seating depth question

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bruno

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for my 270, my manual says to seat the bullet for a col of 3.300"
i,ve got mine at 2.252"
i,ve got the room to make them longer, but this is the length i used when i worked up the load.
i,ve reached max grains with no pressure signs, but am 175 fps slower than the manual states. the manual used a 26" bbl and mine is 22"
does that sound correct? or is it too much of a difference?
also, is there anything to worry about with seating a bullet to deep, provided the load is worked up that way?
 
Generally, here are the considerations for seating depth in a hunting rifle:

It can't be so long it won't fit in the mag. I like to see about a tenth of an inch clearance from the bullet tip to the box.

It can't engage the rifling. You don't want a bullet to pullout, stick in the barrel and put the rifle out of commission. I like to see at least 20 thou off the rifling.

The bullet shank should engage at least half the neck.

Because of differences in chamber throats, magazine lengths and bullet lenght any one of these critera could be the one that determines your COAL. If you have room to move the bullet, go for it. You might then be able to add another half grain of powder, but the velocity you have sounds about right. But seating it out might improve accuracy.
 
It might be just me but 1.048" difference in COL from published data seems like a lot.

Are you measuring base of case to tip of bullet or using a Comparator?
 
Bruno, if you worked up the load, then you should be fine. What was the reason for the length you were seating? If possible, seat close to the rifling as GANDERITE suggested, and work up the load again. You may get much better results, or may not. There's a wild card factor in reloading. Good luck.
 
sorry, measurement should have been 3.252
this is a load i worked up a few years ago, and i don't remember the reason for this length. but i've got a load that will shoot quite well abaout 1.1" 5 shots.
this is a completly factory savage, so i don't expect much better.
 
COAL is an almost arbitrary measurement and is only a reflective guideline. What counts is where the ogive of the bullet sits in relation to the lands of the barrel. The problem with a factory barrel and hunting bullets, is that you may not have the tolerances to get the bullets in the spot where you will get the best possible accuracy and still feed from a magazine.

If you are magazine feeding then you will need to work within the limitations of the magazine; factory throats are often cut very long so seating depth for best accuacy may actually be much longer than the mag will allow and frankly, the bullet length too.

If you can get 1" groups from your hunting rifle, I would say you are doing really well. If you want to fart around and try for tighter groups, I would say seat the bullets out closer to the lands, but you will need to figure out where they are and that is a whole other chapter :)
 
i did figure this out with this bullet a couple of years ago, but i don't remember what it was. i do remember that it was still able to fit in the mag though.
I think i'll leave this as is, and wait until i can build a rifle for accuracy.
 
Don't want to hijack the thread, but I'm looking at the much same thing, I have a Tikka in 22-250, the reloading manual calls for a max. OAL of 2.350, the factory Winchester 55gr is 2.310, but my measurement using a 55gr Nosler Ballistic tip allows for an OAL of 2.451. This seems like a long way over the max. stated in the relaoding manual????
 
tripalm said:
Don't want to hijack the thread, but I'm looking at the much same thing, I have a Tikka in 22-250, the reloading manual calls for a max. OAL of 2.350, the factory Winchester 55gr is 2.310, but my measurement using a 55gr Nosler Ballistic tip allows for an OAL of 2.451. This seems like a long way over the max. stated in the relaoding manual????
Click to expand...

If the 2.451 fits in your mag, feeds well and is accurate then I would stick with that.

Tikka's have a fairly long throat on them, I had a hard time leaving enough bullet in the case while reaching the lands in my Tikka T3 .223.
In my XR-100 I could not reach the lands with my 22-250 loads so I loaded whatever shot best for seating depth.
 
The COL published in the book is meant to tell you what they used and what was max for them. As my post aboves states, thre are 3 criteria that determine the max four YOUR rifle - and it could be any one of the 3.

For starters, seat the first round really long and then seat it back in steps until it has good clearance in the mag. Then chamber it and see if it comes out with a set of markds around the bullet from the rifling. If no, then you now have your MAX COL - determined by the mag.

The manufacturers have a big variation in throat depth. Remington are so deepth that the round will fit the mag it won't even be close to the rifling.

I do a lot of shooting and find throat eriosion in the order of ten thou a year - so my OAl keeps changing for each rifles.

The reason I suggest at least 20 thou off the rifling is that production bullets have a variarion from bullet to bullet in terms of the distance from bullet tip to ogive shoulder (where the rifling engages) If you are 10 thou off, the odd bullet would touch - giving flyers.

Benchrest shooters use custom bullets, a different story.
 
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