dstoenner
Silver $$ Contributor
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 at 100 yards. I was elated. BUT with Eley I had at least 1 and sometimes 2 FTF in a 10 shot group which then my match chamber turned them into also Failure to Extract.
I thought it over, before I rebarreled I had never had either issue. It was rock solid. I asked the gunsmith about it and the headspace. He said he set the headspace at .041 and he had no clue about the FTF. I had already checked the headspace with my go gauge and it wouldn't close on it so what he is saying is good data.
It left onlly one thing I could think of and that was the firing pin spring. I looked all over for a firing pin spring and finally found one at PT&G. I bought it. Put it into my bolt and went to the range to test. Now my beautiful groups were horrible with a couple of flyers in each batch of Eley that I tested making the groups at least 1.3 inches to one group was over 2!!! WHAT.
My guess is that the PT&G spring is too strong and it is doing too much to the case when it hits bottom. Here is a picture:\\

The short one is original and the long one is PT&G. I tried pushing down on the spring with my calipers and I could pretty easily collapse it .300 inches but the PT&G I could only get about .250 inches.
I am putting my original back in and retest to make sure the groups are still good. If so then I am left with a dilemma of what to do moving forward. I am looking for suggestions from those who might have faced this issue.
I think I have maybe 2 options
1) Get a firing pin spring off of ebay that was from some part gun on the hope that it might be just a little better.
2) Cut coils. The current is 2.25 inches. I could maybe cut the PT&G down to 2.500. That would give me a little more umph to hit the Eley and maybe not disturb the accuracy.
I know this is issue and solution are a fine balance of tune of the whole action. What would you do????
Thanks in advance
David
I thought it over, before I rebarreled I had never had either issue. It was rock solid. I asked the gunsmith about it and the headspace. He said he set the headspace at .041 and he had no clue about the FTF. I had already checked the headspace with my go gauge and it wouldn't close on it so what he is saying is good data.
It left onlly one thing I could think of and that was the firing pin spring. I looked all over for a firing pin spring and finally found one at PT&G. I bought it. Put it into my bolt and went to the range to test. Now my beautiful groups were horrible with a couple of flyers in each batch of Eley that I tested making the groups at least 1.3 inches to one group was over 2!!! WHAT.
My guess is that the PT&G spring is too strong and it is doing too much to the case when it hits bottom. Here is a picture:\\

The short one is original and the long one is PT&G. I tried pushing down on the spring with my calipers and I could pretty easily collapse it .300 inches but the PT&G I could only get about .250 inches.
I am putting my original back in and retest to make sure the groups are still good. If so then I am left with a dilemma of what to do moving forward. I am looking for suggestions from those who might have faced this issue.
I think I have maybe 2 options
1) Get a firing pin spring off of ebay that was from some part gun on the hope that it might be just a little better.
2) Cut coils. The current is 2.25 inches. I could maybe cut the PT&G down to 2.500. That would give me a little more umph to hit the Eley and maybe not disturb the accuracy.
I know this is issue and solution are a fine balance of tune of the whole action. What would you do????
Thanks in advance
David