Tanaka k98 power

I'm starting to suspect some serious chrono issues. Here's the reasoning. A BB does not totally obturate the barrel. Some gas escapes between the BB and the wall of the barrel, exciting the muzzle before the BB. There are some chrono's that are so sensitive they will get a reading from this gas cloud!

I've got a few chrono's here (Madbull V1, Satellite, Shooting Chrony F1 & CED Millennium). The CED has been verified against a UKAS (Di will know what i'm on about ) calibrated Chrono. I trust it 100%. CED make the best chrono's out there - bar none.

The others? they vary - some considerably - and I have found that the Satellite is particularly likely to give dodgy results when using it to test gas guns.

I have yet to visit any site in the UK that uses a properly verified/calibrated chrono.

I have an Xcortech X3200. Not tried it with a gas gun yet - soon though.

Oh yes I know about UKAS bain of my life interesting to know that there is one chrono thats been accredited though. Now you see that would lead me onto wonder about the actual performance of all those others being used unaccredited on a variety of sites, cos that means if as Kermit states there are accuracy issues, noone can state 100% their weapons fps as some of those chronos standard deviation (you'd need to experiment to work it out) will be reading very high, and some very low. You'd need to be able to work out where the standard deviation of each chrono is wrong so you could subtract or add this to the fps figure reading.

Interesting stuff.......

That's why historically airsoft sites have said rules are, say, 328fps + 5% maximum variance, just to allow for temperature or chrono variance. I could check my gun at home to be 328fps and turn up at a site only to find their chrono reads 345fps, which would be a bummer. The variance rule sorts that out.

Remember, site chronos aren't there as some sort of standardised and absolute measure - they are just so ensure a level playing field and a reasonable level of playing safety.

I've noticed in the past couple of years that sites have tended to adopt absolute maximum fps rates which in my opinion is much more easy to understand - i.e. AEGs not over 350fps and boltys not over 500fps. The onus is then on the gun owner to make sure that his bolty, for example, is of sufficiently throttled back power not to go over on ANY chrono, whatever their accuracy.

Also, it is standard practice to take several shots/readings to get a sensible idea of a gun's power - everyone knows you get the occasional high power shot and duffer, for airsoft guns aren't high precision instruments and neither are chronos (generally).

I think its also worth bearing in mind that there is no need to get into a tizzy with OMFG HOT GUN cries just because once in a while a K98 throws out a BB at 505fps. It is practically speaking neither here nor there. But if a K98 was shooting at 700fps or more on every shot, no matter what chrono, then clearly the concession to use a rifle at higher-than-AEG fps is being abused. Bolt action owners are allowed to use a higher powered rifle (with MED) to compensate them for their firing rate disadvantage and make a 'sniper' role practical.

I'm intrigued by this ballistic gel thing and I have resolved to do some documented (but unscientific) tests by the end of this month!

And half a kg of gelatine powder now ordered.

HALF A Kg????

That's not the episode of CSI - Derby that I had in mind.

HALF A Kg????

That's not the episode of CSI - Derby that I had in mind.

You don't know what he's making moulds of....

Well it was £1.35 for 20g at Asda or £12 for 500g mail order. I figured it would be worth trying to make a head shape instead of a boring block!

I can just see the conversation in Mr & Mrs Cw's house....
"What are you doing now dear? .... oh just ordering half a kilo of Gelatine... what's that for dear? .... just making heads to shoot!"

Heh, I just asked her if Asda have Halloween stuff in yet (I want a cheap mask for a mould) and she said, in a matter of fact way, "Why, do you want some fake blood?". Hmmm, that woman has the measure of me all right...

I'm sure I can hear distant cries of 'hear, hear' across the land.

I do detect certain hysteria about 500fps rifles as if they are incredibly dangerous. The fact is they aren't. Serious injuries from projectiles shot from barrels are all caused OUTSIDE the airsoft world. Air guns, shot guns, legal and illegal real guns. The serious injuries caused WITHIN the airsoft world are broken limbs, twisted ankles, bumps to the head, cuts and grazes from trips, falls and brambles, heat exhaustion, stomach upsets, chipped teeth. These are all from playing an active, outside pastime. The same sort of injuries that could be caused in many an other pastime.

That's not to say one doesn't try and reduce risk where possible. I'd say rock climbing and pot holing are incredibly dangerous activities, yet thousands do it and mostly without incident due to consideration given to safety.

So, as long as the questions raised as the start of this thread are taken in the context of of risk moderation that's all to the good. Running about with hands in the air shouting "OMFG TANAKAS AM EVIL" isn't the way forward! A concern has been floated and it requires careful examination but not knee jerk reactions, so lets look at it carefully...

So, as long as the questions raised as the start of this thread are taken in the context of of risk moderation that's all to the good.

When I originally posted the question, it was purely that a question, is the first shot more powerful from a heated up gas mag? I'm hoping that tests with gel and all that malarky will prove or disprove that theory, it was certainly not intended to be an "Evil Tanaka" thread, had that shot come from a Marushin or even a gas pistol (though I hope none of ours are running 400-450!) I would have still posted the same question.

Of course ZB, original post intention accepted. But in the context of previous threads that have been distinctly antagonistic against the gas K98 there tends to be the suggestion that they are dangerous and that 350fps AEGs are safe, which is muddled thinking of course.

So, would the questions be summarised as thus:
1) It has been observed that the first bb fired chronos at well above subsequent shots.
- is this phenomena repeatable by others?
- if so, can it be established that it is false chrono reading?

2) If it can be established that the first bb does have a higher power than subsequent what is the reason and can it be prevented.

As additional useful data it would be good to know (as per Kermit's plans) what other K98 user's reading are with temperature/chrono type/gun mod/gas type/bb type & weight recorded.

I'm looking into empirical testing using 'ballistic gel' of skin damage/penetration of BBs using various powered guns and distances, taking particular note of the effects variance with tissue density/mass, working on the theory that normal airsoft gun projectile energy and MED rules can cause penetration in very soft tissue (nose, cheeks, forehead) under certain conditions.

[smug mode]Bloody non Scientists. Don't even know the difference between repeatability and reproducibility[/smug mode]

Just a thought, but as far as I know both the nose and ears are made up of a certain amount of cartilage (feel free to correct me). Whilst they are flexible, they are rather gristly in make up which could allow the penetration.
Fleshy parts such as cheeks, buttock etc. would provide a certain amount of 'bounce', so whilst you may get a welt or bit of blood letting on these parts, the penetration is prevented by the ability of the area to 'flex' or to absorb the initial impact. Foreheads tend to have a big lump of bone immediately behind them which could also produce the 'bounce' effect but more due to the rigidity of the surface.
Hence nose and ears can`t produce enough of the 'bounce' effect due to being somewhere in the middle.....if that makes sense ?
Taking hits in the face from AEGs is commonplace in airsoft, but I`ve never had anything more serious than a welt appear. I took one hit in the forehead from a C02 pistol at about 25m which drew blood and made me see stars for a brief moment, the gun being C02 was hot so I can only surmise that the added fps was a factor to some extent in creating a harder hit than would be 'normal' in the circumstances.

[smug mode]Bloody non Scientists. Don't even know the difference between repeatability and reproducibility[/smug mode]

Heh, us non-scientists are happy with either!

Slick, I mentioned cheeks and forehead embedding since I have seen both first hand, and nose second hand. There is a video on Youtube somewhere showing a close bb impact on the body where you can see the rippling of the tissue as it absorbs the impact (I looked for it again but got depressed with endless videos of Americans titting about with bb guns).

As you say, I'm pretty sure it has to do with what is behind the skin - tip of the nose is spongy tissue with cavity behind, cheek has spongy tissue with nothing behind, forehead has very thin layers of tissue over hard bone. Shots to limbs and torso usually bounce off because of the strength, flexibility and tautness of muscles and mass on organs/bones behind.

From what I remember (I'm sure Kermit will correct me) the ancient Home Office 'lethality' tests from donkey's years ago that gave rise to the 1J 'rule' were conducted on a pig carcase using feathered darts, the sort that airgun users use. Energy above 1J caused the skin layer to break - no idea on what the distance from muzzle to target was though!

Moore vs Gooderham, 1960. Sharpened steel dart into a bit of plywood. Case defined "lethality" as occurring above 1.35J. Been ignored as a precedent for years though (the original science is shite) so lethality is still defined on a case-by-case basis with the ballistic testing carried out by the FSS.

Recent testing by FSS of Scotland & FSS of Northern Ireland put it somewhere between 3 and 4 Joules, as do people like Marty Fackler - the man is GOD, when it comes to Ballistic testing.

**Edit**

http://wapedia.mobi/en/Ballistic_gelatin - Useful link for making up Ballistic Gelatin. Note that the temperatures are important!

Well I can say without a doubt that shots to the forehead and bridge of the nose bleed like hell .as I have a nasty habit of charging in to gunfire in the most stupid manner.

Moore vs Gooderham, 1960. Sharpened steel dart into a bit of plywood...

Thank you for correcting my shaky memory m'lud.

Useful link! Can do the chilled gel thing and probably get close to the 'calibration' thing too although everything I do will be empirical and non-scientific and in layman terms!
I was wondering about distance as it isn't mentioned in that wiki but I see the INS National Firearms Unit Ballistic Gelatin Test Protocol mentions 10ft, so I'll use that. It also mentions a denim covered gelatine test that would be interesting too.

But maybe this is too complicated - since Che has a penchant for this sort of thing perhaps he could be the test target instead of a block of jelly. Oh wait, same thing really.

(Many years ago I did some PR & report work for British Rail on locomotive safety development work. Part of it involved driving scale models of trains into ballistic gel cylinders containing steel 'bones' that simulated cows on the tracks. The aim was to ensure remains are thrown clear of the wheels to avoid derailment. Amazing how solid even jelly can be when hit at speed!)