How shallow can u seat a bullet?

[Joshboyfutre]

Been reloading for a Savage Axis II chambered in 223 Remington that I bought off of my pops, great shooting little rifle. When I measured for seating depth I was surprised to see that the throat is really deep. Normal oal for this round is 2.260 but the rifle measured 2.347. A round loaded to that length (52g SMK) literally only has 0.110 of the bullet inside the brass. Obviously I didn't do that, I ended up doing a set at 2.260 (0.20inside), one at 2.270 (0.19inside), and one at 2.280 (0.18inside). Ive heard you basically want the diameter if the bullet in the case but we always end up under that when seating close to the lands. So Im wondering at what point does this become an issue? I can see a 223 seat 1/10th on an inch in being a saftey issue let alone degrading accuracy. Any thoughts?

 

[Reloadron]

Old rule of thumb was at least one caliber inside the case. So that would be about 0.223 inside the case. That is just a generalization but something to work from. The 2.260" is because that is the overall max length for a round to fit into the magazine on rifles having a magazine. Sierra 80gr BTHP Match bullets are seated to a C.O.L. of 2.550" which will fit in a correct cut NATO chamber but will not cycle through for example an AR 15 magazine.

Ron

 

[Bart B.]

That rule of thumb for bullet seating depth is broken so many times, it's definitely one of the most popular myths in the world of small arms ammunition.

Lots of commercial and military ammo's bullets are seated to a depth where their bearing surface rear point is less than caliber diameter back from case mouth.

How does such a standard impact where bullets are seated for a given jump to the rifling?

 

[Joshboyfutre]

The rifle actually shoots really good with just standard Max oal seating but my thinking is that if I shorten the bullet jump that it will tighten up the groups even more. I would like to try to do .02 or so off the lands but that's obviously not going to happen with this one. I'm scared of seating right on the lands (jam?) because of pressure spikes. Not sure if that question was directed at me or if that answers it. I was mainly just wondering what can happen if you seat too shallow, there's got to be something bad that could happen from that LOL.

 

[Bart B.]

Seating bullets to caliber depth is myth 326 on the list of about a thousand.

Whatever holds the bullet best for its use is 100% wonderful.

Too deep can cause higher pressures. Too close to the lands: ditto. Reduce the powder charge.

 

[someguy2800]

The real question is does it shoot any better seated out than it does seated to a normal oal? Most of my guns shoot best .050" or more off the lands. I never bother to try to seat to the lands anymore. I have 3 guns where the bullet is all the way out of the case before the bullet touches the rifling and they still shoot fine. I have a 25-06 that I have shot the crap out of and the rifling is a full .100" farther out than when I bought it, and it still shoots the same with the same load.

 

[Varminterror]

Long throat rifles are a natural home for mono metal bullets, which prefer a lot of jump.

Excluding mono-metal bullets, I have never found a long jump to be more accurate than a short one. I start at 20thou and work my way in; can't think of a rifle I own which isn't in the 5-15thou ballpark for its ideal depth. It does leave me chasing lands as my throat erodes and my groups open up, but typically, I don't have to make many adjustments before the barrel is toast anyway.

For factory rifles and chambers, there's a lot more going on which a guy needs to worry about before seating depth.

It really, really surprises me to hear you have such a long throat in a Savage 223rem. I have 4 savage 223's (all of which are Wylde chambers/throats), none of them are that long.

 

[243winxb]

The Axis will not feed cartridges longer than 2.300" for me, using 68/69 gr match bullets in the 1-9 twist barrel. The chamber will accept longer if single loaded.

I like to start with the bullets base at the neck/shoulder junction, if possible. If loading 223/69gr bullets, the base will be much deeper into the neck. This is ok when using a starting load and working up the powder charge..

If the bullet has little contact with the neck when trying to reach the rifling, bullets may become crooked when contacting the feed ram on chambering the round.


On firing, the bullet may move before pressure is high enough to burn the power correctly. This is because of light neck tension when the COL is to long. This happens sometime, when using slow burn rates of powder in larger Weatherby type rounds. . Accuracy can be very good with the bullet jumping to the rifling in a factory rifle.

http://www.ar15.com/forums/t_6_42/4...ssure__An_experiment_UPDATE_IN_OP.html&page=1

 

[hdwhit]

Joshboyfutre wrote:
I was mainly just wondering what can happen if you seat too shallow, there's got to be something bad that could happen from that LOL.

Provided you have space in the chamber and the short distance to the rifling doesn't create pressure problems, I can see only one potential downside to seating long bullets shallow. Because of its length and shallow seating depth, forces applied perpendicular to the nose of the bullet will have a greater effect on the neck of the case than bullets seated at a normal depth. This is because the force is operating at a longer distance (what engineers call a "moment arm"). If cartridges are roughly handled, the bullets could be rocked back and forth loosening the neck's grip. Handle the loaded rounds tenderly and you would probably have nothing to worry about.

 

[Joshboyfutre]

So I went and shot the rounds that I had loaded and the 2.26 shot good as they usually do, the 2.27 spread out horizontally a little and the 2.28 spread out in a horizontal line basically. It was a little windy but theres no way the wind did this at 100yds. It was probably a .5 group up and down but about 1.5-2.0 left to right. Would post them but left them at the range unfortunately. The rifle shoots fine with standard seating so thats what I'll probably do. Might try testing them again w/no wind.

 

[HB]

I would load them out as far as you feel comfortable and leave it be. I chased this dragon with my Zastava m70 that has a very long throat... with not much success. It seemed that my shooting technique and ladder test to the right place was sufficient to kill any deer I've seen. On a bench gun I can understand the desire to tinker.