Is this possibly a head space issue?

[Jaxson50]

I took my recently acquired US Model 1917 to the range last week, shooting commercial 180 gr. loads the recoil was pronounced enough that the range master commented on it.
After about 12 rounds it became difficult to pull the bolt back, it rotated well, but after three more rounds it wouldn’t pull back at all. The range master used a rubber mallet to tap it open.
I was slow firing so I don’t believe it was a heat issue. The shells extracted correctly.
I inspected the primers and it did seem they had rounded off, in other words the fired primers were no longer flat but rounded a bit.
After returning home I cleaned it well, the bolt cycles well now, but there was a considerable amount of black caked of goop in the action where the bolt lugs rotate.
To be clear, I have fired more than a few .30 caliber and larger rifles, I’m not a stranger to recoil, my standard range rifle is a M1A.
The recoil was more what I would expect from a 45 70.
Does this sound like a head space issue?

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