As man o fyou know, I've had very good accuracy from the Raptor Prototype I have after in stalling an FX Heavy bbl. for shooting slugs in my gun. However, it was not a happy time. It is well known that the Raptor suffers from a not so well designed valve and seat that loves to fail. Particularly in HP applications.
I've had a hard time keeping this one to myself for about a year now. Don Cothran Machine to the Rescue!
Don wanted the factory valve to see what the issues were as it was in reality a poor copy of his valve designs. Due to work load, and health issues, Mr. Don was held up in the project for quite some time. that and he wanted to completely redesign it to his standards and went even further along with extensive testing.
A fellow member here also sent Mr. Don a complete gun as mine was a prototype and may be different that the production pieces.
The new valve is built like a Tank and is beautifully machined.
Don cautioned me to use very light spring pressure and only the slightest hammer strike and hammer pin setting limiting travel. With his advice, I removed the rather high rate spring and replaced it with a shorter and lighter one I have here. the results were unreal! As often Cothran valves are.
At the very latest setting on the reg, 2300 psi compared the the previous 3000 psi, light spring barley touching he hammer. Well Not actually touch it at all allowing a good bit of free travel, and the striking pin backed out to only allow well less than 3/32nds travel of the valve stem, the gun went super sonic with pellets. (I only used pellets for the initial tune as I don't' normally shoot pellets.
I loaded the 37.6 grain slugs I cast for it and it was already matching the velocity of the heavy set up with no further adjustments what so ever. First shot was 960 fps for 77 fpe.
Woo-Hoo! Finally success with a valve that doesn't have to be taken out every other day. I could not possibly say how many times I've had the gun apart to once again replace the valve seat. Many-Many times. Had it not been at the time my only slug shooter, I would have given up, or simply wrapped it around a tree. GRRRRRRR!!!
Every thing is machined out of billet. Heck, even the screws that retain the valve in the air tube are machined for a custom fit by Mr. Don. Absolutely superb workmanship.
I have heard of Cothran Machine and his work for years, but his workmanship exceeded an expatiations I had.
Her are a few quick and poor pic's of Hiss outstanding work.
The good news is, now that he has it perfected, he has made a limited run of these valves. So they are available for those of us that need them or want higher performance.
Everything fit beautifully as it it was made for it. Oh wait, it was. LOL!
My apologies for not including the pic of the actual transfer port, Getting old I guess.
Man, this thing flows some air! cocking force, as it is a balanced valve is virtually non existent. Just a pure pleasure.
The offending Monster
Knife
Come on man, he actually machined the screws form high tinsel Stainless Steel Round stock. Who does that? A perfectionist.
I've had a hard time keeping this one to myself for about a year now. Don Cothran Machine to the Rescue!
Don wanted the factory valve to see what the issues were as it was in reality a poor copy of his valve designs. Due to work load, and health issues, Mr. Don was held up in the project for quite some time. that and he wanted to completely redesign it to his standards and went even further along with extensive testing.
A fellow member here also sent Mr. Don a complete gun as mine was a prototype and may be different that the production pieces.
The new valve is built like a Tank and is beautifully machined.
Don cautioned me to use very light spring pressure and only the slightest hammer strike and hammer pin setting limiting travel. With his advice, I removed the rather high rate spring and replaced it with a shorter and lighter one I have here. the results were unreal! As often Cothran valves are.
At the very latest setting on the reg, 2300 psi compared the the previous 3000 psi, light spring barley touching he hammer. Well Not actually touch it at all allowing a good bit of free travel, and the striking pin backed out to only allow well less than 3/32nds travel of the valve stem, the gun went super sonic with pellets. (I only used pellets for the initial tune as I don't' normally shoot pellets.
I loaded the 37.6 grain slugs I cast for it and it was already matching the velocity of the heavy set up with no further adjustments what so ever. First shot was 960 fps for 77 fpe.
Woo-Hoo! Finally success with a valve that doesn't have to be taken out every other day. I could not possibly say how many times I've had the gun apart to once again replace the valve seat. Many-Many times. Had it not been at the time my only slug shooter, I would have given up, or simply wrapped it around a tree. GRRRRRRR!!!
Every thing is machined out of billet. Heck, even the screws that retain the valve in the air tube are machined for a custom fit by Mr. Don. Absolutely superb workmanship.
I have heard of Cothran Machine and his work for years, but his workmanship exceeded an expatiations I had.
Her are a few quick and poor pic's of Hiss outstanding work.
The good news is, now that he has it perfected, he has made a limited run of these valves. So they are available for those of us that need them or want higher performance.
Everything fit beautifully as it it was made for it. Oh wait, it was. LOL!
My apologies for not including the pic of the actual transfer port, Getting old I guess.
Man, this thing flows some air! cocking force, as it is a balanced valve is virtually non existent. Just a pure pleasure.
Knife
) to post his results from today's outing at he range...
