I tried a search with no luck. Has anyone tried one of these? I shot my HMR yesterday and was surprised by how fast it got hot, particularly with the suppressor on. On a related note, what temperature range would start to cause issues-either accuracy or accelerated barrel wear?

I bought one of these and used it at a match last weekend.  https://www.amazon.com/gp/product/B073T3H3B4/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

I have no empirical data whether it helped or not.

What was the pace of fire at the match?

My buddy uses a chamber chiller, it seems to help..he is doing load work up and try to have the chamber temp as close to the same as he can get it..he thinks it's helping...

I'm not sure how much they actually do, but the magneto speed is definitely the one that moves the most air through the barrel.  I don't know much about metallurgy, but I just cant picture moving ambient air through and already hot barrel is going to cool it a whole lot.

Matchers I shoot are often 10-12 rounds in 90 seconds, with a typically no less than 30 minutes between the next stage.

These work great
No batteries to replace, rechargeable.

Moving ambient air cools because ambient air is cooler than the barrel. Air cooled internal combustion engines.

Yes, but the question is how much faster.

Faster than no moving air.
Question is, how valuable is your time at the range?

I remember stories of the old school benchrest and target guys just dumping water on their barrels.

The pace TeeRex describes.

Thanks

I guess I don't worry about it.  I shoot competitively and it's pretty harsh firing schedule.

I shoot competitively as well, very often 10 shots in under 120 seconds is the pace. During the warm months the barrel is entirely too hot to touch by the end of a string. If I have ice available, I'll set a cube above the chamber or throat and run it up and down the barrel till it's at ambient-ish temp. If not ice, I'll pour water over it BUT NOT INSIDE IT. I only do this because during the warm months the match is less popular and so I don't have as much time for natural cooling to work between stages.

How hot is too hot, when your skin doesn't like holding on to it with a firm grip, it's already too hot. The result of shooting it while it's too hot is shorter barrel life (specifically throat cooking) and most guns start opening the heck out of their group size as they heat up for a suite of reasons. Competitors firing long strings quickly are also by definition NOT letting the ammo bake in the chamber, we're closing the bolt and promptly sending the round downrange as a matter of necessity. Otherwise it's hard to get 10 rounds off in 90-120 seconds on a bolt gun while actually hitting targets.