I recently purchased an early 2000s SP and am chasing failure to feed problems. I have seen a number of different posts on SPs and have replaced recoil springs, recoil buffer and magazine springs without much luck. I have seen some improvement after scrubbing the chamber but am still having occasional failures where ejection is OK but the next round is not picked up.
When working the bolt by hand, I can feel some roughness near the end of the cycle. On the bottom of the bolt, I can see ridges where it appears one side of the hammer is rubbing during recoil.
Is this wear normal for an SP? Are the ridges likely to be causing my feeding problem? I am tempted to polish out the ridges on the bolt but wonder whether the hammer should be smoothed to more evenly contact the slide as well.
The wear pattern isn't that unusual. The ripples just to the right of the pin are from the hammer bouncing after it is cocked. While a bit ugly, I doubt it has anything to do with your feeding issues.
Some thing to check that might help track down the problem:
1) Does it always occur on the same round in the magazine, or is it random?
2) If the bullet isn't feeing smoothly into the chamber, is it going to high, or too low when it hangs up?
The underside of the bolt looks like it's picking up debris, that could cause some drag. I'd certainly try cleaning it with a solvent and soft rag, and applying a tiny dab of TW25B synthetic grease. Does the hammer show similar deposits? Clean it too.
But I'd suggest NOT attempting to "smooth" the hammer. The surface of the hammer is the hardest layer; cutting through it will cause it to wear. If the simple stuff doesn't work, I'd consider checking the pivot pin and the hole through the hammer where it passes, since the sliding-surface wear does look a tiny bit uneven. That's probably best left to an experienced Pardini 'smith.
At the moment, almost all of my failures are short strokes where no new round is picked up off the magazine. I have tried SK Pistol Match, Aguilla and Federal ammo and the failures seem to be random. I am tracking failures by magazine but do not have any that are particularly bad.
During additional testing over the weekend, I have noticed that the chamber fouls very quickly using SK Pistol Match ammo. After as few as 60 shots the a new round will not drop into the chamber when the barrel is removed. I have a borescope on the way to see what is going on in the chamber.
For now, I will try wiping as much of the lube as possible of the SK ammo to see if that helps.
I highly doubt it's the SK lube. I know many Pardini SP shooters using Pistol Match with no issue - feeding, fouling, etc.
Usually, early chamber fouling is a sign of a weak recoil spring. The bolt kicks back too early, while the powder is still in the initial burning stage. The soot builds up quickly. If the brass succeeds in leaving the chamber during this, it will greatly reduce the recoil speed and travel, and could easily explain your issue.
Another possibility is the chamber is significantly worn. If the round is loose in the socket, it will have a similar behavior.
Some things he discovered after many rounds down range.
The area that encloses the 22lr case head in the bolt had peened smaller. A little work with a small file removed the burr.
The hole for the recoil spring also had peened to a smaller diameter. The removal of the burr was needed.
Check the recoil spring guide rod for straightness and a rough finish. Polish or replace, if needed.
A new SP recoil spring has 0.6mm wire by 130mm length.
Examine the hole in the bolt at the rear where the firing pin head protrudes. Is is also peened? If so, fix.
A less common issue was a broken firing pin. The pin would remain stuck out and block the next round from feeding.
The older Pardini SP barrels are not fully heat treated. The new ones are of a higher Rockwell hardness. The chambers do erode near the case mouth. It will appear as a dark spot when examining a clean barrel from the rear. Usually at the bottom where the powder settles due to gravity.
Should all of the above not cure the issue, have a close look at the extractor and extractor spring.
It appears that my SP is short stroking primarily on the 2nd round of a magazine. I noticed that the trigger is not resetting when this occurs but the case is ejected.
Behavior occurs using SK Pistol Match and Aquilla SV ammo. It seems like the combination of recoil spring, mag spring under maximum compression and resetting the trigger just too much and the bolt makes it back just far enough for the case to sneak out. There is never a double feed or case stuck in the action somewhere.
I have checked the chamber with a borescope and can see a faint ring of crud past the end of the case but otherwise everything looks fine. I can see minor tool marks from when the chamber was cut but no signs of errosion.
Recoil, magazine and recoil buffer are brand new.
I have checked for peening and recoil spring guide rod as suggested by fc60.
I am feeling like it might be time to find a Pardini smith to have a look.
Aguila tends to have a bit less recoil than (for example) CCI. The maximum drag on the bolt is after the 1st round fires, because of the upward force from having 4 rounds in the magazine.
If the pistol is otherwise cycling normally, but the second round isn't being picked up (resulting in an empty chamber), you can often fix this by cutting a few turns of the recoil spring. Just don't forget & feed hotter ammo through it without replacing the spring first.
I checked my notes, and I've fixed three Pardinis so they will cycle Aguila just fine by cutting the recoil spring down. The stock new spring is 88 turns, and 131 mm long. You can try to sneak up on it, but a spring with 76 turns, 110 mm long works well for me.
As for the crud in the chamber, use a .25 caliber rifle brush bent at 90 degrees to REALLY clean the chamber. Even that won't necessarily get rid of the carbon near the case mouth. Bore Tech Rimfire Blend will take out fairly stubborn fouling. If it's really bad, Sharp Shoot R CARB-OUT is even more aggressive.
Also, make sure you are lubricating the bolt adequately. Pardini has a video on cleaning that should cover that.
SK makes Pistol Match Special which is slightly hotter than regular Pistol Match. The box is a lighter shade of green. Of course, both are pretty much impossible to find right now, but if you can, it might be worth a try before you go cutting anything.
SK Standard Plus also shoots well in many pistols.
Gwhite, thank you for your suggestions on spring weight. I have started cutting my older recoil spring down and am seeing decent improvement. My only failure today was on a fully loaded mag with a brand new spring. I will keep working it back a couple of coils at a time until the short stroking stops.
This is a great application for old recoil springs. No point in cutting down a nice new one when you already have a slightly squishy one available. Once you've got one working with a clean pistol, you'll need to knock off a few more turns to give yourself some margin for when it gets a little grubby.
Not seen that kind of wear before, is it from hammer bounce or dry firing with different size stoppers in place?
I doubt hammer bounce would give that kind of pattern.
Pardini hammers are relatively soft, the sear will cut into them, I don't believe they are case hardened, if they are they are ground after hardening.
But that slide looks softer so could be a defective part.
FAS602s occasionally had a rough underside to the slide which needed stoning off, never had a malfunction after that.
I've seen that sort of pattern on Benellis as well. I'm almost certain it's from the hammer bouncing. It gets whacked down by the slide hard enough that it undershoots the slide for a bit, and then when it comes up and hits the underside it bounces a few times as the slide continues backward. It's a bit ugly, but rarely (if ever) causes a functioning problem.