doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Fitting bolt to lumps

I'm fitting an Ithaca/skb barrel and receiver. I've smoked in everything and the fit seems great, with one exception.

When I close the gun, the bolt engages, but not very deeply, and I can force the lever toward center.

Before I mess something up, I thought I would get some help on knowing the right way to fit bolt to lumps. Any suggestions?

I'll post a video link shortly in case that would help.

(This project: I bought two Ithaca 200e guns, one in pretty bad shape, the other in good shape except for a missing forend tip. I've decided to fit the 26" barrels from the scrap gun to the nicer receiver to make a two barrel -26"/28"- set. This is a learning project, but I am planning to sell the finished product. So far it's coming along nicely.)

lots to look at and smoke in to be sure you have correct geometry and bearing surfaces. You have three principle points of contact on a Purdey double under bite system, the hinge pin/hook, the breech face/standing breech and the rear bite and its corresponding slot in the barrel lump. The forward bite should have little bearing if any as its principle purpose is to keep the top lever to the right when the gun is open. A strong top lever spring should seat the bolt firmly on its own. Check all points of contact and for no excessive bearing on your forward bite and you should have a very good idea of what is stopping your bolt travel. Hope that helps.
Steve

Thanks Steve. I've been going very slowly and step wise. There is still some contact at the front lump when I smoke it (on the back side, not the slot). The water table has minimal clearance, and I have a tight fit on the face.

Here's the video to show what I'm seeing. From what you're saying, I'm thinking the problem could be that the front lump slot is a little tight.

https://photos.app.goo.gl/oHJmthyU95e8Z85ZA

If you are tight on the breech face and pin with very little clearance on the water table then you will need to work on the bolt seat slots in the lumps, go slow and try to maintain the correct angles. If you make the angle too steep the bolt will stick. You want nice contact on the bolt/slot and your top lever to seat at about 5:30. You see this type of situation when fitting one set of barrels to another gun. You are on the right track it sounds.
Steve

Thank you. I'm having a hard time seeing any contact points in the slots when I smoke them, but I'm thinking the front slot is the one giving trouble.

I definitely don't want to get in a hurry and find the barrels out of bite. I think I am going to stick with high grit paper over a file and sand/polish it until I get it to go in.

pm sent with a diagram to help.
Steve

Here's a follow-up:
With Steve's input, I determined that the rear lump slot was causing the bolt to bind. I eased the slot with a file and polished it until it closes nicely with the lever just about 15-20 degrees right of center.
Thanks for the help, Steve.

Here's the updated video:
https://photos.app.goo.gl/34it6VhLGvmkzdjq8

Glad to help Jim.
Steve