Bullet Seating Depth and suggest COL's

Pathfinder

Pathfinder

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Does anyone here follow the suggested COL's in the loading manuals or do you seat as far out as possible close to the lands for maximum accuracy .

Example: the suggested COL (Hornady 7th edition) for a 129 grain bullet for 6.5x55 is 2.905* (*cant remember exactly)

The bullet is quite long and I know I can probably seat out to Cartridge maximum COL (3.15) but Im not sure if Im looking at any pitfalls in doing this.

comments appreciated
 
I follow the books measurements all the time. They have tested and approved these lengths for each weight and length of projectile. Some guns like the longer 3" carts and mine functions best with a shorter version, so I went to a lighter bullet. Your gun will tell you the length it likes very quickly. Also the weight it wants to eat.
 
I seat close to published COL in most cases, and in anything that I want to shoot out of the magazine and have reliable feeding.

For target/BR work where I can load one round into the chamber by hand I stretch out to the best length for that particular rifle.

This means your ammo safe might have two or three different loads for some calibers, which isn't much of a problem
 
Well - Those bullets have a cannelure - I presume that corresponds to Hornady's suggested length. If you go longer , then you should check the bullet jump for each rifle you intend to use. For military calibers, there is a wide variation in leade profiles from rifle to rifle. Swede mausers are no exception, I've even found a substantial difference between M96's and M38's.
 
I load to the lands when I don't feed from the magazine. When I feed from the magazine, as a rule, I seat to the cannelure and crimp so as to uniform the round to round bullet pull weight. Crimping also prevents the bullet from being driven back into the case when the round at the bottom of the magazine has multiple rounds fired over it as can be the case with my .375 Ultra. For powerful rifles, I prefer crimping grooves over the more common style of cannelure. Loading to the cannelure also reduces any chambering problems should the ammunition be used in more than one rifle.
 
Forget COL. COL is absolutely meaningless in any discussion of accuracy. The ONLY reason COL exists is to ensure the loaded round fits in the magazine. Otherwise, it's absolutely useless. Why? Because COL is measured to the TIP of the bullet. But it's not the tip that engages the rifling. Different profile bullets will therefore have different COL's when loaded to the exact same point with respect to the rifling.

What you do is this. Load a dummy cartridge, and seat the bullet WAAAY out, as far as you can. See if you can close the bolt on it - don't force it. Seat it a bit further, and try again. Repeat, until the bolt closes with just a tiny amount of noticeable resistance. You're now seated just *into* the lands. That's where I generally find the best accuracy, though you could try seating the bullet a tiny bit deeper, to keep it out of the lands, if you like.
 
I generally seat using prosper's method, although I find I'm fairly regularly having to seat bullets back a bit in order for them to fit into the mag and cycle properly. I defintely like to keep my bullets as close to the lands as is workable however.
 
"Suggested" C.O.A.L ???

What I take from the manuals is that the COAL specified is what they used in their test barrel for that specific bullet & the data thereunder.

That doesn't neccessarily mean it's the recommended or suggested COAL for your gun ... but having said so, it should nevertheless fall withing SAAMI specs for that cartridge.
 
prosper said:
Forget COL. COL is absolutely meaningless in any discussion of accuracy. The ONLY reason COL exists is to ensure the loaded round fits in the magazine. Otherwise, it's absolutely useless. Why? Because COL is measured to the TIP of the bullet. But it's not the tip that engages the rifling. Different profile bullets will therefore have different COL's when loaded to the exact same point with respect to the rifling.
Click to expand...
It's all about the ogive.

One thing you should keep an eye on is damaged or deformed tips as they can throw the COL off too.
 
prosper said:
What you do is this. Load a dummy cartridge, and seat the bullet WAAAY out, as far as you can. See if you can close the bolt on it - don't force it. Seat it a bit further, and try again. Repeat, until the bolt closes with just a tiny amount of noticeable resistance. You're now seated just *into* the lands. That's where I generally find the best accuracy, though you could try seating the bullet a tiny bit deeper, to keep it out of the lands, if you like.
Click to expand...

Sounds like a plan, I already have a batch loaded at suggested col so my next one will have an adjusted length. It will be interesting to compare the groups.
 
I always fit the cartridge to the gun. If I go lower than the "book's" COL (which is rare), I consider accomodating that by reducing the load. I ignore crimp grooves, but try to keep at least enough bullet in the neck so that the entire neck is gripping the bullet.
 
For my target bolt guns I try to get them about 10 thou. into the lands. For semi auto's I keep them about 25 thou. off the lands or what the mag will allow me to seat bullet to. Having them set out as far as you can will give you no problems but if you go to far you end up with a bullet stuck in the lands and a action full of powder which is always a joy. The deeper you seat them in your case is where you start to raise pressures.
I have been loading for a K31 using 168 gr. match king's and am startled at how deep I have to seat these pills into the case to close action. So far I have them seated 110 thou. deeper than what manual recomends with no problems.
 
prosper said:
Forget COL. COL is absolutely meaningless in any discussion of accuracy. The ONLY reason COL exists is to ensure the loaded round fits in the magazine. Otherwise, it's absolutely useless. Why? Because COL is measured to the TIP of the bullet. But it's not the tip that engages the rifling. Different profile bullets will therefore have different COL's when loaded to the exact same point with respect to the rifling.

What you do is this. Load a dummy cartridge, and seat the bullet WAAAY out, as far as you can. See if you can close the bolt on it - don't force it. Seat it a bit further, and try again. Repeat, until the bolt closes with just a tiny amount of noticeable resistance. You're now seated just *into* the lands. That's where I generally find the best accuracy, though you could try seating the bullet a tiny bit deeper, to keep it out of the lands, if you like.
Click to expand...
X2 and much the same process I go through. In addition, I also coat or 'paint' the bullet with a felt pen to clearly see when the lands are being touched and when they are not. Usually, my best accuracy comes when I've minimized the freebore to 0.005" or less.
In a bolt action using the mag, the next C.O.L. determining factor is fitting & feeding from the mag.
On some of the bigger 'stuff', 338 & up and to be used for hunting, I crimp in the crimp groove or cannelure groove just to ensure the bullet doesn't move with the recoil.
In lever actions, such as my Marlins in 444 & 45-70, the determining factor for the C.O.L. is it must be short enough to allow ejection of a live round.
 
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I'm new to reloading.

I have Savage 110 in .22-250. I cut the point off of an old plastic jag and threaded it onto my cleaning rod. I dropped a bullet into the chamber and tapped on it (lightly) to make sure it was properly seated. I put the cleaning rod down the bore until it contacted the tip of the bullet and I made a mark on the rod. I removed the bullet, closed the bolt and made a second mark on the rod. I measure 2.510" between the marks.

So I take a spent case and seat a bullet (same type) to 2.510". It chambers fine.

I know the COL is a guideline, but my 2.510 is .160" more than the 2.350" published maximum. Holding up a bullet next to my dummy cartridge indicates that the bullet (a Hornady 55gr V-Max) is seated to the case neck.

Is it normal to be this far off from the spec?
 
looch said:
I'm new to reloading.

I have Savage 110 in .22-250. I cut the point off of an old plastic jag and threaded it onto my cleaning rod. I dropped a bullet into the chamber and tapped on it (lightly) to make sure it was properly seated. I put the cleaning rod down the bore until it contacted the tip of the bullet and I made a mark on the rod. I removed the bullet, closed the bolt and made a second mark on the rod. I measure 2.510" between the marks.

So I take a spent case and seat a bullet (same type) to 2.510". It chambers fine.

I know the COL is a guideline, but my 2.510 is .160" more than the 2.350" published maximum. Holding up a bullet next to my dummy cartridge indicates that the bullet (a Hornady 55gr V-Max) is seated to the case neck.

Is it normal to be this far off from the spec?
Click to expand...

That is one of the ways to find out where your bullet shoud be seated to touch the lands.

Yes that is normal. Try seating a bullet out far enough in a Tikka to touch the lands (verrrrrry long leade). Every gun is different, even if you have 2 of same make and model you could have 2 very different leades on them.
 
Apparently, I'm not yet done with this thread.

I think it was a post from H4831 that I read, suggesting to take an unprimed case and saw 2 slots vertically down the neck and then seat a bullet just into the mouth. I did this and chambered the round. I extracted and measured it to be 2.370", which .020" over the SAAMI spec, and .140" under my measured value (2.510") using the method described in my previous post.

Head scratching...

So I chamber my relieved dummy round, and then slip my cleaning rod down the barrel and make a mark. Turns out that the mark is exactly .140" away from my original mark that I made when using the bullet only. I did this to isolate the discrepancy to the front of the cartridge.

I seat a bullet into another deprimed case - this one unrelieved - to achieve an overall length of 2.500" (.010" less than my largest measured value, but .130" greater than my "relieved case" dimension). I chamber this round and the bolt closes without issue.

What the heck? Could it be that the resistance offered by my ejector was enough to seat the bullet further into the relieved case, prior to the bolt closing?

The $40-$50 bucks for one of them fancy OAL gauges is starting to look appealing. With my luck, though, I'd probably get a third, different measurement.
 
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