BigNate Posted June 17 Report Share Posted June 17 (edited) So I'm following @Magwa down the 338 LM "next zip code" trail including reloading for this pursuit. I've made a few assumptions, started accumulating stuff, and started to build out a set of questions. Assumptions Materials Powder - I'm starting with Retumbo and VV N570 primarily based on what I'm seeing is a variety of online sources including here - and because I lucked into some of each at the local big-box sporting goods store. If there's a reason to start anywhere else please let me know. Primers - Federal 215M Bullets - I've got 100 each of the Berger 300gr OTM Tactical (MPN 33109) and the Hornady 300gr A-Tip Match (MPN 33389) as they seem to be two of the most commonly chosen and they are near the top of the list for BC without going to Cutting Edge Lazers which are nominally better - but more than twice the price per unit ($125/50 vs about $90/100 for the other two). Brass - Planning to buy 100pcs of new Lapua brass. Equipment Press - I have a Dillon 550B that I'm planning to use. I'll probably load in a way that is much more like a single stage press. This is what I own - and I probably won't be buying something different unless I run into issues (will probably find an older / used but high quality single stage) or win the lottery (I'll go buy all the newest coolest Area 419 stuff)... Dies - I've not yet sourced dies - doing research - would love advice. This will be the first real dive into "precision" reloading. I'm reading up on specialty dies etc. Scales etc. - I have a relatively inexpensive digital scale that I doublecheck with a balance beam scale. I have a manual trickler and I'll be manually trickling each charge until I decide I can't stand it anymore and break down and buy something better. I've come close to buying something a few times but always bail on it because I have a hard time spending $200 - $400 on something that I'm sure I'll want to replace with an FX-120i and auto trickler... Probably an OCD issue... tell me I'm wrong... Software - I'm modeling things with GRT Immediate Questions Dies - I've seen advanced / precision micrometer dies that I understand allow tighter control over seating depth etc. Worth it? No? Also - I've used Dillon, RCBS, Hornady, and Lee dies. For most things I've used basic dies - but I want to go "premium" for this setup - given the purpose of the gun and the degree to which a tiny variance in performance will amplify deviation at long range. Measuring Gear - I have read a bit about tools to measure seating depth from the ogive instead of COAL. It would seem that this would be most appropriate if I'm really concerned about jump to the lands. Too much? Order of Adjustment - Looking for validation or correction on this approach... My intent is to set the bullet about 0.020 off the lands, then work on a load ladder in small increments to try find a load that the gun likes (accuracy node). My question is - when do you start working to adjust distance from the lands, neck tension, etc. and how do you work through the decision to go back to powder / velocity modification after starting the other processes? What Am I Missing - What questions am I not asking that I should be asking? I'm sure that I'll have plenty more questions as things go forward. I'm hoping that this thread is a place where I'll learn and where we can create something that other folks diving down this rabbit hole can ramp up... Thanks in advance... Edited June 17 by BigNate Quote Link to comment Share on other sites More sharing options...
BigNate Posted June 17 Author Report Share Posted June 17 (edited) Well - I work about a mile from Dillon Precision so I ran over this morning to get clarity with them about whether there were any size issues with 338LM in the Dillon 550B (the good news is there is no issue). The good news is that there isn't. The other good news is that after chatting with the guy at the counter for a few minutes he said "hang on a minute" - and ran to the back. He came out with a box of 300gr Nosler Custom Competition and another in the 300gr SMK. They'd brought them in for some sort of testing - and were not an inventory item. I bought the box of Noslers well below street price - because I've got about 1000 factory 2nd 300gr 338 bullets that I bought to load as subsonic 8.6 plinking rounds - that are supposed to be factory 2nd Noslers. Once I get a load worked out for the Bergers or A-Tips - I'll probably do a quick pass at the Noslers and build enough group data for it that I can load up some with the factory 2nds to see if by some chance they perform well. Edited June 17 by BigNate Quote Link to comment Share on other sites More sharing options...
Magwa Posted June 19 Report Share Posted June 19 Buy the best dies you can, and you will need a micro seater die that will not be in the set I like wilson.. also a set of bullet mandrels to set case mouth tension, I always throw a powder charge from a balance beam and then put it on my digital scale and trickle to exact, one at a time . Do Not worry about seating depth till you find the right powder and charge weight for your rifle there are many ways to do it if you want my way PM me it works... Anneal after every firing, I do not tumble or clean my brass just the primer pocket..... Quote Link to comment Share on other sites More sharing options...
BigNate Posted June 24 Author Report Share Posted June 24 Had an interesting conversation with the folks at Dillon Precision. In short, it looks like there's a range of structures out there for case base and extractor grooves on 338LM cases. The guy at the counter said that they have a 338LM specific shellplate for the RL-550 - but they found that it did not work consistently with all brass, and that in some cases the "G" plate (listed as the plate for 45-70, 7.62X54R, etc.) works better. They suggested that I bring in a piece of brass and they'd test fit. I brought in a piece of brand new Lapua brass, and sure enough the "338" shell plate was too tight - would not fully seat the case, and the "G" plate was a perfect fit. Not that it matters - but I've got to put calipers on the brass and compare to SAAMI spec for the cartridge to see where the delta is. I'd like to think that Lapua would be putting out cases that are perfect to the spec... but who knows. Anyway - everything is now in hand - and loading can begin... Quote Link to comment Share on other sites More sharing options...
Magwa Posted June 24 Report Share Posted June 24 (edited) 11 minutes ago, BigNate said: Had an interesting conversation with the folks at Dillon Precision. In short, it looks like there's a range of structures out there for case base and extractor grooves on 338LM cases. The guy at the counter said that they have a 338LM specific shellplate for the RL-550 - but they found that it did not work consistently with all brass, and that in some cases the "G" plate (listed as the plate for 45-70, 7.62X54R, etc.) works better. They suggested that I bring in a piece of brass and they'd test fit. I brought in a piece of brand new Lapua brass, and sure enough the "338" shell plate was too tight - would not fully seat the case, and the "G" plate was a perfect fit. Not that it matters - but I've got to put calipers on the brass and compare to SAAMI spec for the cartridge to see where the delta is. I'd like to think that Lapua would be putting out cases that are perfect to the spec... but who knows. Anyway - everything is now in hand - and loading can begin... Are you going to try and load these round in a progressive press? I would caution against this as they need to be one at a time so you can pay attention to every detail because in the ELR game it is all about details... just saying and their is a lot of hands on in reloading this stuff just my opinion... and your chronograph is your best friend in this game it is all about consistency... Edited June 24 by Magwa Quote Link to comment Share on other sites More sharing options...
BigNate Posted June 24 Author Report Share Posted June 24 3 hours ago, Magwa said: Are you going to try and load these round in a progressive press? I would caution against this as they need to be one at a time so you can pay attention to every detail because in the ELR game it is all about details... just saying and their is a lot of hands on in reloading this stuff just my opinion... and your chronograph is your best friend in this game it is all about consistency... I only have one press - and it's a progressive - but I intend to use it as a single stage press. The thought is - install and set the sizing die and size cases... then finish case prep, then remove the sizing die and prime cases... then manually fill cases with powder (outside of the press)... then install the seating die and set depth and seat bullets... I've thought about buying an old single stage press - but to the best of my understanding, doing that doesn't buy me anything beyond what I can get out of using the 550 in a single stage manner... Some day I may go buy a premium turret style press - but for now I don't see the value. If I'm wrong I'd love to know it. Buying a used Rock Chucker would be in play right now... buying an Area 419 Zero... not so much... 🙂 Quote Link to comment Share on other sites More sharing options...
Magwa Posted June 25 Report Share Posted June 25 19 hours ago, BigNate said: I only have one press - and it's a progressive - but I intend to use it as a single stage press. The thought is - install and set the sizing die and size cases... then finish case prep, then remove the sizing die and prime cases... then manually fill cases with powder (outside of the press)... then install the seating die and set depth and seat bullets... I've thought about buying an old single stage press - but to the best of my understanding, doing that doesn't buy me anything beyond what I can get out of using the 550 in a single stage manner... Some day I may go buy a premium turret style press - but for now I don't see the value. If I'm wrong I'd love to know it. Buying a used Rock Chucker would be in play right now... buying an Area 419 Zero... not so much... 🙂 don't forget about your neck sizing mandrel it is one of the most important steps, setting neck tension, for me this was the single most improvement to lowSD and ES. As I have mentioned before I do Not use the decapping pin and ball that comes on the sizing die.. I take them out and use a large decapping die so my case neck does not get continually stretch back and forth. and after you fire the new cases you will have to bump your shoulder on the sizing die approx.2 thousands for the cases there is a ton of hands on work in this game but it is worth every step. Quote Link to comment Share on other sites More sharing options...
BigNate Posted July 5 Author Report Share Posted July 5 (edited) Well - loaded up 25 rounds for the ladder. I’m a nerd so I started at the recommended starting load and increased by one grain until I got closer to where I think the real work will start. I modeled it in GRT and built out loads that take me through what GRT thinks will produce max pressure loads (about 60,800PSI). Hoping to shoot in the AM. We’ll see if, and if - then what, i need to tear down… These are the Berger 300gr OTM Hybrid bullets, on Retumbo, with 215M primers in Lapua brass. I did nothing to the new brass other than prime them. I loaded to CBTO that should put the bullet 0.020 off the lands. This resulted in a COAL of about 3.8” so they’ll be getting single loaded. Interestingly, the magazine is stamped 3.80 but these are just a touch longer than will load in the magazine… The cartridge with the blue tip in the picture is a factory round that a buddy gave me a while ago when I was looking for a .338 bullet for something I was doing around the 8.6. I’m going to fire it and then thread the case to use with the Hornady OAL length gauge (as opposed to the unfired spec case that I used for the first pass). I didn’t want to sacrifice one of the new Lapua cases - and I’m guessing that for that purpose - it’ll be better than the unfired case. If that’s wrong - let me know. Interestingly - when I look closely at the bullet tips in the picture, they look mangled… I can’t see that much of it on the bullets themselves unless I put on a magnifying lens. I’m not worried about it for load ladder testing - but now I’m reading up on how this gets managed - for future efforts. Edited July 5 by BigNate Quote Link to comment Share on other sites More sharing options...
sketch Posted July 6 Report Share Posted July 6 That is weird the tips do look deformed in the pic? Maybe they are factory 2nds? Quote Link to comment Share on other sites More sharing options...
98Z5V Posted July 6 Report Share Posted July 6 Depends on the seating die... Quote Link to comment Share on other sites More sharing options...
BigNate Posted July 7 Author Report Share Posted July 7 On 7/5/2025 at 10:21 PM, sketch said: That is weird the tips do look deformed in the pic? Maybe they are factory 2nds? I noticed that as well. They are Berger 300s from Midway - not listed as 2nds. I'll take a few bullets out of the box and take pictures of them before being loaded. On 7/5/2025 at 11:41 PM, 98Z5V said: Depends on the seating die... The only precision die I could find that was not backordered was a Hornady set. I picked up the seating stem for the 338 300gr ATip bullets which I understood should work for the 300gr Bergers. I found this thread this morning - https://www.longrangehunting.com/threads/berger-vld-seating-stems.298097/ I'll pull the stem tonight and look at how the bullet sits in the stem. For these first rounds I'm not super worried about it - as "most" of what I'm worried about with these is MV and pressure testing. Quote Link to comment Share on other sites More sharing options...
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