what barrel diameter can I go down to?

[casts_by_fly]

hi guys,

 

I'm finally getting to order my barrel. I want to go as light as possible and I was thinking a lightweight or even featherweight profile. I am going to have it threaded for 1/2 UNF for a moderator. How thin can I go at the muzzle so that the moderator isn't affected? The lightweight and featherweight profiles end up at .57" and .55" respectively. Is that enough to then thread 1/2 UNF on the end?

 

Thanks,

Rick

[Ronin]

I have seen Sako 75 ultralight rifles in 308 with muzzles around .580" that have been threaded 1/2" UNF, this doesnt leave much for the shoulder (or much meat in the barrel wall) however, it works ok.

 

Dont forget that even if the profile finishes at say .55", the gunsmith will be cutting an inch off the end anyway before finishing the crown, and barrel thread so it will probably be a few thou larger diameter than the smallest projected in the profile diagram.

[ejg223]

I would prefer to use a normal sporter weight barrel, cut as short as possible.

Mill weight off the action and use the lightest stock possible, use the lightest mounts.

use a light scope. Some recoil pads weigh 50 grams others over 150.

How much could one save with a ultra thin barrel compared to a standard sporter ?

I'll guess max 300 grams?

 

edi

[casts_by_fly]

ejg,

 

The standard encore barrels are 1" at the chamber tapering to 0.75 (maybe 0.79) at the muzzle. A lightweight will start at 1" and come down to .55 or so. From looking at the shilen profiles, similar tapers are showing a difference of 2 lb or so at 24". I'm only going to 20", so there won't be quite as much difference, but even still it will be more than half. I'm estimating between 1 lb and 1.5lb difference. It is a 17 caliber barrel, so each inch is a little heavier than a 30 caliber barrel.

 

My stock and butt pad are set already. I'm hanging this barrel on an encore (I already have it in a 223) and I won't want to get into a new set of synthetic stocks for it. Shaving the action is not an option. So the barrel and scope are the only places to save any weight. I already have the scope. So realistically saving a pound or more on the barrel is worth it. Plus, this isn't going to be a gun where I'm putting loads of rounds down the tube in quick succesion. It will be one or two here and there. So I don't need a heavy barrel for any reason.

 

Ronin,

 

Thanks for the numbers. It is a 17 cal, so meat in the barrel shouldn't be a problem. The contour profile isn't coming from a set profile, so I can specify 0.55 at the finished muzzle if I want to. I think taking it down to 0.6 or so should leave enough shoulder for the mod to bump against. I think I'm also going to ask that they take the taper down quickly from the 1" chamber diameter to something smaller and then gradually taper to the muzzle.

 

Thanks,

Rick

[ejg223]

I don't know about encore, but if I type in the a No. 5 barrel at albeit 27" length and

0.7" muzzle and compare with the same tapered down to 0.55 I get 4.305 lbs for

the heavy and 3.821 lbs for the light one. below 300 grams difference.

That's with that little excel program from Lilja. maybe it's no good.

 

I had actually meant the difference between a say 0.650 sporter to the very light 0.55 version.

 

edi

[casts_by_fly]

Hi Edi,

 

I was just going by the chart on Lilja website comparing a #5 to a #1 contour and scaling back some of the weight difference because I won't be at 27". I think the difference is that the #1 tapers down to 0.70 quickly past the chamber and then straight down to .525. I think what you did was run a .875 straight down to 5.5. Either way, 300 grams is still a full 12 oz.

 

Thanks,

Rick