Bateman & Horn , building on Bateman & Stemmler , give a conjectured formula for the density of numbers that produce simultaneous primes in a number of fixed polynomials.
The constant is
where $k$ is the number of polynomials and $\omega(p)$ is the number of residues (mod p) where at least one of the polynomials is divisible by $p$.
Is there a good way to calculate this constant for a given set of polynomials? I'm looking at polynomials with 'reasonable' degrees and constants, nothing like the recordbreaking monsters considered by (e.g.) Jacobson & Williams. Also, I don't need high precision (a dozen digits would be great), but of course direct computation is out of the question as the product converges too slowly to get even three or four digits of precision in a reasonable time.
 Paul T. Bateman and Roger A. Horn, "A heuristic asymptotic formula concerning the distribution of prime numbers", Mathematics of Computation 16:79 (1962), pp. 363-367.
 Paul T. Bateman and Rosemarie M. Stemmler, "Waring's problem in algebraic number fields and primes of the form $(p^r - 1)/(p^d-1)$", Illinois Journal of Mathematics 6 (1962), pp. 142-156.