Problem with my new sp101


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Rob P.
May 5, 2009, 05:00 PM
Ok, I'm BAAACK from a shooting class over the weekend. :neener:

I took my S&W 9mm and my new Ruger sp101 to the class. My 9mm functioned flawlessly as usual. (Have I mentioned how much I LOVE that pistol?)

However, the new Ruger decided to be temperamental. I was shooting new Federal .38 spl. lead SWC's and once in awhile the cylinder starting binding and then it locked up. I couldn't even cock the hammer SA let alone get anything to move DA. If I opened the cylinder and closed it again it worked fine. This happened 2 or 3 times.

Anyone know where to start looking? BC gap is .003", no lead buildup on the front of the cylinder either. Charge holes didn't/don't look fouled and the ammo doesn't seem to have any high primers. There is/was no indication of interference on the recoil shield either.

Hints on where to look and what to look for would be welcome. At this point I have not touched the revolver since the class and I need to clean it and check on why it malfunctioned.

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rcmodel
May 5, 2009, 05:02 PM
Check for unburned powder flakes under the extractor star.

rc

whisky19
May 5, 2009, 05:13 PM
Could be ammo related problem. I once bought some cheap 357 at a gun show and shot them out of my sp101. After 2 or 3 shots my cylinder locked up just like yours. What I found was that the bullets weren't crimped very well and were backing out of the cases due to the recoil. This was enough to prevent the cylinder from turning.

Just noticed that you were shooting 38 spl. I don't know if a 38 spl could back out enough to lock up a 357.

Good luck anyway!

Sorry. Reading is fundamental. I noticed you were able to open the cylinder. I don't think its a bullet problem.

wyocarp
May 5, 2009, 05:19 PM
Sounds like a timing issue and means that it needs to see a gunsmith.

BCRider
May 5, 2009, 08:43 PM
From what I've been reading .003 for a cylinder to barrel gap sounds a bit snug. It maybe building up lead flakes or powder residue in the gap that clears when you open and close the cylinder. Or it may be those powder flakes under the star as mentioned.

At a shooting event I was at this past weekend a guy had an SP101 and what having to regularly brush out behind the star. He said it was happening far more than usual but that he was trying some new reloads. So it may be related.

THE MACHINIST
May 5, 2009, 10:00 PM
"Could be ammo related problem. I once bought some cheap 357 at a gun show and shot them out of my sp101. After 2 or 3 shots my cylinder locked up just like yours. What I found was that the bullets weren't crimped very well and were backing out of the cases due to the recoil. This was enough to prevent the cylinder from turning. " yeah this happened to mine...taurus 617

Capt Marvel
May 5, 2009, 10:20 PM
Whereas this is a brand new revolver, mechanicly there is the chance the cylinder may be "out of time". If that is the case, the cylinder is not being perfectly aligned with the barrel when the weapon is cocked. When this happens, even slightly, it will "shave lead" when fired. As such lead fragments can build up on the forcing cone of the barrel. This can result an the cylinder refusing to rotate and the weapon not cocking.

A good gunsmith with a "range rod" should be able to check "the timing". Try to find some one who has been through S&W armours school. Check your local police force as they often attend free of charge. If the PD is carrying Glocks it is unlikely they will have someone.

As stated ammo could be the cause. Check overall cartridge length. Projectile may be seated out to far.

Virginian
May 6, 2009, 01:07 AM
I can't see it, and I don't know what it is, but I will bet money it isn't a timing issue. Not on a new Ruger, and not with these symptoms. I'm not saying it's impossible, I am saying I would bet money. If it was a Smith we were talking about, I would likely bet money it was a timing issue.

fastbolt
May 6, 2009, 02:56 PM
Something similar happened with my SP101 when it was new, and especially after some rounds had been fired and the gun was heating up. Sometimes as quickly as with only a few cylinder loads (less than 50 rounds into the typical session).

My problem turned out to be a nasty burred edge on a part which was raising a corresponding burred edge on another part and there was increasing interference between the parts which was more noticeable when the gun started heating up.

FWIW, I've been an owner and user of Ruger firearms for many years, and I've also had to return a few of them for repair issues over the years. Even new ones. A P90 required a new slide (diagnosed as a tempering problem). A Redhawk required a new hammer, trigger & cylinder. Other little issues arose from time to time in other guns, as well. It can (and does) happen to any manufacturer, FWIW.

You should call Ruger and discuss this issue with them. They could examine and correct any issues.

alde
May 6, 2009, 03:24 PM
It's probably un-burnt powder under the extractor star. For some reason the SP101's have this problem. The cure is to keep that area fairly dry of oil so the powder can't stick.

harmonic
May 6, 2009, 03:32 PM
Give it a very thorough cleaning, then try different ammo. A couple of different brands of ammo.

If the problem repeats itself, send it back to Ruger. The gun is under warranty.

fastbolt
May 6, 2009, 03:32 PM
It's probably un-burnt powder under the extractor star. For some reason the SP101's have this problem. The cure is to keep that area fairly dry of oil so the powder can't stick.

Yep, if or when you decide to call and discuss your experience with Ruger, be prepared to be asked whether you've eliminated this as a potential cause while checking the functioning. As mentioned, it can happen.

Rob P.
May 6, 2009, 04:55 PM
Thanks for the hints on where to look. As of today I still haven't had the time to look at it. Probably won't be for a couple more days until I can get to it. (this is because of a work related problem. Got to earn money to buy toys with.)

I'll post in this thread after I look into it to let everyone know what I found.

BHP FAN
May 6, 2009, 08:46 PM
I'd send it back to Ruger for a FREE tuneup,especially if it's destined to become a carry gun.

Larry Burchfield
May 7, 2009, 06:50 AM
Cylinder gap to close. Check it with feeler guages. Needs to be .004 to .006 on the closest chamber. What is happening is when the gun heats up from shooting the gap closes up and the unburned won't let the cylinder turn and when you open the cylinder it breaks the powder loose. BTDT.
Another good range tool for every revolver shooter to have in his shooting bag is a brass Squib Rod. This is a rod that is about 8 inches long and at least 5/16 inch in dia. to be used on those reloads that didn't get any powder put in the case and locks the cylinder up with a bullet stuck in the forcing cone. BTDT.
Larry Burchfield
SEABEES/RVN/67/68/69
DAV

Rexster
May 9, 2009, 05:14 AM
Since the problem would go away, at least sometimes, by opening and closing the cylinder, I would say it is MOST likely bits of fouling under the extractor, that manages to fall out when you open the cylinder.

This is easy to diagnose! First of all, there should be NO oil anywhere on/in the cylinder assembly. Take an old toothbrush, or similar brush, to the range. With EVERY reload, thoroughly brush under the extractor after dumping the empties, then reload and repeat. This brushing should include the extractor "star" itself, and the recess into which it rests, in the cylinder assembly. If the binding does not happen, then it should be the brushing that prevented it.

Solutions? Keep things dry. Oil acts like flypaper when an unburned powder grain hits it. Use cleaner-burning ammo, at least for carry purposes. Ask Ruger customer service if they can recommend a course of action.

FWIW, I have two older GP100 sixguns, that have "grunge" grooves machined into the surfaces under the extractor. The one I have owned since about 1991 or 1992, which I used as a duty sixgun, has been fired with some really filthy-burning ammo, and never has gummed up. The other is still unfired by me, as I just recently paid it out of layaway. I have a 2002-made GP100 that does not have these grooves, and it can gum up and bind a bit, with dirty ammo. None of my SP101s have these grooves, but none of them have gummed up enough to bind.

One custom gunsmith, perhaps the late Andy Cannon, would machine such grunge grooves as part of a package done to S&W revolvers. I don't know if anyone does this these days.

RugRev
May 9, 2009, 12:30 PM
I think Massad Ayoob mentioned the grooves under the extractor at one point. Aside from Cannon another gunsmith he dealt with is at Tarnhelm Supply in New Hampshire.

springmom
May 9, 2009, 02:43 PM
And don't forget...if it is new, it is something Ruger will take care of for free. They will send UPS out to your house now to pick up the gun (you have to have it boxed up for them, of course) and so the days of waiting for a free shipping label are past.

Call them. Their customer service is great. If cleaning it doesn't do the trick, send it back. That's what warranty service is for.

Jan

SwampWolf
May 9, 2009, 05:07 PM
Though it could be a number of different things as many posters have pointed out, from the op's description of the problem, I have to side with those who have opined that a flake or two under the extractor star is the likely culprit. In 29 years of shooting in mandatory qualification courses (the last few years with a semi-auto), the only occasion when I had a firearm "malfunction" involved a Smith & Wesson Model 13 that I was carrying at the time. This revolver had a particularly nice da pull but, in one of the last strings of fire, the trigger pull became harder and harder and finally refused to budge. The instructor examined the revolver and, sure enough, a couple flakes of unburned powder were found under the star. Because the Model 13 is a blued revolver, the powder flakes were difficult to discern- the flakes will show up better in a s/s gun.

If you're lucky, this will be your problem: it's the cheapest fix of all!

koz4guns
May 9, 2009, 05:21 PM
Could it also be build up in the cylinder from the lead SWC's not letting the rounds seat all of the way in and binding things up?

Koz

win308
May 9, 2009, 08:42 PM
Something to look for....soft primers in the fired cases. If the primer flows back around the firing pin, that will lock you up pretty fast. Change ammo brands and try a session at the range ..... might be your only problem.

Rob P.
May 10, 2009, 11:47 PM
Ok, I looked at it VERRRRY carefully before I cleaned it. What I found:

BC gap is approximately .0045" (A loose .004" and a really tight .005" on my feeler gauge set) Thus, the BC gap is fine and within spec.

It was really dirty behind the extractor star. No unburned power flakes but a lot of gritty looking grunge buildup. The grunge wasn't really gritty, it just looked that way. The extractor has a small indexing pin and that had a bunch of grunge built up around it. The extractor was "level" with the surface of the rear of the cylinder however.

After wiping the grunge out and before cleaning, the extractor now sits a bit "recessed" from the cylinder surface. So, I'm thinking that the grunge buildup was keeping the extractor from seating fully. That kept the ammo from seating fully into the cylinder.

The cylinder face shows no lead buildup. Neither does the forcing cone. So the problem is/was not at the front end of the cylinder.

The ammo that was being used was EXTREMELY dirty. However, the primers on the fired rounds look fine.

The course of fire required us to shoot 4 round strings. Why they required this I don't know. In order to keep track of what was being shot, I only loaded 4 rounds into the cylinder per shot string. This left an empty charge hole which apparently allowed a lot of the powder to blow back through the empty hole. This is what I believe created the grunge under the extractor star. Or at least contributed to it more than it would have otherwise.

After cleaning the revolver function tests perfectly. I'm going to take it to the range and shoot it again and see if I can "make" it malfunction again. Unfortunately I can't use the same ammo as my local range requires "green" ammo only.

johnrobe
May 11, 2009, 10:12 PM
BC gap is approximately .0045" (A loose .004" and a really tight .005" on my feeler gauge set) Thus, the BC gap is fine and within spec.

What is spec for a new SP101?

I could tell there was more cylinder play in my new SP101 than my GP100 so I bought a set of feeler gauges and measured.

SP101

B/C gap: .008
endshake: .004

GP100

B/C gap: .005
endshake: .001

I emailed Ruger last week asking if the SP101 numbers are within spec, but no answer yet.

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