Printing Plate Gas Checks

[castblast]

I have some .011 printing plates and a 35 check maker on the way from Pat.

Has anybody tried using printing plates for checks? They seem pretty hard. Might have to be annealed. Can I do this in an oven?

I'll be using these for 35 Rem and 358 win

Thanks!

[JeffinNZ]

That's pretty much all I use. Mine are 0.3mm or 0.0118 inch. I ply them up with a 0.004 inner layer of soda can wall to make perfect checks for my .303 British loading.

[madsenshooter]

One side and in some cases both sides, is coated with aluminum oxide, an abrasive material, that's a few atoms thick. Others use them though. Until recently I worked at a place that would have been an endless supply, plates 5'x6'!

[bowfin]

Aluminum Oxide...

I must have gone through a couple thousand aluminum oxide wheels in my career as a tool grinder. What grit size do you composes the aluminum oxide buildup on a printing plate?

That is the most important question when considering the cutting efficiency. An aluminum oxide wheel (or piece of sandpaper) is made up of grit bonded to other pieces of grit on a grinding wheel, or in the case of a piece of sandpaper, the paper. Each individual piece of grit is its own cutting tool. When it gets too dull to cut, the pressure overcomes the bond and breaks off that particular piece of grit and exposes a fresh, sharper one. (Norton SG wheels are a law unto themselves)

Larger grit, like 60 or 80 is more aggressive than 120 or 180. 600 grit particles measure .0006 on average. I ran an indicator across an aluminum printing plate, as I have a couple left over from our company's old print shop. IF this aluminum oxide forms individual particles, they are so small as to be inconsequential as a cutting tool. Certainly much smaller than my dial indicator can pick up (.0001"), which is smaller than anyone could ever use, even as a polishing compound.

Think of it another way: ground up glass is abrasive, a sheet of glass is actually slick. The shape of ground up glass provides a cutting tool geometry by providing sharp points. A sheet of glass doesn't, so it can't cut.

If one had a wheel made up of the aluminum oxide particles found on a printing plate, I would bet any amount of money that one could not cut even the slightest amount of steel before the wheel blew up due to too much pressure.

I am thinking the powder will burn out a barrel years and years before aluminum oxide from a gas check would remove a measurable amount of a barrel's rifling.

[Ben]

This " dark cloud " AL oxide issue just keeps hanging around.

I want to see some hard facts. If people are going to continue to contend that AL oxide is wearing out our barrels ( when we shoot aluminum gas checks) , where are the facts ?

I'm certainly no authority on what AL oxide can or can't do, but I'd like to see some facts.
For example, just how big are the AL oxide particles that are on a gas check ? If we know their size, just how many passes down a barrel will it take to change the internal dimensions of a barrel , by even .0001 " ? ?

[bowfin]

I had a pile of the aluminum printing press plates, but I thought that they would be too thin to use. Now I see someone figured it out.

Right now, I have too many irons in the fire to make my own gas checks...the Tyranny of Time.

[JeffinNZ]

I don't buy the whole aluminum oxide thing. First reason, the printing plate is coated on both side with a laquer. Where is the oxide? Secondly, I have shot thousands down my No4 MkII .303 and the old girl is shooting better than ever. She is a sound 1 1/4 MOA rifle with cast.

[Mugs]

A little info from Wikipedia For those that are worried about aluminum oxide. " Aluminum oxide is responsible for resistance of metallic aluminum to weathering. Metallic aluminum is very reactive with atmospheric oxygen, and a thin passivation layer of alumina [4 nm thickness] forms in about 100 picoseconds on any exposed aluminum surface. This layer protects the metal from further oxidation." I don't think anything as small as 4 nm is doing any harm.
Mugs
IHMSA 5940L
"

[Ben]

Mugs

Better be careful, . . . you might wear out your barrel after 456,000 rounds.


JeffinNZ :

That is some fine shooting with your No. 4 Mk II. What is your load ?

[castblast]

Thanks for all the info!

I didn't realize the aluminum oxide thing was a recurring discussion.

If I do need to anneal these plates, will a kitchen oven work? Or will I need something more like a kiln?

[JeffinNZ]

No need to anneal them in my experience.