Home Forums Hunting & Shooting Ask The Gunwriters RETUMBO: A VERY COOL BURN

Bend...thanks for the printout. Interesting..
Barrel length on my rifle is 24 inches. COL 3.627 Wby chambering in a Remington Classic.
Both loads are a grn short of max, per the latest Nos manual.
The quickload print out suggests I should be getting more out of the RL-25 load, and the reverse is the case. I am not getting the velocity the book suggests either, slow by about 30 fps.
With Retunbo, I`m over the suggested book velocity by almost 50 ft. So much for book stuff, tho it is in the ball park.
Neither load showed any signs of excess pressure. At least mone I could see or feel, and looking at the pressure curve caused by RL-25, I should have had a hard bolt lift.

Think I`ll stick with common sence and my crony...:)

I am going to shoot the same load again tomorrow...I`ll tell you how it goes.

WHOA NICE!!

Retumbo is the only powder I use in my 300 RUM these days.

Hmmmm....interesting....I may have to try some Retumbo.Looks good!

Butch Searcy told me many years back that in general the double base powders (R22 and 25,etc) have a " higher " flame temp than the single base powders(7828,Retumbo?),and will give somewhat longer barrel life....by how much I dunno.

Edited: I screwed up above;it's the double base stuff that has the higher temp;Sorry!

Bob,

I need to re-shoot the 73.0 load. Only loaded up three with that charge, out of a clean barrel the first was low, the next two touching.

May be a moot point though. I hung three targets, one behind the other and shot three, three shot groups. The last target (which had all 9 bullet holes) measured just over an inch, all 9 shots touching. That was with the 70.0 load of RL 25.

I mounted that S&B on her last night, yowza!!! Hoping to sight her in Sunday and re-shoot the Retumbo load.

Could be. I don't know how exothermic the combustion of nitroglycerin vs. nitrocellulose is, but according to some calcs done by others here and here, nitroglycerin's expansion ratio is around 3.5 times that of nitrocellulose's. If the combustion of nitroglycerin is less than 3.5x as exothermic, then a double-base powder would show lower temperatures (as well as lower charge volumes) than a single-base.

MZ5: Sorry I screwed up;see edited post above.I got it backwards.

Could still be the exothermic vs. expansion ratio issue, if things are reversed from what I had posted.

My observations, though, are that Ball rifle powders (yes, I mean Winchester) run cooler than stick powders. I don't yet have enough experience with Ramshot vs. the stick competition to comment on them. It is frequently (always, IIRC?) the case that Ball powders are double-base, whereas stick is generally single-base (that's becoming more of a mish-mash these days).

So, either someone somewhere got it backwards, or else there's something about the inhibitors in the specific powders I've compared that's responsible.

In the case here of Retumbo vs. Re-25, the issue could be mainly the pressure difference. I don't really know.

Well, thought I`d call the Horse on this question, so did this morning. Talked to a very nice rep. He didn`t have a clue, and said they, Hodgen, does not check for barrel heat, or heat generated from any powder manufactured or tested by them. At least he was honest!
I would think cooler burning propellants would be something one could "crow" about?
Didn`t get the chance to reshoot last nite, will try again tonite after work.

I'm sure they will be working on a new "coolness" add now

Winchester literature did crow about that when Olin was selling its own propellants.

I'm not sure how to put this delicately, so I'll try to be politely direct:
Some of the people who answer the phone at Hodgdon have proven to be somewhat 'variable(?)' or even unreliable in the information they share with me. I have spoken to the same person on various occasions, and received exactly contradictory info from that person.

My point is merely that I'm not surprised at all that you received the reply you did, nor would I be terribly surprised if you got the opposite response at another time.

Yea, I wondered about that....tho after my explanation of what I`d felt..he came right back to say they didn`t test for barrel heat. He also mentioned Retumbo was not considered to be applicable powder for the 7 Roy. by Hodgen...told him the load came from the latest Nosler book.

Come to think of it, Sierras` tech people seem to be the best with hands on experience.

Then again, how many people do touch the rifle barrel??

Wonder if I get a pay-off in powder for the rest of my life for the new "COOL" ad???