it wants to leave my body REALLY helped with accuracy.

POI shift is really dependent on the barrel, load and shooter. I would say that you are more then likely going to get a POI shift with and without a brake. However, no way to predict how much or in which direction.

Muzzle brakes are a love/hate thing. They make shooting rifles more gentle and even allow you to spot your own hits at LR. However, they are noisy and I try and double up on hearing protection. They are also very uncomfortable to anyone around you.

Kind of neat belching out plumes of smoke out the sides like a howitzer and waking up the countryside. Definitely not your kinder gentler experience.

But your shoulder will thank you.

Jerry
 
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Jerry ,
I know that if i weight up the gun to around 70#s i should not need a brake . But if you were ever at our thousand yard shoot and listen to all the #####en and moanen about the people shooting with them damn noisy muzzle breaks , (and most of them are with 7 mags or 300's ) i think i should get some down right rude comments with a 338 lapua .... i'm lookin forward to it.... are ya comin up in the spring to shoot???

Jerry ,PM Sent

Thanks ,Winchester
 
Muzzle brake

I shoot beside my brother in law with an AI, Lapua 338 mag, yes the earth shakes a bit, but if you can't stand the heat.....

Get out of the Kitchen !...
 
The Lapua will be no louder then any of the big case 7 or 30's. The intensity is related to muzzle pressure and the volume of boom related to the amount of powder burnt.

So burn equal amounts of powder at similar pressures and you get same boom.

Yeah, they are noisy but do help.

I forgot where you are. Burns Lk? I would love to but the odds of the trip is low. I will be trying to get to some shoots around here though. Kamloops/
Chase, Osoyoos, and possibly Chilliwack.

Jerry
 
Gary, how is your project coming along?

Regards,

joe
 
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