A 338 LM pushing a 300 grain bullet with 90 gr of a retumbo what should my velocity be at give or take
338 mv
- Thread starter 7.62_Reaper
- Start date
Not sure. But I have a 25" bbl on mine and use 85.0gr of H1000 behind a 300gr Berger OTM right @ 2580fps. Its a lighter load yes, but still sends shrapnel for 50 yards to either side of my steel target from 500 yards. I enjoy less recoil and longer barrel life with this moderate load and conserve powder and brass as well. Please post your results with the Retumbo as I am interested to see what others are attaining as well...
I get an average of 2733fps using 90.6gr Retumbo. GM215M primer and Berger 300gr OTM out of 26" barrel. I would think you should be close to 2700fps with 90gr of Retumbo out of 26" barrel. But I have had some big swings in velocity lately when switching lots of powder. Previous lot it took 92gr of retumbo to get 2750fps and with the latest lot that got me just over 2800fps. So I would say safe to start at 88gr and work your way up till you find a load that gives you good accuracy and is safe.
Out of a 26" factory barrel I'm getting an honest 2800fps with factory Black HIlls 300gr loads, and Double tap 300gr loads. I've reloaded Hornaday 285gr HPBT with 93 and 94gr of Retumbo with Fed 215M primers/Lapua brass to get 2830 and 2870fps respectively.
I routinely shoot the 300grn Scenar with 90.0 Retumbo in Lapua brass, Fed 215M primers. Last weekend (temp was 55F) I was getting 2780 from a 24" Barrett MRAD.
91.0 of Retumbo under the same conditions was giving me 2820.
90.0 is the best accuracty with the 300grn Scenar in my rifle...loaded .02 off the lands.
Of note, factory Lapua 300grn Scenar gave me 2760 on the same day.
I have noticed that the 300grn Berger OTM gave me significantly less MV using the same powder / primer combo.
91.0 of Retumbo under the same conditions was giving me 2820.
90.0 is the best accuracty with the 300grn Scenar in my rifle...loaded .02 off the lands.
Of note, factory Lapua 300grn Scenar gave me 2760 on the same day.
I have noticed that the 300grn Berger OTM gave me significantly less MV using the same powder / primer combo.
Hodgdon website says 98.0gr is max but I've gone to 99gr without issue. Here's what 96.5grs does at 300yds...2" target dot.
Will start working up loads for 285gr A-Max and 300gr Berger Hybrids soon.
Not to hijack, but can you tell me which program this is, that calculates the group size?
2815fps
28" krieger 1:9.75 twist (could be 9.5)
92.5gr. h1000
300gr. berger OTMs
~1670' altitude
28" krieger 1:9.75 twist (could be 9.5)
92.5gr. h1000
300gr. berger OTMs
~1670' altitude
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2930 fps using Lapua brass, Fed 215M, 95 gr. Retumbo, 300 gr. Berger hybrids, 28.5" barrel with long throat. Rounds are well past CIP mag length, but I use the Seekins bottom metal and magazines, so COAL is 3.855, and I am still off the lands. I may try to go a little longer yet. This velocity was obtained using 3 different chronographs of varying manufacturers, on different days and conditions, so I feel pretty confident that they are at 2900+ fps. Fits with predicted data in FFS also, so I am happy with it. No issue at all getting to 2000 m. Sadly, the true potential of this round is limited by the SAAMI/CIP standards and mag length.
My savage 110ba 26" gets 2805 with 92.0gr and 2830 with 92.6gr retumbo behind 300gr bergers.
My ax is showing me 2800ish right now with 91.5 gr retumbo out if the 27" tube
My ax is showing me 2800ish right now with 91.5 gr retumbo out if the 27" tube
