All of our departments had increases in net sales for the 13 weeks ended August 1, 2020 compared to the corresponding period in fiscal year 2019, led by our hunting and shooting department with an increase in net sales of $98.0 million, or 112.2%. Our camping, fishing, apparel, footwear and optics, electronics, and accessories departments saw increases of $24.9 million, $23.7 million, $5.8 million, $6.3 million and $8.5 million, respectively, in the second quarter of fiscal year 2020 compared to the comparable 13-week period of fiscal year 2019 due to increased traffic within our stores and online. Within hunting, our firearm and ammunition categories saw increases of $51.6 million or 157.6% and $27.0 million or 97.4%, respectively, in the second quarter of fiscal year 2020 compared to the comparable 13-week period of fiscal year 2019, which increases resulted from the drivers of increased demand discussed above.
Each of our departments also had increases in same store sales, for the 13 weeks ended August 1, 2020, again led by our hunting and shooting department, with an increase of 86.6%. Our camping, fishing, apparel, footwear, and optics, electronics and accessories departments had increases of 45.9%, 45.2%, 19.2%, 29.5%, and 43.6%, respectively, for the second quarter of fiscal year 2020 compared to the comparable 13-week period of fiscal year 2019. As of August 1, 2020, we had 92 stores included in our same store sales calculation.
Gross Profit. Gross profit increased to $129.1 million during the 13 weeks ended August 1, 2020 compared to $73.2 million for the corresponding period of fiscal year 2019 primarily as a result of increased sales. As a percentage of net sales, gross profit decreased to 33.9% for the 13 weeks ended August 1, 2020, compared to 34.6% for the corresponding period of fiscal year 2019 due to the change in product mix in the quarter as a result of the majority of revenue being generated from lower margin categories such as firearms and ammunition and a channel mix shift to higher e-commerce driven sales causing increased freight costs. The gross margin decline was partially offset by higher product margins, volume incentives, and other adjustments, which positively impacted gross margin. We expect a continued higher than normal proportion of revenue to come from firearms and ammunition, and a higher volume of sales to be conducted through our eCommerce platform. Both of these factors will continue to put pressure on gross margin partially offset by improved product margins.
Selling, General, and Administrative Expenses. Selling, general, and administrative expenses increased by $20.1 million, or 31.8%, to $83.6 million during the 13 weeks ended August 1, 2020 from $63.5 million for the comparable 13-week period of fiscal year 2019. This increase was primarily due to an increase in our payroll expense of $13.6 million, which mostly resulted from the opening of 13 new stores since the end of the second quarter of fiscal year 2019, minimum wage increases impacting 62 of our stores in fiscal year 2020 and the payment of $1.5 million in hazard pay. We also had increases in other selling, general, and administration expenses, rent, depreciation, and acquisition expenses of $3.9 million due to increased credit card fees, $2.2 million, $0.7 million, and $0.1 million, respectively, during the 13 weeks ended August 1, 2020 primarily related to the opening of 13 new stores since August 3, 2019. As a percentage of net sales, selling, general, and administrative expenses decreased to 21.9% of net sales in the second quarter of fiscal year 2020, compared to 30.0% of net sales in the second quarter of fiscal year 2019, primarily as a result of the significant increase in net sales we experienced in the second quarter of fiscal year 2020 compared to the second quarter of fiscal year 2019.
Interest Expense. Interest expense decreased by $1.3 million, or 56.8%, to $1.0 million during the 13 weeks ended August 1, 2020 from $2.4 million for the comparable 13-week period of fiscal year 2019. Interest expense decreased primarily as a result of a lower debt balance during the second quarter of fiscal year 2020 compared to the second quarter of fiscal year 2019. The outstanding principal amount of our term loan has decreased from $32.0 million as of August 3, 2019 to $16.0 million as of August 1, 2020, which reflects a $10.0 million repayment during the second quarter of fiscal year 2020, and we had outstanding borrowings under our revolving credit facility of $137.3 million as of August 3, 2019 compared to $20.5 million as of August 1, 2020.
Income Taxes. We recognized income tax expense of $12.0 million and $1.9 million during the 13 weeks ended August 1, 2020 and August 3, 2019, respectively. Our effective tax rate for the 13 weeks ended August 1, 2020 and August 3, 2019 was 27.01% and 25.81%, respectively. Our effective tax rate will generally differ from the U.S. Federal statutory rate of 21.0%, due to state taxes, permanent items, and discrete items relating to stock award deductions.
Twenty-Six Weeks Ended August 1, 2020 Compared to Twenty-Six Weeks Ended August 3, 2019
Net Sales. Net sales increased by $242.0 million, or 62.7%, to $ 627.8 million during the 26 weeks ended August 1, 2020 compared to $385.8 million in the corresponding period of fiscal year 2019. Our net sales increased due to a