chris_c wrote:A new variable p356 using an H->2G by simeks and gmc_nxtman improves glider guns for a significant number of periods...

It will be an even more significant number of periods if you include this trivial variant p564+8N. Due to a fairly insignificant bounding box improvement, it can probably replace most of the p00556_Ns in the present collection:

`x = 78, y = 59, rule = LifeHistory`

47.2A$47.A.A$49.A4.2A$28.2A15.4A.2A2.A2.A$27.A.A15.A2.A.A.A.A.2A$21.

2A4.A19.BABABA.A$19.A2.A2.2A.4A16.B2ABA.A$19.2A.A.A.A.A2.A17.2B.BA$

22.A.ABABAB18.3B7.A$22.A.AB2AB10.2A6.4B7.3A$23.AB.2B12.A6.B2A3B8.A$

26.3B11.A.AB3.B2A3B7.A.A$26.4B6.2A3.2AB.10B5.A.AB$24.3B2AB6.A6.13B5.A

3B$9.A14.3B2AB3.BA.A6.14B6.4B$9.3A10.10B.B2A7.15B5.6B$12.A8.13B11.8B

2.4B4.7B$11.2A7.14B11.6B5.4B2.8B.4B.B$11.5B3.15B10.9B4.17B.B2A$13.3B

2.4B2.8B11.4B4.2A5.18B2A$3.2A7.9B5.6B10.4B5.A6.16B.2B$3.A8.8B4.9B8.4B

7.3A3.16B$2A.A.B3.10B5.2A4.4B6.4B10.A3.15B$A2.3AB.2B2A7B6.A5.4B4.4B

11.A.2AB.12B$.2A2.BA3B2A7B3.3A7.4B2.4B10.2A.A.AB2.11B$3.4A12B3.A10.8B

11.A2.A5.10B$3.A.2B3.7B.B2A.A11.6B14.2A5.2B2A6B$4.3AB2.7B.BA.A.2A.2A.

A5.4B21.3B2A6B$7.A4.4B5.A2.A.A.2A4.6B21.10B$2.5A5.4B5.3A2.A6.8B20.8B.

B2A.A$2.A10.4B7.3A5.4B2.4B18.7B3.B2AB3A$4.A9.4B5.A7.4B4.4B17.6B6.B4.A

$3.2A10.4B4.2A5.4B6.4B17.6B4.2A.3A$16.9B4.4B8.4B16.5B4.A2.2A$17.6B5.

4B10.4B14.8B.A.A$17.8B2.4B12.4B4.A8.8BA.A.3A$15.15B14.4B3.3A6.6B.2BAB

.A2.A$15.14B16.4B5.A4.7B2.2B2.A.A.A$15.13B18.4B3.2A4.7B3.B.2A2.A.A$

13.2AB.10B20.4B2.4B.8B2.A.A2.A.A.A$12.A.AB3.B2A3B23.4B3.11B2.2A2.2A.

2A$12.A6.B2A3B24.4B.12B$11.2A6.4B27.B3A12B$20.3B28.A13B10.A$21.2B.BA

26.A9B11.3A$20.B2ABA.A24.12B9.A$19.BABABA.A23.16B6.2A$17.A2.A.A.A.A.

2A13.A6.24B$17.4A.2A2.A2.A13.3A3.23B$21.A4.2A18.A2.24B$19.A.A23.A.B.

24B$19.2A24.2A27B$43.2A2.A22B.4B$42.A2.3A3B3.2B3.B7.2B3.4B$43.A4.2B3.

4B.3B5.BA2B3.4B$44.4A5.B2AB.B2AB4.A.A5.3BA$46.A7.2A3.2A6.A7.ABA$48.A

27.2A$47.2A28.B!

EDIT: First I tried replacing both Snarks with bumpers, which worked nicely with p6 bumpers for example, but didn't quite improve anything -- even periods are pretty well optimized already, I guess. Just one Snark->bumper replacement got me a new smaller p385, though:

`x = 62, y = 54, rule = LifeHistory`

13.2C2.C16.A$13.C2.C.C13.3A$14.C.C.C12.A$13.2C.C.2C11.2A$12.C3.CD.ADB

6.5B$11.C.A2C.BA3D4.BA3B$11.C.D.2C2BC2D4BABA3B$12.CA2C.BA3D.2BA2BA4B$

16.CD.ADB.3B2A4B$10.5C.C.2C5.6B$10.C2.C2.C.C6.3B2D$15.C2.C5.4BDBD$9.A

6.2C5.4B.D3B$9.3A10.4B3.4B$12.A8.4B5.4B$11.2A7.4B7.4B$11.5B3.4B9.4B$

13.3B2.4B11.4B$3.2A7.9B13.4B18.A$3.A8.8B15.4B11.2A3.A.A$2A.A.B3.10B

17.4B11.A3.A2.A$A2.3AB.2B2A7B18.4B10.A.2A.A.A$.2A2.BA3B2A7B19.4B10.A.

A.A.2A$3.4A12B20.4B10.2B2A.A2.A$3.A.2B3.7B.B2A19.4B10.4B2.2A$4.3AB2.

7B.BA.A19.4B6.7B$7.A4.4B5.A20.4B3.8B$2.5A5.4B5.2A15.2A3.2B2A.8B$2.A

10.4B22.A4.BABA8B$4.A9.4B21.A.AB2.A10B.2B$3.2A10.4B10.A10.2AB.14B2A$

16.4B7.3A12.16B2A$17.4B5.A15.14B.2B$13.A4.4B4.2A15.13B$12.A.A4.9B14.

14B.2B$12.A.A5.6B14.18B2A$11.2A.2A5.6B3.B2.2B2.19B.B2A$10.A2.A2.A4.

35B2.B$10.2A2.2AB3.27B.8B$15.14B2A16B2.7B$16.13B2A16B2.7B$17.29B3.7B$

17.17B.B.2B11.6B.BA$18.15B4.3B10.7BA.A$18.15B5.A2B.2A6.8BA$19.13B5.A.

A2B.A6.6B.B$21.13B2.A.AB2.A7.5B$20.8B4.2A.A.A3.A8.6B$20.6B6.2ABA2.4A.

A4.2AB.5B$20.5B8.B2.A.A3.2A3.A.AB3.4B$20.B.B9.2A.2A.A.A6.A7.4B$21.3B

9.A.A3.A.3A2.2A8.3BC$20.B2AB9.A.A4.A2.A13.3BC$21.2A11.A6.2A15.3CB!