2.850 to the lands

sealhunter

sealhunter

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Can someone help clarify.

I have measured to the lands on my rifle (7mm-08) and it is 2.850

I was at the gunshop shooting the s**t and another customer told me that's impossible.

????

I know what it is...
why would he say that...?
 
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When I seat a bullet to the lands, I measure the overall length of the bullet. I would anticipated this is the measurement you obtained.

I would think there is something drastically wrong with your 7mm08 chamber if the lands are at 2.850" but the Cartridge Overall Length could be 2.850 and that would mean the lead is a little long. With a S/A Remington 700 you might find difficulty loading through the magazine.
 
Seat a flat-based bullet nose down in a case with a neck that has loose enough tension to allow the bullet to slide inside the neck under moderate pressure. Chamber the round in your rifle, then retrieve it and measure the length from the head of the cartridge to the base of the bullet, this should provide you with a realistic length to the lands. Repeat several times to ensure the bullet hasn't moved when you eject the round. Although a conventionally loaded 7-08 round might have an OAL of 2.85," the lands are closer to the case mouth than that.
 
Get a case(unsized) fired from your gun and dent the mouth so it will hold a bullet , Take a bullet and color it with a black marker . Put the bullet in the case just enough to hold the bullet and then chamber it in the gun . The dent from the case will scratch the marker off the bullet when chambered , pull the shell out of the gun and the bullet and push the bullet into the case untill you cant see the mark from the dent . that willl give you a rough Idea where your lands are .
Or buy the hornady OAL gage , they work great
 
I am thinking that with the bullet you have, something with a fairly sharp ogive, that your COAL very well could show you 2.850" Something fatter will give you less COAL to the lands.

The published OAL for that cartridge is 2.800".

Here is my findings on the last bullets I loaded:

162 A-max:
2.92" was hard into lands.
2.82" was touching.

150 Match King
2.77" hard into the lands
2.72" was just touching

So you can see that it depends alot on the bullet shape.

Like stated, fit a bullet in the neck with low tension far out of the case, and chamber it, extract it slowly.That gives a close OAL to where your lands are.

OR

What I sometimes do is similar to the above the above, I trying varying seating depths with marker on the bullet, chamber these rounds and you will see when the marker gets rubbed off of the bullet.This test I start shorter on COAL like say 2.700" then work my way into the lands with varying seating depths.

It works for me, don't go by my numbers because your chamber will be different.

Addition: Also, it is a good idea to use a bullet comparator with your caliper to determine length as the bullet tips are not always consistent.
 
I measured again this morning, I measured amany months ago and just assumed I was right in what I was doing.

I took a case, put a small dent in the neck, snugged the bullet, closed the bolt, I could feel the little bit of bush as it seated.

I took it out and COAL is 2.850

I have been loading my cartridges to an COAL of 2.775

Have I made some drastic error??????!!!!!!!

Advice?
 
Kelly Timoffee said:
I am thinking that with the bullet you have, something with a fairly sharp ogive, that your COAL very well could show you 2.850" Something fatter will give you less COAL to the lands.

The published OAL for that cartridge is 2.800".

Here is my findings on the last bullets I loaded:

162 A-max:
2.92" was hard into lands.
2.82" was touching.

150 Match King
2.77" hard into the lands
2.72" was just touching

So you can see that it depends alot on the bullet shape.

Like stated, fit a bullet in the neck with low tension far out of the case, and chamber it, extract it slowly.That gives a close OAL to where your lands are.

OR

What I sometimes do is similar to the above the above, I trying varying seating depths with marker on the bullet, chamber these rounds and you will see when the marker gets rubbed off of the bullet.This test I start shorter on COAL like say 2.700" then work my way into the lands with varying seating depths.

It works for me, don't go by my numbers because your chamber will be different.

Addition: Also, it is a good idea to use a bullet comparator with your caliper to determine length as the bullet tips are not always consistent.
Click to expand...

Wel I am using a 120 gr TSX , so that could be why. Even the 100 gr Speer HP's have me a similar COAL, but a little less,, I suspect it is due to the bullet choice..
 
Here's a good way to do it if you don't have a bullet comparator tool:

- Insert bullet (not a cartridge, just the bullet) into the chamber and tap it gently into the lands of the rifling using a cleaning rod.
- Insert the cleaning rod into the muzzle of the rifle and seat it gently against the tip of the bullet (use a solid tip with a flat face on the cleaning rod so the tip of the bullet butts up agains the rod, rather than going inside of the cleaning rod's female end). Mark the cleaning rod very precisely with a piece of masking tape at the muzzle of the rifle.
- Tap the bullet out with the rod. Insert the bolt into the rifle, and insert the cleaning rod deeper until it touches the bolt face. Mark the cleaning rod again with tape at the muzzle of the barrel.
- Measure the length between the two pieces of tape. This is your MAX COAL with THAT PARTICULAR bullet touching the lands. Then if you measure the distance on that specific bullet between the tip and the faint rifling marks on the ogive of the bullet, you'll know how far back the lands are. Subrtract this length from your MAX COAL to get your distance from bolt face to lands.
 
I took a case, put a small dent in the neck, snugged the bullet, closed the bolt, I could feel the little bit of bush as it seated.

I took it out and COAL is 2.850

I have been loading my cartridges to an COAL of 2.775

Have I made some drastic error??????!!!!!!!
Click to expand...

The method that you are using, works just fine.
 
sealhunter said:
I measured again this morning, I measured amany months ago and just assumed I was right in what I was doing.

I took a case, put a small dent in the neck, snugged the bullet, closed the bolt, I could feel the little bit of bush as it seated.

I took it out and COAL is 2.850

I have been loading my cartridges to an COAL of 2.775

Have I made some drastic error??????!!!!!!!

Advice?
Click to expand...

that sounds exactly what things should measure. SAAMI chambers always have some free-bore and 75 thou is typical.

have a look at this drawing, it may help you understand. The throat starts at around 2.180"

http://www.saami.org/PubResources/CC_Drawings/Rifle/7mm-08%20Remington.pdf
 
rgv said:
that sounds exactly what things should measure. SAAMI chambers always have some free-bore and 75 thou is typical.

have a look at this drawing, it may help you understand. The throat starts at around 2.180"

http://www.saami.org/PubResources/CC_Drawings/Rifle/7mm-08%20Remington.pdf
Click to expand...

This all what I thought and had learned, but when the guy said it was impossibel..well I questioned it all...
 
I have measured to the lands on my rifle (7mm-08) and it is 2.850

If this is what you said to him then "he" is right.

What you meant to say was, "I seated a bullet to the lands the the OAL is 2.850.

Perhaps the following will clarify:

I know you believe you understand what you think I said but I am not sure you realize that what you heard is not what I meant.
 
It's never worked very well for me. The bullet almost assuredly gets pulled out slightly by the friction from the rifling when I extract the cartridge...
Click to expand...

I have been using this method for the past 30+ years,and it usually works fine.However,with certain rifle/bullet combinations, there can be issues.When there is an issue that prevents consistent measurements, using this method, I load a dummy cartridge that is so long that the bolt can't be closed, then seat the bullet .005" deeper at a time,until I can just close the bolt with some slight resistance, compared to an empty case.Once you can close the bolt with some very slight resistance, you can reduce those increments to .001" at a time, until the resistance disappears entirely.
 
Buy an ogive nut with several holes in it for different calibres. A gun shop will call it a nut guage. If you're handy you can make your own. The nice thing about the commercial nut guage is that the holes are drilled on center and the edges have been trimmed.

Load an inert case with a partially sized neck, with the calibre of choice. Don't size the whole neck.

Insert the inert round into your chamber and close the bolt on it. You will find it a bit difficult as you will be pushing the bullet into the case neck.

Extract the cartridge with the bullet pushed back and using the nut gauge, measure from the base of the bullet to the opposite end of the gauge.

This measurement will give you the distance from the bolt face to the leade of the lands in the chamber.

When you set up your seating die, unscrew the seating spud until the bullet won't touch it when your ram is at top dead center and of course the base of the bullet is held in place by a shell head holder.

Screw the spud down, until it just touches the bullet but doesn't push it any further into the case.

Next, blacken the the bullet with felt marker. and insert it into the chamber again. This should leave some bright marks where the rifling engages the bullets. Take another measurement with the nut gauge in place.

Go back to your seating die and and turn in your spud so that your bullet is as far away from the leade as you want. One full turn of the screw should be about .050 inches. Depending on the type of die you have, it may vary a bit.

Make a small adjustment and run the bullet into seater and measure it, using the same hole on the nut each time.

Repeat this operation, until you have the desired distance from the leades. Keep in mind, usually the closer to the leades the bullet is seated, the more accurate it is.

This is the only sure way to measure OAL. Bullets often have different lengths, especially when they are swaged over a lead core and have a protruding tip. It is almost impossible to measure OAL, by measuring the tip of the bullet.

You can eliminate the nut if you must by just using the blackened bullet and adjusting the spud bolt until the bullet is no longer marked by the leades when inserted into the chamber.
 
sealhunter said:
Can someone help clarify.

I have measured to the lands on my rifle (7mm-08) and it is 2.850

I was at the gunshop shooting the s**t and another customer told me that's impossible.

????

I know what it is...
why would he say that...?
Click to expand...

After reading the posts that followed your original, I don't think there is any problem with the process you use. But becasue you said that the distance to the lands was 2.85" rather than the COAL, that is what resulted in a misunderstanding with the fellow in the gunshop. Carry on you're doing fine.
 
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