Airgun Technologies Vulcan 3 HP .30 with added Huma MOD40-4/0 = severe clipping!

[grouch-o]

I recently got a Vulcan 3 HP .30 and had severe problems with slug clipping when i attached a brand new Huma MOD40-4/0.

Since the moderator is modular, i was able to try different configurations, from several meters in POI shift all baffles to a less than 10cm shift of POI on 50m with two baffles.
At last i was at only one segment of the moderator, but i want to test it more before i can say if that has no effect on POI. (Even with just one segment, it still muffles the report a bit.)

I am writing this here, since others might be interested in this set-up as well. i also wrote Huma about it and they confirmed my understanding that this is caused by the
a) small bore in their moderators (1,5 mm + caliber) for best effect
and
b) the fact, that the gun has a shroud with build in moderator over the barrel, which means the external moderator is not directly on the barrel end but on the shroud end causing the projectile not to leave the shroud in the centre of the hole.

Huma suggested, to either use a external moderator one caliber bigger or to drill out the baffles until clipping stops. Bummer, i just goth the thing. =(

 

[Will74]

Interesting...
I have been thinking about Mod50.

You might want to try the moderator straight on to the barrel just for giggles. It should be straight fit.

 

[grouch-o]

Interesting...
I have been thinking about Mod50.

You might want to try the moderator straight on to the barrel just for giggles. It should be straight fit.

i assume mod50 will be no different in .30, unless in your gun everything is super-aligned.
but since the base baffle is longer, you might end up not even being able to use that. =(

after another round of shooting with and without the first huma mod40 segment, it seems there is no difference, except in BANG (with HN 50gr slugs).

strangely (to me) the best group was shot when the remaining pressure was below 200bar, when i shot the last round of 5 on the center dot of the paper again. on that dot i also shot the first round without moderator.

 

[Will74]

Yes well I meant I am probably going to get the Mod50 and for what I know, it could be attached straight on to the barrel to see if the problem is somewhere else. Of course it would look ridiculous without the shroud but I would try it out temporarily.
If the original shroud was round, I would have it shortened by 2 to 3 inches and rely more on the Huma moderator. The original seems rather "rustic" and almost waste of space, all 5 inches of it. But if someone was to install a longer bottle, then the shroud length is crucial especially with bigger diameter moderator.

About the clipping...
I have been told it does not play such a big role on noise if them holes are only a few micrometers larger than the slug. I would just drill them out.
I suppose You have counted for the POI drop which is inevitable when adding anything on the barrel?