First successful attempt at a matrix for the c184 from 4+3_466:

Code:

Sat Sep 12 17:35:10 2020 Msieve v. 1.54 (SVN 1030M)
Sat Sep 12 17:35:10 2020 random seeds: 24ad7ccb b689eb64
Sat Sep 12 17:35:10 2020 factoring 1288420870966541327457423401697563128187770527956826832585494726405215165841980470637608224215821394194152554733348168114523551339058369701611634537845108590062264466133701035309124657 (184 digits)
Sat Sep 12 17:35:11 2020 searching for 15-digit factors
Sat Sep 12 17:35:11 2020 commencing number field sieve (184-digit input)
Sat Sep 12 17:35:11 2020 R0: -400690796617504803266434417211713435
Sat Sep 12 17:35:11 2020 R1: 17433125019345016821281
Sat Sep 12 17:35:11 2020 A0: 974638980914360897045449737219395727892611072
Sat Sep 12 17:35:11 2020 A1: 4219797827063945184925953662650167666
Sat Sep 12 17:35:11 2020 A2: -494543283474842279204870729055
Sat Sep 12 17:35:11 2020 A3: -10129443552045375616276
Sat Sep 12 17:35:11 2020 A4: 34163940584578
Sat Sep 12 17:35:11 2020 A5: 124740
Sat Sep 12 17:35:11 2020 skew 101124293.72, size 6.600e-18, alpha -7.549, combined = 5.544e-14 rroots = 3
Sat Sep 12 17:35:11 2020
Sat Sep 12 17:35:11 2020 commencing relation filtering
Sat Sep 12 17:35:11 2020 setting target matrix density to 100.0
Sat Sep 12 17:35:11 2020 estimated available RAM is 15845.8 MB
Sat Sep 12 17:35:11 2020 commencing duplicate removal, pass 1
Sat Sep 12 18:05:22 2020 found 83600412 hash collisions in 300946431 relations
Sat Sep 12 18:05:43 2020 commencing duplicate removal, pass 2
Sat Sep 12 18:11:32 2020 found 98891655 duplicates and 202054776 unique relations
Sat Sep 12 18:11:32 2020 memory use: 2387.0 MB
Sat Sep 12 18:11:33 2020 reading ideals above 183959552
Sat Sep 12 18:11:33 2020 commencing singleton removal, initial pass
Sat Sep 12 18:27:10 2020 memory use: 5512.0 MB
Sat Sep 12 18:27:11 2020 reading all ideals from disk
Sat Sep 12 18:27:32 2020 memory use: 3530.8 MB
Sat Sep 12 18:27:37 2020 commencing in-memory singleton removal
Sat Sep 12 18:27:42 2020 begin with 202054776 relations and 195951001 unique ideals
Sat Sep 12 18:28:34 2020 reduce to 91808076 relations and 69726710 ideals in 18 passes
Sat Sep 12 18:28:34 2020 max relations containing the same ideal: 30
Sat Sep 12 18:28:40 2020 reading ideals above 720000
Sat Sep 12 18:28:40 2020 commencing singleton removal, initial pass
Sat Sep 12 18:40:14 2020 memory use: 2756.0 MB
Sat Sep 12 18:40:14 2020 reading all ideals from disk
Sat Sep 12 18:40:38 2020 memory use: 3788.1 MB
Sat Sep 12 18:40:45 2020 keeping 89701206 ideals with weight <= 200, target excess is 486271
Sat Sep 12 18:40:53 2020 commencing in-memory singleton removal
Sat Sep 12 18:40:59 2020 begin with 91808076 relations and 89701206 unique ideals
Sat Sep 12 18:42:20 2020 reduce to 91576225 relations and 89469280 ideals in 14 passes
Sat Sep 12 18:42:20 2020 max relations containing the same ideal: 200
Sat Sep 12 18:42:54 2020 removing 4408357 relations and 4008357 ideals in 400000 cliques
Sat Sep 12 18:42:56 2020 commencing in-memory singleton removal
Sat Sep 12 18:43:02 2020 begin with 87167868 relations and 89469280 unique ideals
Sat Sep 12 18:43:52 2020 reduce to 86998225 relations and 85290168 ideals in 9 passes
Sat Sep 12 18:43:52 2020 max relations containing the same ideal: 199
Sat Sep 12 18:44:24 2020 removing 3296653 relations and 2896653 ideals in 400000 cliques
Sat Sep 12 18:44:25 2020 commencing in-memory singleton removal
Sat Sep 12 18:44:31 2020 begin with 83701572 relations and 85290168 unique ideals
Sat Sep 12 18:45:14 2020 reduce to 83597784 relations and 82289128 ideals in 8 passes
Sat Sep 12 18:45:14 2020 max relations containing the same ideal: 195
Sat Sep 12 18:45:45 2020 removing 2943680 relations and 2543680 ideals in 400000 cliques
Sat Sep 12 18:45:46 2020 commencing in-memory singleton removal
Sat Sep 12 18:45:51 2020 begin with 80654104 relations and 82289128 unique ideals
Sat Sep 12 18:46:33 2020 reduce to 80566167 relations and 79657103 ideals in 8 passes
Sat Sep 12 18:46:33 2020 max relations containing the same ideal: 192
Sat Sep 12 18:47:02 2020 removing 2416391 relations and 2071402 ideals in 344989 cliques
Sat Sep 12 18:47:04 2020 commencing in-memory singleton removal
Sat Sep 12 18:47:09 2020 begin with 78149776 relations and 79657103 unique ideals
Sat Sep 12 18:47:49 2020 reduce to 78087981 relations and 77523656 ideals in 8 passes
Sat Sep 12 18:47:49 2020 max relations containing the same ideal: 189
Sat Sep 12 18:48:28 2020 relations with 0 large ideals: 1755
Sat Sep 12 18:48:28 2020 relations with 1 large ideals: 1308
Sat Sep 12 18:48:28 2020 relations with 2 large ideals: 26394
Sat Sep 12 18:48:28 2020 relations with 3 large ideals: 279678
Sat Sep 12 18:48:28 2020 relations with 4 large ideals: 1664509
Sat Sep 12 18:48:28 2020 relations with 5 large ideals: 6065505
Sat Sep 12 18:48:28 2020 relations with 6 large ideals: 14102865
Sat Sep 12 18:48:28 2020 relations with 7+ large ideals: 55945967
Sat Sep 12 18:48:28 2020 commencing 2-way merge
Sat Sep 12 18:49:10 2020 reduce to 47771699 relation sets and 47207374 unique ideals
Sat Sep 12 18:49:10 2020 commencing full merge
Sat Sep 12 19:01:29 2020 memory use: 5643.5 MB
Sat Sep 12 19:01:33 2020 found 22554044 cycles, need 22541574
Sat Sep 12 19:01:39 2020 weight of 22541574 cycles is about 2254542524 (100.02/cycle)
Sat Sep 12 19:01:39 2020 distribution of cycle lengths:
Sat Sep 12 19:01:39 2020 1 relations: 2505630
Sat Sep 12 19:01:39 2020 2 relations: 2281308
Sat Sep 12 19:01:39 2020 3 relations: 2240340
Sat Sep 12 19:01:39 2020 4 relations: 2050168
Sat Sep 12 19:01:39 2020 5 relations: 1873938
Sat Sep 12 19:01:39 2020 6 relations: 1689463
Sat Sep 12 19:01:39 2020 7 relations: 1480064
Sat Sep 12 19:01:39 2020 8 relations: 1281871
Sat Sep 12 19:01:39 2020 9 relations: 1129919
Sat Sep 12 19:01:39 2020 10+ relations: 6008873
Sat Sep 12 19:01:39 2020 heaviest cycle: 28 relations
Sat Sep 12 19:01:42 2020 commencing cycle optimization
Sat Sep 12 19:02:11 2020 start with 157972026 relations
Sat Sep 12 19:05:44 2020 pruned 4774693 relations
Sat Sep 12 19:05:45 2020 memory use: 4817.7 MB
Sat Sep 12 19:05:45 2020 distribution of cycle lengths:
Sat Sep 12 19:05:45 2020 1 relations: 2505630
Sat Sep 12 19:05:45 2020 2 relations: 2342283
Sat Sep 12 19:05:45 2020 3 relations: 2330295
Sat Sep 12 19:05:45 2020 4 relations: 2110706
Sat Sep 12 19:05:45 2020 5 relations: 1931570
Sat Sep 12 19:05:45 2020 6 relations: 1721214
Sat Sep 12 19:05:45 2020 7 relations: 1502020
Sat Sep 12 19:05:45 2020 8 relations: 1291081
Sat Sep 12 19:05:45 2020 9 relations: 1129255
Sat Sep 12 19:05:45 2020 10+ relations: 5677520
Sat Sep 12 19:05:45 2020 heaviest cycle: 28 relations
Sat Sep 12 19:06:23 2020 RelProcTime: 5472
Sat Sep 12 19:06:30 2020
Sat Sep 12 19:06:30 2020 commencing linear algebra
Sat Sep 12 19:06:31 2020 read 22541574 cycles
Sat Sep 12 19:07:06 2020 cycles contain 77557788 unique relations
Sat Sep 12 19:14:45 2020 read 77557788 relations
Sat Sep 12 19:16:28 2020 using 20 quadratic characters above 4294917295
Sat Sep 12 19:21:25 2020 building initial matrix
Sat Sep 12 19:33:28 2020 memory use: 10853.9 MB
Sat Sep 12 19:34:23 2020 read 22541574 cycles
Sat Sep 12 19:34:26 2020 matrix is 22541397 x 22541574 (9232.7 MB) with weight 2833980271 (125.72/col)
Sat Sep 12 19:34:26 2020 sparse part has weight 2149800401 (95.37/col)
Sat Sep 12 19:37:38 2020 filtering completed in 2 passes
Sat Sep 12 19:37:42 2020 matrix is 22540213 x 22540390 (9232.6 MB) with weight 2833930299 (125.73/col)
Sat Sep 12 19:37:42 2020 sparse part has weight 2149790384 (95.38/col)
Sat Sep 12 19:40:48 2020 matrix starts at (0, 0)
Sat Sep 12 19:40:51 2020 matrix is 22540213 x 22540390 (9232.6 MB) with weight 2833930299 (125.73/col)
Sat Sep 12 19:40:51 2020 sparse part has weight 2149790384 (95.38/col)
Sat Sep 12 19:40:51 2020 saving the first 48 matrix rows for later
Sat Sep 12 19:40:53 2020 matrix includes 64 packed rows
Sat Sep 12 19:40:56 2020 matrix is 22540165 x 22540390 (9014.3 MB) with weight 2387432529 (105.92/col)
Sat Sep 12 19:40:56 2020 sparse part has weight 2137643846 (94.84/col)
Sat Sep 12 19:40:56 2020 using block size 8192 and superblock size 884736 for processor cache size 9216 kB
Sat Sep 12 19:42:01 2020 commencing Lanczos iteration (6 threads)
Sat Sep 12 19:42:01 2020 memory use: 8657.6 MB
Sat Sep 12 19:43:06 2020 linear algebra at 0.0%, ETA 255h42m
Sat Sep 12 19:43:26 2020 checkpointing every 90000 dimensions

Increasing the lims doesn't seem to have changed the number of required relations all that much, but the matrix has got bigger.

It also looks like the higher lims give a bit of a speedup; I'll provide some more data once I have a more manageable matrix.