Long Gun Posted November 7, 2017 Report Share Posted November 7, 2017 Hello all, Just started handloading for my 6.5 Creedmoor: IMR 4350, 140 gr SST, loaded to SAAMI coal, out of a 25 inch barrel. Best I could get was 41.4 gr before I started getting definite pressure signs. MV was only 2520. This seems rather low to me but clearly can’t go higher due to pressure. Groups were superb though! Does this sound about right to you guys? Link to comment Share on other sites More sharing options...
Brillo Posted November 7, 2017 Report Share Posted November 7, 2017 IMR 4350 is similar to H4350 and load 42.1 grains with 142 grain SMKs and get 2850 fps from a 28” barrel with no pressure signs. I had a similar problem years ago when developing a load with H4895 and got pressure signs at a relatively low load. It turned out that the cases weren’t obdurating and this produced the same effect on the case head as over pressure signs. You don’t mention which pressure signs you see but I would suggest that 2520 fps is low from a Creedmoor with a 25” barrel and Quickload suggests that you’d still be safe at 42 grains with the SST bullet. Link to comment Share on other sites More sharing options...
Long Gun Posted November 7, 2017 Author Report Share Posted November 7, 2017 Thanks for the reply. Pressure signs were cratering on the primers and heavy bolt lift. How did you overcome your obturation problem? I’m using virgin Lapua brass. Also, I’m looking to move over to reloader 62 in response to the impending EU ban on everything. Link to comment Share on other sites More sharing options...
Brillo Posted November 7, 2017 Report Share Posted November 7, 2017 I cured the obdurating problem by increasing the charge by .5 grains. Link to comment Share on other sites More sharing options...
VarmLR Posted November 9, 2017 Report Share Posted November 9, 2017 Or you could try cleaning the chamber out with a meths soaked mop and dry it off. That worked for me with no need to up charge weights. Link to comment Share on other sites More sharing options...
Long Gun Posted November 9, 2017 Author Report Share Posted November 9, 2017 Hmmmm, interesting Link to comment Share on other sites More sharing options...
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