38 special load with unique and 162 he runs gc

[Beamer]

I have a s and w k-38 masterpiece, 6 inch barrel. Is 5 grains unique with the rcbs 162 gas cal a bit high for this gun? It seems to be fine but don't want to damage the pistol

[tazman]

Every Alliant manual I have shows between 4.4 and 4.7 grains as max for a 158 grain boolit. I would drop the powder charge a bit.
The later manuals show 5.2 as max +P.
I have one of those pistols and it is a fantastic shooter. Mine was made approximately 1950-52 before the model 14 became a thing.

[Petrol & Powder]

WELCOME !

A S&W K-38 is a fantastic revolver !!

That load is a bit too hot ! Standard pressure max with a 158 gr LSWC is achieved at 4.7 grains of Unique. I would back that load down below 4.7 grains. Those are excellent guns, please do not abuse such a classic K-frame.

And, there is NO reason to use a gas check bullet in a 38 Special unless you just happen to have a supply of them. A plain base bullet is all you ever need in the 38 Special.

BTW, while Unique is certainly an acceptable powder for 38 Special loads, there are some other choices available.
Bullseye is the classic powder in 38 Special and it is popular for a good reason - it works really well.
WW231 [also known as HP-38] is an excellent powder for 38 Special.
Both Bullseye and WW231 meter well if you are using a powder measure and for that reason I prefer them over Unique.

[Kraschenbirn]

I agree with P&P...no reason for GCs with .38 Spl. loads. For all around practice/plinking, I load a powder-coated 162 gr RNFP from an Arsenal mold over 5.0 gr. Unique but only shoot it in my .357s. And, the only reason I used Unique for these loads was that it was what I had on-hand at the time. WW231/HP-38 or Herco IMO are both better choices.

Bill

[rintinglen]

These days, I will parrot the fellows who recommend lighter loads, because they don't them make like that any more. My own M-14"s get nothing but mild wadcutters with titegroup, Bullseye or WW231 loads.

But 35 years ago, I shot thousands of 357-446 162-ish grain SWC's over 5.0 grains of Unique, out of my M-15 Smith and it still seemed tight when it went down the road to fund the purchase of my M-66. Unique's MAX load was listed at 5.2 grains, at 16, 200 CUP in the old Lyman 46th edition. Lighter loads with this boolit were less accurate and the heavier load mimicked the 38 +P We carried on duty back then. If those loads were all I had today all I had today, I'd still use 'Em. I'll be gone before I wear out either of these.

[WHITETAIL]

+1 to what P&P said.
I went and dugout my new 4th. ED.
Lyman Cast Bullet Handbook.
They have listed Lyman #358311 160gr.pb.
4.2 to 4.7 Unique.

[FISH4BUGS]

No need for gas checks. I shoot my Model 36 3", Model 28 6" and the Colt Officer's Model Match all with H&G #51 and 4.2 gr ww 231. I have probably 10,000 rounds through the 36 (it is my favorite shooter) and still as tight as the day I got it.
Don't use +p ammo loads. The gun is not built for it. DO find a load below max that will provide the accuracy you need. Try using 231....dirty but cheap and accurate.

[Winger Ed.]

Great gun. I'd load for it on the low side and tweak around a bit for the best accuracy.
If you're hunting those little black paper dots-- ya don't have to hit them very hard, they're pretty easy to kill.

[gwpercle]

Lyman #4 says 4.2 to 4.7 grains Unique for standard load.

Up to 5.3 grains of Unique is max. +P load...don't go there with vintage K38.

For accuracy 2.5 to 3.0 grains Bullseye is just magical.....just try Bullseye once.
I could never get an accurate light target load with Unique... I tried for years and could not get it to work.....Bullseye... 2.8 grains and a 160 grain wadcutter...one ragged hole groups...It's Magical !
Gary

[fredj338]

I rarely run max loads in any of my old S&W. I doubt you hurt anything, the gun will take +P loads, but for punching paper, no real purpose in it. Same for the gc too, just not needed.

[MT Gianni]

Back when the Lyman manual said 5.4 gr Unique was a max load with a 158 gr pb my model 14 saw a number of those. The gun is fine but they aren't making them anymore so it doesn't get warm loads.

[Larry Gibson]

I've been shooting 38 SPLs loaded with Unique under 158 PB and 162 gr GC'd 358156s (your RCBS is very similar) in several M15s since the mid '70s. I used 5 gr Unique as a standard load and shot literally thousands of them as it was my duty practice load when I was an LEO. I also loaded HP'd soft cast 358135s over 5.5 gr Unique which duplicated the carry Winchester 158 LSWCHP "FBI" loads which was our duty ammo.

Subsequently after obtaining the ability to pressure test also I have pressure tested those two loads and various standard 158 factory loads. The SAAMI MAP for the 38 SPL is 17,000 psi (transducer). The 5 gr load of Unique under my 162 gr 358156 runs just under the SAAMI MAP of 17,000 psi out of the no cylinder throat, closed breach test barrel. The +P 5.5 gr load of Unique under the same bullet out of the same test barrel runs just under the SAAMI MAP also.

When my LE department went to 38 SPL +P ammunition S&W confirmed, in writing, that all K frame 38 SPLs made in the '60s and later were safe with +P ammunition both for duty and practice. I still have my 1st issue M15 with a 5" barrel from that department. I have fired thousands of rounds through it and it is still as accurate and tight as when I was issued it. If you want to use the 5 gr load of Unique under your 162 gr RCBS bullet it should be entirely safe and should not cause any more "strain" on your S&W that would equivalent factory ammunition. I found the 5 gr load to be the most accurate load of Unique with both bullets of 158 - 162 gr weight. Lessor amounts of Unique just weren't as accurate.

Attachment 235091

However, if you have any doubts follow the latest data in the Lyman #4 CBH. It lists 4.7 gr as max for a 160 gr cast at 15,900 CUP. The SAAMI CUP MAP for the 38 SPL is 17,000 CUP. so a load of 5 gr would be close to the SAAMI MAP and is as my pressure measurement has verified. The Lyman CBH #4 lists 5.3 gr as a max +P load at 18,500 CUP. The SAAMI MAP for 38 SPL +P is 20,000 CUP. My pressure measurement of 5.5 gr with the 162 gr cast bullet is just under the SAAMI map.

[Beamer]

Thanks, i dropped the unique load to 4.5 grains, velocity at 840 fps,but accuracy also dropped from about 1 inch at 20 yards with the 5 grain load to about 1.5 inch or a little bigger with the 4.5 load. Still ok but apparently the forum advice on unique working better at the high end is correct. Also am trying4.5 grains of w231 .velocity is 910fps. Is this a safe load in the k38? It shoots ok but not spectacular. Part of the problem maybe my older eyes. Thanks

[LAH]

If Unique at 5 grains works with that bullet I personally use it if you Smith is a a late model. Mine was made in 1951 & I use 3.5 gains of Bullseye or Red Dot in mine with a 160.