Some work on .38 Spec.

[Brick]

Here are the results from some testing I did today with some Steel Valley Bullets and differing powders.

SV's 147 grain RN is a 9mm bullet sized up to .358" dia. The 158 RNFP is a standard .38/357 offering in .358" dia. I was originally pinning my hopes on Accurate #5 and wanted to see if Ramshot Silhouette and Hodgdon CFE - Pistol might be OK also.

SV's bullets were correctly sized based on measurements and weights seemed correct also. The coated bullets seem to need a bit more "push" than cast lead. So some added workup will be needed. That being said the 158 gr RNFP loaded with CFE-P (5.1 grs.) was an instant winner and easily exceeds the old IDPA 125K power factor.

As always the screens were located 15" from the muzzle, the instrument was an XP-1 chrono.

I'm unable to explain some of wide variations in individual speeds or the high Std. Dev. all loads were individually weighed and powder trickled in to bring the weight to true. Scale was a beam scale and set to true with check weights. Any suggestions of improving powder dispensing and tightening weighing operation appreciated.

BTW don't forget to look at the attachment!

[DucatiRon]

Nice work Brick.

Alot of times I find hi std dev because of either crimp pressure being inconsistant because of case length or tensile strength of brass being fired and reused multiple times.

[Brick]

Nice work Brick.

Alot of times I find hi std dev because of either crimp pressure being inconsistant because of case length or tensile strength of brass being fired and reused multiple times.

Oh gee! The thought of trimming and chamfering a couple thousand cases doesn't do much to thrill me!

I could also start using a light cardboard wad like I once did. Punched out of empty primer boxes, sized to the inside diameter of the .38/.357 case and set in the case about 0.10" above the powder charge, it holds the charge against the primer for better ignition. The down side is very rarely a wad will get stuck between cylinder and forcing cone and jam the revolver. But, it is not really needed if I can hit the right charge weight.

[DucatiRon]

What about a fiber filler ? Like that pillow stuffing. Plastic stuff. Used to use it to fill up the space in rifle cases on low charge low velocity rounds ?

[cephas]

Could it be the chrono? My ancient Pact chrono instructions recommend screens be set 5-10 ft. away. Depending on what your testing muzzle blast becomes a factor. Learned to use a "blast screen", for lack of a better term. Simply a barrier, plywood or heavier cardboard, with hole in the middle for bullet to pass but blocks majority of blast.
Looked around and found interesting post by Oehler: "You should be more worried about the effects of flash and blast. Nasty things happen near the muzzle and as friend Ken Howell mentioned, a blast shield hides many sins. Remember that the really nasty effects of blast are when you have a subsonic bullet preceded by a blast wave traveling at the speed of sound. That blast wave often fools the skyscreens before the bullet gets there."

Edit: Had a thought. If you think it may be powder position hold the revolver barrel up before each shot, tap the grip a few times then lower slowly and test. Hopefully all the powder will be positioned next to the primer. However this would be unusual with powders in this "burn rate". Keep us informed.

[Brick]

What about a fiber filler ? Like that pillow stuffing. Plastic stuff. Used to use it to fill up the space in rifle cases on low charge low velocity rounds ?

Dacron, Kapok, etc. Some have used it in the past. Come to think of didn't black powder shooters at time use cream of wheat for that purpose. Anyhow I don't think it'll be needed. Once I get the charges right it'll work just fine!

I know I'm working with .38 Spec. and for my own reasons I want to stay with standard rather than +P loads. But I'd bet dollars to donuts that 147 gr bullet would be a real winner as a .357 Magnum load!

[Brick]

cephas asks "Could it be the chrono" Not this time. My brother was with me using his own Chrono on some rifle stuff he was working on. Using ammo that wasn't part of the test loads I was getting similar reading on both machines. I do admit the Pact I'm using now is one of the most finicky machines I've seen! If the battery voltage is a little low it won't work, if the too strong or light is coming from the wrong direction it won't work. I set the screens up 15' away from the muzzle to avoid the effects of blast.

[Brick]

I think I found part of the problem. Months ago I retired my 40+ year old Ohaus 5-0-5 beam scale and replaced it with a new RCBS 5-0-2. I also have a Hornady electric scale. It seems the 5-0-2 has a bit too much slop in the seat for the balance knife edges and even though the scale meets calibration if the beam is too far forward or back it will not read correctly. I discovered that today while loading some test rounds for my rifle. On a significant number of tries after trickling in powder on the beam scale the electric would read over or under. Reweighing on the beam would confirm the error. So for now I've brought the Ohaus out of retirement (really the closet) and I'll go over it with some check weights and be sure it meets spec and for a time I'll use the electric scale to confirm readings. I don't really like the electric that much. Too many times I've seen it change readings for no apparent reason. Often it cannot even read the same weight twice for the tare.

[Bang]

As always the screens were located 15" from the muzzle

The " caused some confusion. I was wondering how you get away with it.
In my somewhat limited experience at checking loads by Chrono, I'd say load (amount of powder) has a definite affect on deviation.
Finding the right load will fall into a .2 grain slot in my experience. That's assuming the chosen powder is appropriate.

Just read the latest post. I have an M5 Lyman purchased in 1970 or so. Still using it. The agate blocks are fine as are the knife edges. I too see inconsistent readings on a Hornady digital during tare. I just don't trust it to maintain a uniform .1 for critical loads, but in my world pistol target bullets aren't that critical.

[Brick]

Just found a reference I had regarding a product called PUFFLON. You can read all about it here: http://www.pufflon.com/