The figures in Genesis show that Joseph died 277 years after the covenant with Abraham with no mention of the Israelites having yet become slaves in Egypt. This leaves only 153 years until the covenant at Sinai meaning the “enslavement” would have been even less than this 153 years that remained and so contradicts Ex 12:40-42 that tells us it was 430 years.
Ethelbert Bullinger in Selected Writings (p11-12) concludes that the 430 years of sojourning started in Ur from "the call of Abraham" when he was 70, that he was 75 when he departed from Haran and that the 400 years of "strangership, servitude and affliction" began "from the birth of Isaac" and includes the time in Canaan, (Ex 6:4). He explains the sojourning of Abrahams "seed" that were "in his loins" was 430 years and that the words "who dwelt in Egypt" "form a relative clause defining who the people were," but Gen 15:13 says they were "oppressed for four hundred years" and Stephen says (Acts 7:6) they were "- in bondage and entreat them evil four hundred years". Exodus 12:40 says "Now the sojourning of the CHILDREN OF ISRAEL who dwelt in Egypt , was four hundred and thirty years," Abraham was not one of "the children of Israel". Bullinger also has a note on Exodus 15:13 calling it an "introversion" where he tries to explain the contradiction by adding parenthesis to change the meaning of the verse and seperate what he says was 215 years of enslavement from 400 years of sojourning "thy seed shall be a stranger in a land that is not theirs, (and shall serve them; and they shall afflict them) four hundred years" Floyd Jones in "Chronology of the Old Testament" follows the same reasoning and thinks we should make a distinction between the length of time spent "sojourning" (430 years) the time of affliction" (400 years) and the length of time "dwelling" in Egypt (215 years) and he says that the actual enslavement lasted for less than 144 years as well as saying it was for less than 128 years to as low as 80 years while on page 59 he says the "dwelling, servitude and affliction in Egypt" was for 215 years. On page 55 he substitutes the term "Jews" who were the descendants of Judah both for "Abraham" and for "the children of Israel" and does little to explain how the "fourth generation" fits into his scheme.The Seventh-Day Adventist Bible Commentary supposing a period of 215 years between Jacob going into Egypt and the time of the Exodus makes the 400 years of affliction begin when Abraham "was 105 and his son Isaac 5 years old (Ch. 21:5) This would be about the time Ishmael who "was born after the flesh persecuted him [Isaac] that was born after the Spirit" (Gal 4:29; Gen 21:9-11) this considers Canaan was part of Egypt. (Vol 1, Genesis, p314-5, 220.7/SEV) but if Canaan was part of Egypt then they didn't come "out" at the Exodus and as Matthew Sturgis says, "They would merely have passed from one Egyptian controlled land to another." (It Ain't Necessarily So, p54, 221.9STU) Gen 15:16-18 says "they shall come HERE again in the fourth generation;" -"- from the river of Egypt unto the great river, the river Euphrates:" Colin Heath thinks the 400 years began from God,s "oath to Isaac" (1 Chron 16:16, Ps 105:9) when Isaac was 30 years of age. (www.bibleinsight.com) Michael Bennett thinks that the 430 years began from when Abram left Haran at 75 years of age and that the 400 years began 30 years later when Isaac was weaned at 5 years of age (Gen 21), and that just as at Kadesh, God "backdated" the 40 years wandering by over a year, to begin from the "disbelief at Marah, just three days after the Red Sea crossing.", so he thinks the counting of the 430 years were "backdated" because the children of Israel were in Abrams loins (Heb 7:9-10), (The Exodus, p12-14). He wants the 430 years "in Egypt" to begin from when Abram left Haran and the 400 years enslavement to begin when Isaac was 5 years old, but then wants the first of the four generations "in Egypt" to begin with the sons of Jacob 215 years later. But if the 430 years began from Abram leaving Haran then the Israelites did not come out of Egypt in "the fourth generation" but several generations later. He says the only person of the fourth generation who entered the Promised Land was Caleb. (Nu 14, Deut 1)  In the WCG "Answers to questions from Genesis" they say "it is evident that the 430 years began when Abraham was ninety-nine years old and ended the year the exodus of his descendants out of Egypt and their appearance at Sinai.", but this ignores the statement that it would be in the "fourth" generation as there was at least six generations between Isaac to Moses. It is also argued that the 400 year period was referring to Abrahams "seed" and so did not necessarily fall within the 430 year time frame but began with Abrahams death 76 years later and ended 6 years after they entered Canaan, but the period before Joseph was taken to Egypt or until the time Jacob arrived there, and the time after the Exodus were not years spent "in Egypt" and the 400 years of enslavement were predicted to be spent "in a land belonging to others" which Ex 12:40 shows was while they were IN EGYPT, and was not referring to any time before or after and so should only be counted from when some actual "enslavement" of Abrahams descendants began. Henk Jens suggesed, "the 400 years for Abrahams "Seed" start from Abrahams death, which is 76 years later after the promise. Abraham's seed, starting with Isaac had 430 - 76 = 354 years to the giving of the Law and so the period Abraham's seed were without their land, comprises those 354 years, the 40 years wandering and the 6 years of Conquest; a total of 354+40+6= 400 years." but again years "without their land" were not the same as years "in Egypt", and Ex 12:40-41 says after 430 years they came "- OUT from the land of EGYPT." The Samaritan text of Ex 12:40 which may have been written around 400BC says "Now the sojourn of the children of Israel and their fathers, which they dwelt in the land of Canaan and in the land of Egypt was 430 years." The Septuagint version that was written about 300BC says, "Now the sojourning of the Israelites which they and their fathers had sojourned in the land of Egypt AND IN THE LAND OF CANAAN was four hundred and thirty years." (Some have 435 years.) A note in Rashi says the addition is; "AND IN OTHER LANDS". (Appendix, p238)  The Mekhilta of Ishmael and Megillot 9a say this was an alteration made by the 72 translators at the time of King Ptolemy, so this question appears to have a long history and there is uncertainty as to whether this was an addition to the text or if it was dropped from the Hebrew text, but as Abraham Isaac and Jacob were not slaves in Canaan their inclusion in the figure of 400 years contradicts that they were not slaves and then also how could it be said the Israelites had come out of Canaan and Egypt when they were now going into Canaan, via the Wilderness, which was neither the slavery of Egypt nor the promised land of Canaan, for they had left one but had not entered the other. [This symbolic 40 years of Gods guidance between "Heaven and Hell" is reflected in the Days of Unleavened Bread, the Feast of Tabernacles and the life of  Christians who have symbolically left Egypt (sin) but have not yet arrived at the Promised land.]  A note in the Targum of  Onkelos thinks the words were an addition and "may have been prompted by the apparent mathematical impossibility of the period." "Kohath was born before Jacob left for Egypt (Gen 46:11) and lived 133 years. His son Amram, the father of Moses, lived 137 years, and Moses himself was 80 years old at the Exodus. So at most the period could be a little more than 300 years. Further, Moses mother was Levi's daughter (Ex 2:1 and 6:20)." Cf Gerhard Larsson, "The Chronology of the Pentateuch: A Comparison of the MT and LXX", JBL 102, no 3 (1983); 401-9. (Targum Onkelos to Exodus, p129, Drazin, KTAV) Rashi had said much the same as this in his Commentary on Exodus. (p61) If 210 years in Egypt was correct then this would mean that the enslavement began five years after Jacob arrived in Egypt or if Exodus 12 means 400 years enslavement and they were in Egypt for 430 years then they only had 30 years of freedom, but as Rashi points out, Jacob entered Egypt when he was 130 years old, (Gen 47:9) and died 17 years later when he was 147 years old (Gen 47:28)
Joseph was born when Jacob was 91 years old, (Gen 30:24-5, 31:38, 41) [Joseph was born at the start of the last six years that Jacob served Laban for his cattle, Gen 31:41 He was 30 when he stood before Pharoah (Gen 41:46) then spent the 7 good years and 2 of the famine years working for Pharoah before Jacob and his family came down to Egypt at 130 years of age (Gen 45:5)] Joseph lived to 110 (Gen 50:22,26) and so was 56 when Jacob died, Joseph then lived for another 54 years which was 71 years after Jacob arrived in Egypt and the enslavement began sometime after this, so if Josephus was right and the 430 years begin from when Abraham came to Canaan then the enslavement lasted for less than 144 years and if Paul was right and the Law came 430 years after God made his covenant with Abraham then as Abraham was 75 years old when he departed from Haran (Gen 12:4) and the covenant was made up to 10 years after his arrival (Gen 16:3) this may have reduced this maximum of 144 years enslavement and so contradicts the statement that they would be "oppressed" 400 years. In an effort to smooth over the contradictions Aryeh Kaplan, a torah translator says in his introduction to "The Living Torah" that the Torah uses "idiomatic language" and that it would be a mistake to translate it literally. His translation of Exodus 12:40-42 says, "The lifestyle that the Israelites endured in Egypt had thus lasted 430 years. At the end of the 430 years, all of God's armies left Egypt in broad daylight. There was a night of vigil for God, (preparing) to bring them out of Egypt. This night remains for the Israelites a vigil to God for all generations." If it was their "lifestyle" that ended after 430 years then how did their "lifestyle" change during the harsh conditions of the following 40 years in the wilderness that resulted in the death of their leaders Moses and Aaron and only two of those who were in Egypt, Joshua and Caleb, entering the "promised land". The difficult "lifestyle" of the Israelites in history continued as they then went through many wars and defeats under  the Judges and Kings with the northern tribes being taken captive by the Assyrians in 721BC, Judah being conquered by the Babylonians in 587-6 BC, conquered by Antiochus 4 in 167 BC, conquered by Herod the Great in 37BC and again by the Romans in AD70. Their "lifestyle" of hardship, being persecued and going into captivity continued under the Nazi's. No! Their "lifestyle" of "servitude" didn't end after 430 years. 

PO Box 345, North Sydney NSW 2060 A ustralia