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338 Build Lapua based

I am building another 338 Lapua based rifle. I have a Stiller 338 action and ended up picking up a Rock Creek 1:10 twist barrel pretty cheap that should finish at about 34 inches. I am considering building a wildcat either Rouge, Ackley or something close. This is also my first time going with an improved or wildcat cartridge. I have heard several people say I could fire my regular 338 Lapua ammo using standard loads and this would fireform my brass. I have heard others say you have to use a light load t o fireform the brass.

Anyway I am curious what version of the cartridge would yeild the best accuracy, velocity and possibly be able to fire standard 338 Lapua loads without a huge loss in accuracy. Also if anyone has tried a barrel this long and possible velocity gains from using 50bmg powder or 20mm cannon powders. Both are very slow burning. I will be trying 300gr bullets and shooting 1000 yds possibly trying longer for fun. I know the twist may be a little slow for lathe turned bullets. any other recommendations would be appreciated.
 
I looked at a few of those this afternoon. I am looking into the 338 Terminator +P but having a hard time finding info on it. I found loads and ballistics but have not had any luck on chamber dimensions.

I am not sure if I want to go with a "throated" chamber. IT seems like the lands must be cut farther back for the long throat. it seems to me this would lead to accelerated throat erosion. I have tons of 338 Lapua Brass so I want to stick with the Lapua case I think.

I am looking at possibly cutting my own reloading dies for this I have never done them before but thinking of using the chamber reamer and bushings like in Redding dies. Possibly using depriming rod and bushings from my standard 338 Lapua dies.
 
I think with the long barrel you will get as much velocity as the +P. I have a 338 IMP with a 35 degree shoulder. I can reach 3100 with 300 grain Berger and the load is still mild on brass. I feel Re33 is the powder with the big bullets. Velocity will depend on barrel, throat and which case you choose.

I have a 36 inch barrel and feel 50 BMG And US 869 is too slow. They also were very dirty, probably because they were not up to pressure and burning clean. Matt
 
If you can't make or source a FL sizing die the rifle will be a PITA. YMMV
I have a 30 degree shoulder version and 3000 FPS is about max with any barrel 30+".
 
too bad you couldn't get a 1-9" twist. IIRC, the 10" twist is on the slow side for the 300 grain bullets as that was one of the downfalls of factory .338LM rifles as they were more set up for 250 grain bullets. sounds like a fun project
 
I've done hundreds of 1-10 twist 338 Lapua barrels and no problems shooting 300's. Accuracy International used 1-11's I believe for the 250's for decades. Many shot 300's in those rifles with no problems.
 
I got a 30 inch barrel on my 338 lapua. I couldnt see going past 30...

Reloader 33 is my go to. Lower pressure and more velocity. I shoot berger 300 hunting vlds..
 
My first 338 LM had a 1x10. No issues out to 1500 yards with 300 SMK's. My current 338 LM Ackley Improved sits in a BAT action (Bedded by D Tooley many years ago as a 300 RUM) with a 32 inch Krieger 1.450 with 1 x 9.25 (35 can remember which). Shoots the 300 gr Bergers with RL 33 but drills with Retumbo and Cutting Edge 277 gr. No issue with either load at 1760 yards. Buddy has same barre twist 30 inch Krieger, also shoots 300gr Bergers with RL 33. Scott
 
I believe the 10 twist will work fine on 300 gr bullets the only bullets it may have a problem with is turned solids which I'm not planning in using. I have used 1/11 twist before with no problems on 300gr.

I am trying to decide if I should build my own now or get Tooley to build the rifle with his 338 improved chamber. Going to an improved may end up being more of a pain than I originally though to get over 3000fps without wearing out the barrel and brass. I like building my own rifles. I actually like building rifles more than I like shooting now days. I already have reamers and dies for standard 338 Lapua. By the time I wait for the custom reamers, making or ordering reloading dies I am not sure it is worth it. Or I can send it to Tooley, who I know builds excellent rifles, and he can make dies and chamber the rifle fairly quickly but I don't get the satisfaction of building it myself. Also just it will cost a few hundred more to build an improved version by the time everything is said and done.
 
If you get a custom reamer get a custom resize reamer ground at the same time and make your own dies. One of the good long range guys I know always gets a resize reamer ground and makes dies out of old barrels. He does quite well with this and his guns shoot. Another good choice is a 338-416 Rigby. He is running 300 grain Sierra at 3200 with RE50. The gun shoots great and has killed out to 2800 yards. He might be running an Improved version, I am not sure. Matt
 
If you get a custom reamer get a custom resize reamer ground at the same time and make your own dies. One of the good long range guys I know always gets a resize reamer ground and makes dies out of old barrels. He does quite well with this and his guns shoot. Another good choice is a 338-416 Rigby. He is running 300 grain Sierra at 3200 with RE50. The gun shoots great and has killed out to 2800 yards. He might be running an Improved version, I am not sure. Matt
2800 yards, buckets, that's a long ways!
 
Don't buy a resize reamer, for less than the cost of the reamer you can have John Whidden make you a full length bushing die by sending him a copy of your chamber reamer print, you get one of the best dies around and it is hardened. Then buy a Forster 338 Lapua micrometer seater die and open up the sleeve with your chamber reamer and you have a quality set of custom dies for less than $200.00

A 1-10 twist WILL stabilize 300gr Berger's and 300gr SMK's and RL33 is the powder for this chambering.

John, tried to call the number you PM'd, left a message call me back.

Dave
 
I looked at a few of those this afternoon. I am looking into the 338 Terminator +P but having a hard time finding info on it. I found loads and ballistics but have not had any luck on chamber dimensions.

I am not sure if I want to go with a "throated" chamber. IT seems like the lands must be cut farther back for the long throat. it seems to me this would lead to accelerated throat erosion. I have tons of 338 Lapua Brass so I want to stick with the Lapua case I think.

I am looking at possibly cutting my own reloading dies for this I have never done them before but thinking of using the chamber reamer and bushings like in Redding dies. Possibly using depriming rod and bushings from my standard 338 Lapua dies.

Send Broz at LRO an email and he will help you with any questions you have about the 338T+P. He is a high character guy and can be trusted.
 
Sorry my phone does not pick up inside. I usually leave it in the truck at night to charge. I will have to try to give you a call tomorrow.

I would love to get over 3000fps my current 338 rifle shoots about 2700 with 300 smk.
 
Part of building a 338 comes down to if you want to mag feed or single feed. Some of the reamers require you to load .050 plus past mag length if you plan to shoot some of the 300gr bullets. Even if your stock will permit CIP length mags your still face with a jump to shoot mag length loads.

Even though the new Hybrids are not length sensitive, make sure bullet of choice will work for your rifle.
 

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