GP100 Forcing Cone Wear

While cleaning I noticed this wear on the forcing cone inner edge. Is this something to be worried about? It is only about 6 months old and maybe 1200 rounds through it.

I'm going to bet you are shooting some hot loads with Lil'Gun powder? :shock:

I'm not an expert, but it isn't something I would worry about. Maybe go easy on the cleaning brush?

Good photos! Please tell us more. Purchased new? What type of ammunition? 1200 rounds of .357 mag? Maximum reloads? The frame around the barrel looks mighty clean and there's no evidence of flame cutting I can see. It looks like someone took a pocket knife and "beveled" the sharp edge of the forcing cone. What is your b/c gap?

Carry_Up

What Jimbo357mag said +1 . It looks like heat caused erosion /checking to me.
I would be rethinking my loads.

Dogmax.... welcome aboard. Photos of your GP-100 are clear enough to show what we call "forcing cone erosion." Technically, "barrel face erosion" might be more accurate, as the cone itself does not erode; or, if it does , erosion is way down the road.

Your forcing cone erosion----with rivulets instead of smooth all around----sometimes indicates a characteristic of the sandblasting effect of large charges of ball powder on stainless steel. The same effect may show somewhat more smoothly on chrome moly steel. Factory .357 mag with 125 JHP erode the cone faster than heavier bullets over a lighter powder charge.

Erosion shown is inconsequential to accuracy. The above mention Lil Gun has achieved the status of NOTORIOUS from some shooters. I haven't the experience with Lil Gun, but it is a question to ask. As you photos show, the GP-100 has plenty meat around the barrel socket, importantly including the six o'clock position. This digression is to compliment you on selecting a strong revolver.

In my loading, I would consider this advanced erosion for 1200 rounds. Which raises the question, what are you shooting?

The 125 JHP is a fine high performance bullet in the .357 mag, capable of excellent accuracy at 100 yards. The 110 JHP much less so. Both tend to more aggressive erosion than the 158 and 180 JHPs.

A forum "diagnosis" is impossible without knowing the ammunition.
David Bradshaw

If that is 'erosion' from stout charges below light bullets, then it is strange to see that level of erosion with no flame cutting of the top strap at all...

Interesting...

+1 David Bradshaw.
I might add the reason the lighter bullets are seen to cause more erosion of the barrel face is because with their shorter length when they come out of the cylinder they allow more hot gas and powder to exit the B/C gap. A longer bullet like a 158gr will keep the B/C gap covered longer and allow slightly less hot gas and powder to escape there. As mentioned the slow, hotter burning ball powders are the worst.

Because there is no flame cutting of the top strap I might change my guess to light bullets and a faster powder. Maybe Winchester White Box 110gr ammo? In any event I think it is time to change your type of ammo. If you wish to carry lighter bullets for self defense, no problem, just practice with something else.

Thanks for all the replies, some great info. I am not a reloader, so everything I shot has been factory loads. When I purchased the revolver (brand new), I did buy a box of remington 125 357 rounds. I still have quite a few of those left so it has seen less than 50 of those. I have put about 60 buffalo bore 180 grain down the pipe. Otherwise the rest of my loads have been 158 grain herters, american eagle and pmc. So I am to assume this isn't normal and a call to ruger is in order.

dogmax said:

Thanks for all the replies, some great info. I am not a reloader, so everything I shot has been factory loads. When I purchased the revolver (brand new), I did buy a box of remington 125 357 rounds. I still have quite a few of those left so it has seen less than 50 of those. I have put about 60 buffalo bore 180 grain down the pipe. Otherwise the rest of my loads have been 158 grain herters, american eagle and pmc. So I am to assume this isn't normal and a call to ruger is in order.

Click to expand...

I agree, a call to Ruger might be in order. It's not too bad but looks like premature wear to me. Maybe you could email or fax pictures to them. :shock:

Dogmax.... with your three photos taken from the left side only, the left edge of the cone is obscured. Nevertheless, the left edge appears sharp. If it is, and not rough as the right edge, I saw chambers are offset slightly to the right (3 o'clock). The forcing cone appears unnecessarily deep, with a few rings. I would lap the forcing cone before I dropped a reamer in it.

Were I to call Ruger, it would concern the forcing cone, not that piddly erosion. In the event the revolver shoots plenty accurate, I wouldn't call Ruger at all.
David Bradshaw

Your Ruger needs the forcing cone cut. This is a touchy subject as factories don't really do this as best needed. I have my own cutter and cut all mine with the 11 degree cut which works best for cast bullets. I believe Ruger does an elementary cut on some revolvers at 9 degrees, which is supposedly better for jacketed bullets. However, many forcing cones on NIB guns appear to me to have no cut at all. Find a local gunsmith who can do this for you. They charge approx. $20.00 or so.

Yep, forcing cone erosion. I replaced two "Six" barrels that were much worse and starting to spit badly after a lot of factory 125s. Neither had flame cutting to the top strap at any time and I still have both guns. It does accelerate over time so when you get tired of the spitting you will be springing for a new barrel.

I have and like a nice GP-100, but never believed the claim that somehow you could run unlimited hot loads through the gun without any effect. A forcing cone is still a forcing cone.

I 'polish' that area on my revolvers with a KLEEN-BORE Lead-Away cloth; I presume ("guess") the microscopic radius the cloth abrades on that cone 'edge' helps reduce/limit erosion.

I test by accuracy, ay?

I also burn alotta Universal........

This is the forcing cone on my 6" half lug stainless GP100. It has a had a steady diet of 158 grain plated bullets on top of 16.5 grains of Lil'gun, and the accuracy is phenomenal.

Laserbait said:

This is the forcing cone on my 6" half lug stainless GP100. It has a had a steady diet of 158 grain plated bullets on top of 16.5 grains of Lil'gun, and the accuracy is phenomenal.

Click to expand...

Good lord, now that's what I was talking about. :shock: :shock:

Just as an update:

I took the gun to a gun smith and had him take a look at it. According to him the forcing cone is cut to deep so I cannot re-cut it. Also made a comment of all the tooling marks and how their should be none. He recommended a rebarrel and that I give ruger a call. I did as he said (I really didn't want to) and now have my rma number with ups picking it up tomorrow. Will let you know when I get it back!

Laserbait.... yes, your GP-100 shows real erosion, and lends credence to the theory that Lil Gun is an especially hot powder. If erosion continues inside the forcing cone, that would support a hot propellant theory. Reckon you experience spitting with this degree of barrel face erosion. Win 296/H110 should give you the accuracy and velocity, while reducing erosion.

Providing erosion doesn't extend down cone and into rifling, I suggest you have the barrel set back. Why? You already said is it very accurate.

If a gunsmith does the work, he may reduce cylinder/barrel gap to less than the factory might. You could send the photos to Ruger Customer Service in Newport, NH. Find whether Ruger will set back the barrel or replace it.
David Bradshaw

I had erosion on my 4" GP-100 to the point it cut throught the forcing cone and looked like a crack, after firing countless Remington 125gr JHPs. I returned it to Ruger who replaced the barrel and reconditioned it to AS NEW free of charge. Not bad for a revolver I bought in 1986.