IMO you can get by with current data and proper stack height. Your velocity would be a little lower as well as your pressures.

However, the correct way is to get 5 tested. I predict you won't get near as many reloads from those hulls using fiber wads because they iron out any crimp. Good luck!

 

i can't speak for accuracy, but apparently using fiber wads has more friction on the way out, and hence builds up more pressure. I can't see it being anything substantial, and if it would matter in a modern gun.

 

So far my tested nitro card and fiber wad loads have all exhibited lower peak chamber pressures and muzzle velocities than my plastic wad loads with the same powder, powder charge weight, and primer. I've heard of people saying that this is not always the case, even though I've never seen it.

Since muzzle velocity correlates to total evolved pressure (and not to peak chamber pressure), for muzzle velocity to be lower means the volume measured under the entire pressure curve that evolves from ignition through muzzle exit must be lower.

 

In the past when loading fiber wads the rule of thumb used for switching to plastic ones was to reduce powder charges by at least 10%. Don't see how a fiber wad with over powder card load can have higher pressures than a plastic one piece wad.

However, as stated before the proper thing to do is get a few tested.

 

Back to the original post, is there no fiber reloading data from older books for the 410? I know there's data for alcan wads in the 12ga.

 

An old Alcan manual has this:

By modern standards those are rather hefty powder charges. Unheard of these days.

Alcan AL-8 was/is in the ballpark relative burn rate range of the likes of Alliant Blue Dot and Vihtavuori 3N38. Aside from a current issue Gualandi manual, no current manuals suggest using powders in this relative burn rate range for .410 bore. Gualandi shows faster powders than AL-8 in .410 Bore loads.

 

Those are a bit on the hot side. Wonder if that's to counter the sloppy sealing with the lack of piston cup? And the trade off was a bit more pressure to make the mediocre velocities?

 

And, the more research, the better, if i do need to send off something to get tested. I'd rather try and build a load as close to standards as possible, otherwise it'd be a waste of money and time for everyone. Well, not precision, they could care less if i mail them 100 rounds and they all fail.

 

Here is an example taken from the Gualandi manual showing a relatively fast powder in .410.

N350 is a lot faster in relative burn rate than AL-8.

36/65 is 2.5" 410 Bore. 14 grams is 1/2 ounce. Round = Roll Crimp. 0.70 grams = 10.80 grains.

 

Where Gualandi states "Plastic Case" it means any high internal volume straight wall Euro hull.

Pressures - Unknown
Velocities - Unknown

 

A lot of faith in this data and metallurgy.... Makes me wonder just how much "just in case" ceiling and "now this is serious" ceiling with saami/cip

 

I've given that a lot of thought over the years.

I've worked with Medical electronics a lot, but also with other technologies, and typically there's a huge safety factor built in. I always designed with a factor of 2, so I never used more than 50% of the capability of anything. One, it's safe, and two , it lasts forever if you do that.

I imagine there's a huge safety factory in loading data and loads the factories make.

 

Modern EU shotguns are proofed to take 1,050 BAR as their MAP. That puts their maximum average pressure allowance at 15,229 PSI.

4140 Alloy should likely be in that league.

When Tom Roster tested them, Remington 870's started coming apart at above 48,000 PSI.

So the safety margin on 4140 is ballpark 3X (for 1,050 BAR) to 4X (for 11,500 PSI).

 

Ahhhhh. Outside of this thread, why to people get all fizzy when a bushing throws another half grain?

 

I don't. I know it makes little to no diffrence in a shotshell and very little in a handgun.

 

Personally, I'm OK with a 4X safety margin.

 

About that safety margin...

A guy I shoot with every week (handguns) was getting a lot of squibs and I told him that he needed to pay more attention to his powder drops. He assured me that squibs wouldn't hurt anything, but I told him not paying attention was a bad practice.

Anyway, he got a double charge in a .44 Magnum case. It was a Uberti single action and all that happened was that the chamber was enlarged substantially but no shrapnel.

The only thing that saved him was that I'd told him that I cut back to what I called light magnums in .44 Magnum, around 1,000 fps instead of 1,250 or so and he decided that was a good idea, so he was using a lighter powder charge.

All that he had to do was buy a new cylinder and have it fitted and he was back in business. Obviously the gun was overengineered to be able to have that little damage from a double charge.

 

In Europe their long standing and strict proof laws allowed them to build guns that are much lighter overall in construction and yet safe with specific ammo.

In the US we just made them robust enough to shoot ANYTHING in them! Personally I like the resulting dynamic guns using the UK, and other European system.

 

I'm not sure if any current USA manufactured shotguns are proof tested. Turkish shotguns are not proof tested.

 

By my reckoning, if 17 grains of a given powder and payload (plus hull, wad, primer, etc...) are bringing your load to 11,500 PSI (on average), then something on the order of about 19.25 grains of the same powder (for all else remaining the same) should take it to ~1,050 BAR. I don't recommend or condone this!

But if you accidently double charge somehow you will be entering, to exceeding, the realm of catastrophic failure pressure.

 

i've been reading the sister site, and some member, who used to do pressure testing, has mentioned after you manage to get a double charge dropped, the rest of the load won't even fit correctly, which would result in probably less payload of ejecta, which is, on the contrary, less pressure?

If the saftey margin is built into the guns design, even a double charge of powder, and a half accounted for payload, there shouldn't be an issue.

Now, a proper assembled shell, with an obstruction, that could be a different game of chaos theory, in my limited experienced opinion

 

Doing pressure testing (I.E., being the employee assigned to pulling the trigger and recording the results) and understanding internal ballistics are distinctly different entities.

 

I should add that if the above is repeated frequently enough observational correlations become apparent. But correlations are often misleadingly subjective (as opposed to objective), and observational correlations can actually expose and/or evolve biases. And lastly "Correlation does not imply causation.".

Admittedly, I'm biased.