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Old December 17, 2013, 11:04 AM   #51
Bart B.
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Picher, heat expands barrel steel about .000006" per degree in every direction. So they get larger in diameter as well as longer.

Only real proof I've seen that their enlargement in the chamber area was with a few match rifles tested at 1000 yards. With a bedding pad under the barrel a few inches in front of the receiver, they all had vertical shot stringing as the barrels heated up. Shortening the pad back an inch reduced the stringing. Totallt removing it resulted in no vertical shot stringing. Others have reported the same thing with rifles, ammo and and abilities to see the difference.

I'm not aware of any significant difference in pillar or conventional receiver bedding as long as the stock screws are torqued to the same amount for each day's shooting. Accuracy's not significantly changed since the '60's when conventional epoxy bedding was all there was then after soft-cored synthetic stocks came out and they needed metal pillars to make the shoot as accurate as conventional epoxy bedding in wood stocks. The best of them are shot under 1/3 MOA at short range, under 1/2 MOA at medium and under 3/4 MOA at long range when properly tested.

Last edited by Bart B.; December 17, 2013 at 11:44 AM.
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Old December 17, 2013, 12:25 PM   #52
Picher
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Due to the difference in barrel wall thickness to the length of barrel within the forend, the barrel lengthens about 20 times as much as the diameter increases, so with a tapered barrel, tightly bedded into a receiver, it has a tendency to rise as it's forced into the "cone" shaped bedding at the barrel taper.

Seasonal wood swelling, shrinkage and warpage has a much greater effect on POI and grouping of tightly-bedded barrels and those having pressure points, than free-floated ones. That fact was noted by Col. Townsend Whelen in his book "Small Arms Design and Ballistics" -1949.

I epoxy-bedded my first rifle, a 30-06, Savage 110, around 1961 (at age 17). The barrel was free-floated from about an inch ahead of the action. The stock was a semi-inletted Bishop blank, the exterior of which I configured closely to the shape of Weatherby MK5s, using only files and sandpaper. The bedding material was marine epoxy. The rifle shot sub-MOA with handloads and a K2.5x Weaver.

Last edited by Picher; December 19, 2013 at 03:35 PM.
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Old December 17, 2013, 03:06 PM   #53
Bart B.
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Picher, many are well aware of wood dimensional changes with temperature and humidity. Which is why so many competitors retorqued their stock screws before each day's shooting. Even Garands were best left stored with their trigger guard half open to relieve the pressure on the receiver and trigger group flats to maintain accuracy each day.

But synthetic stocks had their days of woe, too, when they first came out. 'Twas first noticed on M14's and M1A's layed in the sun atop a shooting stool for a while. The heat on one side expanded it enough to bend the fore end so the stock ferrule pushed to one side. That put extra pressure on the barrel band at that point and zero's changed and sometimes accuracy, too. Bolt guns with free floating barrels in synthetic stocks never had that problem. It tood several years of plastic chemistry changes before synthetic stocks stayed dimensionally stable within reasonable limits.
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Old December 19, 2013, 03:41 PM   #54
Picher
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Interesting Bart. I was never into military target shooting and no very little about accurizing M1s, etc. The CMP sent notices recently that it's offering classes on M1, M1A accurizing. There seems to be quite a bit to it.
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Old October 27, 2014, 02:45 PM   #55
Woolly Bugger
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Old thread, but I thought I'd share my experiences with free-floating a Vanguard S2 in 30-06.

I purchased a synthetic S2 last year and was immediately unhappy with the groups. Two types of 150 grain ammo would string vertically into 2-3" patterns. I was firing fairly quickly, but even one attempt at complete cooling, waiting 10 minutes between shots, didn't help the spray. It's my first centerfire rifle, so while I was fairly certain the problem was not me, I couldn't be absolutely sure. This uncertainty kept me from invoking my 1-MOA warrantee with Weatherby. So...

Step 1: I bought a Bell and Carlson Medalist stock. I should have just screwed it on and shot a variety of ammo it as-is, but I had more ambitious plans. I sanded out the pressure points up front. When that still wouldn't float the barrel I added a washer under the recoil lug and bedded the lug area with epoxy. (didn't do the whole action because I'm new at this and didn't want to risk messing up the stock or my gun.) Went and shot it: groups even worse than before. BUT before I left the range I put some cardboard under the barrel and got a half-decent group out of Barnes 168-grain ammo. Two touching and a third about an inch away. More on that in a minute.

Step 2: I attempted to re-create the cardboard setup with something more solid. I chiseled out the epoxy and washer, then rebedded the lug down flush with the stock chassis. A day later I followed some directions I found online and added a pressure point back to the forend. I did this by applying a spot of epoxy and then weighing down the swing swivel while supporting the barrel on a sandbag. The result was fancy looking but the following trip to the range was another disaster. Groups were in the 2-3" range again. I had used 8 pounds of hanging pressure for the bedding -- was it too much? I guessed so.

Step 3: I chiseled and sanded out the pressure point. This was a little dicey, since it wasn't always clear where my epoxy ended and the stock's fiberglass began. I got a few tufts of fiberglass sticking out and ended up with a bedding area that looked like the surface of the moon, but don't think I did any real damage to the integrity of it. Since there was still some upward pressure (I couldn't get a dollar bill under the barrel) I figured I'd shoot it again and see what happened. But even with 8-10 minutes between shots, it wouldn't group.

*sigh* I had taken my OEM stock along to the range and was staring at it, about to give up on my fancy, $260 B&C. This saddened me, since I love the thicker pistol grip and hard-ringing feel of the B&C. But if I couldn't make it shoot... One last idea. I pulled off the stock. Recalling the cardboard shim from a few weeks back, I tore an inch square off the packaging of my ShootNC targets and covered the moonscape area, then tightened it down. Shot #1: 2.8 inches high. Shot #2... Where is it? Shot #3: 3.1 inches high. HAWT... DAMN.

The combo of Barnes 168 grain factory ammo and a cardboard shim under the barrel gave me a sub-half-inch group. I dialed the scope down .3 Mil and packed up the gun. (I had to be somewhere or I would have confirmed it.) Tore off the target to post on my shop wall.

I guess I'm hunting with cardboard under my barrel.

IF I HAD TO DO IT AGAIN: I probably would do the same thing, since I really wanted to try some of these things. But if you don't aren't eager for a project, be sure to shoot lots of different loads and see if you can avoid it. In any case, my gun seems to be evidence that a good stock and epoxy bedding of the recoil lug aren't always enough to make a free-floated sporter barrel shoot. And that's OK.

Edit: Obviously, the 168-grain ammo shot from my original stock might have been a sweet combo, too. But live and learn.

Last edited by Woolly Bugger; October 27, 2014 at 02:56 PM.
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Old August 8, 2015, 10:28 PM   #56
pools1
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Free floating vanguard

Hello been reading all of the threads. I have a vanguard 2 308. I properly broke the barrel in as per weatherby instructions. I got one good 1/2 Moa group. The rest are horrible. I used hornady custom ammo, along with black hills match and federal match. I put a bell and Carlson stock and bedded the lug. No joy.
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Old November 5, 2015, 02:28 PM   #57
Woolly Bugger
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Pools1,
Sorry to hear of your troubles. I have a few questions/tips that you may already be aware of, so apologies in advance.

-Check your scope mount and tighten if necessary.

-You mention different ammo brands but not the bullet weights. Definitely try different weights if you haven't already.

-At the range, be mindful of the barrel heating up. This is a skinny #2 barrel so you can't shoot it like a bench-rest gun and expect great results. Three shots followed by 10 minutes of cooling is the fastest I would go.

Good luck
WB
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Old November 5, 2015, 08:39 PM   #58
Art Eatman
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The OP has likely done his deal, 2+ years ago.
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