If the gun predates steel, it's probably not safe for steel, esp with a full choke.

It's got nothing to do with pressure, it has to do with the barrel material and it's ability to withstand the steel shot trying to push the choke outward.

 

Thanks for answer.

So if I shoot steel ammunition with it and something goes wrong, only the choke will get destroyed? Or is there possibility of whole barrel explode?

What if I drill full choke to half? Also not recommended?

 

+1 on what Skeetman said. You might peen the chokes. Even if it's Krupp steel.

 

Thanks for answer.

What if I drill full choke to half? Also not recommended?

 

I doubt the barrel would explode, but it would likely expand slowly overtime, and may cause the barrel to split depending on the elasticity of the steel.

If you had the choke opened to modified it'd be better, but still no guarantee the same thing wouldn't happen to a lower severity or over a longer period of time.

If you aren't able to use lead, see if you can find bismuth instead, anything that can shoot lead can shoot bismuth. If you need to run high volumes of shells through the gun, see if you can have steel-rated screw chokes installed. Teague in the UK should be able to do this, although might not be worth $ wise.

 

Thanks.

The problem is that bismuth is also toxic to human body. Less than lead but still. Steel seems the most safe option for eating harvested animals. That's sad because hunting with old renovated gun is indispensable.

 

Bismuth is not toxic and is actually used in some antiacids.

 

Bismuth isn't going to be a problem.

In reality, lead isn't a problem either since you aren't ingesting the pellets, and even if you accidentally did swallow a couple here and there they'd simply pass through your system. Lead is an issue when inhaled or ingested in particulate or vaporized form.