Questionable reduced loads with slow rifle powder. Should I be concerned?

[Swagman00]

So I was talking to an old friend that is thinking of trying his first 20 round batch of reloaded 7.62x54R. At first he thought he was OK, but now has second thoughts after not using specified reload data. I told him to hang on for a bit until I could find out myself.

His loads are 180 gr gas checked pan lubed hard cast RNL .303 British that have already been bore slugged. They're .001 over so he's good in that department. He's also using unloaded unfired steel milsurp berdan primed cases with 32 grains of Varget (roughly a 70% load) and TP as a buffer rather then dacron or kapok. I know Vargant is a rather slow powder and have read several articles about the dangers under-loading slow burning rifle cartridges. The idea he has is to get them down to the 2000 FPS zone to prevent leading, but maintain stability.

No laughing, hazing, heckling or damnation please. I'm just looking out for him.

Information

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[Parashooter]

While "detonation" with reduced loads of slow powders remains a controversial topic (probably happens, but very difficult to reproduce in a controlled setting), your friend could make a more efficient powder choice than Varget for a load in the 2000 fps class. RL-7, 4759, and 5744 are all more effective. They take a lighter charge to produce the same velocity and burn more completely at the reduced pressure involved. FWIW, Varget isn't an especially slow powder and is therefore less likely to produce pressure anomalies in low-density loads than some of the really slow numbers.

It's now generally considered inadvisable to use fillers of any kind in bottleneck cartridges, there being a risk that the filler will compress into a solid obstruction as it tries to pass from case body into the smaller neck. If one has to employ a filler, polyester fluff (Dacron) offers the advantage of burning/melting down to a very small volume when heated.

[browningautorifle]

I would suggest using ONLY data from proven sources and stick with it. Reduced loads can and often ore dangerous to both firer and spectators. Don't reduce below stated loads and use only recommended powders for this. Like para shooter said I wouldn't put the kapoc or dacron in a bottleneck case for filler. Lyman has a lead load book for this very thing.

[Swagman00]

I knew it sounded like a bad idea. I was doing some reading and it sounds like a 70% load of H4895 without any filler is a safe bet for reduced loads.

[Calif-Steve]

I would use 5744. I don't use very low loads of Varget.

[Bruce McAskill]

Varget is in the same burn range as IMR 4064 and not much slower then 4895.

[Pedersoli]

There is good information available on the Cast Bullet Association Inc Forum for this topic. In particular articles written by C. E. Harris.

[jarmann]

dear sirs ,
redused loads are always made with fast burning powders (H4198 ,unique, 5744 n110 n340 2400)(pistol powders/ m1 powders ) this you find all over the differend forums and magazines ,
allways use a keeper over the powder (dacron fluf 2/3 gn ,toilet paper kitchenroll in small amounts ,carton disk on straight walled cases ) I even use them with fmj bullets in springfield 1903a3 and the m17 mostly with N110 vitha
this is not new, it has been done for years ,the only DANGER in this matter is DOUBLE CHARGE , and the flash over ,but that we all new allready a long time !!!!!!AND WE ALL NOW HOW TO AVOID THIS PROBLEM (weight every charge and compleet your rounds piece by piece )no TV no radio ,complete consentration on the matter, like a monk in is cell
What we do ourselfs we mostly do better
greetings from over the pond
jarmann

[Pyno&dyno]

Hi
I have been using reduced load on 30-06 6,5x55 and 7,62x54, initially I used to insert cotton as a filler but now I don't use it anymore. For lead bullet as suggested you should move to a pistol powder. I tested some N340 (because here is easier to find Vithavuory than American powder),then because I shoot fmj bullet I tested the N110 with very good results, the precision is matching the full load charge.

[AKA Hugh Uno]

dear sirs ,
redused loads are always made with fast burning powders (H4198 ,unique, 5744 n110 n340 2400)(pistol powders/ m1 powders ) this you find all over the differend forums and magazines ,
allways use a keeper over the powder (dacron fluf 2/3 gn ,toilet paper kitchenroll in small amounts ,carton disk on straight walled cases ) I even use them with fmj bullets in springfield 1903a3 and the m17 mostly with N110 vitha
this is not new, it has been done for years ,the only DANGER in this matter is DOUBLE CHARGE , and the flash over ,but that we all new allready a long time !!!!!!AND WE ALL NOW HOW TO AVOID THIS PROBLEM (weight every charge and compleet your rounds piece by piece )no TV no radio ,complete consentration on the matter, like a monk in is cell
What we do ourselfs we mostly do better
greetings from over the pond
jarmann

I;m not sure where you get the idea that reduced loads are "only" used with faster powders when this is absolutely not correct. Many loading manuals have reduced loads of medium and slow powders to make reduced recoil, etc. loads.

As for detonation, this (elusive) phenomenon is most closely associated with GALLERY loads (small charges of fast burning pistol powders) in which the internal case (may) result in a flash-over detonation etc. As was alluded to above, NOBODY has been able to reproduce this. What is a ALSO wrong with Gallery loads, especially with fillers/wadding is BARREL "RINGING." Not that I don't occasionally use poly-wadding loads in straight walled rifle cases (45-70/38-55), but I know what the risks are.

4895 and Varget are both DANDY options for reduced loads but make sure you don't stray below manual limits. Likewise, I am a BIG fan of BOTH Trail Boss and Red Dot for rifle loads with JACKETED or LEAD bullets in bottleneck and straight-walled cases..