Theoben Rapid Forum

KevG Lathe work undertaken => kevG section => Topic started by: Swa400 on May 01, 2026, 08:50:33 PM

Title: double tap inertia for rapid mk1
Post by: Swa400 on May 01, 2026, 08:50:33 PM
Hiya,

Ive just found the videos from Ca_Varminter on your inertia weight and I would be very interested in knowing more.

Best wishes,

Stewart
Title: Re: double tap inertia for rapid mk1
Post by: Kernal on May 01, 2026, 08:58:36 PM
Quote from: Swa400 on May 01, 2026, 08:50:33 PMHiya,

Ive just found the videos from Ca_Varminter on your inertia weight and I would be very interested in knowing more.

Best wishes,

Stewart

Pretty good aren't they! Make`s  you wonder just how that hammer really works don`t it!

I do know KevG has been working on upgrade`s and it`s worth contacting him to see what`s on offer regarding the  double tap inertia!

If i was honest i was thinking of adding to this site his very own buy it now item`s!

KevG`s very own buy it now page on upgrade`s to item`s he creates I've been working hard on this code to do just that for him.

It`s not quite complete yet but it`s close to being complete!



Title: Re: double tap inertia for rapid mk1
Post by: Swa400 on May 01, 2026, 09:14:25 PM
Quote from: Kernal on May 01, 2026, 08:58:36 PM
Quote from: Swa400 on May 01, 2026, 08:50:33 PMHiya,

Ive just found the videos from Ca_Varminter on your inertia weight and I would be very interested in knowing more.

Best wishes,

Stewart

Pretty good aren't they! Make`s  you wonder just how that hammer really works don`t it!

I do know KevG has been working on upgrade`s and it`s worth contacting him to see what`s on offer regarding the  double tap inertia!

If i was honest i was thinking of adding to this site his very own buy it now item`s!

KevG`s very own buy it now page on upgrade`s to item`s he creates I've been working hard on this code to do just that for him.

It`s not quite complete yet but it`s close to being complete!





That would be a brilliant addition to the page! From an engineering perspective it makes you wonder how the factory hammer even works at all looking at the difference
Title: Re: double tap inertia for rapid mk1
Post by: Ca_Varminter on May 01, 2026, 11:33:57 PM
Here is another Discussion of KevG Double-Tap from the Tech area.....
https://rapidforum.co.uk/forum/index.php?topic=202.0

Stuart
Title: Re: double tap inertia for rapid mk1
Post by: Squinty on May 02, 2026, 07:07:55 AM
I have one in my .177 S-Type, OE spec is 500 shots/500cc @ 250 bar, I get around 490 shots from 480cc @ 230 bar.
Or a full tin of H&N 9.56gr FTs 400 shots @ 200 bar 8)

Title: Re: double tap inertia for rapid mk1
Post by: Swa400 on May 02, 2026, 07:56:30 PM
I'd be very interested in efficiency. Doubly so when the only recharge I had was a stirrup pump! But luckily I'm not reliant on that anymore. What affect does the mod have on power? And on a different note I've always used crossman accupells with the rapid, but is there a general consensus on which pellet is most preferred in the mk1?
Title: Re: double tap inertia for rapid mk1
Post by: Squinty on May 03, 2026, 09:56:48 AM
You get around 15% more shots, I was going to build a .22 in S-Type spec probably would have been in the region of 850 shots per fill.

Kev reckoned you need a tad more spring because there isn't the extra air from hammer bounce,
Power wise, no issues.
Consistency; spread has been 10fps or less straight from the tin.

The intent of the build was to use heavier pellets,- JSB 10.3s, Baracuda match, Crosman 10.5s and H&N 9.57 FT but some of my original pellet testing gave a 5fps max spread with one older batch AADF 8.4s , mostly 2-3fps.
Think the best was 4 or 5 consecutive shots @ 777fps but as the heavier pellets were performing to expectations I wasn't prepared to chase dies of AADF and Exacts for the sake of paper performance. .