Qwen3.8-27B-Heretic · GSQ-RCO GGUFs

Non-uniform GGUF quantizations of RVN Qwen3.8-27B-Heretic-Abliterated-Uncensored (refusals 0-1/100, KL ~ 0.0085 vs base). Instead of one uniform quantization type for all tensors, each of the 851 tensors carries its own type, following the per-tensor RCO allocation published by IST-DASLab for their GSQ-RCO release of Qwen3.8-27B, quantized locally with llama.cpp and the official importance matrix imatrix-qwen3.8-27b.gguf. Files are standard GGUF and run unmodified in llama.cpp / Ollama / LM Studio.

Why this release exists

This family was made at the request of community member Heidagger44 in discussion #11:

Regarding IQ3_S there is new method: GSQ-RCO, if it's possible to combine your abliteration method with this quantization, we would have a true refusal free Qwen3.8-27B running fully on 16GB cards.

Thanks for the pointer - this is that combination, in four sizes.

Available files

File Target bpw Weights Notes
RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ2_XS.gguf 2.50 8.45 GB Smallest tier - 12 GB-class cards
RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ2_S.gguf 2.75 9.28 GB Balanced low-memory tier
RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ3_XXS.gguf 3.00 10.12 GB Strong sub-10.5 GB operating point
RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ3_S.gguf 3.50 11.80 GB Recommended on 16 GB cards
4 x *-mtp.gguf twins - +0.42 GiB each Embedded official Qwen3.8 MTP/NextN head; main weights identical

Quality - measured, not assumed

Perplexity on wikitext-2 (llama-perplexity, ctx 4096, one RTX PRO 6000 Blackwell, full offload):

Variant PPL (wikitext-2) Delta vs F16
F16 reference (RVN-F16.gguf) 6.1197 -
GSQ-RCO IQ3_S 6.1778 +0.95%
GSQ-RCO IQ3_XXS 6.3486 +3.7%
GSQ-RCO IQ2_S 6.5058 +6.3%
GSQ-RCO IQ2_XS 6.7724 +10.7%
A/B: uniform RVN-IQ3_S.gguf 6.2956 +2.9%

At 3.50 bpw the allocation lands within 1% of F16 - and a same-class uniform quantization sits 1.9% behind it at a larger file size (12.42 GB vs 11.80 GB). Generation speeds (same box, full offload): IQ2_XS 105 t/s, IQ2_S 101 t/s, IQ3_XXS 97 t/s, IQ3_S 90 t/s, IQ3_S-mtp 150 t/s with --spec-type draft-mtp.

How these files were built

  1. Allocation - IST-DASLab's published per-tensor RCO maps for this tier set (851 tensor-to-type entries each; targets 2.50-3.50 bpw).
  2. Quantization - every tensor of RVN-F16.gguf quantized at its assigned type with llama.cpp (--tensor-type-file), using the official imatrix-qwen3.8-27b.gguf.
  3. MTP embedding - the official Qwen3.8 MTP/NextN head (from mtp-RVN.gguf) raw-byte merged into the -mtp twins (block_count=65, nextn_predict_layers=1).

Exactness - header audit per file: 803/851 tensors match the published allocation exactly; the 48 ssm_alpha tensors are held at F32 by llama.cpp's SSM precision rule (the map lists BF16 - strictly higher precision, ~ +24 MB/file).

Provenance note - this reproduces the RCO allocation with optimized local quantization. The per-tensor GSQ refinement pass from ISTA's internal pipeline is not reproduced; its current public implementation is a research checkpoint that regresses end-to-end KL in its own tests. The allocation and the official importance matrix are the published, verifiable ingredients. If the KL-gated refinement lands upstream we will re-run it.

Usage

# 16 GB cards: start here
llama-cli -m RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ3_S.gguf -ngl 99 --temp 1.0 -p "Your prompt"

# speculative decoding with the embedded MTP head (llama.cpp >= b10440):
llama-cli -m RVN-Qwen3.8-27B-Heretic-GSQ-RCO-IQ3_S-mtp.gguf -ngl 99 \
  --spec-type draft-mtp --spec-draft-n-max 2 --parallel 1 -p "Your prompt"

Thinking mode follows the model's chat template. A vLLM/Transformers (compressed-tensors) GSQ variant lives in the companion repository under GSQ-3bit/.

Related repositories

Credits

Per-tensor RCO allocation + official importance matrix: IST-DASLab (GSQ-RCO release). Quantization, verification, and MTP embedding: this repository. Base abliteration (RVN / ARA): see the main repository.

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