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I knew it but I did it without thinking.
bpost Member Posts: 32,405 ✭✭✭✭
A 9mm shoots a JACKETED .355 diameter bullet. Cast bullets should be .001 larger to oburate the bore and shoot more accurately.
Well, dummy me cast 40 pounds of 9mm 120 bullets and sized them all .355. I also loaded 900 of them. Well at 20 yards they keyholed 50% of the time and nary a one hit the bull I was aiming at.
I will now remelt them all and size them to .356 as I have done with thousands of others. Why I did .355 will keep me awake at night.
All 900 rounds were BLASTED out of a AR-9 with 32 round magazines. It did not take long but that AR-9 is one filthy beast.
Sems like measuring the groove diameter of the barrel might be a good idea. Good luck.
I have shot tons of 9MM and have never had one shoot worth a hoot with cast .355 bullets. My G34 gen 5 loves cast bullets over tite group, as long as they are .356. When shooting the .355's last week it was a shot gun pattern not a group.
Bruce, it sounds like you need to lose that .355 mold! 😁 I have learned more things the hard way than I care to mention!!
The mold is .356, it was my moldy mind sizing them .355.
I don't believe .001" will make any difference. bullets are either too soft or pushed too fast
.001 makes a big difference in cast
.001 is huge in cast bullets. It is all the difference between a bullet oburating the bore and taking the rifling to impart spin or skidding helter skelter down the barrel. When the bore is not tightly sealed against gas pressure really bad stuff happens the worst is the leading. I really noticed it when the G-34 target could not keep a 2" group at 20 yards and several shots keyholed.