Well this is a new one...

2685 Views 14 Replies 10 Participants Last post by P15-D24, Apr 9, 2013

jcpowell27

Discussion Starter · Apr 4, 2013

2

I went out to the range yesterday and shot 100 rounds through my 581 series Mini. I did not experience any malfunctions at the range so when I was done, I packed up and went home. When I sat down to clean my rifle, I noticed that two of my gas block screws had sheared themselves apart!

My original thoughts were that I over tightened the screws since I have re-torqued the gas block, but that was last summer and I have since put many rounds (800+/-). The ammo I used was 20 rounds of PMC Bronze .223 55gr. FMJ, 40 rounds of American Eagle .223 55gr. FMJ and 40 rounds of Herter's (repackaged Tulammo) .223 55gr. HP. I don't think that any of that ammunition should have been "too powerful" for the rifle.

Has this happened to anyone here before? What do you all think caused this? What do you think my next course of action should be? Should I send it into Ruger for repairs or should I just order some new screws and install them myself? Thanks in advance!

-Joe

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TxQuail

· #2 · Apr 4, 2013

jcpowell27 said:
I went out to the range yesterday and shot 100 rounds through my 581 series Mini. I did not experience any malfunctions at the range so when I was done, I packed up and went home. When I sat down to clean my rifle, I noticed that two of my gas block screws had sheared themselves apart!

My original thoughts were that I over tightened the screws since I have re-torqued the gas block, but that was last summer and I have since put many rounds (800+/-). The ammo I used was 20 rounds of PMC Bronze .223 55gr. FMJ, 40 rounds of American Eagle .223 55gr. FMJ and 40 rounds of Herter's (repackaged Tulammo) .223 55gr. HP. I don't think that any of that ammunition should have been "too powerful" for the rifle.

Has this happened to anyone here before? What do you all think caused this? What do you think my next course of action should be? Should I send it into Ruger for repairs or should I just order some new screws and install them myself? Thanks in advance!

-Joe

You torqued the bolts too tight.

The gas block heated up faster than the upper. The expansion of the lower stretched the bolts beyond yield strength.

It just took time and a couple of heat cycles to stress the bolts to failure

jcpowell27

Discussion Starter · #3 · Apr 4, 2013

Thanks TxQuail, I figured that was the most likely cause. What do you think I should do? Send it back into Ruger or just get some new bolts and be more diligent about torquing them down?

-Joe

COBrien

· #4 · Apr 4, 2013

My recommendation would be to fix it yourself -- those bolts wouldn't cost you more than $5 at the local hardware store, maybe $10 if you ordered through MidwayUSA or Brownell's.

Use feeler gauges to make sure your gas block halves are evenly spaced, then tighten in an X pattern. It's easy to get carried away and tighten one side of the gas block too much, then torque the sh¡t out of the other side trying to make gaps even. Trust me...

hottarod

· #5 · Apr 4, 2013

Just curious but where did your gas tube go to?

Scarey photo. I'm feeling the need to re-check my gas block torques. I may
have done mine a bit on the side of tight as well. I just recently got an
inch pounds torque wrench. I tend to have to deal with 35 pounds and 50 and 150(automotive stuff). The flywheel nut on an air cooled German engine I'm working on required 320 foot pounds. Torque wrenches for that sort of thing are about 2 1/2 or 3 feet long and are generally for trucks. I took the engine to a shop and paid them to do it.

jcpowell27

Discussion Starter · #6 · Apr 4, 2013

The gas tube and gas bushing are sitting in a ziplock bag on the work bench waiting to be cleaned and reasymbled. Like I said the rifle functioned perfectly at the range when this happened. The only thing I noticed was it wasn't throwing the Herter's (Tulammo) cases quite as far as I'm used to. I thought that was due to poor ammo quality until I got home and started to clean the rifle.

I will be picking up some new gas block screws and an inch pound torque wrench this weekend and doing this the right way this time around. Thanks everyone!

-Joe

tri70

· #7 · Apr 5, 2013

Did you have the screws in upside down, turning from the top half of the block?

P15-D24

· #8 · Apr 5, 2013

Anyone remember the bolt torque settings? 32/inch pds keeps popping up in my mind.

Found my notes:
Gas block screw torque 35 in-lb, The screw is 8-36 (5/16th to 3/8" long) grade 8 cap screws. Hex 9/64 The engineering torque spec for that size screw in stainless steel is 22 inch lbs

Can anyone confirm?

COBrien

· #9 · Apr 5, 2013

P15-D24 said:
Anyone remember the bolt torque settings? 32/inch pds keeps popping up in my mind.

Found my notes:
Gas block screw torque 35 in-lb, The screw is 8-36 (5/16th to 3/8" long) grade 8 cap screws. Hex 9/64 The engineering torque spec for that size screw in stainless steel is 22 inch lbs

Can anyone confirm?

I recall reading on here at one point in time that the recommended torque was 30-36 in-lbs. That's what I torqued mine to, and they're still holding strong.

Oh, and FWIW: #8-36x5/16" Socket Cap Bolt, Alloy Steel, Black Oil Finish - BoltDepot.com. $0.19 each.

EDIT: Sweet Jesus!! Don't order those bolts online -- call Bolt Depot first. They show $13+ just for shipping!

kwg020

· #10 · Apr 6, 2013

Tight but NOT farmer tight. You can only measure farmer tight in foot lbs and not inch lbs. I realize they are not big bolts but I'd hate to see what the shear strength of those bolts are. kwg

fishslayerbob

· #11 · Apr 6, 2013

Hey, hottarod;

Axle nuts, too. In my teenage years I picked up a '60 beetle real cheap because the BOBO didn't get them right and the transaxle made noise. Ah, the good old days!

fishslayerbob

40nascar

· #12 · Apr 6, 2013

jcpowell27 said:
I went out to the range yesterday and shot 100 rounds through my 581 series Mini. I did not experience any malfunctions at the range so when I was done, I packed up and went home. When I sat down to clean my rifle, I noticed that two of my gas block screws had sheared themselves apart!

My original thoughts were that I over tightened the screws since I have re-torqued the gas block, but that was last summer and I have since put many rounds (800+/-). The ammo I used was 20 rounds of PMC Bronze .223 55gr. FMJ, 40 rounds of American Eagle .223 55gr. FMJ and 40 rounds of Herter's (repackaged Tulammo) .223 55gr. HP. I don't think that any of that ammunition should have been "too powerful" for the rifle.

Has this happened to anyone here before? What do you all think caused this? What do you think my next course of action should be? Should I send it into Ruger for repairs or should I just order some new screws and install them myself? Thanks in advance!

-Joe

Yeah, just shows that you need to do research before tearing into a firearm beyond the fieldstripping stage. Applies to all things mechanical. Buy a set of torque wrenches and an armorers manual.

Splicenut

· #13 · Apr 8, 2013

Screw direction?

Just curious about what tri70 brought up. You SHOULDN'T be able to put the screws in upside down, since only the screw holes in the upper half of the gas block are threaded...but, in that one photo it DOES kinda look like a screw head protruding from the top half. Hard to tell from that angle, though.

I suppose that if one put the screws in right side up on one side, and then put the screws in upside down on the other, and gravity held them in place until the rifle was fired, that might cause the unsupported upside down ones to shear...maybe. Or maybe I need new glasses.

tri70

· #14 · Apr 9, 2013

The heads of the screws go in the bottom half of the gas block. If you had them backwards, the threads did not get deep enough and improper torque will fail for sure. The bottom half of the block takes the majority of abuse from the oprod hammering.

P15-D24

· #15 · Apr 9, 2013

Finally found a Grade 8, #8-36 torque chart (Spirol). Dry is 43.3 in/pds, Lubed is 32.5 in/pds. The stainless numbers posted earlier are correct. Grade 5 only goes to 30.8 inch/pds so you really need to use grade 8 bolts.

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