09-16-2013, 11:14 PM
XcountryRider Wrote:Bill Alexander claimed 5R barrels were slower and we needed to add powder to make up the dropped velocity.
As your determination seems to pick a fight and I lack the time to explain fully.
Please read the quote carefully and think about the context of the whole post. 5R barrels within a specific pressure level will allow faster velocity that is why the competition guys love them (they shoot good groups as well). Good lapping will also help for the same reason by allowing the bullet to move easily down the bore. For a given load they will drop the pressure and consequently the velocity. Bring them up to spec and they are fast.
I need +$40k of kit to examine the pressure. Typical load data takes a day at least and a few hundred round. If the results look shaky we cross reference with other manufacturers and provide loads and even reference ammunition to check the results. The whole process may take several weeks are you sure you can do this by eye over five round groups?
Do you not think that we have never encountered 5R rifling or polygonal or ratchet or gain twist or Enfield. That we have not tested multiple permutations of throat and neck design? We do not own adequate kit to quantify a barrel? Lap barrels or measure them mechanically and optically to the 5th decimal.
Polygonal form rifling (BHW makes excellent examples of this and fine barrels) extends the logical progression of 5R. It will drop the pressure slightly more and so you get a slight reduction in velocity.
So the "results" using the term in the broadest sense.
5R unlapped Liberty, most pressure fastest, variable throat and bore fouling so pressure jumps the most and the ES is up.
5R lapped, Very consistent bullet moves a little easier drops a bit of MV nice ES
Polygonal, Smooth, lowest engraving force and least bore resistance, slowest. (good barrel for hand loads that might well allow some improvement over factory velocities)
You did not use a correct standard pattern bore with known cross sectional area for the base line nor was testing controlled to STP. The sample set is not statistically valid. However with all this in mind your enthusiasm for shooting and a zest for knowledge is great. I can do nothing but commend your ideas and your contribution. The testing did show that there is merit in the BHW polygonal pattern and this might well be a great idea in a work carbine. Proof would require much more work but the foundation has been shown. Satern 5R demonstrates that it is a superb barrel as always.