Measuring Lands

[charliegrba]

New to Forum and Reloading with a question. I purchased a 6.5mm rifle and measured the lands after cleaning and prior to oiling the barrel. After numerous measurements with a Hornady OAL gauge 2.345" was my result. I have since passed 400 rounds through the barrel. Today after cleaning my measurement is 2.348" Assuming my measurements were correct is it normal for the distance to the lands to increase .003" after 400 firings?
Thanks in advance for any replies.
Charlie

 

[ngb1787]

Use the Alex Wheeler method to measure, more accurate, repeats every time.
https://www.wheeleraccuracy.com/videos

 

[mikecr]

How would anyone guess on erosion without knowing what 6.5mm rifle cartridge you're shooting?

 

[charliegrba]

Thank you for the link to the video, it was very informative. I understand the distance to the lands will change with usage. Does anyone have a ballpark figure of the expected change after a certain number of firings?

 

[charliegrba]

Sorry, it's a remington 260I

 

[Ned Ludd]

New to Forum and Reloading with a question. I purchased a 6.5mm rifle and measured the lands after cleaning and prior to oiling the barrel. After numerous measurements with a Hornady OAL gauge 2.345" was my result. I have since passed 400 rounds through the barrel. Today after cleaning my measurement is 2.348" Assuming my measurements were correct is it normal for the distance to the lands to increase .003" after 400 firings?
Thanks in advance for any replies.
Charlie

The rate of land erosion can change depending on caliber, powder used, bullet weight, rate of fire, and probably several other factors. It's not a "constant". Your measurement of .003" per 400 rounds is probably within the expected rate for land erosion, but may also be subject to the error inherent in the measurement approach.

Try measuring the distance to touching using several bullets, and repeat the measurement with the same set of bullets on more than one separate occasion, while the round count still remains the same. You will then have a pretty good idea how much variance in measurement you can typically expect in your hands.

 

[Dusty Stevens]

Use the stripped bolt method. Put that gage thing in the drawer its not needed. And are we talking only .003 after 400rds? Id say thats fairly good

 

[charliegrba]

Thanks guys for the excellent responses. This was my first question asked on the forum and your information was greatly appreciated.
I'm going to try the Wheeler (stripped bolt) method as suggested and compare my results. Thanks again.

 

[eric n]

Thanks guys for the excellent responses. This was my first question asked on the forum and your information was greatly appreciated.
I'm going to try the Wheeler (stripped bolt) method as suggested and compare my results. Thanks again.

You may get false readings if the carbon isn’t cleaned out of the throat before measuring.
I have never owned a 6.5 so I may be completely off base here but that rate of erosion is in .223 territory. I’d be a little suspect of carbon build up.

 

[charliegrba]

Thanks, I took that into consideration and both measurements were taken after a detailed cleaning and before oiling the barrel.
Judging from the responses it sounds like there is a greater probability of error with the measurements than change due to erosion.
I will accomplish both methods and add to my notes. Thanks

 

[Texas10]

IMOP a better way to use the Hornaday OAL gage is to neck size the modified cartridge and seat a bullet long. Slide it up the chamber with a firm push and retract. Any tendency to stick upon retraction indicates bullet in the lands. Keep seating deeper until you find the point where there is barely any tendency to "stick" upon retraction. But before doing this test, slide the case without a bullet in the chamber to make sure there is no tendency to stick as that will give false indications. This will give you very consistent measurements.

Once you've mastered this technique you'll quickly decide to use your own fire formed brass and drill and tap to fit a 3 piece cleaning rod for instance, or any threaded push rod you happen to have. You don't have to own a custom action to use this technique, it'll work on any bolt action.

When measuring bores smaller than 30 cal, it is particularly important to make sure the throat is free of carbon, especially with 22 cal bores like the 223 where a little carbon can make a big difference in feel upon retraction. If you don't own a bore scope, at least buy an endoscope for $35 that lets you see into the chamber and leade and confirm your cleaning methods.

 

[T-shooter]

It's possible depending on the load. Whatever method you use to measure, it should be 100% repeatable. Measure it several times each time.

 

[charliegrba]

Result are in after repeatedly using the Hornady OAL gauge and the Wheeler method mentioned above to measure distance to the lands.
Starting with the Hornady gauge distance to the lands measured 2.348", with the Wheeler method 2.349". Difference in readings of .001"
Thank you all for your inputs, I have had a great afternoon at home measuring distance to the lands. Ha!

 

[Dusty Stevens]

Now do those same measurements tomorrow numerous times and see what you get and remember the cost associated with each method

 

[charliegrba]

Dusty, you must be referring this Rabbit Hole thing people just told me about. Sounds like I'm already in up to my neck however that leaves a few dollars for some fast food.
I did not receive any guidance as I ventured into re-loading, only what I read on the Internet. (prior to this forum) Thought I made educated choices of the products purchased however
the light is starting to shine bright as in your example above.

 

[Dusty Stevens]

Dusty, you must be referring this Rabbit Hole thing people just told me about. Sounds like I'm already in up to my neck however that leaves a few dollars for some fast food.
I did not receive any guidance as I ventured into re-loading, only what I read on the Internet. (prior to this forum) Thought I made educated choices of the products purchased however
the light is starting to shine bright as in your example above.

All you have to do is ask any question on here or do a search. We can save you money but for sure spend it too.

 

[6MMsteve]

yep I completely changed ething on reloading and shooting when joining this great site...it saves you headaches but no money..and there is a bunch of great peeps on here that will help you with anything reloading and shooting.optics.rests, food cars axes and such

 

[tmwinds]

Did you use the same bullet for both measurements? The bullet ogive can vary greatly from one lot to another which will cause a false reading.

I also doubt that you can consistently measure .003 erosion with a Stoney Point gauge.
I can't, just to many variables.

 

[charliegrba]

Yes used same bullet, I kept it stored with the Hornady OAL gauge. I also tried a different bullet from the same lot. I'm more than happy with my measurements especially since I used two different methods and had the same results. (OAL length gauge and Wheeler method)
This thread started off with a question about expected erosion of the lands. It turned to accurately measuring the lands and I benefited greatly from all the responses. I now have more confidence that I'm actually seating the bullet .007" into the lands. But one never knows. Ha!

 

[Dusty Stevens]

Yes used same bullet, I kept it stored with the Hornady OAL gauge. I also tried a different bullet from the same lot. I'm more than happy with my measurements especially since I used two different methods and had the same results. (OAL length gauge and Wheeler method)
This thread started off with a question about expected erosion of the lands. It turned to accurately measuring the lands and I benefited greatly from all the responses. I now have more confidence that I'm actually seating the bullet .007" into the lands. But one never knows. Ha!

Measurements from and into the lands really dont matter you just need to be able to repeat a measurement. What you measure on one box of bullets will be different on the next too so its just an arbitrary number. You only need to be able to say with this bullet, this measurement on my tool is .010 off and on this day with this barrel and this box of bullets it shot best at .013 off. I hope tomorrow is the same