Designing a rifle, need help!


Well-Known Member
Oct 30, 2004
I am having a custom rifle put together. Looking for a long range rifle, caliber 338/378 Weatherbe or 30/378. I know it will be on a Remington Action and a 30 or 32 inch barrel. This is my first custom gun being built, how would you reccomend putting it together; what barrel, what twist, etc. The guy seems nice and knows his stuff, just wanna make sure I'm not going to be ripped-off.

I would build it exactly the same way I built my personal 338 Kahn.

First off, I personally feel that for building a rifle in a round of this size, only Chrome-Moly Receivers should be used. This is simply because the CM steel is more resistant to lug and recess set back compared to the softer Stainless Steel.

The Rem 700 is a great action, pleny stout enough for the 338-378 class of round but this is about its limit in cartridge size.

Make sure this guy knows how to properly accurize and action and how to cut the Rem 700 bolt face to min specs to allow as thick a nose section as possible. There is plenty of steel here for the 338-378 but if one gets sloppy then things get thin real quick.

Also, when teh bolt lugs and receiver recesses are tured, it is critical to only take off enough steel to square them up, generally only 0.001" to 0.003" is needed to be removed.

Since we are dealing with the outer limits of this actions, we need all the steel we can get, again there is plenty to start with but if we get sloppy we are just taking strength away from the receiver.

Next the lugs need to be lapped for 100% contact, nothing less. We need a solid large foot print on both sides of the bolt to control the bolt trust produced by either of these rounds.

A properly accurized action is a much stronger action then one that is tuned up poorly. Your smith should know what he is doing if he has been around long.

When fitting a Sako extractor, again, we want things tight with only 0.002" clearance between the extractor and the slot machined into the bolt. This will ensure that an effect gas seal will still be present. If a primer fails or a case head seperates, this tight fit will greatly help in containing the gas leak or at least slow it down to prevent major damage to the action and shooter.

The extractor will also need to be fitted to allow JUST enough clearance to slip over the rim while in the bolt nose recess in the barrel. We want as much steel in the extractor as possible because these are big cases which sometimes can be a little hard to pop loose of the chamber.

Other then that, I would recommend steel bedding an insert into the mag box opening to stiffen up the action. The '378 class rounds are to much for a repeater as far as length goes when loaded with the long range bullets so a single shot is the only way to go.

Weldsmith makes a great inset that perfectly matches the contour of the bottom of the action and alignes the round perfectly with the chamebr for smooth feeding.

Also, have the bolt stop modified to give as much bolt throw as possible. Depending on your throat length, you may still need to pull the bolt to eject a live round when needed but often the bolt stop can be modified to allow a round with an oal of around 3.900" to clear the port freely.

Trigger wise, I went with a Rifles Basix 2 to 6 oz trigger basically to see how it compares to the Jewel. They are fine triggers in my mind but I will admit that I turned mine up to 6 oz because I like to be able to actually feel the trigger on my finger before the rifle fires, 2 oz is to light for this kid!!

I would also recommend replacing the factory striker assmebly with a Gre-Tan assembly. This will greatly reduce firing pin spring rubbing in the bolt body and the stronger spring and lighter firing pin increases lock time considerably. They are also a better fit to the firing pin hole generally which will help limit primer flow into the firing pin hole with top loads.

Now for ahead of the receiver. I would recommend a Holland Comp Recoil Lug which is vastly stronger and basically perfectly even in thickness for that perfect non stressed barrel fit.

As far as the barrel fitting goes, it is important that the barrel be fitted very snug to teh bolt nose with 0.005" clearance in depth and 0.005" total clearance in diameter. This to will increase the controll of a gas leak in such an eveny. A barrel recess fitted this tight can make it tricky to fit the Sako extractor to perform properly, make sure it does before you take the rifle home. If it does not this just tells you the smith did not perform a live fire test on the rifle before sending it home.

Chambering and crowning are pretty general stuff. YOur smith better be using live piloted reamers and cutters so that he can match the pilots perfectly to the diameter of your barrel. This is critical to producing the most accurate product you can.

As far as brands of barrels, I use only Lilja barrels on my personal rifles and on all my customers if they leave it up to me. I have shot enough 1/5 moa groups at 500 yards and sub 1/2 moa groups at 1000 yards to know they will perform eveytime. There are certainly other top quality barrels but I use Lilja.

Barrel length is a personal thing. Anything over 28" is plenty for these calibers, especially the 338. I have a 34.5" Lilja on my 338 Kahn and am very happy with its performance.

Perhaps more important then length is diameter. The Rem 700 will accept a 1.350" diameter barrel and still look good. This is basically the same diameter as the receiver and it actually looks pretty neat to have the barrel, recoil lug and receiver basically the same diameter.

To be honest, I would not recommend building a rifle on the Rem 700 without using a barrel bedding V-Block system. A +28", barrel of at least 1.250" straight cylinder is a heavy barrel. My 34.5" 1.350" barrel weights around 14 lbs. This is far to much weight to hang off a Rem 700 action which only has about .700" of thread engagement with the barrel.

I used my own V-Block system which is 10" long and is embedded inthe forend of the stock starting in front of the recoil lug. This barrel is drilled and tapped for 3, 1/4x28tpi bolts that secure the barrel into the V-Block. The recoil lug area is reinforced with steel bedding compound but the entire action is free floated which turns it into a totally stress free componant of the rifle. You could hang a 30 lb 45" long barrel of 1.750" diameter off it and the receiver would perform totally stress free.

As far as stocks go, my favorite is the McMilland MBR Tooley 1000 yard BR stock. I weighted mine for a finished weight of 8 lbs. This makes for a 26 lb rifle with the addition of a muzzle brake of my own design which is a 4 port brake that weights in at 3/4 lb.

I would recommend a brake on any extreme range rifle especially with a round like the 338-378 firing 300 gr pills at 3000 fps. Recoil is not painful but slowing a 25 lb rifle down after recoil has started it moving will wear on your neck and back something fierce. A quality brake will eliminate this problem. My 338 Kahn with the 300 gr Wildcat ULD loaded to 3100 fps recoils about like a 308 Win in a 10 lb rifle.

Back to barrels, I would go with a 3 groove in the 30-378 for its longer throat life compared to teh conventional 6 groove. IT will also foul less.

In the 338, Lilja does not offer a three groove but this round is not overly hard on the throat compared to the 308 caliber version.

Other then that, have fun with your new cannon. Let us know how it shoots!!!

Good Shooting!!

Kirby Allen(50)
thanks for the help, do u have a pic of the rifle? i'm just gonna go with the standard weatherby 338/378 round and a 30 inch barrel; but what twist would you recommend? i was thinking 10 to 1.

the guy is an ex military sniper and does long range shooting events. i'll try to get his full name and post it up to see how well known he is since he says he is well known.
Thats better.

The pic of the three rounds is of a 338 RUM flanked by two rounds of 338 Kahn loaded with the 300 gr SMK.

Sorry for the trouble, I think I got it figured out.

Kirby Allen(50)

I would go with a 1-9 if you go with the 30-378 for extreme range shooting with the 240-250 gr VLD and ULD bullets.

In the 338 go with a 1-10 for anything up to the 300 gr VLD and ULD bullets.

Wildcat Bullets will be offering a 350 gr .338" ULD here soon. If you want to shoot that one better get a long throat and a 1-9 twist.

I will be testing them in my 1-10 Kahn and I will let you know if they land on point or not.

Good Shooting!!

Kirby Allen
Mr. Allen,

I don't want to get this topic off thread but just have to ask, are you eliminating the action screws then to get the action to free float and relying on the three bedding block bolts?

Thank you.

Waltech Jim,


The only thing on the barreled action and the stock tha tcontact each other is teh V-Block contact points that run down each side of the 10" V-Block and of course the three 1/4-28 bolts that hold the barreled action securely into the V-Block.

That is not entirely true, the Recoil lug touches its reenforced baring surface as well but the entire action and barrel in fornt of the V-Block is totally free floated. There is about 0.040" clearance around the action and the stock.

I will take some detailed pics and post them to show you the design a little better.

The length of the V-Block depends on the weight of the barrel used and the number of mounting bolts is dependent on the weight as well and length of the block.

In all honesty, a single mounting bolt inthe center of the V-Block will securely hole the barreled action in place but with this heavy of a rifle, I prefer using three.

I will post some pics of a smaller caliber V-Block rifle I just finished for a customer using a Holland Signature Laminated Stock and a 7" V-Block.

The action screws for the stock that you will see are "dumby" screws. They are just there for show and to look good, if oyuwill.

I will post some detail pics here soon.

Good Shooting!!

Kirby Allen(50)
ignore this if you have thought it through already as I do not know the purpose of the rifle you are building but unless you are planning on taking an elk at a mile and need the energy, the 300gr .338 is not needed. There are smaller calibers that can match the trajectory if not come awfully close with a lot less recoil. My feelings when shooting long range...... and short range come to think of it. Is that shot placement means more than energy. I have tracked white tails that ran for miles to never be seen again that have been hit with a .300 win. but my .308 and .44 leaver action have never let one run more than 100 yards before it dropped dead.

O.k, I'm not a fan of the .338. I have nothing against them for others but feel that 80-90% that own one, own it for bragging rights and could do just as good with something smaller. Don't get me wrong,If I ever plan to shoot an elk at
1 mile the .338 would be my caliber of choice.
So here's the way I'm thinking
32" Bruton 5C barrel 1-9 twist
175MK or custom bullet in a similar weight.

this is the performance you could expect
at 1500yds. aproxx 1,000 ft.lbs. of energy.
and approx. 34 moa's of drop from 100yd zero.
time of flight approx. 2 seconds.
with aprox. 1.28 lb seconds of momentum.
still supersonic at 2,200 yds!
also this round would be better suited for the Remington 700 action versus a .338/.378
just my .02

Kirby, that's a sweeet lookin' rifle!
curious to see pix on the v-block system
how do you like the super sniper? been thinking about trying one.I assume that's what the scope is?

P.S I have nothing against bragging rights either
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