How do you measure chamber space
- Thread starter pilot24
- Start date
What I did was kinda mickey mouse but it worked well. I seated a bullet in a unprimed case very slightly. I then used a lighter and blackend the bullet. I put the bullet into the gun and chambered it. Now you could see where the bullet hit the lands and in fact mine seated further. I took a measurement and reseated another bullet further and did the same.
In the end I found out that I could have a 7mm mag COL of 3.345" instead of 3.29" that is normally in reloading manuals. The cartridge easily fits in my magazine and chambers perfectly every time. The big thing is the accuracy is now 100 times better and I am still a fair ways away from the lands. It is mind blowing how playing with COL can improve you accuracy.
Jacky
In the end I found out that I could have a 7mm mag COL of 3.345" instead of 3.29" that is normally in reloading manuals. The cartridge easily fits in my magazine and chambers perfectly every time. The big thing is the accuracy is now 100 times better and I am still a fair ways away from the lands. It is mind blowing how playing with COL can improve you accuracy.
Jacky
The way I measure the Max OAL of a bullet choice is to close the action ,insert a cleaning rod down the bore until it bottoms out on the bolt, mark the rod. Open action and insert the bullet you want to load(bullet only not a cartridge) hold the bullet against the rifling with a pencil or something, re-insert the rod until it touches the bullet tip, mark rod again. the difference between the marks is your max OAL for that bullet. Note it can change with a different bullet weight/shape.
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- Somewhere on the Hudson Bay Coast
Sasquatch said:
X2
In the mean time the most accurate means of getting the exact length is as follows:
1) Place a bullet nose down in the muzzle of the barrel and give it a twist - the mark left on the bullet is the point at which the lands will first contact the bullet.
2) Measure the barrel length to the closed bolt face with the cleaning rod, marking the rod at the muzzle.
3) Drop a flat based bullet into the chamber and use a short cleaning rod or a dowel to hold it in place.
4) Again use the cleaning rod to measure - this time from the muzzle to the bullet base, and mark the rod again.
5) The distance between the two measurements is the length from the head of the cartridge to the marked ogive on your bullet.
The method that you used is certainly not mickey mouse.I use a fired case then put a small dent at the end of the neck to hold the bullet in place,and then use the same metod that you describe.However a blackened bullet is not at all required.This method is simple ,and is just as accurate if not moreso than other much more complicated methods,and requires no special tools.
I started reloading my .204 this winter and would like to improve the grouping a little more. What is the recommended distance one should stay away from the lands once the maximum distance is determined, also is there a fear of over pressure in the case if you don't allow enough distance for initial bullet movement after firing (ie: movement of the bullet to the lands)?
i used jacky's trick when i loaded rifle 15 years ago, read it somewhere, works great. pulled the groups in from 12" to 1" at 100 yrds. NOTE: makes the rounds specifically for that gun, make sure to mark the gun the bullets are made for on the ammo box with your reload data. Just in case you have more than one firearm of the same calliber.
Xray
Xray
I've been through all the cleaning rod measurements, but there is a simpler way. Size a neck just enough to make a bullet friction tight. Start a bullet in a case, seat the case in the extractor of the bo lt, then close the bolt. the bullet will be pushed in to the overall length. By the way, there is nothing wrong with seating bullets until they hit the lands, as far as pressure goes, but they may not fit the magazine.
mmmmm
just in case there is some newbies that dont know and try this ,there are some rifles out there that you will not touch the lands with the bullet in the case method,but then you can only go magazine lenght anyways unless your able to lengthen the mag.
just in case there is some newbies that dont know and try this ,there are some rifles out there that you will not touch the lands with the bullet in the case method,but then you can only go magazine lenght anyways unless your able to lengthen the mag.
