• Watch Out for Scammers!

    We've now added a color code for all accounts. Orange accounts are new members, Blue are full members, and Green are Supporters. If you get a message about a sale from an orange account, make sure you pay attention before sending any money!

Gunsmithing Convert a 700 long action to 338LM?

Quickdrawn

Private
Full Member
Minuteman
Oct 11, 2013
42
0
So I have been toying around with the idea of making a light weight 338LM hunting rifle with the parts left over from my custom bench rifle (also 338LM). Most of the custom actions I find out there are around $1,500 and I don't have that kind of money to drop on just one piece to the puzzle. I was wondering if it is at all possible to get my hands on just a plain 700 long action and have a smith do what is necessary to set it up for a 338LM. I'm not looking to have a 2,000yd tack driver here just a rifle that has a round to put enough energy on target at 500yds and beyond to take down elk/moose/bear. I would just go with a 300WM but I already have parts and a butt ton of ammo/reloading stuffs laying around for a 338. Just need an action/bolt is all. I highly value you opinions as they were instrumental in building my first 338 which shoots ragged holes with no issue, it's a beast. Thanks for any input.
 
Agree with Dave. Remington 700 lapua chamber walls are scary thin. You could build anything you want with the money you save from not shooting the 338.
 
Don't be afraid of a LM in a M700. Subject has been beat to all hell.

With that said do what the other 2 dudes mentioned; buy a stiller. You're cost is not much less to have your current action blue printed, new PTG bolt...etc. it's worth the little extra coin.
 
As far as I can tell most custom actions are based off of the 700 anyway so I don't really see the reason for aversion from the 700 platform. As far as the walls being thin I haven't personally heard of any real issues with the 338LM blowing up in the chamber, but that's just me. I'll probably do like you guys said and pick up a stiller action. My one problem is the barrel. It's a medium weight one off of a 700p MLR in 338 (built my 338LM bench rifle from the action the barrel came off of) that's 24" with the 2" muzzle brake. I'm thinking I'll cut down the barrel to 20" and re-thread it to install either a surefire or fat bastard brake (maybe purchasing a silencer in the future). Probably put a custom barrel on order with Krieger now to replace it because the wait time is about 9 months at this point and around 6-9 months for any other barrel maker. I have an H-S precision police rifle stock with a badger bottom metal. Probably just drop in my factory 700 trigger I have laying around until I can afford a match trigger. Doing it little by little. What do you guys think?
 
The stiller is a larger diameter receiver with a larger barrel tenon. Guess stiller didn't like the thin wall or small bolt either. You may have to machine your stock or adjust the seating depth of your magazine system. You may also need a larger diameter barrel so that there will be enough shoulder. My barrel is 1.35 OD at the shoulder. Or spend 450 on a striped action from brownells and pick another caliber.
 
Well there is another issue with getting a custom action than instead of having one blue printed. I would rather not wait for or spend the money on a new barrel that can fit the action when I have one on hand already. Between a rock and a hard place here. Leaning more towards just looking in the shotgun news paper for someone getting rid of long action 700 to re-tool. Didn't even think about maybe needing a different barrel right off the bat for a stiller action.
 
Last edited:
The extra .050 on the bolts of the custom actions does make em much stronger, though a ptg bolt is probably your best bet, for what it's worth I have seen defiance 338 lapua actions and others like em fail due to warm book loads


Sent from my iPad using Tapatalk
 
So I've taken a look at some of the actions I can buy for ~$500 to convert and am thinking is there much of a difference between the 300WM and 300UM in terms of one being better suited for a conversion? Now please note that I am still hovering over the buy button for a stiller action but I'd rather not have to get a new barrel right away if I have one on hand that will fit a standard factory LA.
 
Build a 338 EDGE on the Rem700 action you have.
I have shot mine out to a mile .
If want a Lapua, get a different action.
 
The way you're trying to piece this together it will end up costing you more in the end. Much more before you're done/happy. If you're going to cut the barrel to 20" just get an off the shelf 338 RUM or 338 Win Mag. All you would need are dies and brass. Sell your current parts and start collecting parts for a new LM build.
 
The way you're trying to piece this together it will end up costing you more in the end. Much more before you're done/happy. If you're going to cut the barrel to 20" just get an off the shelf 338 RUM or 338 Win Mag. All you would need are dies and brass. Sell your current parts and start collecting parts for a new LM build.

The thing is that I have all the parts I need besides the action for a 338LM build. They were either taken off of the original rifle I used as a base or were part I decided not to use. I could sell the parts but why sell quality stuff for less than they are worth to get rid of them when I can just turn them into a multipurpose rifle. I'm trying to spend no more than $1,500 all together not counting what I have already. I'm seriously looking at a stiller action but that means getting a new barrel and waiting for it. Plus gun smithing fees for cutting and fitting the blank as opposed to just cutting/threading the barrel I have and fitting it to an action. And like I already said I have plenty of 338LM ammo and reloading supplies. I really don't want to switch to a different caliber and be buying different brass/ammo for the two rifles.

And nobody has answered whether a 300RUM action would be better to blue print than a 300WM. I found those two actions on brownells for $470. I'm not very versed in blue printing an action.
 
Last edited:
Buy a Savage chambered in .338LM, they have one geared towards hunting.

I just looked at the savage 11/111 long range hunter model and with a $1,340 msrp I think that's the best option for me. I didn't even think about savages. Going to sell my parts to grab that rifle and skip the headaches. Thanks.
 
I grabbed a Remington 700 SS on sale, sold the bolt, floor plate and barrel. With a PTG bolt (one piece fluted, 25 deg handle & PTG firing pin), PTG stealth floor plate I have under $600 into. I have blueprinted it myself and will install a brux barrel in a 300 norma. Many have built calibers with a .590 BF and havent had any problems.

Casey
 
So I have been doing the math and a 338 build with the parts left over from my last build will be about ~$2,200 as opposed to doing a brand new 300wm build costing~$4,000. Doesn't look like a 20" barrel really hurts ballistics that bad either based on looking at data on longrangehunting.com and from the barrett 98B 20" 338LM. Maybe ~115-150fps loss compared to a 26" barrel from some people's calculations. I just want a ~10-13lb mountain rifle that I can build with what I have and smack down an elk at 600yds+. At the same time I'll have a stiller action so if I so choose I can just rebarrel the rifle and have a 1,900yd steel smacker just as good as my bench rifle.
 
I have a rem 700 in 338 LM that I built off of a 270 action. It is a single l shot only, but it is very accurate, and done very inexpensively. The worst thing about the build is dropping $250+ on a PTG bolt, and having to wait 3 months for that bolt to be made. Don't be scared of the build. I think because people have heard one bad story about a gun coming apart, they say No No No. When in reality that gun that came apart was loaded super hot and built by some dime store smith.
 
Last edited:
Just to put some numbers to the question. Here are some hoop strength calcs to ponder with a 338 Lapua in a Rem 700 action.

Tenon dia 1" (approximate diameter @ root of thread)
Chamber dia .587"
338 Lapua pressure ~64K psi
416SS RC28 yield strength 105K psi
416SS RC28 ultimate strength 130K psi

64K psi in a tenon that size calculates out to 131.5K psi @ the inner wall and 67.6K psi @ the outer wall.

416R purportedly has slightly better numbers than 416 but I couldn't quickly find numbers for it.

For comparison a Savage w/1.120" tenon: 120.9K psi @ inner wall and 56.9K psi @ outer wall.

Also for comparison a Rem 700 300 Win Mag 109.7K psi at inner wall and 45.7K psi at outer wall.
 
Last edited:
If these numbers are correct how does Remington sell a factory 338 Lapua magnum?

I listed those numbers using 416 steel because that's what I assumed the OP would be using. I also assume Remington is using something along the lines of 41V45 or some form of 4150 steel that has higher yield and ulitmate strengths than 416 if it is heat treated to something in the range of RC32. I've never had a Remington in 338 in my hands so I can't confirm but they supposedly have a long throat which may help keep pressures in check as well. Just because Remington does it doesn't necessarily mean we can do it as safely which is probably why people with experience like Dave Tooley generally urge caution.
 
Last edited:
And before you hold the Savage up as a modern engineering miracle, behold the many threads mentioning 338 Lapua Savages with stuck bolts!!!!

Stiller, or if you can find one, a 1581 XL Surgeon, is the way to go.

Oh, and the Sako TRG 42 - that's another pretty slick option. You never hear complaints about those, and not many get sold afterwards. Maybe the owners are pretty happy with those? I have shot one of those a fair bit, hard not to like it.

OP, selling your old kit of parts, and putting it towards one of these other options, you might come out better than you think.