Thinking of drilling and doweling the breech to the upper
I have done a good bit of wrenching on my guns already and one area of design that bothers me is as follows. I have continually noticed that the breeches and the uppers have room to be manipulated as to their exact alignment and are only limited to the I.D. clearance in the upper and the O.D. diameter of the barrel. None have been perfectly aligned when initially disassembled but I do put them back as close to aligned as possible when I put them together. This alignment is just two flat faces kept in alignment by compressive forces when the moderator is tightened on the barrel. As an example my R3M/R3 .25 have .020″ clearance between the two components. Math would have me believe that .003″ of slippage or movement back there could be compounded to effect POI by almost .500″ at 50 yards with 3 times that much available in extreme shift.
#1: What do the people here think about this modification, It is very reversible with just removing the dowels. ??
#2: Would it be better to make matching counter bores in both components and make a disc that fits and fills both voids for the locator. ??
Doug…
All Replies
:8:
Let us know if NC hooks you up. I would buy one.
Gabe
I sent email to Neil. Ill let you guys know if its possible to do this type of addon moderator.
F&D,
:8:
Let us know if NC hooks you up. I would buy one.
Gabe
Makes sense to me, I am surprised there is not more comment on this thread, a lot of good potential tech talk here.
I would not choose a shroud fastened with only grub screw for the reason you mentioned. It will move. If the frame moves with the barrel, then there might not be dramatic changes in poi. With my gun I experienced shift because the barrel is smaller in od than the holes in the frame. Hence the need for shims. Also, my shroud screws on like the oem unit. However, I can only hand tighten it will never be as tight as the oem unit. My shroud is tight, but not enough to benefit from the “stretching effect”.
Ideally, I would like to keep the oem shroud if I could attach an LDC to make it as quiet as I need it be. For now, my current set up does the job.
Gabe
Yes. I need to email NC and ask him if he can make a Moderator that will go into place of OEM shroud Cover.
Unscrew OEM shroud cover (they are all the same for .22 or .25 R3) . It will expose the baffles. Then screw in replacement cover that is integrated to additional 5-7 inches of bigger in diameter moderator.
With This design there is no need to mess with Barrel mounting. It will retain OEM baffles, retain OEM barrel nut/stretching.
Here is a quick hand drawing LOL
Does it makes sense?
F & D,
I would not choose a shroud fastened with only grub screw for the reason you mentioned. It will move. If the frame moves with the barrel, then there might not be dramatic changes in poi. With my gun I experienced shift because the barrel is smaller in od than the holes in the frame. Hence the need for shims. Also, my shroud screws on like the oem unit. However, I can only hand tighten it will never be as tight as the oem unit. My shroud is tight, but not enough to benefit from the “stretching effect”.
Ideally, I would like to keep the oem shroud if I could attach an LDC to make it as quiet as I need it be. For now, my current set up does the job.
Gabe
When I get the parts tomorrow to build up my .25 I am going to experiment with airtube -vs- barrel spacing and gap as this non doweled fit up is skewed around. My .22 std. is close between the air tube and barrel but also is off at the breech in the direction that could fix this, if the experimenting shown it will help I will break it down and fix it too.
The plot even thickens more if you consider that the whole barrel scope and upper assy. is all attached and controlled and pointed via. the breech block and those two little M3x 25mm screws and at the front clamp where it centers the barrel via an o-ring and then goes around the air tube and goes down and provides the anchor point for the stock attach screw. Wow, It all works but I really can’t see how.
I guess the reality of all this is that we get a full floated air tube and a barrel that is guided by an o-ring but otherwise somewhat floated. I don’t see my dowels hurting any of the design intent in the end so it shall be. !!
There is enough slack that you can move the breech block and cover up and down to either be high or low or flat.
I don’t think that its a big issue as long as you keep the original way the barrel is mounted and then Stretched with moderator nut.
NOW. Here is a question.
I cant understand how the guys don’t get POI shift when they choose not to use stock Barrel Stretch type mounting ( screw into breech block and stretched with moderator) and replace moderator with NC type that just mounts with couple of grub screws.
I do not think that Barrel is designed to be Free floating like that with just being screwed into the breech block/transfer port. It is not sturdy enough like that. It will move around even so slightly.
I agree F&D this gun is not capable of shooting unshrouded due to the upper section the scope is mounted being attached to anything other than the two little screws supporting the front of the trigger assy. Thinking of doing some shroud and un-shrouded testing to check group size is what got me looking at this more closely. I felt there had to be a good better best situation with barrel shroud nut torque that could be optimized. The hole deal bothers me now, the more I look at it the more baffled I become. With all the effort on precision it just seems this would of been done differently with a locator at least. If it don’t move on you it don’t matter !!! but none of us would consider mounting a scope with such an arrangement yet we do mount our scopes to this this upper frame that is held in place with this arrangement. I am going to drop mine at a favorite machine shop in the morning to get this doweled.
I know exactly what you talking about.
There is enough slack that you can move the breech block and cover up and down to either be high or low or flat.
I don’t think that its a big issue as long as you keep the original way the barrel is mounted and then Stretched with moderator nut.
NOW. Here is a question.
I cant understand how the guys don’t get POI shift when they choose not to use stock Barrel Stretch type mounting ( screw into breech block and stretched with moderator) and replace moderator with NC type that just mounts with couple of grub screws.
I do not think that Barrel is designed to be Free floating like that with just being screwed into the breech block/transfer port. It is not sturdy enough like that. It will move around even so slightly.
I am doing the same for now as well, I just cut some stainless shim stock. and wrapped the barrel in that location, I did not bend the tabs as you did, and so far so good but I want a professional fix for it. I might have proper holding fixtures made for doing the drilling for the dowels.
Ride,
I was having the same issues but for different reasons. I was not able to achieve nearly that same compression with the NC shroud compared to the OEM set up. As as a result the scope tower/spacer would move up and down. I figure out that the hole where the barrel travel through the space is not the same size as the barrel’s OD. I made a soda can shim to wrap around the barrel so to prevent up and down movement.
I also made a shim for the front of the spacer.
I was lucky that the thickness of the soda can was a perfect for my needs.
I am no longer experiencing up and down movement.
I understand what you are talking about. The possibility of the spacer/tower rotating on the axis of the barrel. I would think that if you tighten the baffle nut with sufficient force, it should not move. But if you are seeing movement, I think your dowel idea should work great. That would take care of movement in any direction.
Keep us posted on the steps you took. I might be interested in this mod. Only problem with my gun is that the breech is made of steel. Might be a bitch to drill…
Gabe G.
Does that bother you…..
Kinda…if I had all those guns…I’d line them up like they were cannons and fire them in a row.
……………..
I will try to do that, maybe a set of strings coming to a common point, I’ll think on it. Hell, I still want a .25 std. R3 and a Leyla too, maybe a R2.5 as well. I’ll have all of them before I am done. More strings bigger bang I guess. If it makes you feel any better i shot a full tin of pellets through my .22’s today and both are driving tacks at 75 yards,
I was shooting out of our sun room window into a snow bank on a steep hillside and could just keep shooting a new hole in the snow for a fresh target. Both of these guns are tuned to perfection,925 fps, Scopes zeroed and the turrets reset to zero,at 75 yards at 1.5 mildots holdover and are busting starlings like popcorn. Hopefully the parts to finish the R3M to R3 conversion on my .25 will get here tomorrow and it is next, it is going to be a bench gun, so that will never end as far as a project. I was just thinking of doweling it while apart and the barrel is off.
I just want my guns PERFECT and that takes a little work.
Does that bother you…..
Kinda…if I had all those guns…I’d line them up like they were cannons and fire them in a row.
Picture added to original post. The scope rail is part of the upper on the right and not tied down to the barrel other than through compression on the barrel nut through the shroud system. I just don’t get it. I am admittedly over analytical but when I am trying to shoot for precision I have to remove every variable I can find to improve the guns performance. I am just concerned I am missing something.
Ride I’m not sure what you are talking about. Can you take some pictures of the parts you are referring to?
Sent from my SCH-I545 using Tapatalk
- You must be logged in to reply to this topic.
Hi Peter,
I agree with you. That will keep the tension to hold the barrel firmly.
If he can make two piece moderators with regular 1/2-20 adapter are even better. that allows people using their silencer. Just like yours, but break in two.