Home Forums Hunting & Shooting Gunsmithing Interarms Mark X bolt?

I recently purchased an interarms bolt body from another member here on the fire. My plan is to use it with an H&R (Zastava) action that I purchased years ago to build a rifle similar to my H&R model 340 in 7x57. This one will be chambered in 6.5x55. The problem is that I started to put the bolt together with the commercial bolt shroud, firing pin, and cocking piece when I noticed something that didn't seem quite right with the cocking notch (is that right) on the bolt. Instead of being a straight line it has a round dish in it. I am posting a picture with it compared to the bolt out of my 7x57. The new bolt is on the left.

It doesn't really appear to be broken, but either forged or machined that way. Is it something to worry about and can I have a gunsmith fix it?

That "round dish" is where the nose of the cocking piece would sit when the bolt is retracted so that the cocking piece doesn't accidentally slip off the edge and fall into the notch, thereby un-cocking itself. Most bolts have a small notch to prevent this from happening.

The one on the left is a speedlock bolt.

Does anyone else's look like this? My model 70s, M77s, Rem 700, and CZ model 3 all have just a very tiny notch for the cocking piece to rest in.

So a speedlock kit would be the way to go with that bolt I'm guessing.

Speedlock cocking piece.

I don't have access to my Mark X's at the moment or I would supply you with a comparison pic to the standard 98 cocking piece.

This is what you need. Better buy it fast, they aren't exactly common.

http://www.gunpartscorp.com/catalog/Detail.aspx?pid=1262010&catid=10886

Thanks Karnis, will I need a different firing pin with this?

No.

Here is the assembled bolt.

Ah, I see. Thanks again Karnis.

Just ordered the cocking piece.

Karnis, could you possibly give me a measurement of your cocking piece. I received mine in the mail and realized it is the same size as the old one as well as the cocking piece from my other rifle. The pieces measure 1.207in from the front where it engages the bolt body to the flat at the rear.

1.202"

I'd swear it looked bigger in the picture. Thanks

George,

The difference in CP between the Standard and Speedlock is the length of the sear. On mine a standard sear is 0.875 and the speedlock sear is 0.760
Bob

You can easily alter a std CP to work with the Speedlock bolt. No biggie.

So how would you do this?

Just mill or grind back the sear ledge on the cp until the safety camback is right. without a mill or surface grinder I wouldn't say easy though.
Don

Would it benefit my 7x57 to have it's bolt modified as such? i.e. as the Mauser has the worst lock time ever, pretty much.