I have dealt with a large number of samskaras, indeed more than forty of them. The Brahmin is expected to perform sacrifices almost all through his life, thereby making his life itself a sacrifice in the cause of mankind. On his death his body is cremated with the chanting of mantras and this rite also bring good to the world. While the samskaras refine a man, purify him, the mantras chanted at the time create benign vibrations in the world. And, while each karma is apparently meant for the performer as an individual, it also brings benefit to the entire world. In truth there is no karma that does not benefit mankind in general. All rites begin with the prayer, "Jagat--hitaya Krsnaya". When we chant the Gayatri we do not say, "may the sun god quicken or inspire my intelligence", but "our" intelligence. So the gayatri is a prayer made on behalf of all creatures (It would be perverse to argue that it should be enough if one Brahmin did the Gayatri-japa for the benefit of all--the word "our" is not to be construed thus. Brahmins, Kshatriyas and Vaisyas must mutter the Gayatri not only for their own good but for that of all castes, all creatures including animals, birds, insects, all sentient beings. )
You must have seen that sacrifices constitute the major portion of the samaskaras. There is a mantra in the Brhadaranyaka Upanishad(4. 4. 22) which describes the benefits derived from their performance. It says that Brahmins endeavour to realise the Self through Vedic learning, through the performance of sacrifices, through charity, through austerities and through fasts. But when this purpose has been accomplished they renounce all (rites including sacrifices) and become sannyasins. It follows that all the elaborate sacraments are performed for the cessation of these very sacraments. Of all the benefits derived from the rituals like sacrifices this is the highest, the very abandonment of rituals. How does a big karma like a sacrifice prepare you for the renunciation of that very karma, that very sacrifice?
There are two types of karma. One is doing what we like. This, instead of purifying the mind, muddles it and make our burden of karma heavier. The second is the performance of rites without any expectation of rewards, dedicating them to Isvara in a spirit of sacrifice. In the second type we are cleansed inwardly and the burden of our karma is made lighter and ultimately we are taken to the point beyond which it is not necessary to perform any rites. A man who has renounced all works in this way may, with the compassion of Parasakti, continue to work for the good of mankind. But even though he is a doer he will not be conscious of that ability.
How is the impurity of the mind washed away? If you perform a big sacrifice without any desire in your heart, without any feelings of hatred against anybody and without any consideration of loss or gain, success or failure, your mind will be cleansed. The mind, body and speech must be totally involved in it and must remain fixed on a single goal. Then all the impurities will be burnt away. It is like the rays of the sun passing through a magnifying glass and converging on a piece of paper and burning it. There are a hundred thousand things to do in a sacrifice; there are so many mantras to be chanted; so many different materials to be collected. So the performer's mind will be fixed on a single goal.
If a king is to perform a horse sacrifice(asvamedha), he has to look into so many different requirements. Different animals have to be brought to the place of sacrifice including even a tiger. If a man devotes himself for a number of years with a single-minded purpose and devotion to some work or other his mind will be made pure and he will reach the stage when there will be no need for him to perform any more rites. To build a gopuram, to dig a large pond or to be engaged in some other public work is to make one's mind taintless. In fact the mental purity so achieved seems to my mind to be a reward greater than anything else.
Even if a man does not take to sanyasa after performing sacrifices as a householder, he goes to the meritorious world. With the grace of Isvara he becomes one with that very Isvara. And, when Isvara himself is absorbed in the Brahman as the Paramatman, he too becomes one worth him. When Isvara emerges to create the world he does not become trapped in it. Or there is another way of putting it. Krsna Paramatman speaks of the "yoga-bhrasta ", one who dies without realising the Self in spite of practising yoga. In his next birth such a man starts where he left off in the earlier birth and ascends to a higher state. What is said about people who practise yoga applies also to those who perform sacrifices. It means that a man who conducts sacrifices but dies before becoming a sannyasin is born again with a greater sense of discrimination in his next birth and with enough maturity to forsake all karma and become a sannyasin.
Those who are not entitled to all samskaras will reach state by doing their work properly, by being devoted to God, by reciting his praises, by performing aupasana and by offering libations to their fathers.
For a general background, please see here