With the gun assembled place the butt on a solid surface, bore pointing up. Rap the charging handle with a rubber mallet increasing force with each blow until the bolt opens or you fear breaking it. Works on 742's also.
It is possible to just replace the spring on one of these. I've done it several times. Vise it up and tap out the broken part and fit a new spring in place. Make one from any flat spring material like a bolt action mag spring.
Best method is to leave previous round sticking out enough to hold gate down until you have all your rounds in and push last one all the way. works on marlins too.
I have installed several of these kits and if done properly they are quite secure and I have never had one returned because it came loose or broke off. The origin of the thread was DIY or gunsmith. Always better to weld bolts on but I was offering a DIY option. Kit cost half of what a weld job...
ATI makes a turned down bolt kit that is do it yourself if you are handy and have a drill press. It requires removal of original bolt drilling and tapping and installing a new bolt handle. I have done several of these and they work well. Check it out online and see what you think. also allows...
I'm in Ellijay and would be willing to make you a set. I'll need the pistol for screw placement and grip frame measurements. I have over 30 years of stock making experience. PM me and we can discuss details.