I am building a new rifle in 260 AI caliber. I have a problem that is confusing me. I know I could take the rifle to a gunsmith but I think the problem may actually be in my reloading setup so want to be sure there is actually a rifle problem before sending it off, only to get it back unchanged (and with a bill to pay).
The problem is the bolt does not close on reloads. The bolt moves all the way forward, but only starts down a very small amount before stopping. The bolt closes on unfired Lapua brass (not Ackley Improved-- standard 260 Remington) just fine. The bolt also closes on a 260 AI Go Gauge just fine. For these reasons I think the rifle gunsmithing (done by LongRifles) is OK.
I am using brass fire-formed an ANOTHER 260 AI to start the resizing process. My first thought is the shoulder of the 260AI brass was not set back enough. But after a series of gradual trials with my Forster Co-Ax press I finally ended up with the die down as far as it could go in the press and the resulting cases still do not chamber. Throughout these trials I used a Sinclair headspace gauge (the green one that fits on a pair of calipers) and did not see any change in headspace through the trials. So, I am wondering if the dies/press is set up correctly, as the only explanation I can come up with is that the fire-formed brass from the other rifle has already got its shoulder pushed back beyond where the die can set it with maximum compression.
Then I decided to try some other tests. I took a piece of the resized fire-formed brass and trimmed its throat back so it is considerably shorter that a 260 AI should be (to make sure the case length was not interfering with cambering). I tried that in the new chamber, same result. Then I tried thinning the neck very thin, again to see if a too-thick neck was the culprit. No, same result. Finally I trimmed brass from the base of the case (the bottom, where the Lapua name is marked), and finally did get the brass to chamber (with the bolt a tight close).
So, it seemed at this point that the base to shoulder ogive distance was too great, again leading to needing to set the shoulder back some more. But I can't, since the Redding Competition full-length die is already seated to the bottom of the possible travel. I don't know where to go from here.
I find it odd that the die has no "room to maneuver" (ability to push back the shoulder) from a more standard 1 turn up from absolute bottom position. The die is very clean. I've used this press for many years with .223. and .308 dies and it has worked very well.
I used Dycom blue on the case a with a bullet seated and could not see unusual contact after trying to close the bolt on this case hard a couple times. Where i see the rubbing is on the boltface, polishing a circle around the firing pin hole. Could there be an ejector/extractor issue here? But if so, then why does factory brass work fine?
Co-ax presses use proprietary caseholders, so the idea of grinding them down (to get more die travel) is not too attractive. Especially since other caliber dies have worked fine.
I know I can finish the build and go fireform some Lapua 260 standard cases in the rifle and see what happens, but I'd like to understand what is going on. Any ideas?
The problem is the bolt does not close on reloads. The bolt moves all the way forward, but only starts down a very small amount before stopping. The bolt closes on unfired Lapua brass (not Ackley Improved-- standard 260 Remington) just fine. The bolt also closes on a 260 AI Go Gauge just fine. For these reasons I think the rifle gunsmithing (done by LongRifles) is OK.
I am using brass fire-formed an ANOTHER 260 AI to start the resizing process. My first thought is the shoulder of the 260AI brass was not set back enough. But after a series of gradual trials with my Forster Co-Ax press I finally ended up with the die down as far as it could go in the press and the resulting cases still do not chamber. Throughout these trials I used a Sinclair headspace gauge (the green one that fits on a pair of calipers) and did not see any change in headspace through the trials. So, I am wondering if the dies/press is set up correctly, as the only explanation I can come up with is that the fire-formed brass from the other rifle has already got its shoulder pushed back beyond where the die can set it with maximum compression.
Then I decided to try some other tests. I took a piece of the resized fire-formed brass and trimmed its throat back so it is considerably shorter that a 260 AI should be (to make sure the case length was not interfering with cambering). I tried that in the new chamber, same result. Then I tried thinning the neck very thin, again to see if a too-thick neck was the culprit. No, same result. Finally I trimmed brass from the base of the case (the bottom, where the Lapua name is marked), and finally did get the brass to chamber (with the bolt a tight close).
So, it seemed at this point that the base to shoulder ogive distance was too great, again leading to needing to set the shoulder back some more. But I can't, since the Redding Competition full-length die is already seated to the bottom of the possible travel. I don't know where to go from here.
I find it odd that the die has no "room to maneuver" (ability to push back the shoulder) from a more standard 1 turn up from absolute bottom position. The die is very clean. I've used this press for many years with .223. and .308 dies and it has worked very well.
I used Dycom blue on the case a with a bullet seated and could not see unusual contact after trying to close the bolt on this case hard a couple times. Where i see the rubbing is on the boltface, polishing a circle around the firing pin hole. Could there be an ejector/extractor issue here? But if so, then why does factory brass work fine?
Co-ax presses use proprietary caseholders, so the idea of grinding them down (to get more die travel) is not too attractive. Especially since other caliber dies have worked fine.
I know I can finish the build and go fireform some Lapua 260 standard cases in the rifle and see what happens, but I'd like to understand what is going on. Any ideas?
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