338 lm loads

[ken snyder]

I always stick to the upper mid range loads with the 338 LM. For the 300gr SMK I am currently using 76. 4 grains of IMR 4350 When we had the somewhat recent powder primer shortage I found equally good results with 79.2 grains of Re 22. These are Sierra upper mid range load recommendations, The published velocities for these loads has always proven to be a bit on the high side for the Chamber dimensions I choose. The nice thing about upper mid range loads with this cartridge is that they provide a very large sweet spot of consistent velocity spreads over a large range of seating depths. and have found them to be highly immune to a fair shake more than modest barrel erosion. Now you have my secret sauce recipe! The 338 LM is a modest velocity cartridge by super magnum standards but its inherent accuracy is something that the big kids on the block have to prove themselves against. P.S. for obvious reasons I disclaim every load recommendation that has ever been written or spoke including my own.

 

[XMC]

I know you're looking for 300 grain pill loads but thought I would throw out a 250 grain option for you for future reference now that IMR 4350 has come up: my load being 82 grains under 250 SMK with Lapua Brass using GM215 primers getting 2854 fps bors input. I've also had great results with 225 grain TTSX and 89.3 grains of Retumbo 2910 fps bors input.
Pic is a 15 round group with my usual *** flyer above, 5 to 10 min cool down between shots bore cleaned after each set of five.

 

[Brado16]

338 LM Brass, 215M Primers, 300 Grain Scenars, 88 grains of RL 25 @ 2700fps shots 1/2 moa for me out of my 26'' 1-9.4 twist Rock. This is a mild load but accurate- have loaded up to 93 grains w/o pressure signs.

 

[wasp]

All right fellers I got my brass prepped up, and I think I have all the powders at my table except retumbo. I going to use 300 sierras seated at 3.7925. I am going to try each load mentioned here 5 shots at 200 yds and see what happens. Should I clean bore after every 5 shots? I thought it took 2 shots to foul the barrel after cleaning?

 

[XMC]

Yes it will take a couple to foul… once you've found your load, start keeping records of how your rifle responds (poi) between those first five; meaning clean cold bore, second, third etc. Some may disagree but it's a practiced habit I'll probably never break. I keep a constant data book on all of my rifles.

 

[Brado16]

Forgot to mention my COAL is 3.90''- shooting as a repeater with the Seekins DBM.

 

[wasp]

Cold bore is always high with me say like at 100 yds it would be half inch from the group. Should I run a brush thru every 5 shots or just patches with solvent? Or both?

 

[ken snyder]

Wasp, it depends on your barrel. I foul mine and shoot the "Star Trek method " Captain Ive given her all she can take" and then clean. But for testing give em all the same treatment just like you would encounter in actual hunting! - 300 yds is a good testing distance for the long bullets, much shorter than that and you wont be getting a good inherent accuracy appraisal and much longer than that and the wind can make a guy scratch his head too much. Get an extra large target and shoot for group size including the flyer or flyers, as long as you are on paper don't adjust the scope ( shoot me now adjust me later). Its all about bringing your maximum group size down even at the expense of opening up the tight group cluster and then its just you and the wind! an interesting point to consider is if in a hunting situation are you going to have enough time to let the barrel cool down between shots, for me machine gun intervals are closer to the truth than cooling intervals. unfortunately if I havent bowled it over by the third shot there isn't going to be enough bullets in the western hemisphere for me to make a good connection.

 

[XMC]

Ok think of it like this… when you're headed out for hunting what will your rifle have been cleaned with last… will you head to camp a few days early take a few confirmation shots and leave the last set with a couple of fowlers before you hunt or head out with a completely clean bore. It's up to you and what results work best for you cause it's that next shot that counts. Personally I clp brush and patch to clean/dry after five and always do the same thing whenever possible to avoid the hmmm what did I change questions running thru my head when correlating data.
Well I'm hitting the rack… deer hunting tomorrow.

 

[wasp]

I got an arm and a leg in this gun and not happy with the performance yet. And whenever I extract the brass after shooting it dents the mouth of the brass. I told the man that built the gun and he said he built a 308 that did that once and he gave me no answer why anybody no why? Its not as bad if I bolt it slow.

 

[ken snyder]

It's the ejector. some are a little more lively than others. Extractor pulls the cartridge out and the ejector throws it sideways and up. most of the time this occurs when the mouth of the cartridge leaves the confines of the barrel and is thrown up against the side of the action. In some cases the brass can be hitting something else such as a one piece base!

 

[ken snyder]

I should have also mentioned the 338 LM cartridge design in reguards to mouth denting. It is a very tapered cartridge with a shallow neck angle and a longish neck, that can promote mouth dents just by its shape. In cartridges that do not have as much taper, shorter necks and with shorter shoulders the brass will hit further back on the shoulder area and leave small dings that dont cause any real notice, just because of its shape in relation to what hits first and the hardest!

 

[wasp]

I have the smaller exspander ball in my die and its not forming the mouth of the dented pieces of brass back like they should be. I wonder if that is messing with my groups? How many shots can you get out of the brass? I was really hoping the 100 I bought for 3 dollars a piece was going to last me a lifetime. I have been using a instant indicator and resizing the die .002 back from what the indicator read.

 

[ken snyder]

Wasp use a tapered expander instead of a ball type by modifying mine. pretty sure a guy can buy them but have always made my own. If you aren't accidently rolling the lip into itself you should be good to go. The last box of 338 Lapua brass I bought only had 60 + pieces of what I would call good brass, While a box of 6.5 284 purchased at the same time had almost 100 percent. With the long bullets such as the 300 grain type I only get about 600 rounds through a barrel before I screw on a new one. I get 6 reloads on a piece of brass before it turns into a bannana, I can extend the useful life of the brass by using fancy annealing strategies to keep the necks from splitting but that does absolutely nothing for Brass flowing in the rest of the brass. 1 box of 100 = 1 barrel. You can greatly extend the life of your barrel by shooting 250 grain bullets but the brass wont last any longer and I only buy brass 100 at a time and definately will not mix lot #'s or shoot brass in a different chamber even if it has been machined with the same ream. Being the tightwad cheapskate that I am I very much prefer wearing out a barrel and the brass at the same time and replacing both at the same time. If you use that rifle for hunting only it will be your Grandkids that wear out the brass and barrel.