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Chism G
03-24-2013, 08:37 AM
I have an 80lb Rail gun that I'm trying to get to know better. I screwed the action on the barrel and torqued the barreled action to the top part of rail at a recommended 65 inch/lb. see (http://benchrest.com/showthread.php?85632-HELP!-Who-Makes-This-Rail&highlight=rail+Gun)

The Block/Clamp has ten bolts. What are some recommended inch/lb torque settings for the Clamp. I realize that each Rail Design is different. Next question,.. What is the principal behind the torque setting in relation to Rail Gun accuracy in a design similar to this?. As far as I can tell,this gun shoots Ok. I just want to be aware of the possible options for set up.




Glenn

Lawrence W.
03-24-2013, 11:44 AM
The trick in torquing down the barrel block is to put on enough torque so that the barrel doesn't slide, but not enough that you end up putting a squeeze on the barrel. I have a 10 bolt block and 27 INCH pounds has never let a barrel slide in my 12 years of shooting rail guns.

JerrySharrett
07-08-2013, 08:38 AM
The trick in torquing down the barrel block is to put on enough torque so that the barrel doesn't slide, but not enough that you end up putting a squeeze on the barrel. I have a 10 bolt block and 27 INCH pounds has never let a barrel slide in my 12 years of shooting rail guns.

Lawrence, one of the old masters of benchrest contends that a short barrel block, say 4" with 6 bolts, shoots better than rails with long barrel blocks. Whatcha think?

I'm getting ready to set mine up as a cantilevered rig. This way there is no block to restrict the barrel. I know from slugging a blocked barrel that there is some bore restriction. On my old setup and torqueing over about 40 in/lb I can feel the block just with a tight fitting patch.

Lawrence W.
07-08-2013, 11:31 AM
Hello Jerry.

If your old master benchrest shooter has done better than these aggs over over past 10 years in registered 5 shot benchrest matches, then I would say go with the short barrel block. If not, then you should go with the longer barrel block, very lightly torqued.

0.1254
0.1414
0.1472
0.1484
0.1498
0.1558
0.1572
0.1648
0.1682
0.1714
0.1728
0.1750
0.1766
0.1840
0.1858
0.1858
0.1868
0.1870
0.1888
0.1918
0.1944
0.1948
0.1952
0.1962

Chism G
07-08-2013, 01:01 PM
Hello Jerry.

If your old master benchrest shooter has done better than these aggs over over past 10 years in registered 5 shot benchrest matches, then I would say go with the short barrel block. If not, then you should go with the longer barrel block, very lightly torqued.

0.1254
0.1414
0.1472
0.1484
0.1498
0.1558
0.1572
0.1648
0.1682
0.1714
0.1728
0.1750
0.1766
0.1840
0.1858
0.1858
0.1868
0.1870
0.1888
0.1918
0.1944
0.1948
0.1952
0.1962



Lawrence.....Were these aggs shot at 100 or 200yds. I got a Rail Gun not too long ago. Still trying to learn how to shoot it. I'm discovering there are a lot of little mechanical things that can kill your aggs with one of these contraptions.



Glenn

JerrySharrett
07-08-2013, 01:54 PM
Hello Jerry.

If your old master benchrest shooter has done better than these aggs over over past 10 years in registered 5 shot benchrest matches, then I would say go with the short barrel block. If not, then you should go with the longer barrel block, very lightly torqued.

0.1254
0.1414
0.1472
0.1484
0.1498
0.1558
0.1572
0.1648
0.1682
0.1714
0.1728
0.1750
0.1766
0.1840
0.1858
0.1858
0.1868
0.1870
0.1888
0.1918
0.1944
0.1948
0.1952
0.1962

Lawrence, great aggs. PM me an email address and I will send you the details of what they are doing now.

Lawrence W.
07-08-2013, 06:54 PM
Glenn,

Those were all 100 yard aggs.

Charles E
07-08-2013, 09:14 PM
I know from slugging a blocked barrel that there is some bore restriction. On my old setup and torqueing over about 40 in/lb I can feel the block just with a tight fitting patch.Jerry, on a couple long range and one short range bag gun, I've glued the barrel to the block. I don't believe there is any restriction in the bore...

Of course, you have to make a block for each barrel, if you want to have more than one available at any one time. So what?

I can't remember if you were at the Charlotte Regional (the one where we had the hurricane, not the one where everyone set a record -- 2002 was it?), but I shot it there in HG. Top 10. The 1K 17-pounder performs well, too.

If I build another rail, it will be a tension-barrel. But If it weren't, it would be a glued block, like the bag guns.

Chism G
07-10-2013, 11:39 AM
Glenn,

Those were all 100 yard aggs.

Impressive!....That's an average of two five shot teen aggs per year with a Rail Gun. I intend to experiment with different torque settings on my ten bolt clamp.



Glenn

JerrySharrett
07-10-2013, 01:01 PM
If I build another rail, it will be a tension-barrel. But If it weren't, it would be a glued block, like the bag guns.

Charles, the 308W barrel that John Lewis set the IBS 600 record of 0.414 was a barrel I had pressed out of a glued block that Bill Minneman of MTM Products had set up but never used. Now John is shooting a "screwed block" setup. Go John!!

Charles E
07-10-2013, 06:08 PM
Charles, the 308W barrel that John Lewis set the IBS 600 record of 0.414 was a barrel I had pressed out of a glued block that Bill Minneman of MTM Products had set up but never used. Now John is shooting a "screwed block" setup. Go John!!Jerry. a "screwed block" is another idea worth trying. It can distort the bore I suppose, like using a lot of torque on a barrel will distort the chamber a bit -- which only seems to matter in RF.

But I'm not convinced you need much tension with a screwed block. In fact, not much at all, with loc-tite on the nut, might work real good.

Another notion that works is a guage fit. The hole in the block is the same size as the barrel, you use jacking screws to open it to get the barrel in, then lightly clamp with another set of screws. As the barrel is "grabbed" evenly all the way around, I'd doubt there is any distortion.

IIRC, a number of guys have a dedicated block for each barrel. They can be resued, but it is that, not simply taking out the barrel & putting in a new one.

The reasons for the work show on the target. One aspect is, as I've always said (probably too often), a nicety is having the scope point where ever the barrel does. Not as easy as it sounds.

Ian_Owen
07-14-2013, 05:18 AM
Jerry. a "screwed block" is another idea worth trying. It can distort the bore I suppose, like using a lot of torque on a barrel will distort the chamber a bit -- which only seems to matter in RF.

But I'm not convinced you need much tension with a screwed block. In fact, not much at all, with loc-tite on the nut, might work real good.

Another notion that works is a guage fit. The hole in the block is the same size as the barrel, you use jacking screws to open it to get the barrel in, then lightly clamp with another set of screws. As the barrel is "grabbed" evenly all the way around, I'd doubt there is any distortion.

IIRC, a number of guys have a dedicated block for each barrel. They can be resued, but it is that, not simply taking out the barrel & putting in a new one.

The reasons for the work show on the target. One aspect is, as I've always said (probably too often), a nicety is having the scope point where ever the barrel does. Not as easy as it sounds.

Charles can you please explain what you mean by the above statement? You infer that the scope on a rail gun doesn't always point where the barrel points.......why not?.......Ian

Charles E
07-14-2013, 09:30 AM
Charles can you please explain what you mean by the above statement? You infer that the scope on a rail gun doesn't always point where the barrel points.......why not?.......Ian
It was Harold Vaughn, in his book Rifle Accuracy Facts, that tested & showed a scope mounted on the receiver of a rifle is subject to occasionally change it's alignment with the muzzle.

This because the barrel/action joint is "weak" enough to occasionally allow slight changes in alignment. With the shoulder/v-thread setup, it always goes back, but there are those few shots when there's some change, which affects the next shot. If you're using the scope when that happens (you don't always use the scope with a RTB), the barrel will be pointed in a slightly different place than with the last shot, and will print so.

Edit:

I mean chapter 6 in Rifle Accuracy Facts -- Barrel-Receiver Threaded Joint Motion (pp 103-121), not, as you might think, Chapter 5, Scope Sight Problems.

We always seem to think we've addressed what Vaughn found in his studies because we're Benchrest Shooters, but it ain't always so.

Boyd Allen
07-14-2013, 10:26 PM
This one seems to work pretty well. Take a close look.
http://i1021.photobucket.com/albums/af340/fresburgflash/Visalia10-18-09fiveshotunlim017.jpg (http://s1021.photobucket.com/user/fresburgflash/media/Visalia10-18-09fiveshotunlim017.jpg.html)

http://i1021.photobucket.com/albums/af340/fresburgflash/Visalia10-18-09fiveshotunlim015.jpg (http://s1021.photobucket.com/user/fresburgflash/media/Visalia10-18-09fiveshotunlim015.jpg.html)

JerrySharrett
07-15-2013, 05:41 AM
This one seems to work pretty well. Take a close look.

But, the scope on a rail is not used to aim each individual shot.

Charles E
07-15-2013, 07:48 AM
But, the scope on a rail is not used to aim each individual shot.
...until the wind is't cooperating, and it's knob-cranking time. (& I notice the scope in the picture is mounted on the block.)