I used to own an archery shop. Some crossbows use flat nocks, some use the dished style nocks, Excalibur has their threaded nocks to screw in an arrow puller. It'll generally be in your owner's manual which style of nocks your crossbow requires. Using a flat nock when a grooved nock is recommended can lead to dry fires. When the TAC15 crossbow from PSE came along it used a 26" bolt with a regular capture style nock. It was a bolt made specifically for that crossbow. Brass inserts are a must, not only for overall weight but for front of center. Aluminum bolts and arrows are generally a heavier GPI so it's harder to get a higher FOC with them. Bolts are the exception to this though as a lot of the carbon bolts are high gpi because they have to be to get minimum arrow weights over a shorter bolt. FMJ bolts are very high GPI, but they still bend much easier than an all carbon bolt.
Easier target removal though, with the aluminum outer. Heavier bolts do outpenetrate lighter bolts, simple physics. Momentum numbers are higher on heavier bolts and arrows, KE is a worthless measurement of energy. Momentum is the force required to stop an object over the span of one second. KE is the measurement of force required to stop an object in the span of one foot. Simplest analogy is this, which hits harder? A wiffle ball going 90mph or a baseball going 60mph? Mass in motion tends to stay in motion. Light arrows and bolts lose speed and energy exponentially faster at distance than heavier arrows or bolts. You can be too light, or you can be too heavy. Heavier bolts and arrows make your bow quieter and absorb more energy from the bow. Any bow test you read, the highest efficiency numbers are always with the heavier arrows because of this. As for xbows, those Mission Sub-1 bows are compact and extremely accurate. High horsepower the Scorpyds are extremely fast and accurate. Maneuverability goes to the Sub-1 , it's just a much more compact xbow.