Is it alright for a bullet to be touching the lands to shoot?

[manitou210]

Stoop you need to measure ogive on all your bullets and sort all bullets. Tubbs claims
.3000 differance in ogive in one batch and others in batches, Hoover claims to sort in
.2000
from base to ogive. Just did 500 224 Bergers VLD they where up to .2400 differances lots of piles of bullets. would surprise me that Hornadys would be more.

 

[AKD]

Well I just ordered the Hornady LNL oal gauge with a .308 shell and a Hornady comparator with 6 inserts. Is this all I need?

Yup. You will be well settup with them.

I use the hornady oal guage as well and trust me it's a nice tool. I've tried em all and this is the only real way to get exact #'s on how far your lands are for that bullet.

 

[stoop14]

Ya but it won't be here for a few weeks I hope the guys 2.934 will shoot good in the mean time

 

[Obtunded]

Actually, you can bypass the need for the OALG for finding the lands, and for this use ONE bullet.

Take a fired casing and squeeze the case mouth slightly - and I mean slightly - out of round with a pair of pliers. Take a bullet, and push it into the case. It should be snug enough that it stays in place, yet loose enough that you can slide the bullet back and forth in the case with two fingers and moderate pressure....

Take that combination and with the bullet pushed very slightly into the case, chamber it and close the bolt.

Now extract this "dummy round, being very carefull to hold the cartridge straight - don't let the extractor/ejector bend this over to the right as if to eject the casing.

Very gently measure the case-base-to-bullet-tip measurement.

Repeat this several times with the same case and the same bullet and record the length. If there are huge variation in numbers, your case mouth is likely too loose. Of course the ultimate evidence of a loose neck is the bullet staying behind in the rifling.

Once you have a good consistent measurement, take that same bullet and load it into a neck-sized (or FL sized brass) case, BUT start out with the bullet seating too long. Measure that dummy round and keep tweaking the seating depth of the die until the OAL matches what you got with the warped case and bullet.

This is very close your to-the-lands measurement. Because you have used the same bullet, the ogive of that bullet has set the die to give you consistnet results. If you are using non-VLD (Such as Palma bullets) or Sierra bullets. I would try tuning a load at this depth and then work your way back shorter in 5 thou increments.

The secret to success is finding a good tension on that bullet for doing the measurement. You end up using the seating stem of the die as a quasi comparator.

I have a few fancy schmancy gizmos for finding the lands, and this method is every bit as accurate. The secret again, is the right neck tension.

Good Luck

 

[Bolivar]

I use basically the same method, except I start with a FL sized case. I seat a bullet in deeply the stretch the neck, then pull that bullet. Now the neck is opened enough to hold the bullet but it can still be pushed in with mild pressure.

From here I proceed as the above post. As a check, after you determine the distance to the lands with this method, smoke the bullet and insert the cartridge to verify if there are rifling marks.

 

[AKD]

Trust me, your going to be happy with ur oal guage.

 

[zimbu]

I'm not good enough to tell the difference, but I believe I heard somewhere that it's actually a little more consistent to be just off the lands. This way if one is a slight bit longer, maybe due to brass varience or bullet or maybe you just didn't over cam. You'll always be "just off the lands" and have a more consistent pressure curve.

Maybe I'm making stuff up and the really hardcore guys will say that there is no varience in their ammo.

Not the first time I've heard this and I agree. IMHO bullets should be jumped or jammed depending on the application or whatever works best. There is no way to produce ammo consistently enough to guarantee that every cartridge places the bullet "at" the lands. Even if there were, throat erosion would throw a monkey wrench into that.
If loaded "at" the lands the bullet will either be touching the lands or it won't. Barrel vibrations start when the bullet starts to move, so it stands to reason that the barrel will vibrate differently if the bullet starts moving while already engaged in the lands than it will if the bullet hits the lands when already in motion. Maybe not enough to make any difference, but personlly I consider anything closer than .010 to the end of the lands a sort of "no man's land" and avoid it.

 

[Obtunded]

Not the first time I've heard this and I agree. IMHO bullets should be jumped or jammed depending on the application or whatever works best. There is no way to produce ammo consistently enough to guarantee that every cartridge places the bullet "at" the lands. Even if there were, throat erosion would throw a monkey wrench into that.
If loaded "at" the lands the bullet will either be touching the lands or it won't. Barrel vibrations start when the bullet starts to move, so it stands to reason that the barrel will vibrate differently if the bullet starts moving while already engaged in the lands than it will if the bullet hits the lands when already in motion. Maybe not enough to make any difference, but personlly I consider anything closer than .010 to the end of the lands a sort of "no man's land" and avoid it.

You should use what your gun tells you to use, not what you or anyone else happens to "believe"!

It depends on many factors and not all guns or bullets are the same. I use mostly very low drag match bullets in custom barrels with custom chambers. After match reloading tens of thousands of these rounds, after load tuning for many dozens of different combinations in one cartridge alone, I know when working with a VLD bullet, I emperically start 15 thou into the rifling past first land contact.

How that VLD bullet enters the rifling affects its accuracy, and the reality is a difference of merely 5/1000ths of an inch can be the difference between sub quarter minute and plus half minute accuracy.

Tangent ogive bullets like you find in all factory "match" ammo, and in Lapua and Sierra match bullets uses a much less seating depth sensitive style of ogive. Berger has started manufacturing "Hybrid" bullets that incorporate a tangent ogive followed by a secant profile because they KNOW that these two styles of bullets have very different seating dept requirements.

As with everything in shooting, there are exceptions. If you want to speak with experts, check with CGN Paririeguy, CyaN1de, Shockman, Bob Pastor, Inspector, Scout, Terry Perkins, ONT001, rpollock, MPWolf. These are Canadian expert international long range shooters that are high masters in their trade.