Barrel corrosion

[azazel1024]

So the continuing saga of my old, poorly treated 27-2. I got it to the range yesterday. It looks like the corrosion I saw in the barrel is impacting velocities. It is possible it is excessive cylinder gap, but I don't think so.

Lead/coated lead was coming in at roughly the expected velocities. But plated copper and jacketed bullets were running 100-150fps slow. I am guessing the softer, larger diameter lead, is properly filling the grooves and forming a good gas seal, and the harder, slightly smaller diameter plated and jacketed bullets are allowing excessive gas blow by.

The corrosion is about half the length of the barrel, in about the middle of the barrel, along about 1/3 the circumference. It doesn't appear to eat into the lands at all and appears extremely shallow.

The only other thing I can think of is excessive cylinder gap, but I'd imagine that would impact lead velocities also. The only gauge I have is for my dan wesson 44 and it will fit between the forcing cone and cylinder fine with the cylinder pushed back, but there is barely a sliver of daylight showing. I'd guess its .008" range for cylinder gap. Which shouldn't be large enough to have a big impact on velocities, let alone selective impact.

The gun shoots VERY accurately. By far my most accurate gun. It was printing 2" 6-shot groups off hand at 12yds over and over and over again. From a rest not being all that careful it printed a 1" group at 12yds.

I am guessing my only real option is to rebarrel it. It went back to smith and wesson factory to see if they can address a stripped frame yoke screw. As part of the note I asked about the velocity issues and if they could check cylinder gap and the barrel and see if either can be addressed. I assume they can't rebarrel it anymore.

I am seeing around 1150fps for hot H110 (16gr) loaded 158gr XTPs from an 8 3/8" barrel. Which makes me sad. I would think it should be around 1300fps. But coated lead MBC 158gr on top of 4.8gr of Bullseye is turning in 975fps and 4.6gr of BE is showing 950fps. Which seems ballpark of what it should be.

I should around 80 rounds down the bore, starting with the copper plated, then jacketed, then coated lead, and then some plain lead 38spc.

One thing I am wondering is if it is possible that the pitting will fill-up with copper and lead in time and lead to less gas blow by if that is the issue that is going on. Any thoughts on that?

I can keep my eyes open for an 8 3/8 nickel platted barrel. Rebarreling a 27-2 is probably within my wheelhouse to get the old one removed and the new installed and properly timed and gapped. I guess worse comes to worse I've got a lead gun that isn't going to like anything with copper. But I'd love to at least restore this gun to proper function. The action and trigger is like glass on it.

If it helps, something else I saw with the XTPs and H110 is lots of pressure signs sooner than I thought I should see it. At 16gr I saw 1150fps average, 22fps SD. At 16.4 the primers were noticeably flattened and 1146fps and 12fps SD. At 16.7 (yes, I shot them anyway) the primers were flat as a pancake and velocities increased to 1192fps with an SD of 34. At least based on load data, everyone except Hornady says that 16.7gr (and even higher) should be fine. 1.580" COAL and CCI magnum primers if that helps. Just wondering if there is any chance there could be something else going on. Like cylinder chambers too tight, but I am not sure how that would be resulting in very low platted/jacketed velocities.

 

[murphydog]

This is well outside my area, but...

The lead and jacketed bullet loads are showing the same level of accuracy?

Other factors being equal, I think jacketed bullets are not as "slippery"/cause more friction and wear on a barrel? So if these are properly sized I'm not sure slower velocities with the same powder charge compared to a lead bullet is unusual, or worrisome.

The handloaders here will chime in shortly.

 

[jeffrefrig]

If I shot that well, even at 12 yds., I'd act like King of the Hill! Not being a perfectioninst, though, I see your concern. Good luck. I hope S&W can do their magic for you.

 

[steelslaver]

A gap difference of .008-.010 over .004-.006 is unlikely to cause even 10 fps velocity loss. Non lubricated copper would lose some to lubricated led bullets. I doubt the small amount of barrel corrosion is causing much blow by. I would check the velocities of the both types off ammo in another gun to establish a base line difference before blaming it on the gun.

I am curious about what S&W will do about the stripped screw and barrel. I am betting against it being repaired. I do not believe the repair shop is anywhere near what it once was. I hope I am wrong

 

[stansdds]

A number of things here, none likely due to your particular barrel.

H-110/W-296 is the powder that is likely to get you closest to top level factory jacketed bullet velocity, but you might not match factory velocity. Why? Factory ammo is generally not made with the canister powders available to us reloaders. Factories use powder blended specifically for commercial manufacturing of ammo, some of their powders and blends simply do a better job of achieving top velocity while staying within safe pressure limits.

Bullet jacket material has a higher coefficient of friction than lead or polymer coated lead, so for any given load, a jacketed or even a plated bullet is going to exit the muzzle at a lower velocity than the same load using a lead bullet.
Velocities stated in reloading manuals are dependent upon the firearm or test barrel used to develop loads. Your firearm may produce the same, lower, or higher velocity and pressure than what you will find in any reloading manual. This is why it is important to start loads at the low end of the stated "safe" range and work up.

When it comes to reading pressure signs, it is not scientific at all, but is purely subjective. Each firearm is a rule unto itself when it comes to velocity, accuracy, and pressure signs. My rule of thumb is to fire factory ammo and observe the appearance of the spent primers and brass. If my reloads show more flattening or cratering of primers or bulging of brass than the fired factory rounds, then I think there is a good chance I am exceeding safe pressure, or at least what is safe for the brass and/or primers that I am using.

All of the above is also good reason to not shoot someone else's reloads in your firearms or to allow someone else to shoot your reloads in their firearms.

 

[scooter123]

I would suggest that you pick up a box or two of American Eagle Semi Jacketed Soft Point in 357 Magnum. It is labeled at 1250 fps and I found it produces an honest 1250 fps out of my 6 inch Dan Wesson 15-2. On the other hand out of my 4 inch S&W model 620 it only produces 1175 fps.

Notes on the guns used. First, take note of the difference in Barrel length, most load recipes you see were developed with 6 inch or longer barrels for revolvers. Because higher numbers sells more powder. Barrel cylinder gap also matters, my Dan Wesson has a removable barrel and I keep the B/C gap set to 0.003 inches. My model 620 also features a tensioned barrel but the BC gap cannot be adjusted, it's a fixed value of 0.006 inch. In addition the 620 features an early iteration of ECM rifling which is semi polygonal and leads up horribly with lead bullets.

Point is that different revolvers will produce different velocities from one specific load. IMO you should stop obsessing about that small patch of rust and start paying attention to the accuracy you are getting from that model 27. Because you have a very accurate revolver and that is what matters most.

I'll also note that velocity is not nearly as important as many think. I had a period when I thought velocity was mattered and set out to produce a 1400 fps load for my model 620. Ended up loading 21.5 grains of H110 under a 125 grain XTP and only managed to get 1350 fps. Also burned a bit of a cut in the virgin top strap, shot flames halfway down the range, and had several folks from other lanes checking to see if I blew up my gun because it was as loud or louder than a 500 Magnum. After that I really lost interest in pushing the limits on powder charges. Now my pet load for H110 is 14.6 grains with a 158 grain XTP, it's a lot gentler to shoot and shoots under 1 MOA from my 20 inch 1892 Winchester.

 

[azazel1024]

Good questions and calls.

Unfortunately I don't own another .357. I can ask my buddy if he is willing to shoot just a couple of my reloads over a chrono, or going the other way, him shoot some factory/his reloads over the chrono and I'll try a few of his rounds in my 27-2.

I get all of the reload data is based on their specific test setup. But a hot 357 from an 8" barrel shouldn't only be turning in 1150fps. For example, Hornady is claiming from an 8" Python with 15.7gr, same bullet and same COAL should be turning in 1250fps.

I can do some direct comparisons on 38spc as I have an old Colt OP 6". I'll have to test some jacketed loads between the two. But the Winchester white box 158 RNFP I have were only turning in around 710-740fps on the 27-2. That seems abnormally low also.

I only have a few years of reloading experience, but typically I only see about a 5-8% velocity drop going from lead to copper plated or jacketed bullets. Sometimes little to no loss.

With my DW44 and 9.0gr of TG, MBC240 coated SWC are running 1150fps, Xtreme plated RNFP are running 1097fps but I think are seated about .010" longer. 240XTPs are 1147fps, same powder charge.

What I saw was
MBC SWC with 5.0gr of TG ran 999fps average
Xtreme plated copper SWC 5.0gr 909fps
Xtreme plated copper SWC 5.2gr 938fps
FMJ RNFP 5.6gr 923fps
FMJ RNFP 5.8gr 970fps
FMJ RNFP 6.0gr 987fps

20% more powder charge to get slightly less velocity seems like an extreme difference between the coated lead and a jacketed bullet. I suppose it is possible that the shape of the bullet means there is actually quite a bit more case volume with all of those seated to the same 1.580"

 

[Model19man]

I think you need to pay attention to the signs of excess pressure. Be happy with the accuracy. Forget about the velocity. Maybe try a different chronograph. For sure don't change the barrel. That one is fine.

 

[steelslaver]

Velocity is fine, accuracy is final. In other words where you put the bullet is way more important than its velocity.

If it was mine I would fix the yoke screw and stick on there model 27 4" barrel I have in my parts pile. But only because I have it and if I want a barrel longer than 6" I will go to a carbine. I doubt you extra barrel cylinder gap or your barrel imperfections are anything to worry about.

On the barrel cylinder gap check this out
Ballistics by the inch took a revolver and fit the barrels slammed up tight, then with .001 gap then with .006 and fire various ammo through it. They also cut the barrels to check barrel lengths effect on velocity

Their results firing Federal Premium 158 gr hydro shocks with a 8" barrel
no gap-1389fps .0006-1343 then with .006-1302. In other words they lost more velocity in the first .001 of gap (46fps) than they did in the next .005 (41fps)

BBTI - Ballistics by the Inch :: Cylinder Gap Test

 

[azazel1024]

Velocity is fine, accuracy is final. In other words where you put the bullet is way more important than its velocity.

If it was mine I would fix the yoke screw and stick on there model 27 4" barrel I have in my parts pile. But only because I have it and if I want a barrel longer than 6" I will go to a carbine. I doubt you extra barrel cylinder gap or your barrel imperfections are anything to worry about.

On the barrel cylinder gap check this out
Ballistics by the inch took a revolver and fit the barrels slammed up tight, then with .001 gap then with .006 and fire various ammo through it. They also cut the barrels to check barrel lengths effect on velocity

Their results firing Federal Premium 158 gr hydro shocks with a 8" barrel
no gap-1389fps .0006-1343 then with .006-1302. In other words they lost more velocity in the first .001 of gap (46fps) than they did in the next .005 (41fps)

BBTI - Ballistics by the Inch :: Cylinder Gap Test

Neat test, thanks! I saw someone over in Europe did a test with DW in .445 and I think they found a fairly similar thing. Though I want to say they saw a pretty big drop going from .006 to .010", about another 40-50fps. But I suspect I am not losing a ton of velocity from excessive cylinder gap.

Maybe it was chrono issues not liking shiny bullets that day. I was shooting from a covered bench, the chrono was in open shade. It was not overcast, I did have the sun shields in place, and the hotter stuff, especially the H110 loads were for sure shaking the sun shields from muzzle blast, though I want to say I had the chrono at about 12ft. And it was pretty windy.

Whenever I get the revolver back from S&W I am going to try placing the chrono pretty far out, like 20 feet to make absolutely sure blast can't be having any impact. Though I would have expected it to have a large effect on all rounds, rather than just certain ones.

This one I want a target revolver. Which I guess is what I have. My wife isn't a fan of guns (understatement of the century) the fact I own ballpark 25, has her rather hot and bothered. Getting this one ended up in a big fight.

So I have to be somewhat content with what I do own in life. Not that I'll never own any more guns, but it is sadly not as simple as what my finances can manage. If it was that, I would have gotten a very nice condition 27-2, blued, 8 3/8" as a target queen and a 4" in whatever shape as a bump around gun. Instead, it was this puppy for $400 (and I wish I had some pictures to share) with some rough finish spots on the nickel coating because somebody's Dad was a hoarder and they found it in the bottom of a box where it was probably sitting for 20 or 30 years. So the gun store they were consigning it was selling it cheap. My buddy gave me a call that he saw it and new I was looking for something in 357 cheap.

The action and trigger are just so danged nice. I don't want to impugn Dan Wesson's honor, but it might be slicker and nicer than my DW44 and I thought THAT was an amazing gun. Actually, check that, my DW44 is an amazing gun. That one was $550, with a Leupold handgun scope on it and 6" barrel. Same buddy set me on that one from the same gun shop. No idea why it was selling so cheap. So I turned around, sold the scope to that buddy for $180, and bought a 2.5" barrel and fiber front sights for the 2.5" as well as for the 6" barrel the gun came with from Cz. All up, in for basically $600. This 27-2 is more accurate though (not that the DW 44 has bad accuracy, the 27-2 is just better).

I didn't think I'd own a 44, but that Dan Wesson was too good a deal to pass up and I am glad I own a 44 now.

The 27-2, I'd love to hunt with, but if I never do, eh. The DW44 is a better gun for that for deer hunting. Or at least a better caliber.

Part of why I am interested in trying to figure out what might be going on with the velocity. It could be false readings. I don't think it was, but of course I can't now check it till I get it back. I might try my magneto speed on it to. Both to see if it'll work on a revolver, but also to take out chrono issues (I'll also check on my chrono placed further away). I'll also check if putting more rounds down range will change the velocities produced. See if depositing some material in the barrel tightens it up. Since this might be the only 357 for me...

 

[GypsmJim]

My first thought was how did the corrosion happen? It's not that old a gun. I have WWII Victories and Lugers that have zero corrosion. Knowing the reason could certainly help me so none of my guns have the same fate.

 

[Fishinfool]

OP - Couple things. Primer condition is generally not a reliable pressure indicator in revolvers.

Lead bullets are generally faster than jacked because of less resistance going down the barrel.

Speer #10 shows a 158 grn XTP at 1241 fps with 15.8 grn of H-110, using a 6 inch Ruger. The same combo shows 1326 fps with 17.8 grn of H-110, a maximum load.

It does not surprise me you are getting 1150 fps with 16 grains of H-110. It is common for different guns to vary in velocity with the same load, and a longer barrel does not always mean higher velocities. I would up my powder charge if velocity is important. Unless some unseen factor is present, I don't think you are experiencing over pressure loads in the 16 grain range.

Pitting in the bore usually collects lead and copper, and often hurts accuracy. Lead lapping / fire lapping a pitted bore will often smooth it up, and while not removing the pitting, it smooths it out, and can reduce leading and improve accuracy. If your gun is shooting well, I don't know I would mess with the barrel.

I agree with the other posters that say accuracy is what really counts.

Larry

 

[azazel1024]

My first thought was how did the corrosion happen? It's not that old a gun. I have WWII Victories and Lugers that have zero corrosion. Knowing the reason could certainly help me so none of my guns have the same fate.

Unknown. All the shop could tell me is that the estate/family was brining in guns they were finding in their deceased father's house, who was a hoarder and that it was found in a box. There is a some deep pitting in the top strap on the left side, and a couple of other spots where it pitted through the finish with a noticeable pit. The internals were okay. A little bit of corrosion on the trigger rebound housing that was rough enough I stoned it with oil and a 1000# stone for a few passes to clean it up. The trigger and hammer have some almost watermarking type corrosion that is NOT the color case hardening on them.

But it is slick as heck. No idea what caused the corrosion through the nickel plating. The finish itself has some noticeable scratching in it. And then there is the bore corrosion. The rest of the bore is bright and shiny and the bore corrosion is on the opposite side of the barrel as most of the frame/top strap corrosion. There is also a spot on the side plate on the underside (but no matching corrosion on the frame at that point). At a guess, it was stored somewhere with a fair amount of humidity for several decade, without any oiling. Might have even been in a box that got wet one or more times in the past.

 

[azazel1024]

OP - Couple things. Primer condition is generally not a reliable pressure indicator in revolvers.

Lead bullets are generally faster than jacked because of less resistance going down the barrel.

Speer #10 shows a 158 grn XTP at 1241 fps with 15.8 grn of H-110, using a 6 inch Ruger. The same combo shows 1326 fps with 17.8 grn of H-110, a maximum load.

It does not surprise me you are getting 1150 fps with 16 grains of H-110. It is common for different guns to vary in velocity with the same load, and a longer barrel does not always mean higher velocities. I would up my powder charge if velocity is important. Unless some unseen factor is present, I don't think you are experiencing over pressure loads in the 16 grain range.

Pitting in the bore usually collects lead and copper, and often hurts accuracy. Lead lapping / fire lapping a pitted bore will often smooth it up, and while not removing the pitting, it smooths it out, and can reduce leading and improve accuracy. If your gun is shooting well, I don't know I would mess with the barrel.

I agree with the other posters that say accuracy is what really counts.

Larry

The case dropped free of the chamber just fine, but wouldn't flattened primers still be a concern? I know that primers aren't a reliable indicator, but I thought that was more because pistols typically don't run enough pressure to flatten them. So cranking loads higher and higher waiting for primers to flatten or flow was asking for real trouble.

I do agree, I was kind of horrified they flattened at what shouldn't have been over pressure levels based on all of the data, except Hornady, that I could find.

From left to right, 16.7gr charge of H110, 16gr charge, fresh Winchester SPM primer in one of the cases, and then one of the cases from a soft, non-H110 load (unknown primer, I picked up 250 primed starline cases along with a bunch of other 38spc and 357 brass for a song months ago. All of the H110 loads I tested used Rem or Federal brass, with Win SRM primers). The hotter one both looks a little flatter, but I am pretty sure there is a bit of primer flow going on also. There is just enough raised at the edge of the primer crater that it catches my fingernail running across the back of the primer.

Fair warning, the ONLY H110 experience I have is in 30 carbine. I've never loaded it in any handguns until now, and I've never pushed my 44 mag loads to the max with any powder either.

 

[Jim Watson]

The gun shoots VERY accurately. By far my most accurate gun.

That should make it hard to muck about with the barrel.

 

[steelslaver]

Flattened primers in a revolver are not the same as a rifle. A rifle can have much tighter head space because of the action. In a revolver the case must have enough head space to turn into position freely. Then when fired the firing pin pushes the case forward and ignition causes it to slam back into the recoil shield and firing pin bushing. That movement has a different effect on case and primer than just being pressed into the bolt face.

The distance between the case head and recoil shield has some variation as do rim thicknesses . This plus end shake (the amount of forward and reverse movement) your cylinder has will all effect how much inertial energy your case head and primer have when it is slammed into recoil shield. Plus, the fact that pistol primers are not as heavily constructed as rifle primers.

 

[MajorD]

I think you need to pay attention to the signs of excess pressure. Be happy with the accuracy. Forget about the velocity. Maybe try a different chronograph. For sure don't change the barrel. That one is fine.

Agree. Max velocity is something to be avoided most of the time not pursued. Great accuracy means for me, I don’t care one bit what the bore looks like.

In rifle forums I see people angst over what they see when they borescope a rifle.
My advice is always the same. If it shoots good, what the bore looks like is irrelevant- same if it shoots bad.it either shoots well or it doesn’t

Searching for a solution to a nonexistent problem will eventually get you in trouble.

Leave well enough alone

 

[azazel1024]

Flattened primers in a revolver are not the same as a rifle. A rifle can have much tighter head space because of the action. In a revolver the case must have enough head space to turn into position freely. Then when fired the firing pin pushes the case forward and ignition causes it to slam back into the recoil shield and firing pin bushing. That movement has a different effect on case and primer than just being pressed into the bolt face.

The distance between the case head and recoil shield has some variation as do rim thicknesses . This plus end shake (the amount of forward and reverse movement) your cylinder has will all effect how much inertial energy your case head and primer have when it is slammed into recoil shield. Plus, the fact that pistol primers are not as heavily constructed as rifle primers.

Thank you! That makes perfect sense. I assume I probably still generally want to avoid pushing pressures that cause primer flow? And/or try a harder primer like CCI primers, rather than the Win primers?

I don't want to be pushing pressures to, let alone past, the maximum. However, since it seems this runs kind of slow, bumping close to the max recommended and maybe backing off a couple tenths of a grain if still shooting well would be my goal.

Not that it'll be fed a steady diet of full power magnums. It costs me half as much to reload a .357 case with 4.6gr of BE and an MBC 158gr coated SWC as it does with 16+gr of H110 and a 158gr XTP. Other than some extra fun, I don't think the paper cares what it gets hit with. I'll likely load up 150-200 rounds of XTPs once I get my desired load figured out and that will likely last me a few years. Versus, well if I get to the range as much as I'd like, 500 rounds of target loads maybe lasting me 2-3 years. I just don't get out as much as I'd like, and I almost have too many guns to shoot (do NOT let my wife hear me say that).

 

[azazel1024]

Agree. Max velocity is something to be avoided most of the time not pursued. Great accuracy means for me, I don’t care one bit what the bore looks like.

In rifle forums I see people angst over what they see when they borescope a rifle.
My advice is always the same. If it shoots good, what the bore looks like is irrelevant- same if it shoots bad.it either shoots well or it doesn’t

Searching for a solution to a nonexistent problem will eventually get you in trouble.

Leave well enough alone

Thanks! I think ya'll have me convinced. I appreciate it.

 

[steelslaver]

To me a flat revolver primer is OK,, hard extraction means either a rough chamber, a bulged chamber or to much pressure. The first 2 may show up if you carefully examine your fired cases.

A flattened primer that where the edges fill out the primer pocket does mean you have some pressure. Remember the 357, 41 and 44 mags run up to 36,000psi. But, once again how much f a run does your case head get in YOUR revolver?

I quit chasing max velocity some time ago. But, I will say that the model 27 and 28 N frame 357s are tanks. The cylinder is what lets go on a revolver. A model 27 has the same sized cylinder as a 44 mag, and that means there is way more metal around a 357 case. Not saying that as an endorsement to hot rod the ammo.

I am a 45 colt guy, I set up my loads some but only to 45 acp pressure levels. I prefre them ove 44 mags. The 44 mag has the colt beat pretty well in the velocity dept. But a well place 45 colt slug will kill anything just as dead as a 44 mag. A poorly placed round from either will not. After 100 yards both rounds have rainbow trajectories and if you don't understand them your going to miss or wound with either.

If you are just shooting paper a 900fps slug makes the same size hole as one going 1500fps. Just makes more noise, more recoil and more wear and tear on your gun and your wrists.