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bore wear on Weatherby 338/378

 
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  #1  
Old 05-25-2011, 05:21 AM
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bore wear on Weatherby 338/378

My 338/378 Weatherby is loaded with 300 gr Burger Hybrids with a MV of 2674FPS.
My question here for the experienced and knowledgable shooters is: The MV of this rifle is in the 7.62 NATO and or 30/06 range. These two chamberings are not known for heavy bore wear. Since I am shooting at a reasonable MV will my bore last longer with this rifle? 338/378 Weatherbys are or have a reputation for being barrel burrners.

Cheers & Tighter Groups: Eaglesnester
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Old 05-25-2011, 08:05 AM
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Re: bore wear on Weatherby 338/378

Quote:
Originally Posted by eaglesnester View Post
Since I am shooting at a reasonable MV will my bore last longer with this rifle? 338/378 Weatherbys are or have a reputation for being barrel burrners.
With the posted velocities you have listed I feel your tube will last a long time. I have heard that about the 30 and the 338 -378's but haven't seen it. My first 30-378 was looked over good at about 500 rounds and was like new. I would feel your 338 should go over 1500 rounds before you need to take a look. I would also recommend taking time a the range for the tube to cool between shots. I feel this is a huge factor in throat deterioration.

Jeff
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Old 05-25-2011, 08:59 AM
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Re: bore wear on Weatherby 338/378

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Originally Posted by Broz View Post
With the posted velocities you have listed I feel your tube will last a long time. I have heard that about the 30 and the 338 -378's but haven't seen it. My first 30-378 was looked over good at about 500 rounds and was like new. I would feel your 338 should go over 1500 rounds before you need to take a look. I would also recommend taking time a the range for the tube to cool between shots. I feel this is a huge factor in throat deterioration.

Jeff
+1

Velocity and the amount of powder have a direct bearing on throat erosion.

The more of eather/ both the more erosion. add temperature and you accelerate the process.

Like Broz, I have not noticed a drop in accuracy in My 30/378 with my loads (Maximum) but I
am at around 450 rounds down the tube.

I load this rifle hard (The reason I built it) and don't expect great barrel life, but it is a hunting rifle
and if I get even 1000 rounds before accuracy falls of I will be happy.

Yours should last much longer.

J E CUSTOM
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Old 05-25-2011, 09:48 AM
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Re: bore wear on Weatherby 338/378

I own both 30-378 and 338-378 Wbys. I agree with JE custom that throat erosion is the concern and not barrel wear. Throat erosion happens when hot high pressure propellant blows though the bore and raises the surface temperature of the throat to the point it starts to melt. Smalll amouth of the surface of the bore are blown out the barrel. It only happens in the throat because the neck and chamber are protected by the brass while the pressure and temperature are lower further down the bore. The exposure time to the hot gas is also longst right at the bore.
It all has to do with the volume of propellant, the pressure, and the cross section of the barrel.
The effect is very non-linear. If the throat surface doesn't reach the melting point little metal is removed. The temperature rise and fall of the surface temperature is very short duration, only milliseconds. Hoowever, repeated firing raises the base tempearture before each shot and can dramatically reduce barrel life if the rifle gets hot. Few people shoot a 338-378 Wby rapid fire.

Some commercial cartridgs which have a repuation for being hard on barrels inclued
223 WSSM (53.7)
264 Win Mag (82)
7mm Rem Ultra (112)
30-378 Wby (133)
416 Barrett (228)
(case capacity in grains)

The 338-378 Wby isn't on that list. While it has the same pressure and a bit more case capacity than the 30-378 Wby it's larger bore increases barrel lilfe at least 50% over the 30-378. Since both of these are big game rifles and not shot rapidly or frequenty they'll last a long time for the typcal hunter.

If you consider that the typical high power rifle bullet is in the barrel only for about two milliseconds, the actual working life of most rifle barrels ranges from about 2 seconds to a minute. Maybe a few minutes for pistol caliber cartridges.
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Old 05-25-2011, 10:11 AM
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Re: bore wear on Weatherby 338/378

eaglenester,

It's been danced around so far, but I don't think anyone's quite touched on it just yet; bullet weight is (IMHO) the largest factor in play here. As Lou and JE mentioned, throat erosion is the problem here. Velocity can be a problem, but it pales in comparison to what happens when we use heavy bullets at the same sort of pressures. Heavier bullets have more inertia, and overcoming that in getting the projectile moving down the bore allows those hot erosive gasses and high pressures to dwell for a considerably longer period (still talking an incredibly small gap of time here) right there in the throat area. If you take a look under a borescope, you'll normall find shot-out barrels looking nearly pristine just a few inches ahead of the chamber. No cracking or checking whatsoever. Pull the scope back to the area just ahead of the chamber and tyou'll be shocked at the amount of damage. Rough cracking, like a bad asphalt road with chunks missing in places.

I've seen dozens of examples of barrels done in identical chambernings where one was used with heavy bullets exclusively, and the other with lighter bullets. In virtually every example, the barrel used with the heavier bullets had significantly shorter life, usually around half in terms of round count. Lighter bullets, even at very high velocity, just aren't as hard on bore life as the heavier projectils are. We use heavy bullets because they work for the tasks we ask of them, not because they prolong barrel life. But we should also use them with the knowledge that they have costs associated with them, beyond what we originally pay to buy them.
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Old 05-25-2011, 10:48 AM
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Re: bore wear on Weatherby 338/378

Eaglesnester,The 338-378 Weatherby is not a barrel burner under any circumstances. I have seen this thrown around on forums the past few years and it is pure BS by inexperienced shooters trying to find excuses to make there little darling rifle look better for some reason. I have been shooting the 338-378 wby since about 1979 and own seven now. Have some with 1500 rounds that are still in excellent condition. The 338-378 Wby is not even in the discussion as a barrel burner.

Secondly, I would be concerned underloading your rifle to the 2600's fps. You are about 400 fps slower than my 338-378's. For example my 340 wby shoots the 300 SMK at 2735 fps with best accuracy. That is with about 30 grains less powder than the 338-378 wby. Why shoot a 338-378 wby and underload it down to between a 338 winchester and a 340 wby? I just shot some new 225 grain Cutting Edge bullets in one of mine out to 1000 yards at 3466 fps. Shot a 8 5/8" five shot group and the drops plugged into JBM came out .653 BC. The 338-378 Weatherby is a serious long range hunting rifle when loaded properly and is not considered a barrel burner by people who have extensive experience with them and other big 338's.

Since you can't get H-870 any more try Retumbo with a fed 215 match primer. You should get a good accurate load between 108-112 grains that will get good velocity. Look at the slowest powders you can get and your best loads will be with powders slower than Retumbo. I still have a little H-870 remaining, 30 pounds or so, so I haven't really gone out looking for the best to replace it. I have a good friend I built one for and he is doing very well with Retumbo and I tried it so that is why I mentioned it. What load are you shooting?
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Old 05-25-2011, 03:57 PM
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Re: bore wear on Weatherby 338/378

Quote:
Originally Posted by Long Time Long Ranger View Post
Eaglesnester,The 338-378 Weatherby is not a barrel burner under any circumstances. I have seen this thrown around on forums the past few years and it is pure BS by inexperienced shooters trying to find excuses to make there little darling rifle look better for some reason. I have been shooting the 338-378 wby since about 1979 and own seven now. Have some with 1500 rounds that are still in excellent condition. The 338-378 Wby is not even in the discussion as a barrel burner.

Secondly, I would be concerned underloading your rifle to the 2600's fps. You are about 400 fps slower than my 338-378's. For example my 340 wby shoots the 300 SMK at 2735 fps with best accuracy. That is with about 30 grains less powder than the 338-378 wby. Why shoot a 338-378 wby and underload it down to between a 338 winchester and a 340 wby? I just shot some new 225 grain Cutting Edge bullets in one of mine out to 1000 yards at 3466 fps. Shot a 8 5/8" five shot group and the drops plugged into JBM came out .653 BC. The 338-378 Weatherby is a serious long range hunting rifle when loaded properly and is not considered a barrel burner by people who have extensive experience with them and other big 338's.

Since you can't get H-870 any more try Retumbo with a fed 215 match primer. You should get a good accurate load between 108-112 grains that will get good velocity. Look at the slowest powders you can get and your best loads will be with powders slower than Retumbo. I still have a little H-870 remaining, 30 pounds or so, so I haven't really gone out looking for the best to replace it. I have a good friend I built one for and he is doing very well with Retumbo and I tried it so that is why I mentioned it. What load are you shooting?
Thanks heaps for the recipe. I am currently loading Burger 300gr hybreds with 250CCI caps and 96gr RE25 (max loading) as per the recipe I got from Walt Berger using quick load. I will try your combo for sure. I have been meaning to try the Retumbo as it was a load listed by Walt He says 93.5 min load and 103.8max load with 300gr Burger. Your load seems a little heavy, I will load some and try to work up to your weights. Walt Bergers suggestion of 103.8gr of Retumbo lists the 300gr Burger flying at 2721FPS with a loading of 96.1%

Eaglesnester

Last edited by eaglesnester; 05-25-2011 at 04:07 PM.
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