OAL and how to seat a distance from the lands - newbie q

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canoetrpr

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A couple questions on OAL:

1. I've noticed that cases from once fired factory ammunition are not exactly the same size in length. Those that are too long will be trimmed. Some might be a tiny bit shorter than proper case length. When you seat a bullet, should I expect that the OAL will vary slightly as a result - and this is OK? Or should I be constantly adjusting the die to get exactly the right OAL for consistent performance?

2. Been doing some research on Barnes TTSX bullets and the manufacturer suggests you should seat them 0.03 to 0.07 inches from the lands.

How does one go about doing this?

I'd appreciate any wisdom on these.
 
case length should not affect the OAL when you seat the bullet. Get a bullet comparator with a OAL gage and measure your bullet to the ogive instead of the cartridge base to the bullet tip. This will give you better OAL reading and it will help you determine jump or jam to the lands.
 
308BAR said:
case length should not affect the OAL when you seat the bullet. Get a bullet comparator with a OAL gage and measure your bullet to the ogive instead of the cartridge base to the bullet tip. This will give you better OAL reading and it will help you determine jump or jam to the lands.
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Guess I am missing something basic here. I thought OAL was the overall length of the cartridge from base to tip of bullet. Not so? Manuals seem to depict the OAL for each bullet type / weight.

I saw a video showing how to set up a dummy round. He somehow set the neck tension on a cartridge to be just enough so it would hold the bullet but allow it to move with some pressure. Then inserted it into the chamber and closed the bolt. That should have resulted in a cartridge with bullet seated jammed at the lands I am assuming.

A Lee collet die was used for this. I'd appreciate if someone could tell me how to just adjust the neck tension a bit without a collet die if possible.
 
Going back to your original Q the way i read it, you're talking about your brass being different lengths. The brass being shorter does not affect your OAL. It just affects how much bullet is held by the case neck i assume it's off a few thous. Your OAL is determined by the setting on your seating die stem.

The video you saw is an example of seating it to the ogive. A COAL could be taken to the tip but the tips on bullets are inconsistent at the best. The ogive will give you a more consistent OAL to your lands.

Neck tension could be adjusted on the Lee collet die by turning it deeper for more tension and higher for less tension. Follow the instructions if you still have it, if not go to Lee website to fund the instructions.
 
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308BAR said:
Going back to your original Q the way i read it, you're talking about your brass bring different lengths. The brass being shorter does not affect your OAL. It just affects how much bullet is held by the case neck i assume it's off a few thous. Your OAL is determined by the setting on your seating die stem.

The video you saw is an example of seating it to the ogive. A COAL could be taken to the tip but the tips on bullets are inconsistent at the best. The ogive will give you a more consistent OAL to your lands.

Neck tension could be adjusted on the Lee collet die by turning it deeper for more tension and higher for less tension. Follow the instructions if you still have it, if not go to Lee website to fund the instructions.
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Ok this is starting to make more sense now.

Unfortunately I do not have a Lee Collet die. Is there any other way to set the neck tension to only a slight amount so that it will hold the bullet but allow it to slide when pressure is applied?
 
Hornady OAL gage and modified case OR poor mans gage method FL size a case do not prime our charge, cut two slot into the neck with a dremel so that there is spring tension to hold the bullet, insert bullet into neck so that it sticks out, insert case with bullet into chamber, close bolt lightly, extract case carefully to not disturb bullet. Measure COAL repeat 5-10 times w/other bullets from same lot and average out to get your OAL to the lands. Good luck.
 
To add to 308BAR's comments...

Using the dremeled case neck, check 5-10 times with 1 bullet. Make notes. You now have your "touching the lands" length for that bullet. Try other bullets out from that batch. Once your happy with your documented touching the lands length, make a dummy round (no primer, no powder) and seat the bullet until it's. 03-.07" less than your touching the lands length. Note: the starting point I've seen most often is.02" off the lands. Ensure this dummy round chambers ok, fits the mag ok, cycles ok, etc. If all is well you now have a dummy round you can use to adjust your seating die from now on for this bullet, weight etc. Some guys repeat this for every bullet lot. I just do it for different bullet types, weights etc.

To clarify the point on the Hornady OAL comparator: it is used to compare cartridges on the ogive instead of measuring to the tips. Once you have a perfect length cartridge you can put the comparator on the calipers, zero, and now you're comparing lengths. Bullets from the same lot can have different lengths, ballistic tips or lead tips can be too soft or flexible for precise measurements and so on. Comparing from the ogive will save you countless hours beating your head on the reloading bench, trying to chase the perfect length to the tip.
 
Boy am I ever glad I asked this question. While I'm new at this, I am an "exactness" type of guy with a tad of OCD built in. It didn't suit me that I did not really quite follow how deep was the correct depth to seat a bullet.

I think I will bite the bullet (so to speak) and order up a Sinclair bullet OAL guage and bullet comparator. Having some trouble ordering from their website right now so will call them tomorrow.
 
canoetrpr said:
Boy am I ever glad I asked this question. While I'm new at this, I am an "exactness" type of guy with a tad of OCD built in. It didn't suit me that I did not really quite follow how deep was the correct depth to seat a bullet.

I think I will bite the bullet (so to speak) and order up a Sinclair bullet OAL guage and bullet comparator. Having some trouble ordering from their website right now so will call them tomorrow.
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Get them to quote the shipping to you, it might be a surprise.
 
Lets see, you can only afford one type of bullet, and one type of powder - and you are going to pick up some expensive Sinclair gear ....
There is a much easier way to ascertain the correct seating dept that doesn't involve jamming a dummy cartridge. And there is a simple way to maintain the same COL for bullets with soft points.
 
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