Seating Depth Into The Case

[rockywlw]

I'm loading some 22-250 Hornady cases with a 52 gr. Sierra HPBT. I checked my Base to Ogive but if I seat them .020 off the lands I'm going to be very shallow in the case. I'm thinking to more than 1/16th inch. That's pretty shallow isn't it? The rifle in a Remington 700 varmint . Thanks

 

[mdmp5]

Are you asking if you should be concerned about jumping? Answer is no because not every bullet can be seated long. Good example is the 155 palma. Unless you have a custom rifle with a chamber cut with very little freebore, you are gonna jump some with a bullet as small as a 52

 

[rockywlw]

Not jumping, how much is in the case. If I set .020 from the lands I will only have .090 - .100 of the bullet holding in the case. I'm not counting the BT part as that will not be touching the case. Is that enough to retain the bullet?

 

[mdmp5]

I’m saying don’t worry about getting close to the lands if it’s compromising bearing surface in the neck. Seat it a little deeper if necessary. But .1 seems like enough

 

[Deleted member 10043]

Minimum seating =1 caliber.

 

[buffybuster]

Are you going to mag feed or single load? That small amount would be OK single fed, but not for mag feeding.

 

[Codiekfx400]

Seat the bullet at least .224” into the case like Culpeper said. If you can not find a decent load by seating the bullet properly then I would switch to a different bullet.

 

[mdmp5]

Looking at it on a caliper afterwards, .1 is probably just getting by for a 223 but for 22-250 I’d want to go a bit deeper.

 

[pitdog85]

Not jumping, how much is in the case. If I set .020 from the lands I will only have .090 - .100 of the bullet holding in the case. I'm not counting the BT part as that will not be touching the case. Is that enough to retain the bullet?

I have bullets seated a little less that half the bullet diameter in my 6.5 around .130 I believe and they are fine I do single feed though.

 

[MarinePMI]

One caliber depth minimum has been a rule of thumb for God knows how long (as stated above). It helps maintain concentricity and reduce run out if the bullet has enough support on the bearing surface by the case neck.

The other rule of thumb is to never seat a bullet deeper than the shoulder (or into the powder column as it were). It can cause weird ignition as well as inconsistent pressure signs (aka "slugging the bore", which I believe is a phrase Mann or Pope coined back in the late 1800's/early 1900's). The theory ran that some compacted powder in the case could be wedged against the bullet as it began to move, and essentially increasing the weight of the object being accelerated, dramatically raising pressures. Since the amount of powder being pushed was variable, the observed results were erratic pressure signs with identical powder charges (some were fine, others were popping primers with the same powder charge). It's also why deeply cupped bullet bases are avoided (or at least that was what I was told by one Chief Engineer, when were talking about this very subject).

Another thing is that bullets can creep, when loaded into the powder column. Resulting in cases with bullets at slightly different depths after sitting over night. The powder basically pushes against the base of the bullet, and based on neck tension, will push them out ever so much. If annealing is not exact, then some will move more than others.

Okay, enough rambling on my part...

 

[mdmp5]

One caliber depth minimum has been a rule of thumb for God knows how long (as stated above). It helps maintain concentricity and reduce run out if the bullet has enough support on the bearing surface by the case neck.

The other rule of thumb is to never seat a bullet deeper than the shoulder (or into the powder column as it were). It can cause weird ignition as well as inconsistent pressure signs (aka "slugging the bore", which I believe is a phrase Mann or Pope coined back in the late 1800's/early 1900's). The theory ran that some compacted powder in the case could be wedged against the bullet as it began to move, and essentially increasing the weight of the object being accelerated, dramatically raising pressures. Since the amount of powder being pushed was variable, the observed results were erratic pressure signs with identical powder charges (some were fine, others were popping primers with the same powder charge). It's also why deeply cupped bullet bases are avoided (or at least that was what I was told by one Chief Engineer, when were talking about this very subject).

Another thing is that bullets can creep, when loaded into the powder column. Resulting in cases with bullets at slightly different depths after sitting over night. The powder basically pushes against the base of the bullet, and based on neck tension, will push them out ever so much. If annealing is not exact, then some will move more than others.

Okay, enough rambling on my part...

But doesn’t that pretty much say that you should never run a compressed load? Also, it’s near impossible to seat a 77 gr bullet at mag length in an AR without the base of the bullet extending well past the neck

 

[MarinePMI]

No, not necessarily. Just that you shouldn't seat a bullet into a case that doesn't have a full case capacity. With a compressed load, all the bullets are receiving the same (roughly) pressure against the base (and generally seated no where near the shoulder of the case). With a load that is 85% or 90% case capacity, and then seating the bullet into the powder column, some powder moves as the bullet is seated, and some gets pinched between the bullet base and the internal case head. How much is pinched is random; hence, weird ignition, varying seating depths and thereby various degrees of bullet pull/neck tension.

To be clear, this not gospel, but mainly theory, based on observation. Call it "best practices" based on cause and effect. "Why" still remains to be definitively proven, one way or the other.

 

[spife7980]

I don’t think the caliber width equals depth thing has any merit.
Seat where you need to; old rule of thumb be damned.

 

[rockywlw]

Thanks for all the advice and good reading. I love how a question brings out all kinds of ideas. I guess I will back off a little and start testing. Thanks

 

[ruebarb]

Testing is everything. I'm at 0.030 off the lands,
in 6.5 and and still seating deeper in testing, results keep improving

 

[mdmp5]

I don’t think the caliber width equals depth thing has any merit.
Seat where you need to; old rule of thumb be damned.


View attachment 6922846

Where did you dig that up spife?

 

[spife7980]

Where did you dig that up spife?

http://bulletin.accurateshooter.com/2015/11/wildcat-with-almost-no-neck-stan-wares-wicked-wolfpup/

 

[mdmp5]

Sick. Completely out of the box

 

[Milo 2.5]

I don’t think the caliber width equals depth thing has any merit.
Seat where you need to; old rule of thumb be damned.


View attachment 6922846

Thanks for this, lol, doubt many dasher users get a full .243"of depth either, one of the most accurate cases available.

 

[Deleted member 10043]

The wolfpup is a methodical benchrest and doesn't have a neck per se to avoid the problems described above. Seat as shallow as you want. Start a thread about about powder down in your chamber and magazine. Crying about nodes and warts.