DPX 110s and five other loads chrono'd from my 442


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nitesite
September 2, 2007, 04:21 PM
Per the esteemed Jim March's suggestion in another thread here, I did some chronograph testing this afternoon of Cor-Bon DPX 110-gr .38 Special +P ammunition.

The impetus behind his suggestion was because I have had less-than-satisfactory expansion results when I have shot this ammo thru my S&W no-dash 442 2" J-Frame. Jim surmised that I may have a "slow gun" for this particular round, even if it performs well with other brands of ammunition.

So here are the findings and observations I came up with.

First, I assembled five factory .38 Special loads, all rated +P and ranging in weight from 110-grains thru 158-grains. I also added one of my own handloads, 148-gr hard cast BBDEWCs made by Leadheads over 3.8 grains of Titegroup and Federal 100 primers.

http://i4.photobucket.com/albums/y141/nitesite9/442_chronotesting.jpg

First, I soaked the bore and chambers with Kroil then followed up 30-minutes later with a brush and dry patches until everything was clean and dry.

Since we suspected that the DPX bullet might be a sub-performer I selected to shoot them as the first string out of my 442 with the barrel cold. I figured that as things warmed up the velocities might slow down a bit and I wanted to give the DPX it's best run down the barrel.

Chrono data was taken at six feet from muzzle, 669' ASL, 81 Fahrenheit.

I worked thru the various strings with the lightest bullets first because they are either all-copper, Nyclad, or jacketed and I believed that therefore they would not contribute to leading of the barrel. The first lead bullet was the Georgia Arms 158-gr LSWCHP, since their lead is harder than the Remington 158-gr LSWC. The last string was with my handload which is just a standard pressure .38 Special load at lower velocities.

In the second photo you can see the order I chose from L→R for the various strings:

http://i4.photobucket.com/albums/y141/nitesite9/Six_38Spl_loads.jpg

110 DPX +P, Federal Nyclad 125 +P, Gold Dot 135 +P, GA 158 +P, Remington 158 +P and my standard velocity WC load.

So here are the velocity results. Every string was five shots each, and I had good light so there were no errors.

http://i4.photobucket.com/albums/y141/nitesite9/442_chrono_results.jpg

As Jim surmised, the all-copper DPX bullet apparently does not like my gun. Advertised velocities on the box are 1300-fps but all my 2" gun could muster was an average 922-fps.

The entire test showed average velocities that differed by a mere 160-fps, with the Georgia Arms load coming in the slowest. I really thought there would be more than 140-fps difference between my handload WC and the DPX!

The GA load really belched smoke when fired, and there was quite a lot of it. But look at those ES/SD numbers!!!

The Gold Dot load was the only one to show any unburned powder, and it was like yellow-gold flakes not ash or small burned particles.

Remington really made their load amazingly consistent, didn't they?

What surprised me the most about the NyClad load was its sharp recoil. Perhaps it's because I haven't shot any factory ammo from this gun in a while, and I tend to stay with heavier and slower bullets than a 125-gr +P HP. I didn't care for the recoil pulse that I experienced when shooting it.

So thanks, everyone, for taking the time to wade thru all this mess. If you have any comments or suggestions you are always welcome to make them.

Now I guess I'll just shoot up the last of the DPX ammo and harvest the brass. I never was much of a proponent for lightweight bullets from a .38 Special anyway, and now I'm convinced that my little 442 doesn't care for them much either. :p

Bye, Y'all... Enjoy your weekend!

nitesite

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Maddock
September 2, 2007, 06:12 PM
Thanks for the data. How does the point of impact change between the different rounds out of the 442? I find that with mine the Remington 158 +P is about 1 1/2" above POA at 25 yd and the Winchester 110 gr +P is about a foot lower.

Jim March
September 2, 2007, 09:08 PM
YUP! That was it.

OK, for comparo purposes, let's look at Brassfetcher's numbers:

http://www.brassfetcher.com/110%20grain%20Cor-Bon%20DPX.html

He shot five into denim-wrapped gel and speed-tested them at the same time.

Four of his five shots flew close to 1,100fps - all were 1064+.

ONE was slow, a bit over 1,000. And that one barely expanded at all.

There was nothing wrong with Nitesite's test media - thin wet chamois over meat :). He got total expansion failure - now we know why.

So what have we learned?

Something about the DPX 110+P is finicky about what it's shot out of. Nitesite's gun isn't half bad - it's shooting the Remmie 158+Ps a *bit* slower than what we usually see (around 850) but not that far off and still within the Remmie's known performance envelope of "anything past 800".

Upshot: the classic old Remmie turns out to be a more reliable performer in more guns than the Cor-Bon. Second up, the Gold Dot 135+P isn't sucking too badly either but net energy, the Remmie wins.

VERY interesting.

Nitesite: one more thing to check :). What's your barrel/cylinder gap? Can you measure it at full lockup? (See also the "revolver checkout" sticky...)

nitesite
September 2, 2007, 09:52 PM
Good evening, Jim.

I took the time to edit my first post to correct the unfortunate misspelling of your name. Sorry. I hate editing anything I write, but you deserve to be referred to correctly. :o

I also took the time to correct a couple of small spelling errors along the way, but didn't alter any of the body of data or the results.

As to checking the barrel/cylinder gap at lock-up, I cannot do that here at home since I lack a set of feeler gages.

This was FUN and I am very glad to have this forum as a medium to share my experiences, and to read your own personal experiences and expertise!

Maddock~ my observations are about the same as yours.

P. Plainsman
September 4, 2007, 06:49 PM
This was an informative test; thanks so much for putting it together!

Interesting how uniform the Rem and GA loads proved, with their heavy, plain lead slugs.

What follows is utter speculation. I wonder if the problem with the DPX might be that as a solid copper (alloy) bullet, it doesn't obturate much in the barrel, so gas slips by instead of pushing the slug? Maybe your bore is a little larger than the DPX prefers; not enough to make any 'druthers with the other loads, which are plain lead or at least have lead cores under their jacketing; but enough to deprive the DPX of some needed juice.

Total guesswork, that.

Jim March
September 4, 2007, 07:05 PM
Yeah, but it's good guesswork. It's what I suspect...the DPX is barrel-sensitive.

And THAT is interesting. Even the suspicion was worth knowing about and I thank Nitesite for the testing. I know I'm going to chrony DPX in my barrels before carrying them.

Nitesite, understand that I would *never* criticize anybody doing bullet testing and posting online. I'm not set up to do it myself, I wish I was. We *always* learn something from these tests. And I remain convinced your original test media was pretty damn good. Makes more sense than the old hams (literally) used by the Quinn brothers once :). Although to be fair, they were testing the Pow'R'Ball which is allegedly clog-proof...

fast200
September 4, 2007, 10:37 PM
I liked the classic Rem 158 also, until I had to clean the gun. It was probably one of the dirtiest rounds out of my snubbie that I've ever used. Buyer beware.

DawgFvr
September 5, 2007, 01:44 PM
What I gather here is that the 110 Grain Corbon DPX is a good round...if/when fired out of a three inch barrel? I mean...is the implication here that the barrel from the short nose snubby, e.g., 642, 442, etc., is too short to launch the all copper bullet the required 1000 fps needed to expand?

P. Plainsman
September 5, 2007, 02:47 PM
More barrel length will almost certainly help, but we're also speculating that slight differences between different .38s/.357s in the width of the bore may play an important role in determining whether the DPX makes it up to speed in your gun.

Jim March
September 5, 2007, 02:52 PM
What I gather here is that the 110 Grain Corbon DPX is a good round...if/when fired out of a three inch barrel? I mean...is the implication here that the barrel from the short nose snubby, e.g., 642, 442, etc., is too short to launch the all copper bullet the required 1000 fps needed to expand?

No, I'm afraid the situation is weirder than that.

Some 2" S&W snubbies are spitting these out at close to 1,100fps. See also the Brassfetcher test. When they are moving out past 1060fps, they seem to work great. In the brassfetcher test one round went slow, at 1016, and mostly failed.

So JUST the Brassfetcher test tells us these need somewhere between 1016 and 1064fps to work right...depending some on the target (test media or real thing-needing-killing) of course.

Now punch in Nitesite's data: his 2" S&W spit them at under 1,000fps, consistently. He got a total expansion failure. Yet Nitesite's gun isn't a junker, it's spitting Remmie 158+Ps fast enough (still a bit on the low side).

That matches the Brassfetcher data on required velocity. But it leaves us with a real problem: why did this stuff go so slow out of Nitesite's gun!?

We still don't know. Bad news, because even if Nitesite's barrel was 3", that would add about 50fps and we might STILL be under the round's "velocity sweet spot". We have to go out to 4" to be sure that in a worst-case barrel incompatibility situation with this load, we're still going fast enough for expansion.

Yikes.

So esp. in snubbies but really in any gun, we've got to chrony-test the DPX in order to really trust it.

And guys? This may even apply to the DPX in other calibers.

Ouch.

P. Plainsman
September 5, 2007, 03:55 PM
This may even apply to the DPX in other calibers.
That's what I was thinking. Would love to see a few more autoloader tests of the DPX round.

Off the top of my head, here's the redoubtable Mr. Camp testing the 115 grain 9mm+P DPX load:

http://www.hipowersandhandguns.com/Corbon%209mm%20115.htm

Notice he got 1233 fps from this "+P" designated 115 grain round from a full length BHP with Bar-Sto barrel.

Of course, 1233 fps is still decent, and it looks a whole lot different from 922 fps when we're concerned about reliable expansion.

saltydog452
September 5, 2007, 08:36 PM
Thanks for the post.

351 WINCHESTER
September 5, 2007, 10:14 PM
Nice info guys. I think temperature plays a bigger role in velocity than a lot of us think. I helped the infamous brassfetcher test some loads in my 1 7/8 640 and my 4" model 64. Buffalo bore 125 +P was just under 1300fps from a 4" and their 158+P was just under 1200. It was really hot that day - probably 95 or so. I don't recall the mv from my snubbie, but they were "up there". Years ago I bought some of the early corbon +P 110 gr. and they felt like a .357. Corbon used to make a 115 +P (a 9mm bullet) - it was a screamer for sure. I think there were a lot of airweights with stretched frames and corbon had to back off.

Ichiro
September 6, 2007, 01:13 AM
Great stuff. Makes me feel better about my choice to load all 5 of my revolvers with the Remington FBI load.

I've been looking for good reasons not to buy Corbons and Gold Dots for $1 per round :neener:

nitesite
September 6, 2007, 11:33 AM
I really appreciate everyone who helped join in this discussion. I had hoped that my efforts to test, photograph, and report my findings, would be informative.

Many thanks to Jim March and P. Plainsman for their learned observations. Your input and encouragement is appreciated.

Mr. Stephen A. Camp is indeed a respected authority and his writings are held in very high regard. The fact that he uses "scientific mud" and saturated newsprint (even water on occasion) bolsters my belief that gelatin testing is not the "BE ALL ~ END ALL" test medium we must make use of or else we're not credible.

Jim, I keep meaning to take a borrowed set of feeler gages home with me to check my b/c gap.

Respectfully,

Dave (nitesite)

glockman19
September 6, 2007, 12:37 PM
nitesite,

thank you for the analysis.

Jim March
September 6, 2007, 12:53 PM
Nitesite:

I'd like to know the gap, but...it's quite possible that's not it. Or not all of it anyways.

The fact that the Remmie lead loads are losing (comparatively) less speed than the DPX says it may be a "bore issue".

nitesite
September 6, 2007, 05:15 PM
Originally posted by Jim March

Nitesite:

I'd like to know the gap, but...it's quite possible that's not it. Or not all of it anyways.


Hello again, Jim.

Since I couldn't seem to remember to bring the feelers home from work, I just brought the 442 with me to work today.

Three chambers just barely accept the .010" blade, the other two are no-go with .010". My best hunch is .0085" ~ .009" if that's any help.

Thank you for your time and interest in this thread!

nitesite

Jim March
September 6, 2007, 05:37 PM
Ug. That's...wow...big. Worse than I expected. I personally like how my snubby 38spl is down around .002". That's not a universally accepted view: with that sort of gap I have to wipe down the cylinder face and back of barrel around every 40 - 50 shots, sometimes less. Doesn't bother me, ain't no way I'd shoot that many in a fight and it's the penalty I pay at the range for max velocity in a fight.

I know of few informed people who would prefer a gap bigger than .004" in this class weapon. Many view .003" as the sweet spot in guns like ours; I lean to the .002" viewpoint. Some people shooting big-bores like a .005 - .006" to deal with the largest possible soot particles that can happen with some ammo. But in 38/357 that's never necessary. I'm satisfied with the .003" or a hair over I have in my New Vaquero as that has a 4.68" tube making velocity a bit less critical (plus it's a 357!).

Sadly, I believe S&W would still call your gun "in spec".

Your gun is an example of why I run "the checkout" prior to purchase.

B36
September 6, 2007, 07:15 PM
nitesite--remember any test medium must first be consistent.

Next, the test medium [if consistent] allows comparison between various ammo, and really does not tell how any bullet is going to perform in people.

In the testing I have seen or been involved in, 4 layers of denim has always been used--again in order to be consistent.

If you go to www.stoppingpower.net [Test Bed Forum] and do a search for DPX, you will find a lot of information.

Recently we used several blocks of gelatin [Vyse], with about 6 different calibers of DPX. .223, 30 carbine, .38+P, 40, and both .45 loads.

All expanded great, and almost looked alike. This was done at Marshall's Shooting Center in Midland, Mi.

351 WINCHESTER
September 6, 2007, 08:13 PM
S & W specs. for bbl./cyl. gap. Some years ago I bought a new 940. When I got home I noticed a rather large gap. I measured it and it was right at .011. I called Smith the next day & asked them what their max. specs. were and I was told .011. Well I sent it back to them and asked to set it from .004 to .006. I forget what I ended up with, but it's a lot better than .011. By the way, there was no charge as they also had to replace the firing pin which was way too sharp and was piercing primers.

nitesite
September 7, 2007, 12:25 PM
Hasn't this thread taken some interesting twists and turns??? :)

My thanks to all who have participated! Some of us have hopefully learned something by wading thru this topic, myself included.

I guess I should be ashamed at myself for never checking the gap on this revolver, although I've owned it now for several years. I traded for it even up for a NAA .32ACP Guardian that I hated. The 442 was LNIB but no box or docs and I think it was a darned good trade. I've carried it plenty over the years.

So I've got a "slow gun". Things could be a lot worse, right! :D

The upside to this discovery should be that anybody else shooting a similar J-frame should see higher velocities from the same brands of ammo I tested.

Maybe I'll have the gap snugged up by S&W. Maybe not. It still shoots the heavier bullets just fine, and that's all I shoot anyway. In spite of the large gap I still like my 442 as much as ever, and it continues to serve me well as an occasional concealed carry gun. And the fact that it has no lock makes it even more endearing to me. I don't think I'll be looking for a replacement anytime soon.

Thank you, All! See you around THR...

Dave (nitesite)

If you enjoyed reading about "DPX 110s and five other loads chrono'd from my 442" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!