Ogive OAL Seating depth, I'm going NUTS

[Buckoman]

So I talked to the fella that designed my 260 reamer. I'm trying to figure the actual length to the lands. So he give me this calculation of the Ogive at .262 diameter and the an OAL of 2.178 to Ogive should touch the lands at .262 diameter on the bullet. He specifically said .264-.002 to Ogive. This doesn't make sense as my Stoney Point 260rem gauge is 0.256 in diameter. Also I have a Bartlein barrel and the specs for that are 0.256 bore diameter. Does anyone have any idea what this fella is talking about with the whole .264-.002 Ogive calculation?

I have a copy of the reamer diagram. So what is the best way to calculate or measure OAL to Ogive.

thanks,

 

[RyeDaddy]

Re: Ogive OAL Seating depth, I'm going NUTS

The lands would be .256", the bore diameter is .264". If you were cutting the rifling in a barrel you would start with a .256" smooth bore diameter, and cut the grooves .003-.004" deep. Lands on both sides of the barrel (.004 + .004 = .008")would give you a finished diameter of .264" in the grooves. The lands being the part of the barrel that was not cut away during the rifling process, would still have a diameter of .256".

The Stoney point gauge is .256" because that's the diameter of the lands you're trying to seat to.. Your gunsmith is telling you he figured your OAL at a point on the ogive when the bullet is .262", right before the ogive becomes the shank(which will measure .264")

Does this answer your question?

 

[Longshot38]

Re: Ogive OAL Seating depth, I'm going NUTS

Why not just measure it? It will probably take less time then doing all the math based off the reamer.

 

[Buckoman]

Re: Ogive OAL Seating depth, I'm going NUTS

RhyDaddy,

That makes sense, but the stony point tool measures the Ogive about 12 thousandths different. So which one is correct? Measuring the bullet Ogive at .256 which is the diameter of the lands or the .262 right before the shank.

Longshot38,

I'm trying to measure it, but the issue is what Ogive point do I use to measure to. .256 or .262? My logic tells me to use the .256 which is what the stony point tool uses, but the machinist that built the reamer said .262, which doesn't seem to match my measurements. So which Ogive measurement is correct?

 

[Longshot38]

Re: Ogive OAL Seating depth, I'm going NUTS

The whole point is measuring the ogive is to see where the bullet comes in contact with the lands. Your stony point tool using your bullet will give you the best measurement. I'm assuming the .262 dimension you refer to I assuming is the grove diameter of your bore (but that seems odd or at least a tight bore). And your bullet generally doesn't make contact with the groves until it is being pushing down the bore.

 

[SSC]

Re: Ogive OAL Seating depth, I'm going NUTS

take your own using your tools.

 

[RyeDaddy]

Re: Ogive OAL Seating depth, I'm going NUTS

Maybe I'm not understanding the Stoney Point gauge. But at any rate, what you should do is take measurements with the exact bullet you're going to use.

What the gunsmith is saying is that at the OAL he quoted, the .262" section of the bullet will be touching the lands. I think you get that. Who cares what the Stony Point gauge says, or what it measures?

I think you're over-thinking this, just use the bullet you will be shooting, seat it until it touches the lands and measure with a Comparator to whatever point the Comparator measures on the bullet, whether it's .256" or .262" or whatever. Now load ammo and measure with the same Comparator at however far off of or into the lands you want to be. Makes sense, right?

 

[Fuzzball]

Re: Ogive OAL Seating depth, I'm going NUTS

Measure it, calculations may be interesting but the physical measurement is all that you can count on being accurate.

The point of bullet to lands contack is a given. However you choose to measure it will give different numbers but does not change where that contact occurs.

 

[Buckoman]

Re: Ogive OAL Seating depth, I'm going NUTS

The reason I'm going nuts is the fella said the stony point gauge is crap. He said to measure the bullet to .262 diameter. That's the ogive. Then he said to measure the OAL from the base of the cartridge brass 2.178" to ogive. I understand that, but this measurement is WAY off compared to the stony point measurement. Is it possible he meant .252 to ogive? The reason I"m going nuts is the two measurements are so far off from each other.

thank you guys for the responses

 

[Longshot38]

Re: Ogive OAL Seating depth, I'm going NUTS

As has already been stated. The point of using your stony point gauge is get an accurate measurement to the lands using your specific bullet. If you know what your doing with the tool it is capable of providing good data. There are a couple other ways to doing this but since you have the tool in hand you might as well use it. And I would much rather trust actual numbers produced with your firearm and your chamber then any mathematical equation.

 

[RyeDaddy]

Re: Ogive OAL Seating depth, I'm going NUTS

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Master_Blaster</div><div class="ubbcode-body">The reason I'm going nuts is the fella said the stony point gauge is crap. He said to measure the bullet to .262 diameter. That's the ogive. Then he said to measure the OAL from the base of the cartridge brass 2.178" to ogive. I understand that, but this measurement is WAY off compared to the stony point measurement. Is it possible he meant .252 to ogive? The reason I"m going nuts is the two measurements are so far off from each other </div></div>

I would say NO, it's not possible he meant .252", he meant .262" like he said. .252" would be a worthless number in this case, being that it'll never contact anything. If I'm understanding correctly, you're measuring length to the lands with two different diameter objects and are confused as to why you're getting two different readings? You would get a different reading with different bullets as well, as the difference in nose shape would mean a longer or shorter difference between the spot where it's .256, and where it's .262", so just measure with a real bullet and a comparator and stop driving yourself crazy. I know... Sometimes you just can't let things go, but trust us on this one.

 

[Fuzzball]

Re: Ogive OAL Seating depth, I'm going NUTS

"Is it possible he meant .252 to ogive? "

Not if he knows what an ogive is. The ogive is the entire curved section of a bullet from the body/shank to the meplat.