How do you know how close a bullet is to the grooves in the chamber. I would like to try moving some out to improve accuracy but I don't want to cause an over pressure. I am loading a medium load so I should be able to work on bullet position but how do you know where it is in the chamber?
Bullet Position
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Chief RID,
I've addressed this issue two different ways. I've used an O.A.L. gauge and dummy case to match your caliber -- both made by Stoney Point. The gauge is a hollow tube with a shaft inside. The end of the tube is threaded for attaching a dummy case, which in turn is hollow, allowing the shaft to push against the rear end of the bullet. You insert the dummy case with bullet (it's very loose) attached to the gauge rod in the chamber. Once the case is chambered, then push the rod forward, which in turn pushes the loose bullet up against the lands. You then use the set screw on the gauge to set the rod in place and remove the complete apparatus. You then measure the case/bullet lenght and backoff the appropriate amount for seating your bullet. The literature I've read seems to vary about the amount to back-off, ranging from .003 to .020. I back-off .005 and it has worked well for my .223 shooting. By the way, the gauge is approximately ฮ and the dummy case ŭ.
The other process I've used is much cruder. I simply seated a bullet in an empty/non-primed case, leaving the bullet obviously too long to allow chambering (closing the bolt). I keep experimenting with the seating depth until I'm able to close the bolt -- giving me the maximum length.
Apologize for the poor description, but hope it helps a little.
I've addressed this issue two different ways. I've used an O.A.L. gauge and dummy case to match your caliber -- both made by Stoney Point. The gauge is a hollow tube with a shaft inside. The end of the tube is threaded for attaching a dummy case, which in turn is hollow, allowing the shaft to push against the rear end of the bullet. You insert the dummy case with bullet (it's very loose) attached to the gauge rod in the chamber. Once the case is chambered, then push the rod forward, which in turn pushes the loose bullet up against the lands. You then use the set screw on the gauge to set the rod in place and remove the complete apparatus. You then measure the case/bullet lenght and backoff the appropriate amount for seating your bullet. The literature I've read seems to vary about the amount to back-off, ranging from .003 to .020. I back-off .005 and it has worked well for my .223 shooting. By the way, the gauge is approximately ฮ and the dummy case ŭ.
The other process I've used is much cruder. I simply seated a bullet in an empty/non-primed case, leaving the bullet obviously too long to allow chambering (closing the bolt). I keep experimenting with the seating depth until I'm able to close the bolt -- giving me the maximum length.
Apologize for the poor description, but hope it helps a little.
Funny. I just got a Stoney Point OAL gauge last night. After using it, I'm wondering if DOK's 2nd option doesn't work ok, too?
I have played with seating a bullet long and camming the bolt closed. There were slight indications of throat/ogive contact, but the bullet slid into the (necked, uncrimped) case easily using the action. It seemed like a reasonable rough method of gauging max OAL. (Being a rookie at reloading, I broke down and got the SP OAL gauge, anyway)
I figure you just back off the seating die .030-.040 from this "max" measurement and it'd be pretty close to optimal. BR guys might not like it but for hunting rifles it'd be OK(?). (The Federal .270win 130gr load measured .11" short of what the SP OAL gauge read, so anything would be better!).
- Charlie
I have played with seating a bullet long and camming the bolt closed. There were slight indications of throat/ogive contact, but the bullet slid into the (necked, uncrimped) case easily using the action. It seemed like a reasonable rough method of gauging max OAL. (Being a rookie at reloading, I broke down and got the SP OAL gauge, anyway)
I figure you just back off the seating die .030-.040 from this "max" measurement and it'd be pretty close to optimal. BR guys might not like it but for hunting rifles it'd be OK(?). (The Federal .270win 130gr load measured .11" short of what the SP OAL gauge read, so anything would be better!).
- Charlie
Charlie Z / Chief RID,
If you want to get a little fancier/more accurate measurement, you can buy a small device for several dollars that fits on your micrometer and measures the case/bullet length via the bullet's ogive instead of the tip of the bullet. Literature indicated (and I've verified this) that since many bullet tips are lead and get banged around a little, measuring from the tip can be off by several thousanths between bullets. If you're trying for BR type of measurement, such as backing off just .003, that difference in measurement can be significant. But as Charlie Z says, for hunting rifles, would suggest this does not present a problem.
Respectfully,
If you want to get a little fancier/more accurate measurement, you can buy a small device for several dollars that fits on your micrometer and measures the case/bullet length via the bullet's ogive instead of the tip of the bullet. Literature indicated (and I've verified this) that since many bullet tips are lead and get banged around a little, measuring from the tip can be off by several thousanths between bullets. If you're trying for BR type of measurement, such as backing off just .003, that difference in measurement can be significant. But as Charlie Z says, for hunting rifles, would suggest this does not present a problem.
Respectfully,
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2,146 Posts
ChiefRID,
In handloading the primary concern is safety and the next is performance. You can use DOK's "cruder" method with complete safety- you just want to be sure that the bullet is not jammed into the rifling, which can cause an unsafe or at least inconvenient situation.
Then we get to performance. In terms of accuracy, different seating depths can have a big affect, but there is no hard or fast rule and each firearm is a law unto itself. Start at your max seating depth and load 5 rounds in gradually reduced OAL until your rifle tells you what it likes. You don't even need to know how far off the lands the bullet is!! The only caution here is that radically shortened rounds reduce powder space and can raise pressures, but use some care and you can find the depth that's right for your gun. I have one rifle that actually shoots better with the bullets seated with quite a bit of jump before hitting the lands. You never know til you try! Good shooting! :biggrin: ID
In handloading the primary concern is safety and the next is performance. You can use DOK's "cruder" method with complete safety- you just want to be sure that the bullet is not jammed into the rifling, which can cause an unsafe or at least inconvenient situation.
Then we get to performance. In terms of accuracy, different seating depths can have a big affect, but there is no hard or fast rule and each firearm is a law unto itself. Start at your max seating depth and load 5 rounds in gradually reduced OAL until your rifle tells you what it likes. You don't even need to know how far off the lands the bullet is!! The only caution here is that radically shortened rounds reduce powder space and can raise pressures, but use some care and you can find the depth that's right for your gun. I have one rifle that actually shoots better with the bullets seated with quite a bit of jump before hitting the lands. You never know til you try! Good shooting! :biggrin: ID
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