27-2 oddness

[azazel1024]

I am wondering if anyone can help with this. I am seeing some real oddness in my 27-2. She is beat up. Say on a shelf in a box and someone's garage for a couple of decades and the corrosion ate through the nickel finish some. Cleaned it up, it shoots FANTASTIC. The bore does have some corrosion. It does not appear to be awful to me though. And it certainly is not impacting accuracy. However, I can't figure out velocity on this thing. I think she might just be a lead gun, but trying to figure this out. I realize there is so much that can be different between different guns you should not compare different models to each other. But I can't help it anyway. So I have some comparison's with my friend's Ruger Blackhawk 7.5" against my S&W 27-2 8 3/8". I figure they should be very similar.

Well, my 27-2 is coming is really low versus both handbook data (even when similar guns were used as test platforms), as well as my buddy's gun in actual chrono testing.

But mostly just with jacketed bullets and the discrepancy is larger with heavier bullets.

For example, at Hornady's max load of H110 and a 158gr XTP (same Win SPM primer and COAL) I am seeing about 1150fps. Hornady says 1250fps with a 8" Colt Python. I think that is 16gr? With 16.5gr I am seeing 1199fps. My Buddy's 7.5" BH is running 1311fps. The Buddy's friend who runs a small ammo company had some 125gr SJHP magnum loads that are 1117fps out of my buddy's 2.5" snubbie and I think box says 1500fps from a 6". I am seeing about 1550fps. The BH is doing 1631fps. That at least feels a lot closer.

Running Hornady's H110 max load (19.7gr? 19.5?) under a 125gr XTP I am seeing 1447fps. Hornady says 1500fps. No comparison with my buddy. But something I DID see, was as I increased over Hornady's max load and approached Hogdon's max load, no change in velocity. Even going up more than a grain. I'd normally expect that to mean I am pushing past the maximum safe pressure, but every other manual other than Hornady says 21+ grains of H110 is well within safe pressure. Heck, plenty of people pushing 22+gr under a 125gr. Something I am wondering there is if I need a hotter primer to ignite all that powder. Especially has the ~20gr range is a compressed load. The CCI SPM (550) and SR (400) primers from my understanding are hotter than Winchester small pistol magnum primers. Though Hogdon's own website calls for Win SPM for their 22gr H110 load. But, anyway, my data is still a lot closer to Hornady's there. Only about 60fps under, unlike the 158gr data, which is 100fps. I would expect it to be reversed, where the slower heavier load is closer.

And I see similar things with Tightgroup with jacketed bullets and plated bullets. A generic 158gr RNFP is running about 80-100fps under what the manuals say it should be. I am seeing 997fps with 6.0gr of TG. I don't have as much trust in the data as Hogdon is using a 10" test fixture, not a real gun, and it is an XTP, not a RNFP bullet so it is seated a little more compressed because the bullet is slightly longer for the same weight, even again known good long barreled .357's, there data seems to run a solid 100-200fps faster than a 6-8" .357 revolver. But I'd still expect it to be running in the 1100fps range. My Xtreme 158gr SWC plated running under 5.2gr of TG are coming in at 917fps.

As a point of comparison, the 158gr RNFP FMJ on 5.6gr of TG was 923fps, very close to the 917fps of the Xtreme bullets on 5.2gr. Yes, I am aware that FMJ is going to run a little slower than plated bullets will. Which will run a little slower than lead.

Now for the lead. Running MBC 158gr SWR coated lead, with 4.8gr of TG, I am seeing 999FPS average velocity. I forget the load (3.6gr? 3.8?), but my 38spc 158gr MBC coated lead bullseye loads for my Colt Official Police 6" are running only about 10fps slow versus the Colt. The Colt clocks in around 820-825fps and my 27-2 is seeing 812fps, which makes sense to me. Not much pushing it and the longer barrel could be slowing it down.

But that direct comparison of the MBC coated lead with 4.8gr of TG to the Xtreme. Same weight bullet. Almost the same length of bullet. Same profile of bullet. Same powder. Same cases. Same primers. That is a huge velocity difference. My experience of Xtreme bullets versus coated lead, for the exact same powder charge, I usually see about 50-80fps higher velocities with the lead. I am seeing 80fps faster for the lead, with ~8% lower powder charger. If it was the same powder charge, I'd guess that would be more like a 150fps velocity difference.

Last one for you. I picked up a box of Hornady American Gunner 125gr XTP. Box velocity is 1500fps. The little bit I can find on the internet, I am seeing around 1400fps out of a 4" barrel. I am guessing Hornady used a 6" for the box testing. My 8 3/8" 27-2 is actually running 1551fps average velocity. Fairly respectable. No clue on the powder, but I find it interesting that my H110 max load is clocking 100fps slower than Hornady's load, using the SAME bullet. Even using my buddy's 125gr XTP H110 handload, exact same powder charger and I also saw about the 1450fps as mine. So I don't think it is something odd I am doing like not crimping enough.

I have some 140gr MBC coated "zingers", truncated cone. I am going to load them later today. Some at "fast action" velocities using I think CFE Pistol or Titegroup. And some at magnum velocities with H110. Probably also try to redo some 125gr xtp using CCI small rifle primers since they are the same as small pistol magnum for them.

So I am just stupidly stumped at this point. Some even jacketed loads actually seem to be running reasonably close to expected velocities. Still a little low, but I am thinking in the ballpark of what a 6" 357 should be running. But lead loads seem to be running right about where I would expect an 8" barreled 357 to be running. I know coated lead tends to run a little faster than bare lead. But looking at Hornady's data, they stop at an extremely conservative 4.1gr for TG, but 900fps from an 8" Coly Python. At 4.6gr I am seeing 999fps. Hornady is showing a gain of about 50fps per .3gr. So this should be running in the 980-990fps range. Pretty bang on Hornady's numbers if you extrapolate out.

I can't remember what Alliant's numbers are, but if I am remembering right, I am seeing the same with Bullseye and those MBC 158gr. I think they claim ~950fps at a 4.6gr load. That's what I am seeing.

I apologize for the novel. Just trying to figure this thing out. My last few years of reloading experience, I haven't seen anything like this with any of my other guns. I don't have any other 357s to test things in, but I have been loading for 13 other calibers for the last few years.

Any thoughts? Is there maybe something about H110 my gun doesn't like? I mean, seems like it would be the same for titegroup with jacketed bullets. Bigger velocity loss with heavier bullets. But Hornady American gunner doesn't seem to really have much velocity loss...I don't know. Is the heavier bullet allowing more gas leakage from large cylinder gap or something? Which doesn't make sense to me as lead should be just as impacted by a large cylinder gap. More blow by on the low spots of the barrel from some corrosion? Lead sealing that up better as it passes? And faster and lighter jacketed bullets passing across that area faster so less gas leaks by?

I don't necessarily need to "solve" this. The gun is a HOOT to shoot. The action is incredibly smooth. The trigger is just fantastic on this gun. And after 68 rounds at 15yds I chewed a smaller than fist sized hole out of the target with only another 6-8 holes around the chewed hole. All off hand. That is roughly 90% of rounds in to a maybe 2" hole. I cannot do that with any other gun I own. Some of those were DA also. And I get enough velocity to no make me shed a lot of tears. It isn't like I am getting 2" snubbie velocities out of it. A 4-6" Magnum isn't something to sneeze at. And if lead does consistently hold up, 180gr hard cast out of an 8", if I can get full velocity out of hard cast lead, is not going to be something anything is going to sneer at. Not Like this is going to be a carry gun. I've got a Dan Wesson 44 if I wanted something for bears.

 

[USBP SW]

I would not try to compare any revolvers against another, even the same make, model and barrel length can have significant variations in m
manufacturing tolerances that affect both velocity and accuracy. Work within the parameters of what your particular revolver prefers, you'll be happy and your revolver will give you a lifetime or more of enjoyment.

 

[SGT ROCK 11B]

You are over thinking it.

For example, for 38 Special a 158 grain LSWC over 3.5 grains of Bullseye is accurate in all my 38 Special and 357 Magnum revolvers over the last 40+ years. Regardless if its my Colt SAA, a S&W 15-2 from 1966 or my new S&W 686 Plus.

 

[stansdds]

The velocity difference is likely due to the barrels. Different internal dimensions of a barrel can not only affect accuracy, but also velocity.

 

[rockquarry]

The original post is a quite lengthy way of summarizing that one's velocity figures don't correspond with book figures. The numbers are actually much closer than what many find after chronographing their own handloads
and comparing them with published load data from reputable sources.

 

[BSA1]

Why the need for speed?

As a reloader it is easy for you to tweak your loads a few 1/10’s of a grain +/- or so and measure velocity changes.

 

[azazel1024]

Why the need for speed?

As a reloader it is easy for you to tweak your loads a few 1/10’s of a grain +/- or so and measure velocity changes.

Because I am Maverick in this case, and I feel a need for speed

Thanks all. I do appreciate the "you are over thinking this!".

I loaded up some 125gr XTP with CCI SR primers to test (full ladder, not just swapping primers). As well as some MBC 140gr "zinger" on top of H110 (win SPM) to see what'll do. The 140s are loaded a little softer with 17, 1.5, and 18gr. I can't find good 140gr hard cast lead data, so I used Hornady's XTP 140gr data. Bullet is a bit shorter than the truncated cone coated lead MBC bullets and Hornady says max is I think 18.7gr. So this should be a fair amount below max.

In part, I am most curious about the 125 xtp why the velocity seemed to plateau completely. 1396fps at 19.5gr, 1464fps at 20.0gr, 1466fps at 20.5gr and 1454fps at 21gr.

I do understand that is sometimes a sign of over pressure. But I don't see any sign in the primers. No cratering. No piercing. A bit bigger fireballs, that was it. The ladder I redid was only 19.5, 20.0 and 20.5gr. I didn't load up 21gr. I am curious if the hotter CCI #400 small rifle primers will push them faster with more complete combustion.

One thing I DID notice is I am using mixed head stamp cases. Welp, I learned something after noticing that the bullets and cannular were not coming up the same spot. I thought the XTP bullets weren't uniform. A few more rounds loaded and I realized it is that most of the Hornady 357 cases are short. 1.250", not 1.290" of everyone else. Damned FTX loads!

So I have 4 with the shorter cases, and I adjusted after I realized and rejected the hornady cases. They are all loaded to the same COAL, so less grip on the hornady cases.

This likely happened with my last test loads. I am working with 500 nickel cases I got from capitol armory about a year ago when I was thinking of getting a 357. I'd been giving all my scrounged 357 brass to my buddy. Then changed my mind when I decided I was going to get a 357 and decided to pickup some range brass. I've since picked up a few hundred more cases, between range pickups and the same buddy sold me a bunch of tumbled as well as primed 38spc and 357 brass he picked up cheap as a bulk component deal with someone and he has so much he wasn't planning to hold on to it.

Anyway, I've got no clue what those cases are primed with. So I am using them only for standard powders, not H110 loads.

Looking over 50 cases, it looks like about 15 are Hornady cases. So about 3 in 10. I'll sort all the rest out and put them aside for their own custom load someday. And I'll separate out the test data from the 4 rounds I just loaded that are Hornady cases. The rounds aren't loaded short, so I figure at worst, the reduced grip on the bullet will result in reduced velocity. Should not result in a OP situation. They still have a strong crimp on them.

 

[M29since14]

Lightweight bullets and H110 are a “less than ideal combination” in the .357 Magnum, IMO.

Years ago I had two S&W Model 19 4-inch .357 Magnums that consistently showed over 100 FPS difference with the same ammunition. One blue and one nickel, but that had nothing to do with it. Anyway, I’d just bought my first chronograph and this seemed like quite a revelation to me. When I told him about it, one of my older, and much more knowledgeable, shooting friends thought nothing much of it. His only question was, “Which one is more accurate? I’d keep that one.”

 

[Pisgah]

For most of the loads mentioned the differences are so small as to be utterly insignificant overall. They could vary as much or more shot-to-shot in the same revolver, let alone in different revolvers or a manufacturer's test barrel.

 

[Model19man]

Instead of worrying about a few feet of speed variation why not try for the best accuracy? It's a lot more important.

 

[6GUNSONLY]

Different gun almost always equals different results even with same/similar barrel lengths. Internal barrel differences, barrel/cylinder gap differences, etc..