Threaded tuners?
- Thread starter DSM
- Start date
George Atkins
Active member
main reasons
1. A .22RF does not need to be threaded, really no danger of blowing it off.
2. One less machining process on a already expensive barrel.
3. Crown exit, when you have a .900 + or- barrel, turning it down to .500 may let the muzzle open up, be it ever so slightly, that may cause accuracy to degrade.
1. A .22RF does not need to be threaded, really no danger of blowing it off.
2. One less machining process on a already expensive barrel.
3. Crown exit, when you have a .900 + or- barrel, turning it down to .500 may let the muzzle open up, be it ever so slightly, that may cause accuracy to degrade.
mwezell
Mike Ezell
^^^This^^^. Actually, I've found that EVERY joint in the system does move at high enough frequencies. As long as they are repeatable, I don't see that one way is better than another, on a rf. But if I can do away with a joint(variable) in the system, I prefer to do just that. My tuners only require thread depth for a 7/8-32 to be removed from a .900 straight bbl. If it's my bbl, I'll do a direct, threaded attachment, in that scenario. Yes, a bore can grow if you machine much off of the od and due to the very low muzzle pressures with a rf rifle, it MIGHT or might not be detrimental to accuracy but I've never seen the bore grow at all when threading a .900 to 7/8-323...none...and I got rid of a whole joint that DOES move, in the system. RF is not cf in this regard but it's not like night and day. I've seen a bunch shoot and tune great with 1/2-28 threads at the muzzle, so we're splitting fine hair that we have to shoot well enough to PROVE any difference. Myself, I'd get rid of that joint so long as as don't have to turn the bbl down more that roughly .100"
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Here is my take on this, it's only my opinion, but as an engineer, I think at it from that standpoint.
1. There is so little recoil, that almost no force is needed to keep the tuner from moving on the barrel. Therefore, almost any attachment method will work.
2. Threading the muzzle requires a step that is precision in nature and must be concentric, parallel etc. I am not saying it is hard, but if it is not done, it can't be f'ed up.
3. The joint in question needs good connection from a structural standpoint to transmit the vibration, although I have also put a compliant material in the joint in the past trying to soften it up some. I have mainly used blue masking tape. In the end, I could not see any real difference. It think it depends on how you think the tuner works. If you believe it extends the length and changes mode shapes, it needs to be structural. If you believe it is more of a dampening device, the compliance may be better.
4. Reducing the OD of the barrel WILL open up the bore. How much and how much matters is up to discussion. I don't think 0.020 off the diameter has enough effect to notice. I cannot determine any change using deltronic pins for that amount. 0.100 on the other hand, can be detected and will open it up. You feel much more with a slug. It is more sensitive then the pins can measure. Put a barrel in a machine vise and slug it back and forth depending on how tight you make the vise. You will be amazed at how little force can be felt. When lapping barrels I am VERY CAREFUL to limit my force in the vise to just enough to hold it. Opening the end of the barrel up is not good if the barrel is properly taper lapped in my opinion.
5. Attaching the threaded tuner requires specs to be applied as to the method of tightening. Tightness directly relates to what happens to the bore. By definition there is clearance in the threads for them to work, so there is really not a good structural connection in the threads themselves. A lot of the structural connection is at the face where it tightens against. Other options are loctite etc, but the glue is only good for about 2500 psi stiffness compared to 60,000 and 150,000 psi in the aluminum and steel. There are lots of areas of concern for the joint in the bore shape. Same holds for the chamber end. I have found anything over 400 in-lbs on the barrel torque will compress the bore. Under 200 in-lbs and the joint unloads under chamber pressure and vibration induced motion. I use 300 in-lbs on all my 750-16 threaded barrels.
Personally, I believe the best joint is a close fit (0.001) between the tuner and the barrel and very light tightening of the screws to hold it in place. I use the small leg of the wrench to hold and tighten them with.
1. There is so little recoil, that almost no force is needed to keep the tuner from moving on the barrel. Therefore, almost any attachment method will work.
2. Threading the muzzle requires a step that is precision in nature and must be concentric, parallel etc. I am not saying it is hard, but if it is not done, it can't be f'ed up.
3. The joint in question needs good connection from a structural standpoint to transmit the vibration, although I have also put a compliant material in the joint in the past trying to soften it up some. I have mainly used blue masking tape. In the end, I could not see any real difference. It think it depends on how you think the tuner works. If you believe it extends the length and changes mode shapes, it needs to be structural. If you believe it is more of a dampening device, the compliance may be better.
4. Reducing the OD of the barrel WILL open up the bore. How much and how much matters is up to discussion. I don't think 0.020 off the diameter has enough effect to notice. I cannot determine any change using deltronic pins for that amount. 0.100 on the other hand, can be detected and will open it up. You feel much more with a slug. It is more sensitive then the pins can measure. Put a barrel in a machine vise and slug it back and forth depending on how tight you make the vise. You will be amazed at how little force can be felt. When lapping barrels I am VERY CAREFUL to limit my force in the vise to just enough to hold it. Opening the end of the barrel up is not good if the barrel is properly taper lapped in my opinion.
5. Attaching the threaded tuner requires specs to be applied as to the method of tightening. Tightness directly relates to what happens to the bore. By definition there is clearance in the threads for them to work, so there is really not a good structural connection in the threads themselves. A lot of the structural connection is at the face where it tightens against. Other options are loctite etc, but the glue is only good for about 2500 psi stiffness compared to 60,000 and 150,000 psi in the aluminum and steel. There are lots of areas of concern for the joint in the bore shape. Same holds for the chamber end. I have found anything over 400 in-lbs on the barrel torque will compress the bore. Under 200 in-lbs and the joint unloads under chamber pressure and vibration induced motion. I use 300 in-lbs on all my 750-16 threaded barrels.
Personally, I believe the best joint is a close fit (0.001) between the tuner and the barrel and very light tightening of the screws to hold it in place. I use the small leg of the wrench to hold and tighten them with.
mwezell
Mike Ezell
So, if you think the bore needs to be tighter at the crown, I'd suggest a close fitting clamp on design and affect the bore diameter with torque? Nothing else has been quantified, so why not?
One way absolutely adds stress to the bbl(squeezes) and the other other might or might not relieve ANY stress, from a properly stress relieved bbl... Right? But the absolute method isn't measurable, but the other way most certainly relieves stress by some unknown amount? What am I missing here? Testing is how we truly know these things, Jerry.
I don't like turning a .,900 to 1/2-28 but the results have been very good. That said, turning one to 875-32 has not shown to me, any bore growth nor accuracy difference. If it did, I'd question the bbl maker's stress relieving process as well as the overall quality of said bbl.
This isn't your playground, my friend. BRC has always been the site that questions everything, posted by anyone. Please post definitive numbers. I've done it. Can't say all bbl's are 100% equal but I can say that I have never ever found any measurable growth at the bore by threading a .900 to ,875-32. At least not to my own capabilities. I have seen growth on button barrels threaded 1/2-28 but I can't say they didn't still shoot well afterward. fwiw. And because I've seen bore growth of around .0002 at 1/2-28 threaded bbls, I'll agree at that extreme but still, the results didn't support it and I've never seen ANY form of evidence that turning a .900 for an .875-32 direct attachment has shown neither measurable bore growth nor accuracy detriment. I just want evidence to the contrary to be quantified is all. Be it measurable bore growth or accuracy. You know, or should know, that I do respect your opinion but your post is more one of what I read for years and literally tested to be wrong.. at least to my own satisfaction.
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Mike, I in no way intended to discredit anything you posted. I was just answering the op with what information I know. I'm not sure what the playground insinuation is, but I have been here since pretty much day 1. I have pages of data and information from analysis and tests I have ran through the last 20 years on this subject. If anyone wants me to, I can present some of it. I am happy to do it here if anyone requests it or on RA if they ask over there. As I said, I'm an engineer so most of my information has basis and backup.
Hi-NV Shooter
Member
Jerry, in post #4 you mentioned a detectable bore growth when reducing the OD by .100 or more and you feel this is not good, so I understand you are speaking of strictly the muzzle end? what are your thoughts on reducing the OD at the chamber end?
Thanks,
Lee
Thanks,
Lee
Now I’m curious, why would you do that?
Hi-NV Shooter
Member
Well, I guess that answers that question although I cannot imagine simply not getting a RF blank .900” +- even for a 40X type tenon.
First of all, I am only shooting 50 yard ARA type of benchrest currently. ALL of my efforts go to that goal. I think most of my issues and data apply at longer range, but absolute accuracy is maybe less important due to outside environmental conditions in longer range. I do most of my testing indoors where anything that happens is due to the equipment in general. I have went to extreme lengths to build the most accurate guns in the world. At the last indoor nationals, my actions finished top 6 and I personally built 3 of the top six guns and finished 3rd myself.
I have been lapping my barrels for probably the past 5 years. I have probably lapped, chambered and tested at least 300 hundred barrels in that time. Probably more than anyone that is not a barrel maker in all reality. My goal for the finished blank is to have an EVEN taper from breech to muzzle. I don't want a variance in how the barrel tapers as it goes. The ONLY way to really tell how the lapping and taper is done is to slug the barrel bi-directional. The slug can see probably 10 times more sensitive than any measuring device.
If I am going to turn down the OD in any particular place more than about 0.020, I will do it before lapping. I always rough out the tenon on the chamber end on the bigger barrels for the 0.750 tenon. I have done it on the 0.900 barrels, but I have not noticed it to matter as the effected zone is only about 0.150 from the lead to the shoulder. If the shoulder was further down the barrel I would rough them all.
As an experiment I took a mediocre 0.900 barrel and lapped it as straight as I could and then just put a tiny bit of taper in it, just so you could feel the slug. I then took it into the lathe and started turning the OD down in the center for about 6 inches. I wanted to see when I could feel it open up. At about 0.050 off the OD it could easily tell when the slug hit that spot. It was not dramatic, but probably 0.000050 change. Seems small, but normal end to end taper is 0.000200. At about 0.100 off you could really tell. At 0.200 off it had no resistance at all. That usually is about 0.000200 in my experience. That told me just how important not doing anything to the OD was. I cut the barrel in half and using deltronic pins it showed 0.000100 to 0.000200 of opening up.
To answer your question, it applies to the whole barrel. No matter where you do it, it affects the bore. I want it as I lapped it in the first place. IF you are going to have it open up though, THE BREECH END IS MANY TIMES LESS IMPORTANT THAN THE MUZZLE. I would never want even a quarter inch of muzzle end opening up. Once it happens, there really is no fixing it with clamps etc. No matter how you affect the end, it isn't even like it should be.
I have reams of data on those kind of experiments too. Too much to type and probably read though
Hi-NV Shooter
Member
Hi-NV Shooter
Member
First of all, I am only shooting 50 yard ARA type of benchrest currently. ALL of my efforts go to that goal. I think most of my issues and data apply at longer range, but absolute accuracy is maybe less important due to outside environmental conditions in longer range. I do most of my testing indoors where anything that happens is due to the equipment in general. I have went to extreme lengths to build the most accurate guns in the world. At the last indoor nationals, my actions finished top 6 and I personally built 3 of the top six guns and finished 3rd myself.
I have been lapping my barrels for probably the past 5 years. I have probably lapped, chambered and tested at least 300 hundred barrels in that time. Probably more than anyone that is not a barrel maker in all reality. My goal for the finished blank is to have an EVEN taper from breech to muzzle. I don't want a variance in how the barrel tapers as it goes. The ONLY way to really tell how the lapping and taper is done is to slug the barrel bi-directional. The slug can see probably 10 times more sensitive than any measuring device.
If I am going to turn down the OD in any particular place more than about 0.020, I will do it before lapping. I always rough out the tenon on the chamber end on the bigger barrels for the 0.750 tenon. I have done it on the 0.900 barrels, but I have not noticed it to matter as the effected zone is only about 0.150 from the lead to the shoulder. If the shoulder was further down the barrel I would rough them all.
As an experiment I took a mediocre 0.900 barrel and lapped it as straight as I could and then just put a tiny bit of taper in it, just so you could feel the slug. I then took it into the lathe and started turning the OD down in the center for about 6 inches. I wanted to see when I could feel it open up. At about 0.050 off the OD it could easily tell when the slug hit that spot. It was not dramatic, but probably 0.000050 change. Seems small, but normal end to end taper is 0.000200. At about 0.100 off you could really tell. At 0.200 off it had no resistance at all. That usually is about 0.000200 in my experience. That told me just how important not doing anything to the OD was. I cut the barrel in half and using deltronic pins it showed 0.000100 to 0.000200 of opening up.
To answer your question, it applies to the whole barrel. No matter where you do it, it affects the bore. I want it as I lapped it in the first place. IF you are going to have it open up though, THE BREECH END IS MANY TIMES LESS IMPORTANT THAN THE MUZZLE. I would never want even a quarter inch of muzzle end opening up. Once it happens, there really is no fixing it with clamps etc. No matter how you affect the end, it isn't even like it should be.
I have reams of data on those kind of experiments too. Too much to type and probably read though
Thanks, Jerry, for sharing your experiences when turning the OD of a barrel. you shared a lot more than I expected. my question was directed in reference to the chamber end. I would never want the muzzle end turned down.
I think it is great that not only do you produce actions for RFBR but also compete with them nothing like seeing the maker out there going head to head with his own customers.
Thanks,
Lee
tonykharper
Well-known member
Yeah...tuner will be bored to match whatever. I figure it would be better for the tuner to shoulder on something?
Depending on the tuner, the bottom of the bore inside hits the end of the barrel. I am mostly familiar with Harrels and my Holeshot versions. They are approx 1.175 deep on the bore. You are really better off not cutting the barrel unless you have to. IF you have to bore the tuner anyways, just bore it to fit and cut the depth to hit the end of the barrel.
How about make a tuner to fit? Haha. Almost finished. Weight needs marks engraved and detent grooves milled inside.
In my quest for a tuner here in Australia (after asking for advice on this excellent forum) I found a local manufacturer and after phone contact I was asked to accurately measure my barrel diameter (within 0.04 mm) at the muzzle and and then each 10mm after that for 40mm.
In imperial terms this means to measure to the nearest 0.001" then every 0.040" along the barrel for 1.6"
My tuner arrived after a few weeks, perfectly bored to a snug fit on my old Annie and included a 'Locator' which was a stop to be permanently affixed to the barrel as a reference and it featured a precision drilled hole to ensure that the tuner engaged accurately with a pin each time after it was removed for cleaning.
Very happy, my scores have improved enough for some people to be heard muttering about 'banning tuners' Ha Ha.
My beaut Aussie made tuner came from http://www.loweyproducts.com/products.html
* doggie *