Note: Please post discussions specific to rifle load flyers on this other thread -
http://www.thehighroad.org/showthread.php?t=761019
Both threads specifically exclude shooter input as a factor to keep discussion related to reloading variables.
While posting on jmorris' thread on "Your most accurate 9mm load" for carbine at 100 yards, since I must use mixed range brass for "plinking" loads, I pondered when a group becomes a pattern or whether a pattern is a cluster of flyers, especially at 50-100 yards.
So I decided to return to reloading basics and read through this thread and got the following summary which were heavily derived from bullseye match shooting links and THR bullseye match shooters:
- Quality/consistency of load directly affects flyers.
- To greatly eliminate flyers, new brass needs to be used (which is not an option for me).
- To reduce flyers, once-fired brass from same lot should be used (since my 9mm carbine loads are replacing 22LR plinking, I must use mixed range brass).
- 9mm carbine load accuracy, especially at longer range of 50-100 yards, depends heavily on bullet type (I ordered bullets to include JHP/HP plated bullets in addition to FMJ/RN bullets but within cost constrains as I can't use more expensive bullets like Gold Dot/HAP for plinking loads).
- Certain powders/charge loads are better than some other powders.
- Lower SD number loads don't necessarily produce smallest shot groups.
- Variations in neck tension (case wall thickness) and bullet seating depth (OAL/case length) are contributing factors.
- Flat/flatter base bullets may produce more consistent chamber pressures than bevel/rounded base bullets.
- Bullet setback during feeding from magazine can significantly affect chamber pressure.
So far I have only tested 115 gr Winchester FMJ/Berry's HBRN/RMR HM RN with W231/HP-38 and Promo loaded to 1.135" as my reference loads at 25/50/100 yards. While 25 yard groups were around 1"-2", 50/100 yard groups definitely opened up with obvious signs of flyers -
http://www.thehighroad.org/showthread.php?p=10184059#post10184059
As I continue my load development and accuracy testing of 9mm carbine loads at 25/50/100 yards, I will be looking at above variables along with:
- Carbine barrel leade/freebore length and using longer OAL with 124/147 gr bullets, even with 115 gr using near max load data
- Sorting of brass by resized lengths in addition to head stamp
- Checking for bullet setback