Very expensive and the wrong part - Tiger Rock AR-15 Steel 1/2inx28 Threaded Muzzle Brake Jam Nut

Unfortunately for me, I did not get around to testing this product out for about 6 months. I bought it to use with a muzzle break that requires 1/2x28 threads. My muzzle device threads on fine, thread protector threads on, but this jam nut will NOT go on. I suspect this may be the nut for 9mm ar’s put in the wrong package, or the threads are not cut deep enough. Very disappointed for the cost. I could have gotten a 5 pack from Amazon for this price. I expected Optics Planet to ship quality and correct parts. Roll the dice elsewhere, or check immediately.