ds1 Posted September 20, 2020 Report Share Posted September 20, 2020 So, standard load for me over the last 10 years has been Vhit n165 with with a 250 grn Scenar or Berger. Time for something new and hopefully better. It has to work in an AXMC mag with a 20”,25” & 27” barrel for distances from 10m to 1O00m and very occasionally to 1500m. Banging steel and paper comps. Primary barrel will be the 20”. Boutique bullets - badlands, Lehigh and flatliners are a non starter. So what are people’s thoughts, recommendations and experiences with the following combinations please: powders: n170, n570, RS 80 bullets: Berger 300grn hybrid OTM, Hornady 285grn ELD-M Gut feeling is that n170 will be slow, n570 will toast the barrel and RS 80 could be a good compromise.....but I have no experience of this powder. Bullets: 300grn Berger are proven and still popular but the Hornady 285grn ELD-M seem a better option on paper and particularly for the 20” barrel - are they winning anything? Quote Link to comment Share on other sites More sharing options...
Popsbengo Posted September 20, 2020 Report Share Posted September 20, 2020 Not an answer regarding your choice of barrel but I use N570. I haven't seen any disturbing level of erosion after 580 rounds 32" 1:9.5 twist Truflite. Horn. 285gr ELD-M 2,850 fps. from 93.5gr. Quote Link to comment Share on other sites More sharing options...
Catch-22 Posted September 20, 2020 Report Share Posted September 20, 2020 Not a .338LM but I have the .338Norma Mag (only 6% less case capacity) and I shoot 300gn Scenars in a 27” Bartlein 1.9-3” twist at 2800fps with 94.5gn RS80. I think RS80 is a lovely powder in these big magnums. I’ve found it to be very clean burning and easy to get loads with SD/ES in single digits. Absolutely zero pressure signs. Id definitely suggest its one for you to try! Quote Link to comment Share on other sites More sharing options...
ds1 Posted September 20, 2020 Author Report Share Posted September 20, 2020 Thank you for the replies Pops and Catch. More or less decided to try the 285 ELDs first - just making my mind up about which powder (RS80 or N570). Anyway 1 kg of either or both is not the end of the world. Quote Link to comment Share on other sites More sharing options...
Ronin Posted September 21, 2020 Report Share Posted September 21, 2020 Have you considered solids David ? Not sure on availability in CZ but were I looking at 338 and larger (and I may in the near future) I’d steer towards high BC monoliths Quote Link to comment Share on other sites More sharing options...
ds1 Posted September 21, 2020 Author Report Share Posted September 21, 2020 Andy, I used solids in 50g but could not get a decent supply in 338. Just been having a look at these: http://www.topstrely.cz/kategorie/celomosazne-strely/cal-338/225gr-tactical/ I will get more info (bc and length) and availability cost about 50p a pop. Also I noticed something similar from a French manufacturer. Stuff from the USA ( badlands etc) is a non starter. Mag length also becomes more of an issue. Quote Link to comment Share on other sites More sharing options...
Jagged 77 Posted September 21, 2020 Report Share Posted September 21, 2020 I've used both N570 and N170 in mine and found a good combination with 88gr N170 and 300gr Scenars. I've got some 285's to try but not loaded any yet, again will probably stick with the N170 - I just always have got on better with the N100 series powders in most of my rifles. Barrel is 28" 1/10" twist Quote Link to comment Share on other sites More sharing options...
ds1 Posted October 29, 2020 Author Report Share Posted October 29, 2020 Wanted to update this after a lot of load testing. It turned out to be a tail of two barrels. Both rifles are AXMCs one with a 20” after market barrel - Krieger and with tight chamber - it’s a pain but shoots everything well. The other is a 27” original AI barrel and very fussy. Two powders RS 80 and RS 76. I found RS 80 too slow. Did not try it with 250 grain bullets at all and no cigar with 285 grain Eldm’s. RS 76, I started off with different powder charges with 250 grain bullets Lapua Scenars and 250 grain Berger OTMs. Tried from 96.0 grain to 99.0 grain in one grain increments at 95.5mm COAL at 15c. Soon settled on 96.0 grains. Slight minting at 99.0 grains but no hard extraction etc. At 96.0 grains a healthy 50k psi pressure prediction. Hornady 285 Eldm’s - I really wanted this bullet to work- it did in the 20” barrel but not the 27”. Again 95.5mm COAL ( max practical mag length) with RS 76 from 92.0 grains to 96.0 grains. Again settled on 92.0 grains. With 20” barrel loads were giving an ES of 4 m/s ( Autotrickler now ordered). 3 shot groups at 50m - max length of my range. 285 Hornady Eldm's 20” barrel, ave 798 m/s @ 15c. 92.0 grains RS 76 250 Berger OTM Hybrid: 20” barrel, ave 838 m/s @ 15c. 96.0 grains RS 76 I did several more groups over 2 days - the results with the 20” barrel were repeatable. The 27” did not like any combination of load or seating depth for Bergers or Eldm’s. However loves Lapua Scenars- tested with a 91.2mm COAL and 95.5mm COAL both shot well with lowish ES 5 m/s. Only paradox being that the longer COAL was 5 m/s faster than the short COAL. It was not touching the lands. Tested on 3 consecutive days pictures from today: Lapua 250 grain Scenars 27” barrel ave 880 m/s and 885 m/s . 91.2mm and 95.5mm COAL @ 10c. 96.0 grains RS 76. The longer COAL also felt softer to shoot. 250 grain Berger OTM Hybrid, 27” barrel, ave 873 m/s @10c. 92.8 mm and 95.5mm, COAL, 96.0 grains RS76. Crap 285 Hornady Eldm’s 28” barrel ave 836 m/s @10c 93.3mm COAL. 92.0 grains RS 76. Crap. The usual disclaimers about these loads being safe in these rifles apply. I worked up to the max I tested checking for pressure signs and using the bbt P Max software. Trying to keep pressure to around a predicted 50k psi. Velocity measurements were from a Labradar. Reloading practices are good- all ammunition loaded at the same time - once fired lem cleaned Lapua brass, annealed, body sized, neck bushing sized ( Redding comp dies ), brushed case necks, trimmed necks, powder charging done on a charge master lite, head space checked, concentricity checked, OAL checked. Biggest difference to me so far is obviously the chambers ( maybe throats) and how I think they handle secant vs tangent ogives ( speculation). Obviously need to test the Lapua’s at longer ranges but no point in testing anything else in the 27” tube. The 27” AXMC is my mates rifle, I have the 20” AXMC but it is good to use the same bullets when we shoot together so I’m stuck with Lapua also - it’s just the bc sucks compared to the Eldm’s. Still really surprised at the difference between the Scenars and Bergers. Quote Link to comment Share on other sites More sharing options...
ds1 Posted October 30, 2020 Author Report Share Posted October 30, 2020 Note on why 95.5mm COAL. It’s a practical max mag length in AMMC mags without function issues. Bullets are still not touching the lands and the bullet bearing surface is above the neck / shoulder junction (donut) area for 250 grain bullets. The Eldm’s are well down in the case. This avoids potential inconsistent neck tension issues with subsequent firing of the cases at least for the 250 grain pills. Quote Link to comment Share on other sites More sharing options...
Catch-22 Posted October 30, 2020 Report Share Posted October 30, 2020 Interesting. I can see how RS80 would be too slow, especially with such a short barrel and lighter (250gn) bullets. I don’t remember reading the specs of the barrels to be used on your OP. But I’m still surprised it was too slow with the 285s though. I do think RS80 is best used with the heavy 300gn bullets, works superbly for me. What twist are the barrels? Perhaps that’s the key as to why the Lapua Scenar 250s did so well. The bearing surface is a lot shorter (as noted in your last photo) and would suit a slower twist if that’s what the guns possess. Glad you’ve found a load / combo that works for you! Quote Link to comment Share on other sites More sharing options...
ds1 Posted October 30, 2020 Author Report Share Posted October 30, 2020 Catch, AI spec the twist in the 27” barrel as 1:9.33”.When Krieger made the 20” tube up I specked the same twist 1:9.33”. Even if they made it 1:9.5” it would not be a significant difference. After Christmas the 27” barrel is going to be replaced with a Brux. It will be chambered with the same reamer as the 20” barrel. Interesting to see what that likes to be fed - I am guessing the 285 Eldm’s will do much better. RS 80, the bbt Pmax software only shows about an 84% burn with 285 Eldm’s- using a measured case capacity of 101.1 grains H2O. To get a reasonable velocity you end up using 99 grains of powder. It’s good that it works much better for you with 300 grain bullets. Quote Link to comment Share on other sites More sharing options...
Catch-22 Posted October 30, 2020 Report Share Posted October 30, 2020 Very interesting. My 338NM (only 6% less case capacity than the 338LM) is also a 27” 1:9.3” twist, but a Bartlein. Still surprised you weren’t able to get the 285ELDm to shoot. Well, good luck with any forthcoming comps! Quote Link to comment Share on other sites More sharing options...
ds1 Posted November 9, 2020 Author Report Share Posted November 9, 2020 A quick update. Changed the 27” AI barrel for a new 27” AI barrel from the USA. During “break in” tested the Bergers and Hornady Eldm’s again. Both shot excellent. Not sure what is up with the original AI 27” barrel but it won’t shoot Bergers or Eldm’s bit excellent with Scenars. Bore scope shows no abnormal signs. Best load so far with new 27” barrel and 20” barrel is: Hornady 285 Eldm, 92.0 grains RS 76 , Lapua brass, CCI mag primer, 95.5mm COAL. Quote Link to comment Share on other sites More sharing options...
ds1 Posted November 28, 2020 Author Report Share Posted November 28, 2020 Last update on this tested: Hornady 285 Eldm, 92.0 grains RS 76 , Lapua brass, CCI mag primer, 95.54mm COAL. at 100m, sub 1/2 moa 5 shot groups, at 300m, sub 1/2 moa 5 shot groups 550m, small plate cca 10cm, consistent hits 800m, range of plates-smallest 13cm diameter. Some but not consistent hits on this . Go to a 20cm ( 1moa ) plate - consistent hits. Shooting off basically sand berms - not ideal conditions. I think it’s a very good half moa load. Very consistent ES speed ( 4 m/s) and relatively temperature stable. Quote Link to comment Share on other sites More sharing options...
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