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Showing results for tags '3n37'.
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Lots of cracked slides these days caused by less than perfect metallurgy, hardness, fitting, etc.. compounded by high pressure 9major loads. My goal in developing a great load is to maximize performance while NOT destroying me or my gun. The common sense recommendation is to use a slower powder to reduce case pressure. OK, slower powders measured & ranked how? Powder manufacturers charts are considered 'guidelines' as to 'relative' burn rates, and should maybe be considered most accurate with their own product? Add to this, the different burn rate charts available have conflicting ranks among the most popular powders used for 9major. And now for the rule of thumb Slower powders usually require more charge weight than fast powders to achieve the same velocity (assuming same bullet, barrel, primer & cart.). More conflict. So all of this has got me thinking... (probably over-thinking) The following is compiled from my own 9major load data over the years. This is a high level comparison - not a true apples to apples, since this is with 4 different barrel configurations, different temps, etc.. The last column is the charge weight of a 100% full 9mm case. Nice for relative density comparisons.
I'm hoping I can get some advice. I'm sure I'll work through this eventually, but here's what I've got. I have a LOT of VV 3N37 and am a new reloader working on a Dillon 650. Changing powder at this point is really not an option. Loading Montana Gold 147 gr FMJ, I started with 4.2 grs of 3N37. The load data below puts 4.2 at 879 fps. I was falling around 675 fps and not cycling the Glock 34 (Obviously) So I loaded some at 4.5 grs and am still only getting to around 775 fps I loaded 5 rounds at 4.8 and still only got an average of 825 fps. The crimp looks good. I'm trying to find a soft load that makes IDPA PF of 125,000 with a little fudge factor, (min would be 851 fps, so 875-885 would be perfect) I ran some new AA 147 gr through my chronograph and it was right around 900 fps, so I don't think the new RCBS Chrono is the problem. Any ideas or advice is welcome! 147 Hornady HPBT-XTP Vihtavuori VV-3N37 4.2 879 Remarks: overall loaded length (inches): 1.100 147 Hornady HPBT-XTP Vihtavuori VV-3N37 5.0 1023