C.o.l

[badbrass]

If you don't have a ogive gauge? does the oal matter, I know it cannot be against the lands. and the danger with that, but taking the COL of a finished round and keeping all the rounds the same does it help, some say yes and some say no? Thanks.

 

[Gibbs505]

What kind of round are you talking about?
Some rounds, COL matters a lot! Others, withind limits, not so much.

 

[badbrass]

Just a hunting round !

 

[stubblejumper]

I don't have any special tools for measuring the ogive,but that doesn't mean that I have no way to measure how far I am seating the bullets off of the lands.

 

[1/2 MOA]

Yes COL matters and having it consistent matters. A bullet comparator and a dial or digital caliper gives you a measurement from the ogive of your bullet to the base of your case. You can still get a COL measurement with out a comparator you just need a dial or digital caliper to measure from the tip of your bullet to the base of your case. This is the measurement that is in your reloading manual under COL. Having this COL measurement and keeping all your rounds the same length will make a big difference in the accuracy you achieve. Making a rounds OAL longer or shorter by as little as 15 thou can mean the difference between a 3" five shot group at 100m and a 1/2" 5 shot group at 100m.

 

[CyaN1de]

Since your bullet seater does not use the tip of the bullet to seat, once it is set, your COL will be the same every time with that particular bullet.

If you change bullet brand or type....your COL will change and you will have to correct the seater die to compensate.

If you measure off the tip of your bullets you will constantly be trying to adjust your seater die to match the other rounds.....the tip to base measurement on bullets can be as far as .020 different on bullets measured from the same box. Therefore, measuring to the tip of the bullet is futile and will tell you nothing unless you used that ONE single bullet to determine your length to the lands to set your die.

Find yourself something to put between the caliper and the bullet tip such as a smaller diameter pistol case, 22 caliber case or something that will sit closer to the ogive of the bullet and use that to determine whether your rounds are the same.

Load a dummy round long and test it in your gun, chances are that if it is a mag fed rifle, your Max OAL will be determined by the magazine and not the lands.

 

[bearhunter]

There are two things that you can do.

1) Buy a nut gauge. A nut gauge is a hexagonaly shaped piece of metal drilled on each flat with a different sized hole, to accomodate different diameter bullets. The loaded cartridge is measued from the base to the top side of the nut gauge. This will give you a consistant measurement of each ogive shape you load.

2) Take a felt marker and color the bullet and insert it into the rifle (NO PRIMER of course and seated out long), close the bolt and check the marks of the lands on the bullet. Then set your seating spud down a bit and repeat the process. It may take several attempts but you will reach a point where the bullet will be seated the desired distance from the lands.

The threads on the spud are a finite distance from tip to tip. Figure out the lead of the thread, say 16 threads per inch equals .062 inches per turn. Then figure out how many turns are needed to adjust the spud to the desired depth.

Another VERY IMPORTANT thing, KEEP RECORDS OF EVERYTHING YOU DO. Then if you're memory fails you, as mine does often, you can always go back to square one.

 

[badbrass]

If you measure off the tip of your bullets you will constantly be trying to adjust your seater die to match the other rounds.....the tip to base measurement on bullets can be as far as .020 different on bullets measured from the same box. Therefore, measuring to the tip of the bullet is futile and will tell you nothing unless you used that ONE single bullet to determine your length to the lands to set your die.

That's what I was talking about!

 

[badbrass]

Find yourself something to put between the caliper and the bullet tip such as a smaller diameter pistol case, 22 caliber case or something that will sit closer to the ogive of the bullet and use that to determine whether your rounds are the same.

I will try that! Thanks Guys!

 

[Al-Sway]

If you are loading hunting rounds, the COL does not matter very much. The first criterion is that the cartridge fits in your magazine and cycles through the action. Then, if there is any room, you could play with the COL. If you are a beginner, or keeping it very simple with a few hunting rounds, you don't need fancy gauges. If you want, make up a dummy cartridge (sized, deprimed, no powder, with a bullet seated), to your preferred length and use that to set your seating die for the next batch. It is good as long as you use the same bullets.
COL really matters for straight wall cases, whether pistol or rifle (ie .45-70) as a small change in seating depth will drastically change the pressue level. For most bottleneck cases (.30-30, .308, .270, etc), a small change in COL will not affect the pressure, as long as you are close to factory specifications.