Low power reload

[Simon_S]

I using 3gr tightgroup in 357mag case with 180gr Tc work well out of my Rugger 77/357 at 50M getting some nice groups.
Don't try and use at 100 drops like brick

[junkyard dog]

Back in the day the favorite load for a PP1 comp with a .38 was 2.8 grn of N310 (Same as bullseye) behind a 148gn wadcutter (lead) seen many a 300 scored with that.

[Turnup]

Also be aware, as I've just been reminded, of the phenomina of flashover. I've never seen it or even met anyone who's seen it, but apparently it does exist. If a light charge is distributed along a large case and the primer flash ignites the whole lot at once, rather than passing the fire from grain to grain, it can build up a huge pressure peak and blow up the gun. In Rifle cases people often use kapok or tissue on top of a light charge to prevent this.

Deffo a myth. When trying to find any credible research into the claims of light load detonation I came across a powder manufacturer (don't remember who) who has looked into powder orientation in lightly loaded cases. They were measuring peak pressures for various distributions of loose powder in the case:

a) all powder at primer end of case - airspace between powder and bullet

b) all powder at bullet end of case - airspace at primer end of case

c) powder evenly distributed along the case length (as best as they could) with airspace above


Case pressures were highest in b), lowest in a) and somewhere between in c), but the differences were not great.

Use of fillers will increase peak pressures since there is less effective volume inside the case.

Reports of gun damage when using light loads (where properly investigated) reveal :

Distortions and failures consistent with excessive pressure caused by barrel obstruction, often showing ring bulges and (where there were burst actions or barrels) stretching of the material prior to failure. This is indicative of a bullet lodged in the barrel (more possible with really light loads) and a second fired behind it.

Zero evidence for detonation. Detonation of an explosive is defined to occur where the reaction propagates through the explosive supersonically (that is faster than the speed of sound in the explosive). Materials which can do this are termed high explosives. Such events will be characterised by shattering rather than stretching deformations. None of the properly documented cases I found showed shattering damage.

Lots of arm waving claims of the "it stands to reason" type, not properly backed up (if at all).

If it were possible to cause nitro powders to detonate do you think we would be allowed to buy it?

[tacfoley]

might be a .357 underlever and he wants to use .38 specials etc

Ah, right. Forgot about them underlevers.... Still, the lowest load in the handbook is something that should NEVER be reduced any further, especially shooting such loads in a 16" barrel or similar...

[Turnup]

Ah, right. Forgot about them underlevers.... Still, the lowest load in the handbook is something that should NEVER be reduced any further, especially shooting such loads in a 16" barrel or similar...

Many many folk are shooting .38 spls at well below the manufacturers starting loads, both in underlevers and in a bygone age, revolvers. The only possible risk is that the bullet does not leave the barrel so reduced loads are not for rapid firing until the reloader has successfully discharged at least 100 rounds with 100% success. For my peace of mind I have reduced my loads below my chosen the optimum to establish that they still reliably leave the barrel, thus moving up a tad gives a good margin.

Alliant list the nominal load for Bullseye as 3.5 gn and suggest starting loads at 10% under, so that's a little over 3.1. The magic load for revolvers, used by many, was 2.7 gn.

Lovex D032 (Accurate #2) startin load is given as 3.6 gn, yet I have been happily using 2.4 - 2.8 gn for many years now.

The thoughtful reloader should recognise that many powder manufacturers do not provide low load data because of the concern that the bullet might not leave the barrel, but with care and understanding the light load regime can be safely explored.

[sarge4318]

I've always considered this an "urban myth".... you said yourself, you, or anyone else you know, has never seen it... and all those of us who used to shoot 2.7 gns of BE back in the day never had a problem with it....

When loading light loads in 44mag cases (IIRC about 2.5gn Bullseye) I would occasionally get a round that sounded a little louder than usual and have a bit more recoil. It wouldn't make much difference on paper from the unsupported position at 25yds. I was a bit worried when it first happened but it never blew the gun up and the cartridge didn't show signs of pressure.
Whether this was 'flash-over', 'auto-ignition' or some other situation or term, I don't know.

ETA: I have twice seen when a half charge in a rifle case has caused a pressure spike large enough to flow the brass around the bolt in one case and in the other blow the bolt out of battery (half cycle the action on an AR) and blow it's magazine to pieces. I think it was only the strength of the AR system that held the rifles all together as much as it did. What you call this I don't know.

[boff180]

I want to make a really low power 38sp load for quietness. My question is how low can I go without encountering problems eg bullet stuck in barrel?

I've got Herco and Blue dot btw

Try a high volume powder such as Viht N32C.

Minimum charge for Cowboy Action in a .38spl with a 158grn grain lead head is 3.3 grains of powder.

[harrysmith]

Try a high volume powder such as Viht N32C.

Minimum charge for Cowboy Action in a .38spl with a 158grn grain lead head is 3.3 grains of powder.

That won't be possible for a while as it's impossible to buy powder atm, hence I've got to use the powder I already have but thanks anyway.

[svincett]

I using 3gr tightgroup in 357mag case with 180gr Tc work well out of my Rugger 77/357 at 50M getting some nice groups.
Don't try and use at 100 drops like brick

I use 2.7 titegroup in 38 & 3.1 in 357 in my lever action

Good powder

Cheers Steve

[223AI]

My trail boss 158 gr load does a massive 350 FPS from a 20” barrel......