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Discussion Starter · #1 ·
I just bought a 357 GP100 4" 7-shot revolver a week or so ago and have been to the range to shoot some 357 and 38 ammo through it a couple times and have noticed some binding issues that I only managed to figure out today.

When I load up factory Blazer Brass 38 spl FHP, the last round causes the rim to bind against the rims of the already loaded rounds. In other words, the rounds are so close together in the 7-shot cylinder, that the rims touch. It doesn't matter which chamber is loaded last and it doesn't matter which round is loaded last. It is not a round specific or chamber specific problem.

Unless I push the round in with some thumb pressure, it will stick out enough to bind against the frame of the gun when I close the cylinder interfering with the rotation of the cylinder and operation of the trigger.

If I push the round in with some thumb pressure, it will go in, the cylinder will close, and everything works fine. But, when I then try to eject the spent rounds, I have to really push on the ejector rod to get the casings to elect.

Using a caliper, I measured the 38 Blazer Brass FMJ rims and they come in at about 0.435" or so, which is less than the 0.440" specification for .38 and .357 mag. But, when I measure the 357 Blazer Brass mag rounds, the rims are definitely slightly smaller in diameter and I do NOT have this problem with their 357 ammo.

So, the question is whether anyone has heard of this issue with GP100 or any other 7 or 8 shot revolver where the cylinder chambers are so close together.

I plan to contact Ruger and Blazer to see what they say. I will report back here if/when they reply.

I did a google search to see if this issue has already been reported by someone else, but couldn't find anything. If someone has already posted about this please let me know. I may not have used effective search terms.
 

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Have you tried any other .38 spl, besides Blazer?
 

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Discussion Starter · #3 ·
Nope. I have not tried any other ammo yet, although I'm hoping that will solve the issue. I got the gun primarily to shoot 38s, not 357. I wanted a heavy gun and it just so happens heavy 357s are common.
 

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I don't have a GP 100, so can't comment on that, but would guess the problem is probably with the Blazer .38 ammo and would be the simplest answer/problem......Occam's razor.
 

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Discussion Starter · #5 ·
I don't have a GP 100, so can't comment on that, but would guess the problem is probably with the Blazer .38 ammo and would be the simplest answer/problem......Occam's razor.
Well there's no doubt that their 357 bases have slightly smaller diameter rims, at least with the batch that I have. Since the spec for the rim diameter of the 357 and 38 spl are the same, one would expect them to be the same on both types of ammo. However, the 38 Blazer ammo that I measured seems to all be within the 0.440" spec, measuring about 0.435" with my 30 year old cheapo craftsman vernier caliper. I will measure a few more and see if there are some odd balls that I am not catching that could account for the problem. Also, I have no idea what the tolerance is on that 0.440" spec,so I assume it can actually be slightly bigger than that.
 

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Discussion Starter · #7 ·
Well, I bought four other brands of ammo and did some comparisons and testing. All four brands worked fine, so this looks like a Blazer Brass issue to me. I posted the list of brands and test results in an update on the Youtube video description.

I'm glad it's merely an ammo issue, but I will think twice before I ever get another revolver that has the cylinder chambers crammed so close together. This particular problem could never happen with the 6-shooter version of this revolver. Same probably goes for other revolver brands as well.
 

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Live and learn-right?
 

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I just looked up the SAAMI specifications for the rim diameters and rim recess (in the cylinder) diameters for both .38 Special and .357 Magnum cartridges. The numbers are identical for both cartridges. The cartridge rim diameter spec is ".440 -.012" (0.428" minimum, 0.440" maximum). The recess diameter in the cylinder (that the rim fits into) spec is ".440 +.012" (.440" minimum, .456" maximum).

I suspect the recess diameter in your pistol is at or slightly less than the minimum spec and at the same time the cartridge rims in the ammo you have is at or slightly greater than the maximum spec. It would take some special tools to truly accurately measure both dimensions, particularly the inside diameter of the recess in the cylinder. Hopefully you won't have too much problem finding ammo that works properly in the cylinder.
 

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I don't think his chambers are recessed Skip .
 

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No room for rims on the high side of tolerances with 7 round cylinder. Anyone know if these non typical capacity cylinders are prone to timing issues ?
 

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Discussion Starter · #13 ·
Thanks for the dimensional info. I can understand wanting to keep the chambers as close together as possible to keep the cylinder diameter as small as possible and save weight, but I can't imagine dipping below the specs necessary to accommodate all ammo that is in spec just to make the cylinder a tiny bit smaller. I don't have enough confidence in my caliper to state categorically that the Blazer Brass rounds are in spec, but there is a possibility that the cylinder was designed to accommodate some rounds being max rim diameter while assuming it's unlikely that all the rounds loaded at a given time would be at the max.

Pennsy's correct that the chambers in the GP100 are not recessed, so the max rim dimension from the revolver's point of view would be the maximum allowable without interference with rims from adjacent rounds. Of course, there is some wiggle room in the chambers, so some rounds could be a tiny bit oversized as long as there are some rounds that are slightly undersized. Hell, maybe that's part of the logic for not having recessed chambers.

Where I shop, I think Blazer Brass ammo is the low cost stuff. It sells well and probably works fine in most guns, but perhaps their standards are not up to the same level as Remington, Winchester, etc.
 

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I'm interested in what Ruger and CCI tell you . It is not unusual for chambers to be tight or loose and for ammo to be long or short for example . Both will probably say that their product is within specs . Nice gun anyway .
 

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Discussion Starter · #15 ·
I made my last reply without noticing that the thread had expanded to a second page, so I missed a couple comments.

Pennsy, I'm not sure what you mean by timing issues. I assume the cylinder is mechanically interlocked to the trigger and hammer in a way that prevents mistiming. Maybe I am misinterpreting what you meant. It's also possible I don't know what I'm talking about. I'm pretty new to guns, so I am still on the learning curve.

I'd be surprised if I heard back from Blazer or Ruger. I think they would view this as a "can of worms" issue, but you're probably right about how they'd respond if they did reply back to me. If I hear from them, I will post about what they say.

I didn't realize until just now that Blazer and Federal are owned by the same umbrella corporation (Vista Outdoor).
 

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I was just speculating about timing . Seems to me , as the round count goes up , timing becomes harder to accomplish . After searching around though , I found very little about it on the web . Totally unrelated to your problem anyway , just thinking out loud .
 

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Discussion Starter · #17 ·
I received two form-letter style replies to my emails to Ruger describing the problem. One suggested I clean the gun and the other said that they would look at the gun if I called and requested an RMA number.

I received a more informed reply from Blazer asking whether I have any ammo left and, if so, to send them the date codes. If I send them the ammo, they will measure it to see if it is out of spec.

If they ask for it, I plan to send the ammo to Blazer, but will probably not send the gun to Ruger since there is no way they are likely to conclude their gun is defective or out of spec if it only has problems with ammo from one manufacturer. The form letters also didn't inspire much confidence that they would take the issue seriously enough to conduct more than a superficial analysis.

None of my testing allows me to definitively conclude that the ammo is out of spec or that the chamber spacing is too tight on the gun. All I can say is that the Blazer Brass .38 Special ammo has slightly larger diameter rims than the 4 other brands that I tested and will not work properly in my 7-shot GP100.

Finally, I made a followup video to demonstrate that the binding issue persists even after thoroughly cleaning the cylinder chambers:
 

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Discussion Starter · #18 ·
I was just speculating about timing . Seems to me , as the round count goes up , timing becomes harder to accomplish . After searching around though , I found very little about it on the web . Totally unrelated to your problem anyway , just thinking out loud .
Kind of unrelated, but when I was searching the web to see if anyone else had this issue, I started to wonder if the thin walls between cylinder chambers wasn't also a hazard. Probably not, but that never occurred to be before I bought the 7-shot version of the GP100. If I knew of these concerns before I paid extra for that 7th chamber, I might have gone with the 6-shooter instead. The 7-shot gun now seems less robust.
 

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Discussion Starter · #20 ·
Find a self defense round you like and trust and fits and you are good . Here is an article that might interest you although it about snubby ammo . The FBI load gives god penetration with moderate expansion :

https://www.gun-tests.com/issues/24...2127841a:&st=email&s=p_wss020218#.WnWne66nGM8

https://cdn.gun-tests.com/media/pdfs/38DEFENSE.pdf
Thanks. I haven't bought any self-defense ammo yet. I'm new to guns and am still just trying to practice consistent technique by dry firing and range shooting. I will check out these links.
 
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