Seated Bullet below Cartridge OAL

[KnightofCydonia]

Hi,

I was adjusting with the bullet seating die as I like to seat off the lands for my .270 winchester. I accidentally loaded one round to ~3.244" which is well below my 3.405" max overall case length in my rifle. The 270's Cartridge OAL is 3.340", can I still shoot this underspec round and be safe without causing too much pressure? I loaded 150 gr Nosler BT into neck sized brass.

[NHSHOOTER]

Be on the safe side, pull the bullet and reseat..

[hdwhit]

...can I still shoot this underspec round and be safe without causing too much pressure?

Is the reduction in case volume significant? Does the reduction in case volume materially impact the burn characteristics of the powder? There's really no way to tell.

NHSHOOTER is correct; the only safe course of action is to pull the bullet and reseat it.

[KnightofCydonia]

Yeah going to go safe and just pull the bullet out and reseat it.

[RC20]

To assess right we would really need to know powder and how much.

you can use a kinetic hammer and tap it out a bit, I then put back to what OAL I wanted, do that at the range at times as I have a light seating press and the dies with me.

The issue is not the length short but longer and in the lands with a high end load.

Weatherby got their performance by letting bullets jump a long way.

[reynolds357]

You can shoot it. Contrary to the old wives tales, the further you move the bullet off the lands, the more you reduce the peak pressure when fired.

[KnightofCydonia]

But don't you increase the pressure within the case as there's less space for the powder charge to combust and for the pressures to expand?

[Don Fischer]

Got an inertia bullet puller, hammer type? Just move the bullet out a bit with it and reseat it.

[KnightofCydonia]

I was able to use a pair of wire cutters and on my press pull the bullet out enough and reseated to appropriate COAL. Thanks for the help!

[44 AMP]

You loaded a round 0.096" below max listed length and you're worried about it???

I think, in .270 Winchester, your worry is misplaced.

[KnightofCydonia]

Not if you’re a newbie and don’t know..

[cw308]

It takes time , then you'll start chasing the lands . After my first barrel change and measuring CBTO , OAL don't mean a thing . Unless your loading for a magazine feed .

[reynolds357]

.But don't you increase the pressure within the case as there's less space for the powder charge to combust and for the pressures to expand?

No, That has been proven false by modern pressure barrels. Increase jump to lands always more than offsets reduction in case capacity.

[Rangerrich99]

I worried about COAL and my seating depth for years. Then one day after accidentally loading yet another .224 bullet .15 inches deeper than COAL, I impulsively checked the length of several different factory rounds. Imagine my surprise when I found that several of these brands were consistently more than 0.2 inches under any published COAL I could find in my 8 reloading manuals.

I stopped worrying about a tenth or two after that.

Now if I were loading at 100% powder charge or over, I'd probably disassemble the bullet. Just to be safe.

[RC20]

Ok, first of all you did the right thing and asked. Dumb people just jump off a cliff and think to ask as they are about to hit the rocks below.

don't you increase the pressure within the case as there's less space for the powder charge to combust and for the pressures to expand?But

Short answer is kind of no but its not universal (very small capacity pistol cases come to mind)

The other aspect the "what a dumb questions type" are not telling you is you can compress loads and compressed loads can do funny things. Or over compress a compressed load. There be dragons.

So yes its a good question and I would happily work around you vs people that jump first and wonder why things went to hell.

Never been sorry I was safe but I sure as hell have been sorry when I was not.

[RC20]

Now if I were loading at 100% powder charge or over, I'd probably disassemble the bullet. Just to be safe.

One gun at 100% vs another is ??????????/

I would take a look at the load, the powder, the listed PSI or Cup for that load and make a decision based on more data (including variability in the reload manuals)

And its going to shoot different so if I am trying to tack drive that is a reason to be even as I can.

If it pencils out ok and its a hunting load, maybe not but I have the kinetic with me so.......

[reynolds357]

The other aspect the "what a dumb questions type" are not telling you is you can compress loads and compressed loads can do funny things. Or over compress a compressed load. There be dragons.

Without a godawful heavy crimp, that extremely overcompressed load will uncompress.

[RC20]

Like I said, I like working around people that go the extra mile and its a good question to ask.

[KnightofCydonia]

Another dumb question. If loading off the lands, is it general practice to load about 0.002" below where the bullet just touches the lands to avoid overpressure but maximize accuracy?

[44 AMP]

Another dumb question....

they're not dumb questions. None of this is instinctive to any of us, we all started at zero and learned from there.

Mostly by reading what others have done, and then finding out whether or not it applied to our guns and ammo, and if it was at all useful, if it did.

So that's my question back to you, you said its a .270, but what .270 makes a difference. Loading match grade ammo for a minute of deer rifle is, in my opinion, a waste of time.

What kind of groups are you getting with ammo loaded to standard factory lengths? are you seeing any significant improvement if you load long, to "x" off the lands?

[Rimfire5]

KnightofCydonia

I would use 0.020, not 0.002, as a working distance off the lands.
At 0.002 you are probably already going to experience the beginnings of a pressure increase spike.
Unless you are particularly experienced with a reloading press, you probably already have 0.002 variance in your cartridge base to ogive lengths and that would put some of your rounds into the lands causing a real spike in pressure.

I have loaded over 48,000 rounds in the last 9 years and get very good accuracy results at 0.020 to 0.010 off the lands without worrying about getting an odd round out too close to the lands and causing overpressure inadvertently.

[T. O'Heir]

SAAMI minimum OAL for the .270 Win is 3.065". Your 3.244" is perfectly safe the way it is.
3.405" is way over SAAMI Max OAL for the .270. Case length has nothing to do with it. It's the Cartridge OAL that matters.
Burn rates are about the chemicals used in the powder. Not the case capacity. Or where the bullet is in relation to the lands.
"...is it general practice to load about 0.002"..." There is no such thing. Every chamber of every rifle is slightly different. Even two identical consecutively numbered rifles. Hence, every rifle has a slightly different "sweet spot". The off-the-lands stuff is 100% trial and error. It's a load tweaking technique you don't absolutely have to do, at all.
You can Forget the off-the-lands stuff until you have worked up the load. Then fiddle with it if you feel like it.
Like Amp says, there is no such thing as a 'dumb' question, except the one not asked. I'd suggest you read your loading manuial's reference chapters.

[hounddawg]

I was able to use a pair of wire cutters and on my press pull the bullet out enough and reseated to appropriate COAL.

thumbs up for using common sense and ingenuity but shooting the bullet at the original seating depth would have resulted in a lower pressure not a higher one as some have stated. Not intuitive and once I used to believe the same but that is how it works in real life. Paragraph 2

In a "normal" load with the bullet seated to allow about 1/32nd of an inch gap [Fig. 29] between the bullet and the initial contact with the rifling, pressure builds very smoothly and steadily even as the bullet takes the rifling. Pressure remains safe throughout the powder burning period [Fig. 30], and the velocity obtained—3,500 feet per second (fps)—is "normal" for this load in this rifle.

Seating the bullet deeper to allow more travel before it takes the rifling, as in these next two illustrations, permits the bullet to get a good running start [Fig. 31]. Powder gasses quickly have more room in which to expand without resistance, and their pressure thus never reaches the "normal" level. Nor does the velocity; with the same powder charge, it only comes to 3,400 fps [Fig. 32].

When the bullet is seated to touch the rifling, as in the accompanying illustrations, it does not move when the pressure is low [Fig. 33], and not having a good run at the rifling as did the other bullets, it takes greatly increased pressure to force it into the rifling. As the rapidly expanding gasses now find less room than they should have at this time in their burning, the pressure rise under these conditions is both rapid and excessive [Fig. 34]. Velocity is high at 3,650 fps—but at the expense of rather dangerous pressure. Many rifles deliver their best groups when bullets are seated just touching the rifling. Seating bullets thus can be done quite safely if the reloader will reduce his charge by a few grains. The lighter load will still produce the "normal" velocity without excessive pressure.

https://www.hornady.com/team-hornady...nal-ballistics

[Bart B.]

When I toured Hornady's plant a few years ago, I asked them why their ammo and rifle terminology was different than the industry standard listed in SAAMI's glossary. Especially when Hornady is a voting and supporting SAAMI member. Their answer in so many words was SAAMI is wrong.

Their use of "headspace" and "throat" are examples in

https://www.hornady.com/team-hornady...nal-ballistics

Their comment:

Though some rifles deliver their best groups when full-length resized, neck sizing alone usually promotes better accuracy, because when our reloaded cartridge is returned to the chamber, it is almost a perfect fit. Headspace is just right with all cases, whether rimmed, belted, or rimless; and most helpfully of all, the new bullet is almost perfectly aligned with the bore.

contrasts a lot with what match winners and record setters do. And how cases fit chambers when fired.

[reynolds357]

Yep, I think neck sizing has all but disappeared from competitive bench rest shooting.