Wadcutter Velocity in Snubbie

[docsleepy]

Is it normal for double ended wadcutters to significantly perform better than SemiWadcutters in 1-7/8" S&W 642 snubbies?

For target practice, I'm used to 500 fps/3.0 grains W231; 560 fps/3.4 grains W231 with 158 grain lead semi-wadcutters moderately crimped at the crimping grove, conical portion sticking out.

Today for the first time I tried some 158 grain double-ended wadcutters, lead, crimped same amount at the groove so just a tiny nubbin stuck out of the case, 3.0 grains of W231 and was astounded to measure 638, 610 and 624 fps with the same chrony. Rechecked a SWC 3.0grain-498; SWC 3.4 grain--555 fps.

Is this normal?

Is it because the wadcutter starts out maybe 1/4" further aft, and therefore maybe spends a little more TIME in the high pressure gasses?

Or does it have to do with reducing the available volume in the case because the WC is so much more INTO the case than the SWC?

I was impressed. It adds a lotta foot-lbs!!

 

[jfh]

If I follow you correctly--the issue really rests in the seating depth of your two rounds. Measure that--i.e., how much more of the bullet is in the case with a DEWC, versus the depth of a LSWC. To simply this, just remember that halving the case volume would raise the pressure by twice or more....

Jim H.

 

[docsleepy]

Well, the DEWC was certainly seated deeper! But it wasn't compressing the powder at all. I could understand an increase in pressure, but do you think it would be able to explain the 30-40% increase in ft lbs? There were no pressure signs on the primers (but then, these are fairly low power loads both of them I think). Thanks!

 

[Gordon]

Decrease in case volume = higher pressure= higher velocity

 

[docsleepy]

OK, I may make a trial and either seat the SWC at same depth, or alternately seat the DEWC way out so they are same depth. You guys are starting to convince me.

 

[jfh]

Try the latter, docsleepy--i.e., seat the DEWC out so that the seating depth of both the DEWC and the LSWC is identical. Measure the seating depth prior to loading, and tweak your seater so that both bullets are seated to the same depth, but (presumably) with the same crimp, in a groove. I'll bet the results are virtually identical with the same load.

Gordon explained it concisely--and yes, that depth change / decreased volume can explain the foot-lbs. difference you've identified. That change, incidentally, can be critical in working with max loads in, for example, a high-pressure cartridge like the 10mm Auto.

Jim H.

 

[docsleepy]

I don't have "QuickLoad" but searching around I found several posts where people calculated widely different pressures depending on how deeply the DEWC was loaded....suggesting you guys are right on!

 

[docsleepy]

jfh: Very smart suggestion. Yep, didn't realize I was so dumb. Glad I was using only 3-3.4 grains of W231! I measured the velocities because I wanted SOME indication of what was going on, and sure glad I did. I'll seat a DEWC out to nearly the same position as a SWC and recheck velocity. You're probably exactly right that the result will be right back down in the 500's.

 

[docsleepy]

I spent some time with Hodgdon loading data and you guys are certainly correct. They have data for a 148 Gr LHBWC loaded flat FLUSH with the end of the case, and a 140 XTP (similar weight) loaded considerably longer -- and the max loads differ by 0.6 grains of W231!

Extrapolating from their data, I was still well within a max load, but the depth was clearly the causative factor. Lesson learned.....I should have much more carefully planned. I was just lucky that I used a load that turned out to be within limits....I certainly didn't read enough beforehand!

 

[jmortimer]

Here is standard pressure 150 grain hard cast DEWC from Buffalo Bore at 900 fps penetrating 24" of ballistic gelatin out of S&W 642 with 1 7/8" barrel. That is a lot of "gun" considering it is "only" a standard pressure .38 Special. A picture worth a thousand words http://www.brassfetcher.com/Buffalo...r standard pressure Hard Cast Wad Cutter.html

 

[Ed Harris]

Don't see how they can get 900 f.p.s. from a 1-7/8" snubby at so-called standard pressure. That's what I get with 147-gr. Federal Hydrashok +P+ LE loads in those guns. Ordinary factory HBWC ammo of any make gets about 700 f.p.s. from the J-frame snubs. To get 900 f.p.s. from a 146 DEWC bullet from a 2-inch snubby I have to load 9 grs. of #2400 and THAT IS NOT a standard pressure load. It exceeds factory +P pressure, and approximates the velocity of the HydraShok 147-gr. +P+ in these guns.

My standard pressure DEWC load with the Saeco #348 bullet uses 3.5 grains of Bullseye, with the bullet crimped in the normal crimp groove. This gives 720 f.p.s. in a 2 inch snub, 800 f.p.s. in a 4-inch. and 870 in a 6." It is a full charge, but standard pressure load. Have not tested it in gelatin, but I get 26-30 inches of water jug penetration, which would approximate 17-20 inches of gelatin.

This is a well proven, safe load useable in any sound .38 Special revolver.

 

[Texasgunlover]

Make sure to check specs. A deep seat+ a firm crimp can be a disaster.

 

[jglcolosprgs]

Okay, let me throw this out there.

Were the wadcutters 148 grain? Not 158? Maybe a mis-marked box?

Just a thought.

 

[docsleepy]

jgl: wow, what a detective!
I'm getting more embarrased by the minute here. I went back and looked at the box and bingo: it is 148 not 158....I weighed three of them on a good digital scale and they're right at 149-150, which presumably is the added mass of the lube.

I don't have a load chart specifically for AJ Cast Bullets lead, beveled base double ended wad cutters, 148 grain,

but the Hodgdon manual for 148 Gr hornady LHBWC suggests Win231 4.0 max, loaded to a COL of 1.160 (that's flush)
giving a velocity of 956 (but in a 7.7" barrel!!!!) with a pressure of 15,900 CUP.
My seating was a tad longer than that because I crimped lightly in the groove, not over the end.

I used 3.0 grains of W231 and got 600+ out of a 1-7/8" barrel (much higher than I expected since I wasn't thinking about the seating and didn't realize they were 10 grains lighter than what I'm used to)-- but I was throwing the powder (not weighing individually). I was using very low loads, but still red-faced over all the things I messed up on...sorry for all the confusion....

 

[Oyeboten]

This is good reading...


So many 'little things' in re-loading, which are not little things at all.

'Details'...

 

[jglcolosprgs]

You know, we all learn from our mistakes.

Therefore:

I should be the smartest guy on the planet.

Someday I'll let you know how I tripped to looking at the bullet weight. LOL!

 

[336A]

Is it normal for double ended wadcutters to significantly perform better than SemiWadcutters in 1-7/8" S&W 642 snubbies?

For target practice, I'm used to 500 fps/3.0 grains W231; 560 fps/3.4 grains W231 with 158 grain lead semi-wadcutters moderately crimped at the crimping grove, conical portion sticking out.

Today for the first time I tried some 158 grain double-ended wadcutters, lead, crimped same amount at the groove so just a tiny nubbin stuck out of the case, 3.0 grains of W231 and was astounded to measure 638, 610 and 624 fps with the same chrony. Rechecked a SWC 3.0grain-498; SWC 3.4 grain--555 fps.

Is this normal?

Is it because the wadcutter starts out maybe 1/4" further aft, and therefore maybe spends a little more TIME in the high pressure gasses?

Or does it have to do with reducing the available volume in the case because the WC is so much more INTO the case than the SWC?

I was impressed. It adds a lotta foot-lbs!!

Yes due to the fact that the bullet is 10gr lighter. The bullets have less friction to overcome when moving down the barrel because they are shorter. Take a look at what is listed for the 148gr DEWC with Unique in the Speer #13 manual. I don't have the book in front of me at the moment but it is a standard pressure load and the performance will suprise you.

Ed the Federal +p+ 147GR Hydrashok is poducing more pressure because it is a jacketed bullet. A lead bullet will move down a barrel a lot easier than a jacketed bullet wlll and move faster at lower pressure due to having less friction. It is a given that a lead bullet that is propelled by an equal amount of pressure as a jacketed bullet will always travel faster.

BTW here is a interesting bit of ifo on that +P+ load. I thought that I would pass this along as there are always a lot of questions regarding this loading. A member over at the S&W forum emailed Federal about the 147gr +P+ load to find out what pressure this load operated at. IIRC he got a reply back that the load was breifly going into +P+ pressure as it was hitting a MAP of about 22,500 PSI. It certainly is not operating quite at the nuclear level pressures that a lot of folks believed it to be operating at.