View Full Version : I am confused (presure signs)
04-13-2009, 09:26 AM
358 win, 1 in 12 twist, .360, 196g pb ww,wd, carnuba red,xmr5744. where I am getting confused is I was fire forming some cut down 30-06 and getting alot of lead blow back on the necks with 21g 5744, my first thought is not enough pressure, then I thought I should totaly ignore these I am fire forming. so I loaded some already formed brass from 21g to 28g one grain increase at a time, and the results tell me I was right to discount the fire form cases. 21g still had a very small amount of neck deposits ( i beleive lube and powder residue ) with each 1g increase the deposits moved farther down the neck and could see some lead in the deposits. up to 25g, then 26g, 27g, and 28g the deposits gradualy reduced back to the leavel of the 21g load. I am so confused!!! heavy deposits on neck = no leading in barrel vs light deposits = heavy barrel leading. I am considering trying 19g to 20g just to see what happens. is this the right dirrection to take? or just give up on the 5744 (only have 1/4 lb left) my bullets shoot well with 10.4g red dot even when fire forming. I will most likely go back to red dot, but would really like to know what my results with 5744 mean! I appreciate any help!!![smilie=b:
04-13-2009, 09:39 AM
Think obturation! The boolit is not obturating enough to make a zero total clearance. Sometimes a softer case neck helps, but when it does, the timing problem still exists, and will show up in your groups if not on the case necks themselves via smoke. Use a faster powder, or a softer, or a bigger boolit or some combo thereof. In other words, don't let the boolit escape the case neck without some friction. ... felix
04-13-2009, 10:14 AM
so would the first step be to try air cooled instead of the water droped. and when I was thinking more presure my reasoning was for more obturation with a higher power charge, which helped with blow back on the cases, but leaded like **** . so now I am thinking I need to acheive the obturation another way, not more powder but softer bullet? am I on the right track with my thinking? faster power would explain why red dot works better, I did notice 3 cases out of 20 did not fully fire form with 21g 5744, but always do with 10.4 red dot. mabye I should use the 5744 to fertelize my wifes flowers! and use what I know works! but I would not be casting and handloading if I did not like to expeirment! that and I am too cheep to buy jacked bullets!!!!
04-13-2009, 10:17 AM
+1 to what Felix just said.
Best wishes from the Boer Ranch,
04-13-2009, 10:32 AM
i was fireforming with unique and red and a plain basedboolit.
the results were similar had gunk bout a foot down the bbl went to a slower powder to keep the boolit under pressure down the bbl further finally cleaned the gunk out.
i think the pressure was letting off bout there and the relaxing of the boolit was letting the lube stick to the bbl.
with the lighter loads i think you need to either keep the pressure up till exit or get it over with asap.
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