Confused about "not for steel" chokes

Hello Ladies and Gentlemen. 

Maybe the combined wealth of knowledge in here can give me a bit of help/guidance. 

Not starting the whole choke debate which seams to be a forewer on going subject. I shoot trap, and are still in the beginning stages. But I'd like to change the chokes so I can learn to shoot with the standard 3/4 and 1/1 from the get go.

My gun is proofed to 1370 bar (Denmark is stupidly not a CIP member so wrote the maker).  Normally I shoot a 24 gr, 2,4 mm pellet size MPS V1 410 in first barrel, and second barrel is the same but pellet size is 2,8 mm (apperently in Danish competition rulles we have a dispensation from ISSF rules on load). All are steel shot (very few grounds accept lead in Denmark) 

My 3/4 and 1/1 chokes are marked "not for steel shot". It might be totally daft to wonder if it's ok to shoot the target loads through them, but on my reasonable side of me says is it made for being over causios from the makers side. The chokes are stock that came with the gun. 

There was a longer thread on this, which gave me some idea, but it turned out to be a bit personal the end, and  the message drowned in it. 

So in short, if I go for it will it be OK? Or will the barrels become way bigger than the factory 18,4mm? 

Lars 

I have a feeling most manufacturers recommend up to half choke for steel shot so if it were me I'd refrain from shooting them through 3/4 & Full.

H is correct, also steel patterns tighter so it could be a disadvantage.

A couple of makers produce guns that can shoot steel through full choke, Longthorne being one..

What gun is it and how old?

I've been trying tp work this one out. It's not the easiest thing in the world to get a straight answer to.

My take on what i"ve read so far;-

In principle if it is designed to be steel proof then you can shoot any load through it at any choke up to 4.1mm (BB). Over 4.1mm then half choke max to be used.

As your gun is proofed at 1370 bar then I woud think it a modern gun designed for steel. (UKsteel  proof is 1320) 

If it's been made after 2006 by a european manufacturer and has 3" chambers it more than likely will be designed for steel..

From what I can work out It is not just pressure that determins whether a gun will withstand steel but also speed and the momentum gererated by the shot as it hits the choke. Although a gun probably won"t blow up as it's proofed to the higher pressire  too much momentum in a gun not designed for steel  may cause the choke to expand and/or bulge the barrel. Bigger shot sizes dont squash together as easily as small shot so this also has to be taken in to consideration. 

However Steel needs a lot less choke to get the same pattern and it's said amything tighter than 1/2 makes little difference and could blow the pattern and make it ineffective.

My Browning 725 which is steel shot proofed to cip regulations  chokes have the choke size etched on them for using lead and steel. E.g. The 1/2 choke for lead says 3/4 fof steel. The 3/4 for lead choke says full for steel. The full choke says lead only. 

 The chokes on your gun seem to be designed to take steel up to 1/2 so prob best stick to that. 

On older guns only the lower speed steel ( i believe 400 metres per S. But thats from memory so check. High velocity steel is I believe somewhere aroumd 430 Mps. )  should be used and only up to 2.4mm through any choke. Bigger shot sizes need the gun to be steel proofed..

Thanks for the answers. I'll just keep the 1/4 and 1/2 in it.  . 

Fiind it strange though. If I buy and aftermarket choke that is steel proof up to full it would be OK (in theory and no patterning issues taking in to consideration). I just can't get my head around how a choke can bulge and expand. If the barrels are proofed to 1370 bar. Chokes are flush against the inside the barrel. How can they then expand? If they bulge and expand, won't the barrels bulge and expand too? It would make more sense to me if the reason is that they'd rip the threads and shoot out. Like a champagne Cork under to much pressure. 

Well this is one of those things I'll never understand, but just have to learn by heart and do  as said, I go no further than half, forget what's in the gun and learn to shoot... 

Lars,

 You are thinking along the correct lines .

Because soft iron is not as deformable as lead the danger with steel shot and tight chokes is exactly as you thought . When the 'plug' of plastic wrapped pellets hit the choke constriction , something has to give . Pellet deformation /redistribution or in a horror scenario barrel deformation or choke thread stripping .

Lars we still don't konw the make and model of your gun - it may come in handy.

I am shooting steel on regular basis through my Steel proven MK70 and 5/8 (0.025) Teague choke, despite being advised against by the choke maker. 5/8 deals with trap targets just fine - still it is my gun. Through my gun steel doesn't pattern tighter, but spread noticeably more...

P.S. On the other side - 1/2 patterns very close to 1/1 so in the end it isn't worth it.

LarsJ said:

That's what I have come to as well after this thread. But was also curious if it was "don't dry your cat in the microwave"  warning thing

Click to expand...

Obviously there are many shooters who like the general population would suffocate if breathing were not an autonomic function.

Why would the "Not For Steel" note be in place and an alternative available if there were not some reason the manufacturer felt important?

I'm all for defying authority but ..........................