O-ring diameter and thickness for RCBS LAM2

[Land Owner]

I have not had this thing for one week and the O-ring has failed, but I have run 3 complete "tubes" of lube through it already!

The "instructions" that came with the unit do not give either diameter or thickness. Perhaps attesting to folks that call them up to purchase OEM parts. I am certain that Ace Hardware can get me going again tomorrow if I know what to purchase.

Is failure of the O-ring normal? This soon? Perhaps I am going at this too hard? Too fast? I used RCBS green-lube that came with it the first time, then poured hot lube, 1/3 softer by comparison, NRA lube for the 2nd and 3rd fillings. Perhaps it was too hot? Or I used it too soon while it was hot?

[870TC]

I get the o-rings from "Menards" locally, its like a Home Depot. Package says 1-1/16 x 13/16 x 1/8 and o-ring #16 Stock #35733B. Not sure why yours failed so quickly.

[Land Owner]

That is a PERFECT fit. Thank you!

Ace Hardware...$0.59 and a deal at twice the price when your equipment is down.

[Tom W.]

I blew out a few when I was learning about mine, too. RCBS sent me 3 or 4 at a time until I got a bit wiser...

[Land Owner]

Tom...ever figure out what was wrong? I would like to prevent a repeat performance, but I bought 3 extras in case I am a slow learner.

[fishnbob]

I get the o-rings from "Menards" locally, its like a Home Depot. Package says 1-1/16 x 13/16 x 1/8 and o-ring #16 Stock #35733B. Not sure why yours failed so quickly.

I have looked everywhere for a #16 O Ring and no one has it. They have #15 and #17 but no # 16. I emailed RCBS and they graciously sent me some Sizer Dies O Rings that I am sure I can find locally. If I didn't have bad luck..............!

[RidgerunnerAk]

This issue with the RCBS O rings is caused by three things - using a relatively hard lube, room/equipment temperature, and how fast you advance the piston. I've dealt with this issue for 30years. If I went downstairs into my cold basement right now and tried to size I'd blow the O rings out of my lubrisizer in 15 seconds. I recently switched to SPG lube for my .45-90 bullets. It's much softer than the relatively hard RCBS lube, which I am done with, and works much better in the RCBS unit. Regardless of what lube I use, I have to either bring the sizer up into the main cabin to warm up overnight or use a heat gun to carefully heat up the entire sizer before I use it. You also have to be careful how rapidly you advance the piston. If I resize in summer it's never a problem unless I crank the piston down too much too fast. So, do it in a nice warm room and be ginger with advancing the piston. I've replaced my O rings a number of times over the decades.

[fishnbob]

I put an aluminum plate under my RCBS LAM and set my wife's iron on it and that softened the carnuba red to a good workable lube. I would not try it without it, plus I have heat in my shop reloading room but I only keep the temperature around 63*-64* in cold weather. I'd rather wear a sweater than to sweat. I was wondering if the finish on the inside of the lube reservoir might have an impact of the longevity of the O rings? A little roughness in the casting would play havoc with an O ring, I would think. Maybe those having to replace them often should check for this and little polishing up might do the trick.