dstoenner
Silver $$ Contributor
Back in December I posted about getting my new barrel on my 40X receiver and did some testing. Here is that thread
I figured rather than bury this I would just start a new thread. If you want to see the what lead to all of this you can read that thread.
So as I reported in the first string I was trying to fix a failure to fire on Eley, both black box and 10X. All SK and R-50 were fine. I found a replacement spring at PTG and when I installed it and tested Eley the FTF was fixed but the groups had gone from 1.020 and .640 to 1.255 to 1.760 on the same lot of Eley. R-50 went to 2.445. Looking at the picture in the original thread with the old spring and new spring, the new spring was longer and also had more coils. But I had scrubed things down while I had the firing pin apart so I first tested the original again. The FTF was still there but 1 in 20 rather than 2 in 10. Groups were back to normal (as previous testing).
So I tried the next logical conclusion. That the old spring after 60 years had taken a set. So I took the new spring and cut it down to the exact same number of coils. Put it all back together and wanted to test. I tried back January to see what effect it had but it was in the 30's when I shot the test groups and Eley in particular for me has always been a warm weather ammo. But I had no FTF in about 70 rounds.
So I waited and finally got a day in the mid sixties today to try again. I took Lapua Center-X, R-50, Eley black box 1045 and Eley 10X 1041. The center-X was so-so with the 1 group I shot. I had a flier? that dropped low in the 9 ring. The other 9 shots were a small group about .8 inches but the 10th doubled it. Then I went to R-50. I fired 2 10 shot group. Both fired 100. The second group was the best at 100-8x and 1.020.
Next I shot Eley Match with kind of scattered group but much better than the with the new unaltered firing pin. Time was running out so I wanted to get the 10X shot. I didn't have time to shot any foulers but since I was going within Eley I figured it would be OK. I also didn't try to center the group in the bull but just let it fall where it was.
And the winner is....
I came away seeing that this was the fix for the firing pin and for sure I had 2 really good ammo choices to shoot the upcoming Rimfire F-Class match. Last time before I worked on the firing pin, I shot R-50 knowing it was good and that I had not had a FTF with it or Lapua. I shot 148-37X in a 800-900-1000 yard progression. One point was me moving the gun with my finger in the trigger guard. I Know I know. The 2nd point lost was a low at 6 o'clock in the 9 ring. I looked my setup over and could not see any thing that would have caused it other then the ammo. But I was elated that I shot so well in my first time shooting rimfire f-class. I normally shoot centerfire f-class off a bipod not a front benchrest.
So for any of you out there that has a 40X rimfire with a 60 year old firing pin spring, here is your fix.
David
PS, I also accidentally hung all of the target upside down :-(
40X rimfire firing pin spring
After I got my rebarreled 40X action back, I started doing some ammo testing to see what the new barrel liked. I first tried Centr-x and Midas+ Groups were about 40% better than the original barrel. Then I tried Eley and the groups wer more than 50% improved, in fact 1 10 shot group was .670...
forum.accurateshooter.com
I figured rather than bury this I would just start a new thread. If you want to see the what lead to all of this you can read that thread.
So as I reported in the first string I was trying to fix a failure to fire on Eley, both black box and 10X. All SK and R-50 were fine. I found a replacement spring at PTG and when I installed it and tested Eley the FTF was fixed but the groups had gone from 1.020 and .640 to 1.255 to 1.760 on the same lot of Eley. R-50 went to 2.445. Looking at the picture in the original thread with the old spring and new spring, the new spring was longer and also had more coils. But I had scrubed things down while I had the firing pin apart so I first tested the original again. The FTF was still there but 1 in 20 rather than 2 in 10. Groups were back to normal (as previous testing).
So I tried the next logical conclusion. That the old spring after 60 years had taken a set. So I took the new spring and cut it down to the exact same number of coils. Put it all back together and wanted to test. I tried back January to see what effect it had but it was in the 30's when I shot the test groups and Eley in particular for me has always been a warm weather ammo. But I had no FTF in about 70 rounds.
So I waited and finally got a day in the mid sixties today to try again. I took Lapua Center-X, R-50, Eley black box 1045 and Eley 10X 1041. The center-X was so-so with the 1 group I shot. I had a flier? that dropped low in the 9 ring. The other 9 shots were a small group about .8 inches but the 10th doubled it. Then I went to R-50. I fired 2 10 shot group. Both fired 100. The second group was the best at 100-8x and 1.020.
Next I shot Eley Match with kind of scattered group but much better than the with the new unaltered firing pin. Time was running out so I wanted to get the 10X shot. I didn't have time to shot any foulers but since I was going within Eley I figured it would be OK. I also didn't try to center the group in the bull but just let it fall where it was.
And the winner is....
I came away seeing that this was the fix for the firing pin and for sure I had 2 really good ammo choices to shoot the upcoming Rimfire F-Class match. Last time before I worked on the firing pin, I shot R-50 knowing it was good and that I had not had a FTF with it or Lapua. I shot 148-37X in a 800-900-1000 yard progression. One point was me moving the gun with my finger in the trigger guard. I Know I know. The 2nd point lost was a low at 6 o'clock in the 9 ring. I looked my setup over and could not see any thing that would have caused it other then the ammo. But I was elated that I shot so well in my first time shooting rimfire f-class. I normally shoot centerfire f-class off a bipod not a front benchrest.
So for any of you out there that has a 40X rimfire with a 60 year old firing pin spring, here is your fix.
David
PS, I also accidentally hung all of the target upside down :-(
