Okay - so first off I am just starting with reloading and very much enjoying it. I wanted to get my length to lands measurement. (Loading 300WSM). I am using the method where the bolt plunger and firing pin are removed and then feeling for contact/lack of contact with the bolt. I had loaded one dummy round that matched the ogive to base on the factory ammo I have been shooting/hunting. It and I am using the hornady CX bullet. This round chambered fine. Then I started to seat one further and further feeling contact as the bolt got closer and closer to closing - only to end up seating this bullet deeper then the factory load before it would close! By 34 thousandths. Then I was confused so I conducted the test again. This time the bolt would close with a seating depth of 10 thousandths MORE then the factory round. More like what I had expected. But what give? I am using a bullet comparator to measure these so it’s not the tip.
Measuring lands - discrepancy! (Noob)
- Thread starter BearPeak
- Start date
Jdne5b
Gold $$ Contributor
Watch the video part way down titled: Finding Your Lands, it uses a similar method but I’ve found to be very accurate and repeatable. Your bolt will close on a jammed bullet. Feeling when opening is more consistent for me.
www.wheeleraccuracy.com
Videos | wheeleraccuracy
It’s a possibility that the first time the brass wasn’t sized enough and the second one was.
I had that thought and maybe though I put them all in a gauge and they seemed to be the same.
Make sure your brass fits also first in the chamber like on Wheeler’s other video.
I will try it on the up swing instead of just bolt close. but it seemed pretty dramatically different that I am not sure that this will totally solve it. That said I can “feel” my brass slightly as currently sized so maybe trying it sized back a bit more will help.Watch the video part way down titled: Finding Your Lands, it uses a similar method but I’ve found to be very accurate and repeatable. Your bolt will close on a jammed bullet. Feeling when opening is more consistent for me.
Videos | wheeleraccuracy
that’s helpful on its own. I do have some feel on the bolt handle with my brass as sized so I will probably bump that back a bit more now.
It’s due for a cleaning.
Here's what I do:
- Take the firing pin and the ejector out of your bolt.
- Insert stripped bolt into action and push it forward and the bolt should just drop closed totally loose.
- Take a a few pieces of fired, de-primed, but unsized brass and using a comparator, measure the distance from the base to shoulder and record the number (assuming they all measure the same).
- Now place a piece of fired brass into chamber and you will see that the bolt does not close on it's own. Don't try and close it yourself, you're just verifying that the bolt does not fall down on it's own with a fired, unsized case.
- Back your resizing die off and run a case through it so the shoulder is not getting pushed back at all, and then very slowly keep inching your sizing die down a half thousandth at a time and checking bolt drop after each increment. You will eventually begin to see the handle starting to drop on it's own. You will reach a point, where the bolt needs just the tiniest help to close, and then it will drop shut all by itself. When that happens, remove the case and take a new base to shoulder measurement and record it. This is the touch point for the shoulder of your case.
- Now move your resizing die so you push the shoulder back1-2 thousands more. Bolt should totally fall loose and on it's own at this point.
- You next do the same thing with your bullet to find the lands. Seat a bullet so that it is definitely way too long
- Insert in chamber and see if bolt falls closed on it's own (do not try and force bolt forwards while doing this, or you will possibly get bullet stuck in the lands. The bolt should not close at this time.
- Remove round and seat the bullet .005 deeper and try again. Repeat this process until bolt begins to drop slightly on it's own. At this point, start only seating .001 more at a time until bolt just barely drops on it's own, but not totally loose.
- Once you reach this point, the bolt closes with just the tiniest bit of help. Now you need to close the bolt, then slowly raise the bolt while gently pulling back on it at the same time. When it just opens, you will feel a slight "click" or "pop" as it opens. Seat the bullet .001 at a time and you will feel the pop get less and less until you reach the exact point where the bolt slowly opens with slight pulling to the rear and does not pop or click at all as it opens. The bolt should then drop closed completely loose with no drag. Measure the cartridge base to ogive with a comparator and this will be the current distance to the lands where the bullet just touches. (Keep in mind, if you change bullets or even lot #'s you will have to do this again with the new bullets. Case measurements should only need to be done once.
- Write measurement on outside of case and save as a sample
This is a good tool and I was just using it the other night on a Savage. While it’s fresh on my mind, the instructions say to use a bore guide to help drop the Bullet into the lands on the first step. If you do this and just turn the rifle down and let the bullet free-fall to the lands it will set to deep past touch, mine was 12 thousandths in doing this. You need to take rods and work the bullet from both ends to find that starting touch point before using the Sinclair measure tool.
There are old threads about this in the Archives but it may be referring to the Hornady tool, I didn’t take time to look it up.
CharlieNC
Gold $$ Contributor
The neck tension from your brass needs to be very loose, or the high force required to seat the bullet when closing the bolt will also jamb the bullet tight into the lands. If you simply pull the bullet and use the same piece of brass for this measurement multiple times, the neck will quickly loosen to obtain consistent results.
Dusty Stevens
Shiner
If you polish the bullet with steel wool then kinda rub oil or die wax on the bullet lightly itll help
Gargoyle
Finder Outer
Tooless method:
1. Size a piece of brass with shoulder bumped .002” from fired size.
2. Load a bullet a bit long in the case.
3. Remove bolt. Push the round into the chamber with a finger. Press hard.
4. Point muzzle upwards. If round doesn’t fall out the bullet is stuck in the rifling. Unstick with cleaning rod.
5. Seat bullet .002-003” and repeat until the round falls free by gravity.
6. You will know that you’re within .003” adjust bullet back out if you desire to find .001”
I can do this procedure in 2-3 mins.
1. Size a piece of brass with shoulder bumped .002” from fired size.
2. Load a bullet a bit long in the case.
3. Remove bolt. Push the round into the chamber with a finger. Press hard.
4. Point muzzle upwards. If round doesn’t fall out the bullet is stuck in the rifling. Unstick with cleaning rod.
5. Seat bullet .002-003” and repeat until the round falls free by gravity.
6. You will know that you’re within .003” adjust bullet back out if you desire to find .001”
I can do this procedure in 2-3 mins.
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The easiest and simplest method I found is using the Frankfort Arsenal Tool which essentially measures the distance from the muzzle to the bolt face then the distance from the muzzle to the bullet insert into the lands. You don't need to use any cases in this method thus eliminating any variables due to case fit. You don't need to strip the bolt either which can be cumbersome.
The nice aspect of this method is that you can quickly and easily measure several bullets thus obtain a range and average of measurements since variations in bullet ogive can often yield different results. Also, it's quite easy to check a new lot of bullets which is a good idea due to possible manufacturing variations in bullet ogives.
While the tool is relatively inexpensive, I made my own. All you need is two spacers that will insert into a cleaning rod and some means to lock them in place at the appropriate location. I purchased two nylon spacers a hardware store, drilled and tapped them and installed a nylon screw in each.
Helpful hints if you use this method:
1. A rod guide makes it easy to guide the bullet through the chamber into the lands. An appropriately sized wooden dowel can then be used to seat the bullet into the lands.
2. A jag that has the tip ground down to form a flat surface is essential to prevent the point on jag entering the firing pin hole thus giving you an erroneous reading.
3. Bolt must be cocked when locating the muzzle to bolt face distance.
The nice aspect of this method is that you can quickly and easily measure several bullets thus obtain a range and average of measurements since variations in bullet ogive can often yield different results. Also, it's quite easy to check a new lot of bullets which is a good idea due to possible manufacturing variations in bullet ogives.
While the tool is relatively inexpensive, I made my own. All you need is two spacers that will insert into a cleaning rod and some means to lock them in place at the appropriate location. I purchased two nylon spacers a hardware store, drilled and tapped them and installed a nylon screw in each.
Helpful hints if you use this method:
1. A rod guide makes it easy to guide the bullet through the chamber into the lands. An appropriately sized wooden dowel can then be used to seat the bullet into the lands.
2. A jag that has the tip ground down to form a flat surface is essential to prevent the point on jag entering the firing pin hole thus giving you an erroneous reading.
3. Bolt must be cocked when locating the muzzle to bolt face distance.
bucweet
Gold $$ Contributor
Make a dummy round. Seat the bullet long. Color the bullet that's exposed with a black magic marker, let dry. Insert the dummy round in the chamber. When you extract the round you should see marks on the bullet like small diamond shaped. If you have a 5 grove barrel there will be that many marks. Modify the seating depth accordingly. Repeat until you hardly notice the marks. That in my opinion is where it is contacting the lands.
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