FN SPR: Barrel completion

In this post I will complete the work I did on this project for my second semester. The last step is to cut the barrel to size and crown it. The crown of the barrel is very important for the accuracy of the rifle. It must be cut square to the bore. If the crown is not square to the bore or damaged, the gases that propel the bullet will push it slightly of course.

First the easy part. I marked and cut the barrel to length using a hacksaw.

Ready to cut

Rough cut done

After this I installed the barrel in a four jaw chuck on the lathe and set it up.

Setup for crowning

Once I completed the setup, the cutting started. First I did a smooth cut square to the bore.

High speed!

I then used the compound of the lathe to cut an 11° crown. On the Remington project a square crown was acceptable as I installed a muzzle brake. For the FN I chose the 11º crown. While there is some debate about which type of crown is better, I just chose to do a few different types.

Crowned!

This concludes the work for my second semester on the FN project. Thank you for following along!

2 Responses to “FN SPR: Barrel completion”

  • Freiheit:

    ” While there is some debate about which type of crown is better, I just chose to do a few different types.” – What objective measures support this debate?

    • Neil:

      The idea of the crown is to have all the gases behind the bullet exit the barrel as evenly as possible. I think that the intended use of the weapon and personal preference is the determining factors.

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