Straight Shooters has real nice one. Not cheap but it comes with shims and is very well made. http://www.straightshooters.com/ss-muzzlebrake.html
HPA Sports used to offer one, but teir website looks to be un-attended lol -
Try JM or Wolf air guns. Remember the barrel is sleeved. 15 mm barrel with out the front sight.
Without cutting the sleeve back you will have only the length of the front sight in the brake and hang over making the gun longer.
Sleeve is easy to cut back but the enter sleeve you have to be careful cutting. Very easy to damage.
The old HPA was made for the 48 and worked great. JMO
To answer your question, Diana made a muzzle brake specifically for the end of the 48/52/54 rifles. It had a screw off end and was made of steel. I think I still have one but I am holding onto it. I hope to try a 54 one more time (a .177 this time) and I am saving the brake for that.
David Enoch
David is partially correct. I have a Diana 52 (I also owned a 48 for awhile). I love the look of a muzzle break and searched high and low for one. About a year a go I got lucky and bought one off of the AA classifieds. It is marked RWS. After you remove the front sight, it slides on and is held there with two grub screws. It finishes the barrel perfectly especially when you remove the rear sight (3mm screws to fill the rear sight holes, BTW).
If you are only looking to replace the muzzle piece that holds the front sight, then any of the commercially available muzzle weights can be drilled out to use the 15 mm's inner barrel diameter and the 18 mm's sleeve's OD to make a good piece.
If you REALLY want to get maximum precision out of your 48, then you will need to use a well made muzzle piece as tuning device.
When you have the time, and if you have the inclination, please read this:
https://www.ctcustomairguns.com/hectors-airgun-blog/controlling-harmonics-in-a-barrel
Hope it explains how important that part can be.
Keep well and shoot straight!
HM
