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Posted: 2/13/2012 9:12:39 AM EDT
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I've been loading for my OBR for a while now with good results. However, yesterday I was messing with it and after measuring, then chambering and ejecting a mag worth of reloads, I discovered that the OAL of the loaded rounds is increasing by .004-.005 after chambering them. So, I checked my neck tension and found that I am getting .0015-.002 neck tension when loading. Thinking this may not be sufficient, I went ahead and tried crimping some rounds, but even after progressing to what I think is a pretty aggressive crimp, I'm still getting increasing OAL after chambering. I'm out of ideas, so I though I'd ask people more experienced than I what they think. In case it is important, I am using twice fired RP brass sized in a RCBS full-length competition sizing die and loading Nosler custom competition 155s.
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you may want to ask this question in the reloading sub forum you will probably
get more help. |
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Quoted: you may want to ask this question in the reloading sub forum you will probably get more help. Will do, thanks. Joe |
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What weight bullets?
How many times has the brass been reloaded? What dies? How thick are the neck walls? Usually .003 to .004" neck tension should be sufficient...there are things that can have an impact on that though (work hardening of the brass, etc..) ....If your using heavier bullets and dropping the bolt on them it can act like a inertia bullet puller and dislodge the bullet forward slightly, even with a crimp.... If the neck walls on the brass has started to flow and thin from several reloadings there's not much you can do about it, using an undersized expander and neck bushig die would be a temp fix, but cracking from work hardening and thinning are sure to come if that is the case.... ETA: oooops I see the weight and times fired brass....micro reading on my cell isn't helping... Twice fired seems like should have more than a thow and a half..have you measured the expander? |
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Quoted:
What weight bullets? How many times has the brass been reloaded? What dies? How thick are the neck walls? Usually .003 to .004" neck tension should be sufficient...there are things that can have an impact on that though (work hardening of the brass, etc..) ....If your using heavier bullets and dropping the bolt on them it can act like a inertia bullet puller and dislodge the bullet forward slightly, even with a crimp.... If the neck walls on the brass has started to flow and thin from several reloadings there's not much you can do about it, using an undersized expander and neck bushig die would be a temp fix, but cracking from work hardening and thinning are sure to come if that is the case.... ETA: oooops I see the weight and times fired brass....micro reading on my cell isn't helping... Twice fired seems like should have more than a thow and a half..have you measured the expander? 762x40mm nailed it. I like Redding's #77155 FL S bushing sizer die with .003" neck tension. |
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Quoted: Quoted: What weight bullets? How many times has the brass been reloaded? What dies? How thick are the neck walls? Usually .003 to .004" neck tension should be sufficient...there are things that can have an impact on that though (work hardening of the brass, etc..) ....If your using heavier bullets and dropping the bolt on them it can act like a inertia bullet puller and dislodge the bullet forward slightly, even with a crimp.... If the neck walls on the brass has started to flow and thin from several reloadings there's not much you can do about it, using an undersized expander and neck bushig die would be a temp fix, but cracking from work hardening and thinning are sure to come if that is the case.... ETA: oooops I see the weight and times fired brass....micro reading on my cell isn't helping... Twice fired seems like should have more than a thow and a half..have you measured the expander? 762x40mm nailed it. I like Redding's #77155 FL S bushing sizer die with .003" neck tension. A good buddy of mine is actually loaning me that very die with the appropriate bushing set this evening to try it out. |
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Quoted:
Quoted:
Quoted:
What weight bullets? How many times has the brass been reloaded? What dies? How thick are the neck walls? Usually .003 to .004" neck tension should be sufficient...there are things that can have an impact on that though (work hardening of the brass, etc..) ....If your using heavier bullets and dropping the bolt on them it can act like a inertia bullet puller and dislodge the bullet forward slightly, even with a crimp.... If the neck walls on the brass has started to flow and thin from several reloadings there's not much you can do about it, using an undersized expander and neck bushig die would be a temp fix, but cracking from work hardening and thinning are sure to come if that is the case.... ETA: oooops I see the weight and times fired brass....micro reading on my cell isn't helping... Twice fired seems like should have more than a thow and a half..have you measured the expander? 762x40mm nailed it. I like Redding's #77155 FL S bushing sizer die with .003" neck tension. A good buddy of mine is actually loaning me that very die with the appropriate bushing set this evening to try it out. A very good buddy, indeed. |
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Quoted: Quoted: Quoted: Quoted: What weight bullets? How many times has the brass been reloaded? What dies? How thick are the neck walls? Usually .003 to .004" neck tension should be sufficient...there are things that can have an impact on that though (work hardening of the brass, etc..) ....If your using heavier bullets and dropping the bolt on them it can act like a inertia bullet puller and dislodge the bullet forward slightly, even with a crimp.... If the neck walls on the brass has started to flow and thin from several reloadings there's not much you can do about it, using an undersized expander and neck bushig die would be a temp fix, but cracking from work hardening and thinning are sure to come if that is the case.... ETA: oooops I see the weight and times fired brass....micro reading on my cell isn't helping... Twice fired seems like should have more than a thow and a half..have you measured the expander? 762x40mm nailed it. I like Redding's #77155 FL S bushing sizer die with .003" neck tension. A good buddy of mine is actually loaning me that very die with the appropriate bushing set this evening to try it out. A very good buddy, indeed. The same buddy is essentially a reloading guru as well. He basically taught me how to reload and shoot long range. A great guy. |
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If you do a controlled test with heavy neck tension and crimp, you would discover that a semi-auto will almost always have an effect on the OAL when allowed to slam the cartridge.
Do this several times and measure OAL and you would see almost no amount of workable neck tension or crimp will stop this short of a bond from a sealant. Accuracy suffers at those levels of grip. Bottom line, test like you shoot. Establish enough neck tension during single feed and then test magazine loads in rapid strings. If your neck tension and precision are good enough, count your blessings. You will eventually find yourself neck turning and annealing if you are careful enough to track your brass life. Welcome to the world of precision semi-auto shooting. |
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Or keep it easy. Just chamber your rounds once. That is what I do, except hunting where I rotate my ammo to put a fresh round on top. Factory pistol ammo can have bullets pulled from the case through repeated chambering. (depends on the gun, some jam the bullet back from hitting the feed ramp)
Like a previous poster said, welcom to the world of self loaders. There are a lot of different issues with them. |
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