Quote:
Originally Posted by elkhunter11
Most people that are using Lil Gun have discovered that a load of around 9.5 grains will match or exceed the velocity listed for the max load of 10gr in the Hodgdon data. Once I saw 3680fps at 20 degrees, I didn't bother trying to work up the load any hotter. If my velocity at 9.5gr exceeds the velocity for the maximum load, it only makes sense that increasing the powder charge to 9.8 or 10 gr, would produce excessive pressure, especially in hot weather.
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Yes that is exactly right and what I suggested when working up a load for the CFE BLK as the 12.8 Max load did appear to be too hot at 3779 when it only developed 3650 at 48,100 PSI in Hodgdons Max Load. Of course this leaves a 1900 PSI cushion, in the 50,000 PSI case, and measuring Case Expansion at the .200" Datum (PRE) would likely show less than the Saami Max Cartridge Diameter, .2982" especially if a new case was used which would measure around .295".
This discrepancy could also be because one of "Hornady's new factory cases" was used. I found them to be nearly 0.1grain heavier and hold nearly 1 grain less N120 than the original factory cases. This is a major consideration when re-loading and a very good reason to start low and measure PRE, or case expansion at the .200 Datum, while looking for pressure as primers are not a good pressure indicator in the 17 H. Also Rem 7 1/2 primers will blow long before the bolt shows any signs of seizing in both the Savage 25 and CZ 527 although primers will begin to flow into the firing pin hole before that happens. The 17 H case head can expand up to 0.005" before it is noticeable to the eye and before the primer will let loose. These pictures show primer pocket reamer diameter and primer pocket diameter of + 0.007" on a blown factory loaded case extreme temperature and sustained fire ( 7th round).
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