Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Chambering | P1 diameter (mm) | A external (cm 2 ) | P max ( bar ) | F bolt ( kgf ) | F bolt |
| --- | --- | --- | --- | --- | --- |
| 5.45x39mm | 10.00 | 0.7854 | 3800.0 | 2985.0 | N ( lbf ) |
| .223 Remington | 9.58 | 0.7208 | 4300.0 | 3099.0 | N (lbf) |
| 7.62x39mm | 11.35 | 1.0118 | 3550.0 | 3592.0 | N (lbf) |
| .308 Winchester | 11.96 | 1.1234 | 4150.0 | 4662.0 | N (lbf) |
| .300 Winchester Magnum | 13.03 | 1.3335 | 4300.0 | 5734.0 | N (lbf) |
| .300 WSM | 14.12 | 1.5659 | 4450.0 | 6968.0 | N (lbf) |
| .300 Remington Ultra Magnum | 13.97 | 1.5328 | 4480.0 | 6876.0 | N (lbf) |
| .338 Lapua Magnum | 14.91 | 1.7460 | 4200.0 | 7333.0 | N (lbf) |
| .300 Lapua Magnum | 14.91 | 1.7460 | 4700.0 | 8339.0 | N (lbf) |
| .50 BMG | 20.42 | 3.2749 | 3700.0 | 12117.0 | N (lbf) |
Question:
What is the  p1 diameter (mm) when .300 lapua magnum is the chambering?
Answer:
14.91