converting a bolt face.

[sam4485]

I am considering to build a 338 Lapua or 338-378. I have an unused action currently sized for 300 Weatherby. Of course the 338s have a larger diameter bolt face. How difficult would it be to convert the bolt face to the larger cartridge?

 

[J E Custom]

I am considering to build a 338 Lapua or 338-378. I have an unused action currently sized for 300 Weatherby. Of course the 338s have a larger diameter bolt face. How difficult would it be to convert the bolt face to the larger cartridge?

It is not that difficult if you have the right bolt, and figure on some extractor work and action rail opening + the bolt stop has to be extended and so does the Magazine to handle the bigger/longer cartridge.

What action do you have ?

J E CUSTOM

 

[Deleted member 46119]

I am considering to build a 338 Lapua or 338-378. I have an unused action currently sized for 300 Weatherby. Of course the 338s have a larger diameter bolt face. How difficult would it be to convert the bolt face to the larger cartridge?

You say the current bolt face is for a 300 Weatherby chambering.

Does that mean it's a Mark V Weatherby?

 

[sam4485]

The action is a Weatherby Vangard chambered for a 300 Weatherby.

 

[sam4485]

I am a little surprised that the magazine would have to be lengthened. The max OAL for the 300 Wby is 3.56 and the 338 Lapua is 3.602. That's only 4 tenths

 

[Deleted member 46119]

Ok, now I know what you are using.

I have a Vanguard in 300 Weatherby. I have never measured the bolt to determine if it can go as far as 338 Lapua.

It's well past bed time (2:30am) and I'm done in the shop for yesterday.

Later today I'll get out the VG and have a look.

The biggest challenge is the extractor. There is no extractor for the .590 bolt face of the Lapua for the VG bolt. You will have to customize.

If you single feed, the magazine is not important. If you want to mag feed, again some customization will be required. The follower won't be quite right, the feed lips of the magazine box will have to be massaged. There are plenty of loads for the Lapua that are shorter than 3.56. Again, I'll have to measure the mag box to see what's up there.

You didn't say what the intended use for the rifle will be. Hunting, "target" or 1 mile plus?

Since I have experience in this area I'll opine a bit. Converting a Vanguard to 338 Lapua is more work than it is worth. I have 4 Vanguards and love them but there are easier and more cost effective roads than that one.

I have an alternative suggestion for you if you want a 338 but are not married to the Lapua. Try a 338/28-Nosler. I have one and love it. No modifications required. It will just work. Depending on your intended use and barrel length you can achieve very decent performance and every load should mag feed.

Example: With a 28" barrel, 300grain Berger Hybrid over IMR7828 should reach 2750fps. That would keep the bullet well supersonic past 1 mile.

or if you are hunting

Example: With a 24" barrel, 185 Barnes TTSX over Reloader 17, 3250fps. Starts with muzzle energy over 4000'lb. with a 325yard zero "flat" to almost 400 yards and at that point would still have well over 2000'lb impact energy and impact velocity of 2350.

I have shot many combinations of bullets with the 338/28-Nosler. I have confidence in my data. I killed a cow elk a couple years ago with it.

Another alternative is a 338 RUM. There are hunting loads that will mag feed. "Target" loads that will make a mile or more. It's a bit crowded in the magazine length department but it will work. Speed will be between 50 and 100fps faster than a 338/28-Nosler.

 

[shortgrass]

The diameter of the Vanguard bolt is actually less than the diameter of the Remington 700 bolts. Besides that, the threaded tenon diameter is smaller than the 700. It's a "no-go" for anyone but a hobbiest that doesn't mind riding on the ragged edge.

 

[J E Custom]

The diameter of the Vanguard bolt is actually less than the diameter of the Remington 700 bolts. Besides that, the threaded tenon diameter is smaller than the 700. It's a "no-go" for anyone but a hobbiest that doesn't mind riding on the ragged edge.

+1

The Lapua requires a larger bolt and bolt face than the vanguard has and it would not be usable.
I recommend a mark 5 action for the 378 and Lapua sized cartridges.

If you want a 338 that will work in the Vanguard, a 338 Ultra Mag would work good and performance is very close to the Lapua. the 338 Edge will top the Lapua by a small margin.

If you still want a Lapua, I would look at the improved versions for there performance and try to find a Mark 5 action or a big custom action to build on.

J E CUSTOM

 

[sam4485]

From the responses I have received, it doesn't look like a 300 Wby Vanguard is a suitable choice to build a 338 Lapua on. Thanks for the impute. I haven't been able to find ballistics/reloading data on the 338/28 Nosler cartridge. I don't care for the 338 RUM. I do like the 338 Norma Mag, but there again I run into the bolt face issue. I am not married to the Vanguard action. It appears that if I want to build a rifle around a .58 - .62 cartridge base I will have to obtain a 416 Rigby size action. If I have to go that route, I have considered the Remington 700 style long magnum type actions, a CZ 550 and Montana 1999. Is there any other suggestions.

 

[Deleted member 46119]

Hi Sam4485,

JE and others are correct about the VG bolt face. It is .680 and the base of the 338LM is .590. Add clearance and there's not much left. I didn't bother to measure the mag length.

It is possible, however, may not be practical. It appears easier and depending on your DIYness, cheaper to use something else like a Mark V or other action that has 338LM already.

As for the 338/26-Nosler (338/28-Nosler same thing). I know a guy who has all sorts of data. His name is..... me.

I thought I entered it on one of my Nosler wildcat threads.

I have flown every 338 pill I could with that thing. Everything fits the magazine, feeds perfect out of something that was a belted magnum or Weatherby magnum or RUM with no modifications.

Tell me what pill you want to push, what barrel and what purpose and I can give you numbers.

 

[Hired Gun]

I am not really a wildcat kind of guy but I think the 338 Edge is the most bang for the buck. No bolt face mods needed on the Vanguard. Same feed rails will work fine. It will send 300 grain bullets at 2850 real easy in a 28" barrel.

 

[sam4485]

I want to put 250 gr, 338 caliber projectile down range with a MV minimum of 3,000 ft/sec. I want it to be a exceptional long range hunting rifle that I will also do some bench rest @ 1,000 yd range. I want to marry the action to a 28"-30" polygonal barrel (with a very efficient muzzle break). I am a do it yourselfer with some work but know my limitations. I went through SF light weapons training in 1969 then served 2 tours in RVN. One with 75th Inf and the other with 173d Airborne and 101st Airborne. I got away from this for a number of years while I worked a lot of the time out of the country. Now I have retired and have time. I uncrated my Rockchucker and Dillon presses and I am jumping back in. I am finding that there are so many more choices in powders. some slow, others fast. Much more varied selection. Now you know more about me and what I am looking to do.

 

[Hired Gun]

I didn't run the numbers because I don't know what bullet you have in mind. There is nothing magic about 3000 fps anymore. I think you will find a 300 grain bullet at 2850 fps takes less elevation, wind correction and hits harder 1000 yards than your 250 grain bullet does at 3000. The sectional density will also make for a much deeper penetrating bullet. In this game ballistic coefficient is everything.

 

[Deleted member 46119]

A 338/26-Nosler is not much of a wildcat, close to the 33-Nosler but has more capacity.

A 338/26-Nosler with a 28" barrel will do 3000fps without much trouble.

A 338 RUM is not a wildcat at all. Loaded to magazine length it is the same as a 338/26-Nosler, maybe a bit of an advantage with sub 250 grain bullets. If you single feed and load long for more powder capacity then the 338 RUM has a nice edge on the 338/26-Nosler.

A 338 Edge is not much of a wildcat either. Just neck up 300 RUM. Head stamp brass is available. It beats the 338 Lapua. Taking advantage of all that capacity means loading long. In the Vanguard that means unloading a live round could mean removing the bolt.

Choose any of these 3 and with a 28 or longer barrel, you will have a ball.

An Octagon barrel for long range would be a cool thing to see.

Build it and they will go oooo.