SP101 327 cylinder throat .3085

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clone

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I have been casting for a couple years with success, using lee molds in 30-30 (150gr .309 LFN), 45-70 (405gr .457 LFN), 32SWL (90gr .314), and 32 H&R mag using the same mold. I am using wheel weights for lead. Worked with 9mm (124 gr LFN TL) with no success and it has been put on the back burner for now, until I can try a different mold.

So thinking revolvers would be easier with cast bullets, I bought a SP101 in 327 and loaded a few Hornady .312 85gr and 100gr XTP with ok results, but still working with them. When I tried the Lee 90gr mold with the 327 I am getting excessive leading no matter what speed I push them. Checked the 327 throats and bore with calipers and to my surprise .308 throats and .309 bore.

Is this normal for 327's or do I have an odd ball? .308 seems excessive even for .312 jacketed much less .314 lead. Even the bore seems a bit small but maybe that's normal? Should I get a 30 carbine mold and work from there or should I have the throats reamed by a gun smith? Would Ruger say this is in spec?

What are you folks getting with your 327 revolvers?
 
.3135 to .314 and that seems to be the most common size for Ruger .327's while other manufacturers seem to prefer .313 for their .32 Mag revolvers.

If I had a choice it would be to make all my .32 revolver throats .312 to .313.
 
Welcome to Ruger ownership. It took me about 5 different Ruger revolvers to finally figure out the cylinder throats were all too tight. I sent the cylinder of my single remaining Ruger off to have the throats opened up and reamed... the gunsmith said not one of them was the same.
 
My SP101 mics at .314 in the throats. It matches what TTv2 is saying.

If yours mics at .308-.309" then it is a total screw up from Ruger, and a dangerous one at that, BUT,

Just make sure that's what the throats and barrel measure, before calling Ruger, even if you have to have someone else measure them with their equipment.

The cylinders and barrels would be made by different departments, or at least different people, so it would be a real coincidence for both to be the same measurement that is that far off.

It sounds like to me your calipers are out of calibration. Please check to see that they are zeroed when completely closed.

If your calipers were open part ways and you pushed the zero button, that takes away from the measurement your trying to take.
Just a guess from my experience of dumb things I have done over the years.
 
tightgroup tiger,

Yes I had thought user error when I first measured as well. So I tried my other caliper and same reading.
Whats worse is that I have shot 100 or so 85gr xtp's through this thing before trying 20 or so lead bullets working up a load.
Just glad no one was hurt.:scrutiny:
 
Ohen Cepel,

I agree that sluging will be more accurate on the bore. But no I had done a quick measure with the calipers for the moment. I might slug the bore later for giggles, but the major problem as I see it at the moment is the throats. Was just looking for the cause of the leading when I decided to measure.

Just for reference, I just measured the throats on the H&R 732 it measures .313 and the NEF 32 H&R mag measures .3125.
 
Sounds pretty messed up. I would be getting a return label from Ruger I think. Odd that they got both the throats and the barrel wrong but strange things happen at times.

I'm bummed that Contender .32mag barrels are all .308, and made that way be design. However, this isn't a decision Ruger made but a mistake.
 
Charlie98 said:
Welcome to Ruger ownership. It took me about 5 different Ruger revolvers to finally figure out the cylinder throats were all too tight. I sent the cylinder of my single remaining Ruger off to have the throats opened up and reamed... the gunsmith said not one of them was the same.
Click to expand...

Had a Super Blackhawk 44mag and a Blackhawk in 357mag that a local smith said the same thing ... he said he has seen it many times
 
Ohen Cepel said:
Sounds pretty messed up. I would be getting a return label from Ruger I think. Odd that they got both the throats and the barrel wrong but strange things happen at times.

I'm bummed that Contender .32mag barrels are all .308, and made that way be design. However, this isn't a decision Ruger made but a mistake.
Click to expand...
Match Grade Machine is a company in Utah and they will make T/C barrels in a variety of .30 and .32 chamberings on either a .308 or .311 dia groove bore.

Of course buying from them means you take of them not getting the headspacing right and will require you to send the frame in along with the barrel.
 
Way back when Ruger first released an SP-101 in 32 mag my bud and I both bought one. We both like the 32 mag round. Mine wouldn't shoot lead bullets worth a flip. I sluged the bore and found it was right on at .312. But the throats on my gun were .309 and the throats on my buds guns were .310. So I bought a .3125 reamer and reamed the throats on both guns. What a difference that made.

If your barrel has an odd nuber of lands and grooves you really can't measure it with calipers. You will need to slug the barrel. And the best advice would be to call Ruger and let them repair the gun. I have read that they gang ream the cylinders to save time and that would explain throats being different on each chamber.
 
ThomasT

If your barrel has an odd nuber of lands and grooves you really can't measure it with calipers.
Click to expand...

Ya thats what I was thinking.

I will contact Ruger when I get the time, with work and all its a challenge. I will post back when I hear something.
 
I used some .315 balls I bought for Gallery type loads to slug my bore. Then you can for sure get on the high spots and get an accurate measurement.
 
So I contacted Ruger through there web site, and got a puzzling response.

This is what I wrote:

I have been shooting my sp101 in 327 a bit with 85gr xtp and accuracy was a bit off. So I figured I would try to work up a load with lee's 90 gr swc bullets, .314 dia. I was getting a lot of leading no matter how slow I pushed them. So I checked the cylinder throats with two different calipers and come up with .308 throats. Is this normal for the SP101 in 327 magnum? What are my options?
Click to expand...

This is there response:

Thank you for contacting Ruger Customer Service.
Your Customer Service Issue # is 10249030

The throat dameter for the .327 cylinder throats are .3402 +/- .0010

Ruger Customer Service
Click to expand...

It was a bit short, as I was on my phone one my lunch break. but I thought I had gotten my point across. I suppose not.
Given that response I'm not sure they even read the whole inquiry.
I will try calling Monday and see how that goes.
 
@clone when you call, don't mention you loaded up your own ammo, just say you've tried shooting it with lead factory ammo and no matter what you shoot, it's leading and out of all the revolvers you've owned you've never had leading issues like this before. Then tell them you suspect the cylinder throat diameters are off.
 
There is one other thing no one has mentioned... the dreaded Ruger torque bulge.

I had a very nice Flattop .44SPC, which, like every other Ruger revolver I've had, showed terrible accuracy. I sent the cylinder off to have it reamed, which helped, but didn't change the POI problems. The gunsmith that reamed the cylinder told me to shove a very tight patch down the bore and feel for a restriction near the forcing cone. Sure enough, just past the forcing cone was a restriction... enough I could feel it. When Ruger tightened up the barrel, they overtorqued it to get it to clock right... the excessive torque creates a slight bulge in the barrel basically where the barrel threads into the frame. You might check for that.
 
Two years ago I had the same experience mentioned here with the SP 101 .327 cylinder.
Would not eject spent .327 brass and some .32 H&R Magnum brass. Took three trips back to Ruger to get it right. For the last return I put the trigger lock on and left three of the spent brass casings that would not eject in the cylinder. I’ll admit my LGS handled everything so the only things of consequence to me was a 10 week period w/o my new firearm and subsequent range time.

First ever problem with a Ruger and I’ve owned and still own several and would not hesitate to buy another.
 
Last edited:
Thank you for contacting Ruger Customer Service.
Your Customer Service Issue # is 10249030

The throat dameter for the .327 cylinder throats are .3402 +/- .0010

Ruger Customer Service
Click to expand...

They actually said the throat diameter is .340" for an Sp101 in .327 FM? Not .314"?
 
Update:

So I called and they said send it in. So I shipped it in on my dime.
Received my SP101 .327 back yesterday. With an itemized list of what was done.

Replaced Cylinder
Safety check
Proof test, range test, & cleaning

Cylinder throat measures .312 now. Still not .314, and the outside of the cylinder is ground to a taper.
Is that normal? My old one was not and I think it looks stupid. Not happy with the tapper.
Is this something new they are doing with new production revolvers for looks or is this another goof?

Thinking now I should have taken it to a gunsmith and to have it done properly.
But now with the tapper if I have it sized, it may be to thin and be unsafe.
 
tightgroup tiger,

Yes, I'm guessing they just breezed over it and didn't read what I had wrote, and assumed chamber dia.
 
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