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OAL LENGTH TO LANDS QUESTION.
scottsdale
Member Posts: 14 ✭✭
USING A HORNADY/STONEY POINT OAL GAUGE AND COMPARATOR TO DETERMINE WHERE BULLET TOUCHES LANDS ON A 25-06 REM.I HAVE A MEASURMENT RECORDED.OBVIOUSLY THIS MEASUERMENT IS W/OUT CLOSING A BOLT ON THE CASE. MY QUESTION IS IF I MAKE A DUMMY CARTRIDGE MADE TO THAT LENGTH,HOW FAR WILL THE BULLET BE PUSHED IN WHEN BOLT IS CLOSED.IS THERE ANY "RULE OF THUMB" TO DETERMINE THIS TRUE OAL MEASUREMENT? THANKS FOR THE TIME/ASSISTANCE.
Comments
THANKS, SO IF I MAKE A DUMMY SEATED TO THE STONEY POINT MEASUREMENT THEN CHAMBER IT, BULLET WILL CRAM INTO THE LAND RATHER THAT BE PUSHED INTO CASE?
Cant say for certain but it should cram into the lands. Probably depends on the bullet jacket and what the oal is. Measure before and after and youll have your answer. If the bullet is seated really long, theres a possibility that itll stay stuck in the lands when you remove the case. Just knock it out with a cleaning rod if it does. Thats why we use dummy rounds for this. No worries that way.
the flaw with the stoney point tool is that is uses a dummy cartridge that can be many thousandths of an inch different in dimension than your chamber. Using a fired case pretty much duplicates your chamber except for a few .001"s "springback".
THEN, after you seat a bullet to the exact OAL at the lands, you use your comparator to get a measurement, and you now have the "to the lands" measurement that you can use to seat any other type of bullet to the lands, without having to use the tool again.
made dummy to that length,chambered it and it left no marks and no change in oal.its a boattail bullet and seated just barely ahead of boattail taper.
you said you're loading for a 25-06 rem. is this a remington 700 rifle? How much effort did it take to close the bolt on the dummy round? It should be smooth with about finger pressure to close it. If it's really firm, you're definitely on the lands.
Or, your cases aren't sized correctly. There is another way I use to size my cases. I take the firing pin out of the bolt and chamber an empty sized case with no bullet. The bolt should require just a hair more than gravity to close when they're sized correctly. Just slight fingertip pressure should close it. Too hard, and the cases are too long and are crushing when you close the bolt. Bolt falling on it's own with only gravity, and the cases are too short and aren't fitting correctly in the chamber.
Which bullets are you using and are you SURE there are no marks from the lands? They can be hard to see without a magnifying glass. If I remember correctly, the marks will be on the shoulders of the bullet (where the comparator sits)
My methods are only good for Remington 700 rifles though. They might work with other rifles, but I've never tried it. Therefore, I wouldn't feel confident advising these methods. They require a "feel" to know when everything is correct. I'm sure if you know what you're doing with other rifles, it could be done. But I don't feel qualified to say.
Before I got the sinclair OAL stuff, for bolt action and single shot rifles I made up about 3 dummy rounds and carefully sized the necks so as the bullet was not tight, just good snug and then take a propane cigarette lighter and apply soot to the jacketed bullet, (the sooting the bullet is easy, just play with the distance from the flame to the bullet and it will quickly apply the soot and the soot gives a easy to see readout) When you get the neck tension correct you can carefully chamber, open the bolt slowly and then take the OAL reading OR best here to use the Sinclair bullet comparator and record the Ogive OAL reading, then just subtract for the amount of bullet jump you desire.
Record your comparator readings and go back after you have shot couple hundred rounds and see how much the throat has eroded, but don't get worried here if she is still grouping good. You will usually find some throat erosion and you can tehn move your ogive longer to give the original bullet jump.
At least, Get yourself at least a sinclair bullet comparator, best thing since sliced bread![;)]
The Stoney Point is a good tool to help load accurate ammo if used properly.
get rid of the stoney point tool and buy the Sinclair tool. It uses a FIRED case, from YOUR CHAMBER. A much more reliable tool IMHO.
JustC...do they send you a tap to thread your case or what? I have the Stoney Point and I have to buy a drilled and tapped case for every caliber I have.
Do you have a link to the Sinclair tool? Thanks!
those are the 2 "stops" that are are on the rod. First a bullet is dropped into the chamber, and the first stop is slid onto the rod, and set after the rod is insterted and comes into contact with the base of the bullet. Next, the bullet is removed, and the fired case is dropped into the chamber. Then the second stop is set when it contacts the casehead.. The rod they slide on indexes on the back of the bullet, and the back of the fired case for setting each stop, so you know that you are using your own chamber for the measurements, not a case from some "standard" size factory die. You use the calipers to measure the distance from stop to stop, and then the bullet. Add those together and you have the EXACT distance to lands/OAL for ANY bullet you use the tool with. Trust me, it is far superior.
THEN, after you seat a bullet to the exact OAL at the lands, you use your comparator to get a measurement, and you now have the "to the lands" measurement that you can use to seat any other type of bullet to the lands, without having to use the tool again.
How do you determine the length to the ogive using this method? I can see you having the length from the case head to the back of the bullet, but what about the length from the back of the bullet to the Ogive? Thanks again!
You now take the measurement from stop to stop, add the bullet length, and that is your OAL at the lands. Now you seat a bullet in a case or charged case, then when you have that OAL, you use your comparator to determine the measurement at the lands with regards to the ogive.
Remember to use YOUR comparator, since that is the one you used when you set the original OAL.
This method uses YOUR fired case from YOUR chamber, with a bullet sitting at YOUR rifling. It is the absolute best tool I have used or seen for determining OAL at the lands.
There is NO tapping of a case. One stop is set when a fired case is dropped into the chamber, and the rod the stops slide on, is slid through the action guide, untill it hits the base of the case. This is AFTER the first stop is set by sliding the rod through the action guide, until it makes contact with the bullet that has been dropped into the rifling and that stop is set.
You now take the measurement from stop to stop, add the bullet length, and that is your OAL at the lands. Now you seat a bullet in a case or charged case, then when you have that OAL, you use your comparator to determine the measurement at the lands with regards to the ogive.
Remember to use YOUR comparator, since that is the one you used when you set the original OAL.
This method uses YOUR fired case from YOUR chamber, with a bullet sitting at YOUR rifling. It is the absolute best tool I have used or seen for determining OAL at the lands.
The Stoney Point gauge doesn't allow you to use a fired case from your rifle, but it does allow you to use your compartor to measure the OAL to the lands (or ogive) with the bullet still in the case...which is a nice feature. You don't have to measure the bullet and add that measurement to your other measurements...you also get the exact measurement to the Ogive without having to work backwards.
So why not skip that whole comparator tool nonsense and just find the most accurate seating depth to begin with? AFTER that, you can quickly and easily determine where to seat the bullet you used or ANY other bullet and get the same "off lands" distance - using only a caliper.
Here's how...
http://www.reloadingroom.com/index_files/Off%20Lands.htm
quote:Originally posted by JustC
There is NO tapping of a case. One stop is set when a fired case is dropped into the chamber, and the rod the stops slide on, is slid through the action guide, untill it hits the base of the case. This is AFTER the first stop is set by sliding the rod through the action guide, until it makes contact with the bullet that has been dropped into the rifling and that stop is set.
You now take the measurement from stop to stop, add the bullet length, and that is your OAL at the lands. Now you seat a bullet in a case or charged case, then when you have that OAL, you use your comparator to determine the measurement at the lands with regards to the ogive.
Remember to use YOUR comparator, since that is the one you used when you set the original OAL.
This method uses YOUR fired case from YOUR chamber, with a bullet sitting at YOUR rifling. It is the absolute best tool I have used or seen for determining OAL at the lands.
The Stoney Point gauge doesn't allow you to use a fired case from your rifle, but it does allow you to use your compartor to measure the OAL to the lands (or ogive) with the bullet still in the case...which is a nice feature. You don't have to measure the bullet and add that measurement to your other measurements...you also get the exact measurement to the Ogive without having to work backwards.
you are working off the assumption that the stoney point case matches your chamber dimensions. It most always will NOT. Using your fired case, you know what you are working with. I can set the stops, and measure them and the bullet, and have my OAL in under 5 minutes with the Sinclair guage. Then you slide the comparator on, and know you KNOW the measurement to OGIVE to be at the lands with ANY bullet you choose to use. As long as the measurement to ogive is the same, it doesn't matter what bullet you have loaded after the first time. The measurement from casehead to ogive will ALWAYS be the same, until the throat is eroded (which most shooters have never had happen, this really only happens with competition rifles fired a hundred or more times per match)
As far as the correct seating depth, I find my measurement at the lands, and choose a starting depth. For a hunting rifle, I like to start at ~.025"-.050" off the lands, or whatever the magazine will allow. Once I start the ladder, I can usually find well under MOA with one of the loads, if not I'll switch powders. The seating depth and primer are the last things I "tweak".