bedding a 33 inch barrelled rifle properly

[jrstraw]

Hello,
Recently I acquired a 33 inch barrel , unchambered, in .338 caliber.1-10 twist It is a full length bull barrel of 1 1/2" in diameter with no taper. I have done some Quikload research and received help from others, to find that in using 200-250 grain bullets in a .338 Winchester magnum cartridge I can achieve near 338 EDGE velocities with from 19% to 23% less powder. These ballistics seem impressive to me, especially with 4 different powders.
I have a Master Class benchrest stock with a long forend for this rifle, which is presently bedded for a Stolle Panda action.
In placing a yardstick in the barrel channel I find the barrel and muzzlebrake extend more than 24 inches in front of the stock. Lord, it seems to run on forever!
I understand enough applied physics that I know no action could stand the stresses produced on the action screws by this huge barrel, that I know of, or wish to buy.
I looked at the barrel channel and find its 1 /2" wide. The easy answer of a barrel bedding block is out since the stock is not wide enough to accept a bedding block. I had the stock, trigger, scope and mounts when the opportunity came to purchase this large barrel.
So, from a practical standpoint would it make sense to bed the barrel where it fits in the stock for 12" and "free float" the action? There are stresses here I have never dealt with. Also, the barrel will be bedded for 1/3 of its total length and how might that affect the vibration node? I am doing this because the winds really move around my lighter 6.5 bullets laterally here in the high altitude of the Rockies.

I would suggest contacting the ELR guys— F-Class shooters run 30 to 31 inch free floated straight barrels all the time—those are 1 1/4 barrels not 1 1/2– the ELR guys run what you are talking about— ask David Tubb—

 

[Rflshootr]

If cross section of the stock is so thin that there isn't enough room to put a pillar in the bottom of the fore end, then the stock is too thin to support the weight of a barrel that weighs 15-16 lbs. All the Master Class benchrest stocks with 3" forearms that I have seen pics of, should have plenty of room to under the barrel to add support, unless you simply don't want to do that. A Panda action is 1.5 wide and 1.720 tall, the same width as the barrel diameter. I can understand the width of the stock isn't wide enough for a full blown 2 piece bedding block, but underneath is a different story. Another viable option may be to cut a straight taper on the barrel with a 5" long straight section at the chamber end, and taper to 1.25 at the muzzle, you could lose about 2 lbs. of barrel weight. I'd like to see a picture of the stock and the barrel channel from a couple of different angles.

 

[Darryle]

NULA beds their entire pencil thin barrels and look at their results.

I would bed the entire thing, but I would also put a set of training wheels on it to haul that beast around and possibly kidnap a sherpa

 

[wildcat westerner]

Hello,
Thanks for all your insights into this matter and I shall continue to pursue the many options of bedding this huge barrel. Before attending college I carried things a lot heavier than this finished weapon, although it will be a challenge. If you are aware of a biathalon sling where the weapon is supported by both shoulders with the weapon carried right down parallel to the spine, I have one and can add extra padding to make this challenge less of an issue. I am content with the size of this barrel for a couple of reasons. Repeated firing will simply be less of a problem due to heat factors, and also all this weight will reduce the recoil. It seems there are two responders to this topic, heavy 338's set up for target shooting wherein there are strict rules to be followed and the rest are hunters using this cartridge for hunting and usually using 185-225 grain weight bullets. This weapon won't be used for competition, therefore many of the biases due to legal restrictions simply do not exist with regard to this build. With regard to the lighter hunting bullets for the .338, I understand their usage for shorter ranges with lesser recoil. Some .338 rifles I have shot have been difficult to the point of being brutal off the benchrest. I have just received a wide amount of 338 bullets for testing and in checking their retail prices was surprised at the costs. I really appreciate the wide variety, with a lot of 225's. If this rifle does not shoot it won't be because I did not test the different bullets adequately. The Tactical Kelbly should be arriving this coming week and then I must setup the exchange for the Panda.
ON another issue, how do you arrive at a weight balance for the weapon so the bipod is placed correctly? If I measure from the muzzle back on this weapon and compare it to the rest of my rifles the bipod placement will be well ahead of the stock foreend. This stock already has an extended fore end for bench shooting, would it be stupid to add a further extension to it so the bipod is placed correctly?

WW

 

[FEENIX]

I understand enough applied physics that I know no action could stand the stresses produced on the action screws by this huge barrel, that I know of, or wish to buy.

My gunsmith build block rifles for your type of set-up.

This stock was originally inletted for a Ruger. With a little (maybe a lot of) work, now it's got a Defiance living in it. This was chambered in 338 Lapua using a Light Block rifle contour barrel. It is a repeater with the DBM held into place by threaded pillars secured into the stock to keep the receiver floating.

This is a basic single shot medium block rifle with a 32" Heavy Varmint Contour Bartlein barrel. Imagine the stress that this barrel would subject even the strongest action to. We've ensured that our blocks are minimally obstructive and allow for the use of traditional scopes, stocks and rings/mounts. They also add very little weight to the rifle.

Good luck with your project build.

 

[wildcat westerner]

Thanks to some great insights from fellow readers I now have this new insight. Filling the block on the barrel with epoxy when its already fluted could be a time consuming mess. This was suggested since the exterior of the bedding block will be so large it will look ugly, especially in place when in the stock. Turn down the area where the barrel bedding block will be placed till the flutes, at least are gone. Turn it to a dimension of a common I.D. of a tube for superior fit. That way recoil movement potential is eliminated with proper fit. The exterior of the tube will require some relief on the stock, but it will not be hugely ugly. The bottom of the bedding block tube will have a square solid block added to it. This, in essence, becomes a huge recoil lug. several stock screws for attachment will allow the barrel on one side and the action on the other of the block to free float. Thus, when all this is accomplished a 8 inch barrel bedding block would still have 24 of the 33 inch barrel vibrating uniformally, so the barrel harmonics should not be affected. Are there experienced tool and die makers out there, and advanced gunsmiths who have worked similarly with outsized barrels and attempted this suggested procedure?

WW

 

[Pat Byrne]

I would NOT glue the barrel and action.. Action yes and screws.. Probably bed the barrel or a portion of it but if you glued the whole mess I don't know how you'd ever get it apart to salvage the stock when that barrel is toast.. Also like the idea of sending the barrel back to it maker and having it tapered down to 1'' at the muzzle.. From my BR days, there seemed to be a point of diminishing returns on straight, no taper, barrels and length when it came ultimate accuracy. But all that was in a 100, 200, and 300 yard environment... So maybe look at the F Class and 1000 yard BR guys and their setups.
Don't know Alex but have heard nothing but good about him..

 

[Hugnot]

I once had a .300 WM with a "telephone pole" barrel. Not quite like the OP's but close. No flutes. I had the barrel turned down to a straight taper leaving a 8" cylinder rear, 1.2" diameter & epoxy bedded the entire 8", then a straight taper to .75, for the remaining 20" of a 28" barrel. It shot just as good but looked & handled much better. A .25 diameter action screw when turned in tight at about 50 inch pounds can generate some 900 pounds of tension force (close to 1/2 ton), enough to bend & crush stuff . My thinking was the 8" tight bedding contact would absorb much recoil force. Worked just fine with a ordinary wood (walnut) stock having about .1 " of steel re-enforced epoxy supporting action, recoil lug, & 8" of barrel, apparently good vibes.

 

[wildcat westerner]

Thanks guys, things are evolving here. A neighbor has died and I have been given a vertical mill. My gunsmith will help me with the Morse tapers to fit a 3/4" chuck I also received. So, with the raw materials, time, a redesign of my bedding block that has now become a "bolt in" with 1/4" bolts this barreled action will fit a prone stock which has an action bedding block which presently extends to within 2 inches of the end of the forend. Harrel has made a special 1 1/2" brake with exhaust holes only on the top half of the brake. If you have seen a 338 Lapua Improved fired from the prone with a radial ported brake you will NEVER forget it!
WW

 

[Alex Wheeler]

Humor me on this.
Take that barreled action over to your work bench. Lay your finger on the bench and put the front of the action on top of your finger. Push down on the tang of the action enough to lift the barrel off the bench so all of its weight is now on your finger. Then tell me if you think your bending the action. I have measured the action flex with some very heavy barrels and I think your over thinking this.

 

[Tucker65]

Humor me on this.
Take that barreled action over to your work bench. Lay your finger on the bench and put the front of the action on top of your finger. Push down on the tang of the action enough to lift the barrel off the bench so all of its weight is now on your finger. Then tell me if you think your bending the action. I have measured the action flex with some very heavy barrels and I think your over thinking this.

Alex,
On something like this would you float the whole barrel or would you bed the first inch or so of the barrel shank also.

 

[Alex Wheeler]

Alex,
On something like this would you float the whole barrel or would you bed the first inch or so of the barrel shank also.

 

[bigngreen]

In the whole scheme of things there are larger barrels out there hung on rifle build for accuracy, free floated barrels and bedded actions. Like Alex said, your over thinking this!!

 

[wildcat westerner]

Thanks all for your input. With all your, and David Tubbs,' input this is what I will be doing. We will be creating a 9" barrel bedding block. The barrel will be relieved so the exterior of the bedding block is slightly larger than the barrel. Wall thickness of the bedding block with e 5/16". The action will float on one side and the 24 inches of barrel beyond the block will be floating on the other end. I can't turn the barrel over to the maker since he has passed on. I have decided I don't want to. This length and diameter has extra weight that will absorb recoil. It will be a PIA to carry to position, even with the Biatholon type sling. Once in place with the bipod used on the extended stock and the Harrell brake with ports only on the top half, I believe the rifle will provide very good accuracy and not brutal recoil. I have fired an ultralight rifle at Whittington in .338 mag just ONCE, never again!. Thank you all so much for your good input. I note that going outside the norm and physical comfort zone of most shooters tends to cause some consternation. I shall report to you when the rifle is completed.

Thanks very much,

WW