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Old 07-11-2018, 06:42 AM
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Float a GM sporter barrel or not??



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Getting ready to replace my factory 22" sporter barrel which is fairly tight in the channel with a GM sporter barrel; probably 20" but maybe the 24 fluted. Would there be any advantage to opening the barrel channel for the better quality barrel or not.

Hank
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Old 07-11-2018, 06:48 AM
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I've found that most sporter weight barrels like a little pressure from beneath them, so I don't free float the lighter barrels
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Old 07-11-2018, 11:13 AM
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GM sporter

Hi Hank! Presume you're not going to use a barrel band? Is the factory "bump" still in the barrel channel? I've had best shooting with a sporter with a bicycle inner tube patch at the forend. I've floated some but always had better groups with pressure either in front of the tenon or better at the front, back just far enough to hide the pad(s.) Amazing the POI shifts you can see with different pad thicknesses and uniform action screw torque. Must you have a sporter contour/weight barrel? The heavy taper barrels are always better shooters. Clean out the barrel channel removing the front bedding bump and rubber shim for those. jim
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Old 07-11-2018, 01:16 PM
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Quote:
Originally Posted by cleanprone View Post
Hi Hank! Presume you're not going to use a barrel band? Is the factory "bump" still in the barrel channel? I've had best shooting with a sporter with a bicycle inner tube patch at the forend. I've floated some but always had better groups with pressure either in front of the tenon or better at the front, back just far enough to hide the pad(s.) Amazing the POI shifts you can see with different pad thicknesses and uniform action screw torque. Must you have a sporter contour/weight barrel? The heavy taper barrels are always better shooters. Clean out the barrel channel removing the front bedding bump and rubber shim for those. jim
I'm with cleanpone.

Float the barrel channel, so a business card will slide down the channel. Then try a piece of inner tube in a few different spots to make your own support.

Last edited by Hawkeye57; 07-11-2018 at 01:18 PM.
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Old 07-11-2018, 04:05 PM
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Quote:
Originally Posted by cleanprone View Post
Hi Hank! Presume you're not going to use a barrel band? Is the factory "bump" still in the barrel channel? I've had best shooting with a sporter with a bicycle inner tube patch at the forend. I've floated some but always had better groups with pressure either in front of the tenon or better at the front, back just far enough to hide the pad(s.) Amazing the POI shifts you can see with different pad thicknesses and uniform action screw torque. Must you have a sporter contour/weight barrel? The heavy taper barrels are always better shooters. Clean out the barrel channel removing the front bedding bump and rubber shim for those. jim
I appreciate your comments, Jim. There is no barrel band. The rifle is a sporter with a 22"barrel. There is not much of a bump at the end of the channel. Less than the last carbine I had. I'm using the rifle for offhand shooting at 25 and 50 yards. That's about all I do now. I had a rifle a few year a go with a 17" heavy taper barrel that shot very, very well. Sub .350 groups at 50 yards from the bench were common. But, the rifle didn't balance well for offhand for me because of the heavier barrel. The rifle I have now with the 22" inch factory barrel balances fine. I need to renew my inner tube supply so I can try the various pressure points. I have my trusty torque driver so it will be interesting trying to finding the optimum combination.

So, pressure on the sporter barrel it will be. Thanks folks.

Hank
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Old 07-11-2018, 11:56 PM
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It’s been my experience that GM sporters and heavy tapers do best with a pressure pad. I’ve built/bedded several 17” & 19” GMHTs and currently have an outstanding shooter with a GM 20” fluted taper. The HTs have generally performed best with a 1” long pad of bicycle inner tube in the barrel channel around 4-6” from the V-block.
The 20” sporter (fluted taper) we have likes a 1.5” long pad fixed about 8” from the v block.

This might help, copied and pasted from another post long ago:

Quote:
Originally Posted by DrGunner
Free Float vs Pressure Pad


If you have a free float, test shoot it first. Then skip down to the section describing testing with pressure pads.

And if you have contact between the barrel and stock, test shoot it first.

Then to create a free float for testing, put a thin washer or stack some aluminum tape under the front of the receiver surrounding the takedown screw area in order to elevate the front slightly and float the barrel. Then you can test it in that configuration without changing anything.

If it shoots better with the shim under the receiver, then sand out any contact areas in the barrel channel creating enough space for a free float. IMO, a dollar bill space is insufficient. I prefer one or two business cards, depending upon thickness but the rule of thumb I use is one business card for rimfire, two for centerfire. You are not creating space to tame horrendous barrel whip, but the amount that a stock can expand and contract with moisture and the amount of flex present when shooting off a bipod mounted to the front of the foreend can be enough to make a difference.

If it shoots better with contact between the barrel and stock, then the next stage of tuning will involve testing barrel contact with a pressure pad. I prefer slices of bicycle inner tube, of varying thicknesses. I make three, one of them 1 inch long, another 2 inches long, and another 3 inches long. Work with the one that is 2 inches long, and mark out your barrel channel in 1 inch increments. Start with the pressure pad right at the receiver, test shoot and then move it forward 1 inch, test shoot apply, lather, rinse, repeat. Once you find the "sweet spot", try the 1" and 3" pads at the same spot.
Pick the best of the three, then
work forward and back in 1/4" increments to fine tune.
When that's done, you will have found what I nickname the rifle's “G-spot”- as in “Good”. (Shame on all you perverts that thought otherwise.)


Then you just need to experiment with different size, thickness, and density of material before committing and gluing something in place. Once I find the “G spot” and have fine tuned the pad position in 1/4” increments, I then test different pad lengths. I prefer to experiment with different lengths by working in increments of 1/4” longer and shorter than the “best of 3” pad.


I prefer to use thin double sided adhesive tape to hold pressure pads in. Glue and epoxy can stiffen the pressure pad and change its properties.

It has been my experience that MOST, but not ALL .920/Bull barrels shoot better with a free float- which requires a rear tang or other hold down to achieve.
As a general rule, those bull barrels that do shoot better with a pressure pad usually perform best with the pressure pad very close, if not right against the takedown area/receiver. I have free floated many 20-21" .920 barrels weighing 3-4 lb mounted with a slip fit in all manner of receivers and have never seen the "weight of the barrel deform the receiver"...
I have seen droop induced by over tightening the V Block screws- one good remedy to prevent this is to use a Gunsmither Block which creates a straight pull.
It also helps to use a proper inch/lb torque wrench and torque them to 12-15 inch/lb MAX.

I have also seen droop in a rifle that had a sloppy fit between the barrel stub and counterbore in the receiver- the result of an out of spec stub in two cases and counterbore on a receiver twice. I have always been able to remedy that problem with Loctite 603.

My preference is the interference fit provided by the Kidd receivers. I use the heat/cold process and have never had a problem putting one together or taking one apart.


In my experience most Taper/Sporter profile barrel shoot best with a pressure pad, the distance from the receiver varies greatly but as a general rule of thumb-
In general, most of my heavy tapers and short (16.5-18”) barrels shoot best with a 1-1.5” pad placed 4-6” from the V-block. Most of my longer barrels (20-24”) do best with a 2-2.5” pad often very near the end of the barrel channel.

I do not claim this process to be "RIGHT", just what works for me.
There are exceptions to every rule.


Hope this helps-

DrGunner
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Old 07-12-2018, 06:22 PM
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I have two Gr.Mnt. match sport barrels a 16.5 & a 20".
This how I have bedded them, then I have the barrel free floated like a dollar bill gap.



I shot the 5 shot group last Sun. with the 16.5" flutted barrel.



Works for me anyway.

Midwest Swiss

Last edited by midwest swiss; 07-12-2018 at 06:25 PM.
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Old 07-12-2018, 11:16 PM
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This is where I landed with the pad, about 1 1/2" in front of the front tang. GM 22" fluted sporter, stainless.





Edit: apparently there's something wrong with my image hosting site, so my pics are only displaying with Internet Explorer or by phone. Chrome and Firefox won't display

Edit2: looks like it only happens on those browsers when viewing this site. other sites will display.

http://oi67.tinypic.com/2rxxwro.jpg

Last edited by rawhp; 07-13-2018 at 01:02 AM.
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Old 07-13-2018, 06:53 PM
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I have a GM 20" sporter barrel that I installed on a 10-22 DSP. Bedded the first 2" in front on the action and floated the rest of the barrel. The action is bedded also. To date it seems to like CCI Standard Velocity ammo, as I have shot a .170 group at 50 yards. I would recommend the GM barrels, but this is the only GM barrel I have.
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Old 07-13-2018, 07:26 PM
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When I get the barrel installed, I believe I'll start with pads closer to the action and the rest floated. I'll put pads at the end of the channel if that doesn't work.

I appreciate all of the suggestion.

Hank
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Old 07-13-2018, 07:57 PM
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Old 07-14-2018, 02:50 AM
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Originally Posted by Pastprime View Post
When I get the barrel installed, I believe I'll start with pads closer to the action and the rest floated. I'll put pads at the end of the channel if that doesn't work.

I appreciate all of the suggestion.

Hank
Yes. From my limited experience with the 10/22..... this is what I'd do.
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Old 07-14-2018, 06:50 AM
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Quote:
Originally Posted by rawhp View Post
This is where I landed with the pad, about 1 1/2" in front of the front tang. GM 22" fluted sporter, stainless.
Me Too!!

Bedded this way on all 4 of my sporters that made the 1/4" club.
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Old 07-14-2018, 09:25 AM
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I did not float my Sporter.
Shoots very well.
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Old 07-15-2018, 08:35 PM
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.920 bbl

will this also work with the bull bbl thats .920?
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