Consequences of disregarding bullet shape dangerous?

M

Machineguntony

New member
I've been reloading since my early 20s, and I've always used this approach: I find a recipe with a similar bullet weigh, and then load based off the bullet weight. I completely disregard bullet shape or design, or even if it is lead, plated, or jacketed.

For COAL, I just find an average.

Is this dangerous? What are the consequences, if any?

Opinions?
 
This is mostly going to be dangerous (or perhaps reckless is a better word choice) when the perfect storm aligns against you.

If you have a load that is already running at max pressure...
Especially if it is a high pressure/small case...
If you swap in some new brass that tends to be on the tight/small side...
If you substitute a hotter primer...
All of that AND you jump in with a new bullet?

Reckless, could be dangerous.

As to bullet shape, it should go without saying that if the weight is the same, a JHP is going to be longer than a solid or Soft point/FMJ. You also don't just stick a JHP in to an already worked up max load, especially in a small volume/high pressure case.

The only other thing that comes to mind with bullet substitution is that the ogive will give you fits in a different gun if you haven't yet tried it. (Semiauto)
 
Different bullet shapes have different fiction in the bore. Long bearing surfaces = more resistance to the bullet being pushed= greater pressure with the same load

The same is true for different bullet materials. Lead vs. Jacketed for example.

A shorter COAL is usually a result of seating the bullet deeper in the case, also increases pressure. A longer COAL could result in the bullet touching the lands of your rifle...also increases pressure.

So the bottom line is, Yeah. Those things matter. How much they matter is dependent on too many factors to speak to on a forum such as this.

If your current loads do not show signs of over pressure and the velocities are consistant with the puplished data, then i think youre fine
 
I've been reloading since Aug 2013, with around 4K rounds (pistol & rifle) to my credit (I know, I'm still VERY NEW at this).

While reading my manuals, studying data & getting advise from a mentor & forums like this, I realized that there is little data for a specific bullet/powder data (EXAMPLE: I could find data for say Bullseye powder & Hornady XTP bullets but nothing for Bullseye & Gold Dot Bullets. Or Bullseye & Golden Saber bullets. I had some Gold Dots I wanted to load).

My mentor, members of this & other forums I frequent &, to some extent, email responses from powder & bullet makers advised that, since all of the above were JACKETED bullets, then to use data for JACKETED bullets. OAL would depend on how the completed rounds "plunked" in the barrel & functioned in my magazines.

Same applies to plated & lead bullets.

I don't worry so much about bullet shape when building my loads as I do about bullet weight (185, 200, 230) & type (jacketed, plated, lead).

Again, OAL is dependent upon barrel plunk & mag fit/function. Charges ALWAYS start at the low end, adjusting OAL to get the BEST out of that particular bullet/charge combination, then working up.

I rarely get close to MAX charge because I usually find the BEST before I get there.

To date, I've had some FTF's (fail to function properly) but those were very few & far between (I figure part of the learning process) & have had ZERO over-pressure signs. I still have all my fingers & my guns are undamaged.:D

Knowing how dangerous reloading CAN BE, I choose to pay attention to detail, take my time & be as safe as I can possibly be.

If you value your health, tools & equipment, you'll do the same.

Just my humble opinion. I'm sure we won't all agree.
 
Thanks for asking our advice

As Sevens hinted, the length of the actual BULLET is important.

The outside length is important for feeding through your action or fitting in your cylinder (so the bullet nose clears the back of the barrel as its chamber rotates around ) or chamber (in other action types, where the bullet may bump up against the rifling).

The INSIDE length (more to the point, the free volume inside the loaded case) is important for pressure considerations. A longer bullet (in Seven's example, a hollowpoint) set at the same overall outside length as a shorter bullet will have its base set deeper in the case than the shorter bullet. Therefore, less free volume in side the case and subsequently higher pressure.

If you are shooting a short bullet (say, a solid) and you are already at nearly maximum pressure and switch to a longer bullet (Sevens' hollowpoint) set to the same overall outside length, you will have even higher pressure when that round goes off in the same gun. Yes, risky, and possibly dangerous.

Lost Sheep
 
How hard or easy the jacket allows the rifling to engrave ,then the friction of the bullet in the bore does effect pressure.

The length of the jacket bearing surface matters .

I don't know the exact science,but I can speculate if you double the pressure required to engrave the rifling then have a 20% increase in the bore friction you will get significantly higher pressures.Add to that,as pressure climbs.powder burn rate can accelerate.

Cartridge expansion ratio will come into play.A.308 will be more forgiving than a .264 Win Mag,a .257 Wby,or a 7 MM STW .

Along with that,heavy for caliber bullets expose a small area for pressure to act on,typically longer bearing surface,and a tight twist.
 
Wouldn't this also depend on which end of the loading spectrum he is on? I.E. for someone loading mouse fart/cowboy action loads it probably won't ever be a problem but for someone loading near-max loads it could become a serious problem very quickly.
 
Wouldn't this also depend on which end of the loading spectrum he is on? I.E. for someone loading mouse fart/cowboy action loads it probably won't ever be a problem but for someone loading near-max loads it could become a serious problem very quickly.
Click to expand...

Sure. I bottom scale load might only reach mid-level pressures. But the question is do we want to have pressures increases unknown to us just because we substituted a different bullet and didnt do a proper load workup?
 
I don't disregard individual bullets, but always start low and work up using a chronograph regardless. When using a bullet different from that specified in the load manual it is especially important. As said, on the low end you should be fine. As you approach max loads it becomes more important.

Same advice if using different brass or primers than specified.
 
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