Monocore from a barrel blank... or is it a bad idea

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partsguy22
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Monocore from a barrel blank... or is it a bad idea

Post by partsguy22 »

Im getting ready to start on my last F1 can for a while :roll: .... I can stop any time I swear... :lol:

I want to build a .22lr monocore ... because I've never built one... a monocore anyway

I have successfully scraped 3 pieces of 1-1/8 7068 al... :|
and I'm convinced its not possible for ME to bore a small diameter hole that's 5" or so long and straight / centered.

so new plan If I were to take a piece of .22 barrel blank and use that I can just ream/ enlarge the bore to the size I want and ... wouldn't ya know its already straight..ish so my drill should follow the bore close...ish enough to make it work.

then I just have to thread for muzzle threads, turn down for the sleeve/tube to fit ,and cut my chambers and , and your done... :|

what am I missing ?
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Re: Monocore from a barrel blank... or is it a bad idea

Post by propeine »

partsguy22 wrote:Im getting ready to start on my last F1 can for a while :roll: .... I can stop any time I swear... :lol:

I want to build a .22lr monocore ... because I've never built one... a monocore anyway

I have successfully scraped 3 pieces of 1-1/8 7068 al... :|
and I'm convinced its not possible for ME to bore a small diameter hole that's 5" or so long and straight / centered.

so new plan If I were to take a piece of .22 barrel blank and use that I can just ream/ enlarge the bore to the size I want and ... wouldn't ya know its already straight..ish so my drill should follow the bore close...ish enough to make it work.

then I just have to thread for muzzle threads, turn down for the sleeve/tube to fit ,and cut my chambers and , and your done... :|

what am I missing ?
Its been done before on rifle barrels. Backbore, cross drill, voila instant monocore. The words to search aren't treating me very well at the moment but somewhere on this forum there is a very straightforward monocore for 22lr that is basically exactly as you've described except it was an integral.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by T-Rex »

Aside from propeine's response to the bbl blank, how have you gone about drilling the bore hole? No reason you can't use a .302 drill bit. Go at it from both sides and where they meet is going to be the center of a chamber (don't have to worry about perfect alignment). Turn between centers and you should have no issues. No way you're going to lose the clearance from a .302 bit in a 2.5"L drilled hole.

But yeah, no reason a .22 bull bbl can't be used as the building material.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by partsguy22 »

T-Rex wrote:Aside from propeine's response to the bbl blank, how have you gone about drilling the bore hole? ...
Chuck and centered in the lathe
turned the o.d.(on the first 2)
Center drill
Peck drill ~.050-.075" at a time
I first tried an aircraft drill... Big mistake it drifted .125 or so off center ... but it was fairly straight
I tried your idea and was still around .050" off where they met with the bore being far from straight

The best Ive gotten so far I drilled with an extension drill then turned the o.d. between centers and it will work but I'm not really happy with it, the bore has a bit of a curve/bow to it.. I could re-bore it but then I'd have a larger bore than what I was shooting for.

I think I'm going to shelf that idea and put my new non concentric thick wall 7068 tubing in my scrap bin for spacer material or what ever in the future

Green Mountain has 1" o.d. 11"OAL. stainless .22 mag. barrel blanks for 36 bucks,
I figure I'd run a 1/4" drill thru it then ream it to .265" and turn the o.d.

Which brings me to my next bad idea

How do you think .020" wall 3Al-2.5V Ti would do for a tube it will just be a captive sleeve, no threading
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Re: Monocore from a barrel blank... or is it a bad idea

Post by T-Rex »

partsguy22 wrote:
How do you think .020" wall 3Al-2.5V Ti would do for a tube it will just be a captive sleeve, no threading
Safety factor of 2.5, bursting pressure is 3200psi, working is about 1300. Were you planning to do a clamshell as well?
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Re: Monocore from a barrel blank... or is it a bad idea

Post by John A. »

Don't see why you couldn't ream a barrel.

Dr. Dater used to do it all the time with old R10 and 77/22 integrals.

Though in all fairness, he was using the entire barrel, but it's pretty much the same concept as you are asking about.

https://awcsilencers.com/files/2014/10/awc-tm-r10.pdf
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Re: Monocore from a barrel blank... or is it a bad idea

Post by cdhknives »

I have thought a lot about the deep drill issue and wondered why I couldn't build a monocore in 2 pieces? Treat it like a baffle stack of 2. Drill oversize stock, ream, center with a spider to align the bore, turn the outside concentric. What am I missing? I know it wouldn't be a 'traditional' monocore, but surely most of us can do much better at drilling a straight 3" hole than a 5-6" hole!

Just a thought when thinking through the OP's problem...
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Re: Monocore from a barrel blank... or is it a bad idea

Post by partsguy22 »

No clam shells just a little extra clearance like .010" core to tube
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Re: Monocore from a barrel blank... or is it a bad idea

Post by a_canadian »

Makes sense. Two 1.5" holes for each 3" piece are unlikely to wander too far, even with a dull twist drill. And if you wAnt it all in one piece you can weld it together, or use stainless index pins. I suspect such a build would end up being slightly heavier than a single piece monocore owing to redundancy of structure at the meeting ends, but with some care it wouldn't have to be a lot of difference.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by propeine »

I'll be honest there are only two reasons I would do a monocore.
1) I didn't have a lathe
2) It's an integral or needs pinned and welded to make 16in. but also needs to be cleaned.

Without CNC equipment I think it's difficult to get the level of suppression you can get with baffles. Liberty does very well with them but we aren't talking about simple shapes in the core any more.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by UCF_Sniper1583 »

Image

How would you turn this into a suppressor when it lacks the exterior threads?
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Re: Monocore from a barrel blank... or is it a bad idea

Post by John A. »

Pretty simple really.

Just turn down the front and rear edge of it down some and make some threads. Then make a cap. Lots of room there to do it.

Or, there are other more permanent ways of doing it if you don't mind a sealed can. Which on a 22lr, I don't personally recommend, but I guess it depends a lot on how particular you are of it needing cleaned and never being able to do it.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by UCF_Sniper1583 »

John A. wrote:Pretty simple really.

Just turn down the front and rear edge of it down some and make some threads. Then make a cap. Lots of room there to do it.

Or, there are other more permanent ways of doing it if you don't mind a sealed can. Which on a 22lr, I don't personally recommend, but I guess it depends a lot on how particular you are of it needing cleaned and never being able to do it.

This is for a 308. What do you mean by turn down? I wasn't going to go with a sealed can either.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by T-Rex »

The particular piece you referenced would be for 22lr.
By turn down, he means to put in a lathe and cut the metal to except threads and capture an outer sleeve/tube.

W/o machine tools or contracting someone with them, I'd sleeve the monocore and fix with a couple button head cap screws, front and rear. Not sure if I'd go this approach for .308, though.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by John A. »

If it's the one I remember seeing on ebay or amazon a while back, it's only 1 inch in diameter. If so, that would be woefully inadequate to try to tame the 308.

And the wrong thread pitch to be compatible with 308 barrels in the first place.

Not to mention being made out of aluminum.

Even if you could screw it onto your barrel, it wouldn't take long to find it laying downrange in pieces if you tried to contain the pressures that the 308 will produce. Be sure to wear eye and ear protection.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by T-Rex »

John A. wrote:If it's the one I remember seeing on ebay
I think you got it right here. If it's the same guy, he was tried by the ATF for selling silencer parts. The only reason he was acquitted was because the ATF never in fact tested the device to prove it reduced the report of a firearm. Pretty brilliant defense really.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by bnmorgan »

John A. wrote:Pretty simple really.

Just turn down the front and rear edge of it down some and make some threads. Then make a cap. Lots of room there to do it.

Or, there are other more permanent ways of doing it if you don't mind a sealed can. Which on a 22lr, I don't personally recommend, but I guess it depends a lot on how particular you are of it needing cleaned and never being able to do it.
another approach might be to use a tube with a flange welded into the far end, and a couple small screws out in the far end....if there's room. less machining required, if welding is an option. just drill and tap the core, and clearance drill the sleeve-cup. may want an o-ring on the opposite end. if you're good with a file, no machine work required there.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by partsguy22 »

I originally was going to make the core ~.75" longer than the tube
the first ~.25" will be the same O.D. as the tube as well as bored and threaded internally for 1/2-28
the next 4.5" the o.d. of the core will be ~.008? smaller than the I.D. of the tube
the last ~.5 will be threaded 5/8-24 or something close with a nut to capture the tube against the rear shoulder
then mill out the chambers in the core

I understand that with the tools at my disposal I can (and have) make a standard baffle type can but I was just thinking of trying something different
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Re: Monocore from a barrel blank... or is it a bad idea

Post by fishman »

Instead of using a nut to keep the tube on, just thread the ID of the end of the tube and cut threads into the OD of the core (just on the blast chamber end). Then turn down the rest of the core to fit in the tube.
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partsguy22
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Re: Monocore from a barrel blank... or is it a bad idea

Post by partsguy22 »

I thought of that but I was thinking of using some .020" wall Ti tubing I've got in the scrap pile for the tube
But if I'm going to use a steel core it I can use a different tube material since the weight isn't an issue any more

My original intention was a ridiculously light .22 can that would go on a Savage Cub MK1 for my 2 youngest sons some thing that would not make the gun any more muzzle heavy. :|

Now I'm seriously considering an integral and building this can as another .22 pistol can .
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Re: Monocore from a barrel blank... or is it a bad idea

Post by propeine »

partsguy22 wrote:I thought of that but I was thinking of using some .020" wall Ti tubing I've got in the scrap pile for the tube
When I get around to doing an integral on a rifle, I'll be doing almost exactly as you've described in order to keep it 16in plus. Thinner tube = more volume. The muzzle nut won't have to be very thick at all and would be easy to put flats or holes in for easy removal as well.
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Re: Monocore from a barrel blank... or is it a bad idea

Post by Capt. Link. »

If you are thinking about the monocore for 10/22 built into a barrel it was done by CMV that is similar to this:

Image
577enfield built this from one of my designs
You can contact me for the minor changes needed for this to work best bult into a barrel.

You can bore a straight hole but standard drills won't work.Using a minimum of a split point 135* drill is needed along with reamers.The best is a split point parabolic drill unless you can gun drill a hole.

Set your work-piece in a spider w/ zero runout on both ends.This is set into a 4 jaw and zeroed out.
Use a heavy spotting drill at high speed for light alloys.
Using a undersized drill drill to maximum recommended depth then ream hole for the next larger bit.This trued hole acts as a guide so the drill will be on center.Flip spider jig around to do other side.Last is to ream hole full length then turn piece to run true w/ hole.

You should have a true hole w/ zero runout.I've cut them as long as 8.00" using this technique.

You can also bore a small deep hole up to half of the lathes bed length but you must mount the work piece on the apron and build a bore to run between centers.The process is complex but rewards are high.

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