The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

dromia wrote:

tackb wrote:unique and red dot were ok but tiny charges run the risk of detonation

Why do you say that?

There is no evidence at all that small charges of fast burning pistol powder cause "detonation".

With reduced charges of medium or slower burning rifle powder there is a chance of SEE (Secondary Explosion Effect).

I have tried Trail Boss in many rifle calibres and it has worked just as well as any other fast pistol powder, but had no other benefits than being fluffy, just my experience.

selective quoting there !

re-read the whole thing again and you'll see I'm yet to be convinced that SEE is an actual thing , I think I'm right in saying that it's never been replicated reliably ?

I think what dronia was saying was that it is thought to be with slow burning rifle powders. Not with fast pistol powders. If it is real and not just theoretical.

Yes, so why refer to it in first place?

That is why I selectively quoted that particular part of your post.

See Firearms Pressure Factors by Brownell.

Even my club has made a modest contribution to debunking this myth, 1/4 million such rounds shot over the past 15 years with no issues whatsoever is starting to have some statistical significance.

This "detonation" nonsense needs to be put to bed, referring to it in any shape or form just gives it more oxygen and perpetuates a totally unsubstantiated doubt.

dromia wrote:Yes, so why refer to it in first place?

That is why I selectively quoted that particular part of your post.

See Firearms Pressure Factors by Brownell.

Even my club has made a modest contribution to debunking this myth, 1/4 million such rounds shot over the past 15 years with no issues whatsoever is starting to have some statistical significance.

This "detonation" nonsense needs to be put to bed, referring to it in any shape or form just gives it more oxygen and perpetuates a totally unsubstantiated doubt.

because it is relevant to the subject I was commenting on , if you'd prefer me not to comment just say ?

As it isn't true why is it of relevance?

For those who've not seen this before, the treatise on using small charges for double-based pistol powders in rifle cartridges in 'Levergun Performance Studies' is well worth reading. It gives a very convincing explanation of how disc shape pistol powders ignite and burn in very low fill-ratio applications, and why the practice is very safe (provided as always that overloads aren't incurred).

http://www.gmdr.com/lever/lowveldata.htm


Detonation from too-low charges is linked exclusively to very low fill-ratios of coarse grained slow burning powders in large capacity / over-bore capacity rifle cartridges, primarily magnum types. That is why many larger magnums have relatively high starting loads listed for their 'standard' propellant grades and a warning not to drop below them is given. Even there, it has proven very difficult indeed to replicate detonations. When Hodgdon Powder first received occasional reports of these occurrences in the Weatherby Magnums, and a few other large cased numbers way back in the 1950s or 60s, they were initially sceptical. When eventually convinced, they loaded and fired hundreds of such likely dangerous combinations and failed to get a single over-pressure result never mind a rifle destroying detonation.

That's not to say that excessive under-charges are ever a good thing. Even in smaller cartridges such as 308 size, a too low charge of a 'standard' burning rate powder can produce mild hangfires with consequently large ES values and poor performance. Moving to a faster than normal burning powder normally cures this. Hodgdon still lists 'youth loads' of H4895 in several popular deerstalking cartridges, some loads getting on for 40% below normal. Speer used to publish very low velocity / low fill-ratio reduced loads for jacketed bullets in a range of cartridges in its manuals, usually employing IMR-4198. These would give MVs at around half normal levels, but it was strongly advised not to reduce minimum listed loads - not for the risk of detonation, but rather that jacketed bullets need a minimum pressure / speed to behave consistently in the rifle barrel, and of course if loads are reduced too much, there is a serious risk of leaving a bullet lodged within the barrel. Lead bullets give much greater latitudes as they work consistently at significantly lower pressures.