High Pressure or What???

[shooting on a shoestring]

Its a puzzler to me.

The gun is an early 1920 Colt Police Positive Special chambered in .38 Spl (says so on the barrel, and the chamber has the right dimensions). The barrel is 4 inches, some pitting, the chambers are shiney. The barrel slugs at 0.357 groove diameter, the throats are all very uniform and hover right around 0.358, I wish new revolvers would come with such dimensions. The barrel/cylinder gap is 0.010", yep kind of wide. The end shake is the same 0.010". Upon cocking, the cylinder face thrusts against the rear of the forcing cone. If cocked slowly, the cylinder will not quite rotate into battery. If cocked smartly, it will. All the shooting described here was with the cylinder checked to be locked up correctly before pulling the trigger.

The load is 3.0 grains Bullseye, Remington 1&1/2, 358477 cast 50%WW/50% Pure Lead, air cooled, Felix lube.

The spent cases look like .357s. The primers are flattened, the radius at the corner of the primers is extremely small, some of the primers show piercing in the bottom of the primer indention. Looks like high pressure.

From the chronograph 5 shots avereraged 726 fps, SDEV 20.

Same loads fired in 2.25" SP101 over chronograph show expected round corners on the primers, no piercings and chronographed 655 fps SDEV 20.

The Colt PPS shoots 2.5 grs Bullseye, Rem 1&1/2, 358087 at 667 fps/SDEV 13, all looks normal, no flat primers, no piercings.

Is the 3 gr BE/358477 load really high pressure in this gun, or is something going on with the end shake, or what else could be happening?

[JMtoolman]

I suspect the cyl is slamming back after the chamber has fired, flatting the primers. Remove the end shake, and everything should be all right. Just my guess though. The toolman

[Bass Ackward]

http://powercustom.com/store/index.php?main_page=product_info&cPath=12&products_id=114&zenid=f212e5c1a1f5aa23a926493cca02ec28

[canyon-ghost]

Is the 3 gr BE/358477 load really high pressure in this gun

I use a load of 3.2 gr BE in 9mm, shouldn't be the that hot, especially in a big old 38.

Ron

PS: your Dad was a wise man, lol.

[theperfessor]

JMtoolman is right on target. Get rid of the end shake.

[spqrzilla]

Its the slop in the cylinder. Basically, the excessive "headspace" (for want of a better word) is allowing the primer to extrude back out of the case on initial ignition. Then as pressure builds, the case comes back, forcing the primer back in. The result is a quite flattened primer that is unrelated to pressure.

[shooting on a shoestring]

Well sounds like the thing to do is get rid of some end shake. Certainly couldn't hurt, might well be the cure.

Thanks for the replies.

Anyone know if the ejector rod has righthand threads? I should know before I apply force.

[olafhardt]

The old colts dont make final lockup until the trigger is pulled Its the way they are made. To check the true end shake and cylinder gap cock the revolver, hold the hammer back and pull the trigger. At this time the cylinder should make a slight jump into place. This is the true shake and gap location. I think it is very cool to watch. It also allows the revolver to tolerate a iot of crud on the cylinder face and still have a small gap. I have gotten 1100 fps out of my 32 s&w long police positive 6inch with 3.2 grains of Unique and the 90gr Hornady swc. I also got alot of leading too. Most gun people seem unaware of this characteristic of old colts. You are forbidden to use this technique todemonstrate to someone that grandpas old colt is out of time and the price should be reduced.

[olafhardt]

Let me add there is probably nothing wrong with this revolver, thats how it was built.

[MtGun44]

Hand is a bit short, needs stretching a bit, the cyl lock should drop into place when cocked
very slowly, just as the hammer reaches full cock. End shake is a PITA on Colt revolvers,
either shims if you can find them or there is a special tool (big $$) to swage the little snout
that sticks out of the front of the cyl. OR - the right way is to remove and strip the cyl,
machine out a hole in the front where the snout is and press in a new one, machined to
exacting dimensions but too long, then fitted properly. Not easy or cheap if you are paying
to do it, but it is the right way.

There is a good 'how to' on doing this for Pythons (same basic design) on the web somewhere.

I have an older Police Positive with the same issues, stretching the hand fixed part of it but,
the cyl end shake is still a bit excessive. I plan on doing the machine and press in a new
snout deal "one of these days". I have the lathe and should be able to do it, we'll see.

There are very good reasons that Colt revolvers are not made any more. I like them but
the reality is that the design is cranky, absolutely MUST be hand fitted on original manufacture
and easily goes out of time, plus it is much trickier to set up correctly than a S&W. This
means that they HAVE TO cost more due to the skilled hand work needed to assemble and
setup at the factory. I imagine it became very difficult to find people that could do this
exacting hand fitting work.

I own, like and work on both, but have no illusions on which is the superior piece of engineering.

I'm sure that the Colt lovers will get out the pitchforks and torches, but this is my considered
opinion based on owning and working on (serious stuff, not cleaning and lubing) both S&W
and Colt revolvers. I do like Colts, but the are just more tempermental than S&Ws. Actually,
a well set up Colt, like a Python, is often extremely accurate due to tight tolerances on the
barrels.

Bill

[Bret4207]

I use a load of 3.2 gr BE in 9mm, shouldn't be the that hot, especially in a big old 38.

Ron

PS: your Dad was a wise man, lol.

No offense intended, just FYI- the Police Positive was a little small framed rig, near a J frame Smith size. You may be thinking of the Official Police which was on the 41 frame, same as the Python.

[ironhead7544]

It seems some guns just dont like some bullet and powder combinations. I would just try some other powder. I once had a 41 Mag M57 that I tried a minimum load with a cast bullet. Had to knock the cases out with a dowel. Stuck tight. I checked the charge weight and it was correct. Also had a M29 and a M64 that seemed to "hate" 2400.

I would try 231 with your revolver.

[MtGun44]

I also agree with Bret, the Police Positive frame is very small, not a gun to be pushing too
hard. Slightly larger than the J-frame and it has 1920s metallurgy, which is to say fairly
soft steel by today's standards. This is why they feel so good, light, handy and small
compared to a K-frame S&W, yet hold 6 rounds.

Regardless of the reason, the gun is talking to you, and needs less pressure. If the
cyl is slightly misaligned at the instant of firing due to the short hand, the boolit slamming
into the forcing cone with some misalignment may be causing higher than normal pressures.

Bill

[shooting on a shoestring]

MtGun44 Thanks for taking an interest.

I did just check as you indicated. Yep. Cocking slowly, holding the hammer, pulling the trigger, the trigger seems to push the locking bolt back a tad which in turn pulls the cylinder into alignment and oddly pushes the cylinder forward a half a smidge. While in this final lock up position with the hammer and trigger being held back, the cylinder gap is very tight, but the cylinder can be pushed rearward which has the odd effect of pushing the trigger forward as the gap is forced wider.

Hmm...

So I need to find some info on how to disassemble the cylinder/ejector rod. Before I decide whether to try bushings I want to have a look inside. And if I do try bushings, I'll need to have it apart any how.

Its a really cute size, has plenty of power for its intended purpose, and just may get carried in a little while.

[MtGun44]

IIRC, the ejector is not intended to be removed, like a press fit. This is why the fix
is not easy. I have studied this briefly because my gun needs this fix, too. I was
hoping to use shims but the dissassembly is not simple, and I forget exactly what I
found out - just that I decided to do the counterbore and insert a new 'snout" for want
of a better word, custom machined and pressed in place.

Here is the link:

http://coltpython.blogspot.com/search/label/gunsmithing

scroll WAY down until you hit "fixing end shake on 41 Mag Python" and follow that
article. This is the proper way to do it, not too bad if you have a lathe. You
have to click on the "Read more" at the end of the 'intro' to follow the article
to the end. He does a fantastic job with pix and text and shows you really
how to do it.

His site is also super good on learning the guts of the Colt revolver action (all
of the early ones are basically the same design in different sizes) and the coolest
is careful dissassembly and photos of action reworks by some of the top
gunsmiths. Some of the action work isn't much to look at, IMO, but apparently
works.

Bill

[shooting on a shoestring]

Well thank you sir. Good read, good pictures, good info.

[leftiye]

Re: failure to rotate into battery - Check also the size of the hole in the trigger where the hand fits. My PPS does this also, and it has a brand new hand. The hole where the hand attaches into the trigger is worn oval shape. Remember the trigger return side of the V mainspring rests on the hand pin and applies force against the trigger.

Ejector should unscrew. Mine does. RH thread. You must unscrew the ratchet to remove the cylinder from the crane. The spring everything works against is housed inside the crane with a special notched screwdriver type hollow threaded tube at the rear, but when you get the ratchet off, the cylinder comes off the back and the ejector rod pulls out the front. You can reduce headspace by shortening the thickness of the ratchet, but be muy careful (don't over do it or it's over). After that you might want to set the barel back some to reduce barrel/cylinder gap.

[shooting on a shoestring]

Leftiye, Good to know.
This is turning into an education on Colt engineering. I wasn't aware before I got this little gem that there was as much difference between Colt and Smith systems.
Its amazing to see this stuff and realize its 1920's. No CAD, CNC, just build and cut the hard way...slowly. Quite a creation actually.

[harvester]

Sounds like the hand definetly needs to be stretched and the cylinder collar needs to be stretched and refit as well. Colts don't get the bushing repair like some others.

[MtGun44]

Like I said - there is a good reason Colt doesn't make revolvers any more. The design is
VERY different from S&W and needs very skilled hand fitting at the first assembly.

Hand stretch is fairly straightforward, I did mine without problems. The cyl snout stretching
tool looks real expensive in the books, and the counterbore and press in a new, custom
made one, seems more viable to me, if you have a lathe.

Bill

[harvester]

Yes stretching the hand and letting it out a little is easy. I think fixing the cylinder collar is a Colt job if they will still do it on an old gun. Perhaps someone else knows who can do it then it will be fixed for another, what, 90 years, not too bad.

[shooting on a shoestring]

It was the end shake. I built a 0.005" shim and put it between the cylinder and the crane. Took it to the range today and the primers looked very low pressure as should be with 3.2 grains of Bullseye under 358477. It won't see many loaded that hot (relative term) I have other modern .38s and .357s to push same boolit fast as I want. This old Colt is for fun and character.

Also, with the cylinder shimmed rearward (back where it should be), the cylinder rolls up into battery as it should.

It was a good day.