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Air Gun Home Forum Index » Airgun Smithing » increase swept volume    View previous topic :: View next topic  increase swept volume   Posted: Wed Dec 14, 2011 8:42 pm Pat Robb New Member Joined: 14 Dec 2011 Posts: 5 Location: The Hammer What are the best ways to icrease swept volume in a classic .22   Posted: Wed Dec 14, 2011 8:52 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario Unfortunately there is no easy way to increase the swept volume of the Benjamin classic 22 or any of the B18/19 platforms. The stroke cannot be effectively made longer because the cocking slot is already exposed when the piston is cocked. I suppose you could squeeze a couple cc's by reducing the headspace of the piston but I'm not sure you would get much gain. I'm guessing your question relates to a 495fps version? _________________ Sean   Posted: Wed Dec 14, 2011 9:01 pm Pat Robb New Member Joined: 14 Dec 2011 Posts: 5 Location: The Hammer yes, that makes a high of 728 on the chrony ,always looking for more   Posted: Wed Dec 14, 2011 9:09 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario Your right on the numbers. That is the most I have ever gotten with a gas ram. I'd be the last person to say that trying to reduce the headspace and possibly a really heavy honing wouldn't be fun to try. You would need to find a set and lock type hone though. A three arm or a ball hone would be no good for that kind of material removal. _________________ Sean   Posted: Wed Dec 14, 2011 9:23 pm Pat Robb New Member Joined: 14 Dec 2011 Posts: 5 Location: The Hammer how about shorting an old the piston to the max on the seal side. is it worth the im guessing 1/4" and time cutting re welding / crimping- also making new top hat to include my 3 penny's that are inside . what would 1/4 equate too/fps   Posted: Wed Dec 14, 2011 9:34 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario As I said the problem is the piston seal already comes out as far as the cocking slot. So shortening the piston a 1/4" is just going to expose another 1/4" of the slot. While the seal is in the slot area it's not compressing anything because the air will just escape. _________________ Sean   Posted: Tue Jan 03, 2012 7:36 am Remtom1200 Member Joined: 02 Jan 2012 Posts: 53 What is this reducing headspace you speak of? I do not think I have heard of this before now.   Posted: Tue Jan 03, 2012 10:15 am SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario The space between the ruler and the piston is your ultimate headspace. Headspace is a term that engine builders toss around a lot and something that determines the final compression of a swept volume cylinder Please note: I am not advocating there is any real gain here...the area is tiny. I made a custom piston that had near 0.000" headspace and I did see a small gain in velocity. However.... Was the gain from the headspace tighter tolerances hardened and swirl polished body skirt buttons or the few grams of extra weight?????? We'll never know because increasing the velocity wasn't my goal. I just wanted to make a very high quality piston to improve deviation. _________________ Sean   Posted: Tue Jan 03, 2012 1:25 pm Remtom1200 Member Joined: 02 Jan 2012 Posts: 53 oh ok, I think i am interested in adding buttons though..thanks for the info   Posted: Tue Jan 03, 2012 2:15 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario skirt buttons are a cool little mod and they certainly seem to smooth the shot cycle. Google "JM's old school buttons" or make your own from wafers of 3/16 brass rod silver soldered onto the skirt. _________________ Sean   Posted: Tue Jan 03, 2012 5:04 pm Slavia Moderator Joined: 31 Mar 2008 Posts: 4382 Location: Waseca, Minnesota, USA In my B3 I used brass from spent .45-70 shells and ordinary solder. Whichever way you go the surface has to be completely clean and degreased. _________________ ¡Listo! ¡Apunte! ¡Fuego!   Posted: Tue Jan 03, 2012 11:13 pm SMP Silver Status Member Joined: 04 Feb 2011 Posts: 1183 Location: Just south of "Out There"- Land O Lakes Ontario Ya agreed regular solder would be more than fine... Old habits are hard to break...Marine guys gotta silver solder everything _________________ Sean increase swept volume     Air Gun Home Forum Index » Airgun Smithing You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum All times are GMT - 5 Hours   Page 1 of 1   All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First  Select a forum Main Forums----------------AirGunHome Q&AGeneral Air Gun Questions and TopicsPicture GalleryTarget Shooting: Casual, Fun and CompetitionHunting, Pest Control, Varminting People/Events/Airgun Issue Discussion----------------Introduce YourselfThe BS TopicClubs/Events/Regional/Political Airgun Issues Maintenance, Modification and Reviews----------------RiflesPistolsAntique, Collector and Novelty AirgunsBB GunsPellets/AmmoOpticsAccessoriesAirgun Smithing Buy, Sell or Trade Forums----------------For SaleWant to Buy   Note: If you are seeing "Please enter your username and password to log in." 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