What's the difference between Downloading and Hand loading.

[phaedra1106]

There's no evidence that tumbling a live round changes the powder, the original "test" which found that powder turned to dust after tumbling for several hours was found to have been done with improperly cleaned cases and the resulting "powder dust" was in fact carbon residue from the inside of the case walls. A subsequent test using clean cases was done and no "powder dust" or evidence of any change in size to the powder kernels was found.

In fact the majority of factory rounds are tumble cleaned to remove any traces of the manufacturing process before being shipped, the shipping process itself incurs more vibration to the ammunition than tumbling does, ammunition is shipped for thousands of miles by rail and road without any degradation to the powder.

[zanes]

I suspect this will turn into a "typical" reloading thread, but here goes.

That's chemistry mate - the propellent has oxygen in its molecular structure it does not need air to burn. indeed excess oxygen can cause over burn & react with air / gas, moisture to form steam or nitrogen to form nitrous oxide all gasses that take up more volume, so an unfilled case can have excess oxygen & over burn & that increases pressures. there is a sociometry that is ideal for over burn & some people call that a detonation so it goes bang inside & can damage your kit / hand / eye etc so to avoid that use a low density faster powder or a filler to exclude the air volume & its oxygen. Add to that the gas laws dPdV=nRdT & reaction rates & you can get all sorts of effects.

Oddly enough, I have it in writing from several powder manufacturers/load data publishers that they have never been able to replicate this "detonation" theory in any of their [extensive] tests.

Take bullseye for instance- I've got a speer manual that specifies 6.0Gr as a maximum load for a .44 Magnum (I loaded well below that for 25 yard work). That's <way> below a full case.

This detonation theory always seems to be explained by some slightly dodgy science (for a start, did you mean "stoichiometry" and since when does water+oxygen=steam?)- I suspect that whilst it is a possibility that there is some odd effect with "underfilled" cases that the powder manufacturers/load publishers can't replicate and can't convincingly explain the overwhelming number of these detonation incidents are due to double charges, which are very difficult to see in these sorts of loads (I deliberately double charged a case with a fired primer; by eye it was virtually impossible to discern it from single charges).

[dromia]

Hells teeth this has been done to death on here many times before but here we go again.

The "detonation effect" is about reduced loads of medium or slower rifle powders, not fast rifle or pistol powders.

Brownell did the definitive works on this in Firearms Pressure Factors in which amongst other things he showed that there was a statistical probability of Secondary Explosion Effect (SEE) with medium or slower rifle powders.

There is absolutely no evidence of these faster powders causing "detonation" problems when reduced, I suspect the myth comes about from people like the person that wrote the NSRA document writing without understanding and just regurgitating what has been written by others without applying any intelligence or knowledge to the matter.

[hitchphil]

There's no evidence that tumbling a live round changes the powder, ............... .

In fact the majority of factory rounds are tumble cleaned to remove any traces of the manufacturing process before being shipped, the shipping process itself incurs more vibration to the ammunition than tumbling does, ammunition is shipped for thousands of miles by rail and road without any degradation to the powder.

10 rnds of 1988 RG cleaned by scrubbing vs tumbling were demonstrably 1-1.5 moa lower than the tumbled versions at the same distance & gun, day, wind etc.

Factory tumbling is a short process to finish clean. These were tumbled longer. From work on delicate spacecraft instruments road, rail & air transportation are fairly benign vs deliberate vibration. There is more shock loading than vibration transmission in transport (especially UK roads!); The round contents are very light so have low momentum & are not constrained (unlike the case & head that are constrained by packaging) i.e. they are a 'powder' so transmission of vibration between particles is very low i.e. damped.

During tumbling they are rolling over each other in a fluid state & continuously contacting each other. The particles are relatively soft so will degrade & yes will recover any carbon from the case walls if reloads & not clean & carbon in a very hot energetic environment with a little extra air will burn & add to the overall energy of the reaction & end result of the round.

[hitchphil]

I suspect this will turn into a "typical" reloading thread, but here goes.

.........slightly dodgy science (for a start, did you mean "stoichiometry" and since when does water+oxygen=steam?)-.

Yep the spell-checker had its effect ....

... add water to a aggressive exothermic reaction i.e. excess burning of propellent in excess air (O2) in a confined space & it will turn to super heated steam, the gas law states that every 1mm3 of a solid & many liquids will generate about 22mm3 of steam / gas - that increases pressures. - super heated steam is also weird stuff its behaves more like a plasma than a gas & that will join in with the burning reaction so the 2O will disassociate from H & add to the burning reaction by preferentially reacting with C or S or N. All that causes excessive pressure & the MV goes up a bit more. Gibbs free energy states - H2 is more stable the hotter it gets - partly thats why the bloody Sun does not blast us all to oblivion in one go. After burning it will re-react with O2 to form water vapour & S to form sulphurous acid & thats just great in any barrel.

I have seen rounds go out of the black at 12:00 from GB class competitors at 300yds! because there was water on their round / chamber.

This is the same reason that on a damp day many older (no Engine management) cars will be slightly more fuel efficient at the expense of increased ablation of valve & piston surfaces.

Quite rational science really

[Demonic69]

We've now got an NSRA document to sign and file with the club before the end of August or we're not allowed to down-load

[dromia]

It is not worth the paper it is written upon, the NSRA are obviously not fit for purpose imposing this tosh on clubs just to get round their poor insurance arrangements.

Far easier and safer to switch your club affiliation to the NRA, at the end of the day the only benefit of affiliation is the club insurance, when we shifted the NRA actually came out cheaper as well and their insurance isn't predicated on the NSRA "down loaded" nonsense.

The NSRA do not deserve club support as they are serving the clubs so badly and treating them with contempt.

If you shoot full bore at your club then join a full bore body for the insurance not a body that knows nothing of full bore, cares even less and just sees it as a botheration to their primary function of miss managing the Lord Roberts centre.

[dromia]

There is nothing stopping you handloading other than the NSRA insurance not being fit for purpose.

It is the responsibility of all clubs to ensure that all the ammunition (factory and handloads) used on their range is within the safety certificate limits for that range, any sensible club would introduce procedures to ensure and evidence this.

All this downloading tosh is a complete red herring started by Durham police going on a fishing expedition last year after an incompetent FEO in their ranks started making up his own rules based on ignorance

[nickb834]

We've now got an NSRA document to sign and file with the club before the end of August or we're not allowed to down-load

It strikes me that the membership over there needs to present a united front to the committee and demand that this changes.

Whilst you're at it - I can't understand how an ex-home guard range is only authorised upto 38 special limits when clearly it's had full power 303 rounds shot at it in the past!

My club looked into getting our range design changed and re-authorised, we dealt with a firm that builds ranges for many types of bodies / institutions. When it comes to range limits etc - you may be surprised to learn that as far as the law is concerned, the club can set it's own limits. In effect you certify your own range for the calibres / energy you're happy with (ignore velocity IMHO) agree it with your insurers and you're good to go. The MOD/ NSRA / NRA have no legal mandate to authorise ranges anymore, the NRA when pushed will provide an "opinion" on what you've done to your range but will not sign off on said range - that's all down to you.

If this pops up (the NSRA document) at my club then I will do my damndest to get it shot down, IIRC my club is actually affiliated to both NSRA and NRA (don't ask) so it shouldn't take more than 30 seconds to kill it off.......

[Demonic69]

Whilst you're at it - I can't understand how an ex-home guard range is only authorised upto 38 special limits when clearly it's had full power 303 rounds shot at it in the past!

I think they may have built houses behind the range, changing the limits for misses, but I'm not sure TBH.

The membership are far from united. Seems like the same old story of the select-few making the decisions. I can't complain though, I missed the last AGM as I was away, I'll have to attend the next one and see what comes up.