trouble calculating length to lands

martinbns

martinbns

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I am working with a new rifle in 7mm SAUM to find the OAL to the lands.

Normally I do a smoked bullet set lightly into a case, close the action to get a max OAL. In this case the necks are too tight to get a bullet in without using a die. First I tried new sized cases, then after going to the range today I tried it with both once fired sized and unsized cases, same thing.

When I measure the expander ball the widest part is .281, is this normal?

Any suggestions?
 
I take a fired case like yourself and pinch the neck a slight amount - just enough to grab the bullet. I don't even smoke the bullet. What I do is measure the bullet/case together on my OAL gauge (Stoney Point) and get an average reading from the Ogive. I usually do it about 10 times and it frequently is within .002-.003".
 
Martin, have you got the handloaders eraser, AKA the bullet puller? The impact green hammer type? Size your case and seat your bullet. Then knock out the bullet and seat the bullet back in the same case. Do that a couple of times and the neck tension will be lessened to where you can seat the bullet by closing the overlength dummy cartridge.
 
RickF said:
Martin, have you got the handloaders eraser, AKA the bullet puller? The impact green hammer type? Size your case and seat your bullet. Then knock out the bullet and seat the bullet back in the same case. Do that a couple of times and the neck tension will be lessened to where you can seat the bullet by closing the overlength dummy cartridge.
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I have the collet type, will they work?

On the campfire somebody said my brass is too thick or the chanber is too tight? Loaded rounds both factory and .030 shorter than Saami chambered fine.
 
Glock4ever said:
I take a fired case like yourself and pinch the neck a slight amount - just enough to grab the bullet. I don't even smoke the bullet. What I do is measure the bullet/case together on my OAL gauge (Stoney Point) and get an average reading from the Ogive. I usually do it about 10 times and it frequently is within .002-.003".
Click to expand...

The problem is I can't get the bullet into the case neck except with a die, it's too tight.
 
As long as it removes the bullet, you bet it will work. I should have noted that in the first place, it's just that I use the impact type and didn't stop to think that all I'm doing is removing a bullet from a sized case. How you get the bullet out is irrelevant, providing the neck is not damaged.

As far as " brass is too thick or the chamber is too tight?", who knows. Not enough information. The sizer die may be necking down more than you need for your chamber and brass, but that's not important for this to work. All you're doing by repeated seating/pulling is lessening the neck tension so you can start the bullet in the case and then be able to seat it with the camming action of the bolt action.
 
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martinbns said:
Any suggestions?
Click to expand...
Put a square faced jag on the end of your cleaning rod.

Close the bolt and run the cleaning rod down the barrel until the jab is sitting on the bolt face. Pull the cleaning rod out of the barrel slightly and run a black magic marker around the circumference of the cleaning rod. Now bottom the cleaning rod out against the bolt face, put a slim bladed knife or razor blade across the muzzle square, then spin the cleaning rod. You'll end up with a nice bright line around the rod.

Now open the bolt, drop a bullet into the chamber, and give it a very LIGHT tap on the base - just enough so that when you put the rifle muzzle up the bullet won't fall out.

Run the rod back into the barrel again, carefully letting it come to rest against the tip of the bullet. Now do the magic marker/thin knife blade thing again.

Retrieve your bullet and use your verniers to measure the distance between the two lines scribed on your cleaning rod. That measurement is the length of a loaded round using your sample bullet. Once your seating die is adjusted to give that overall length with that bullet, it is set up to seat bullets with that ogive to touch the lands.

You can buy some simple little accessories which will let you do the same thing a little bit easier, but the method above doesn't cost a penny, is very exact, and requires nothing but very simple, simple stuff you already have around the house.

Has been working for me for nearly 40 years now.
 
I use a fired case,and just barely dent the end of the case mouth or barely start it into a sizing die so it will just allow a bullet to be seated with your fingers if you push hard.I then start the bullet into the case with my fingers,and then chamber it in the gun so the bullet is forced into the case as I close the bolt.I take a few readings to make sure that I get consistent results.I also perform this with a few bullets to rule out bullet inconsistencies.
 
martinbns, I've found the 0000 steel wool method to be the easy way. Seat a bullet normally but too long. Keep seating it until you can chamber it. Clean that bullet with 0000 steel wool and rechamber it, note the marks made by the throat and or lands. Use the 0000 steel wool to clean up the bullet perfectly and the marks made are crystal clear, adjust the die until your marks are gone. I switched to this method after years of black markers, smoke, spilt necks, loose necks etc etc.

Edited to add, you may not see groove marks from the lands. Depending on the angle of the throat and the shape of the bullet, you may see a ring instead of groove marks. This is not a problem, it just means the bullet is contacting the barrel on the throat not the lands. Treat this the same as if you had land contact.
 
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Tape up a cleaning rod and put it in to the face of the (closed) bolt. Mark the tape and then remove the bolt and drop a bullet into the chamber. Hold it in place with a pencil and mark the tape again. Then measure between the two marks and use that length. Should get you right touching or just a coarse hair too long or short, depending on how well you measured and how sharp your marking pencil was.
 
Lots of suggestions here! What I do is take an empty case that has been fired in my rifle. Then I split the neck with a hacksaw blade, so as to allow easy insertion of whatever bullet I am loading. Make sure to smooth out any rough edges with sandpaper/steel wool. Just chamber the empty case with the bullet inserted and slowly eject the case. That should be the length of THAT PARTICULAR BULLET to the lands. From there, you can mic it and subtract how ever many though you want. Then, you can put that case aside and use it as a reference if you decide to try a different type/weight of bullet. That seems to work for me.
 
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Unless the beer is affecting my thinkling, it seems to me you have a match chamber, your brass should last a long time without resizing.
 
Wow, even fired cases? I guess the only option is to use the rod method. Basically, take a bullet and put it into the bore (from the breech) and take a rod and measure to the back of the bullet. Take out bullet and drop in a fired case and measure the rod the back of the case. The difference between the two will tell you how far out the bullet needs to sit. The Sinclair OAL gauge uses this technique - I may have screwed up the explanation but I am sure you can muddle your way through.
 
BigUglyMan said:
Tape up a cleaning rod and put it in to the face of the (closed) bolt. Mark the tape and then remove the bolt and drop a bullet into the chamber. Hold it in place with a pencil and mark the tape again. Then measure between the two marks and use that length. Should get you right touching or just a coarse hair too long or short, depending on how well you measured and how sharp your marking pencil was.
Click to expand...

+1. Simple, cheap, and it works. - dan
 
I did the cleaning rod thing, thanks guys.

It was just a surprise to me that in the 20-25 guns I had loaded for this had never been a problem before.
 
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