i have just recieved my delrin bolt for my evo and wondered why it had o rings on it. the delrin bolts that i had for my impulse did away with the rings due to the properties of the delrin. does anyone knwo the reason for this?
delrin bolts on autocockers
- Thread starter smartecosse
- Start date
ahh. that clears that up, thank you. 
was amazed that the bolt was almost half the weight of the standrd evo one.
was amazed that the bolt was almost half the weight of the standrd evo one.
I'm sure that's the likely thinking but I would disagree. A well timed cocker doesn't need O-rings on a delrin bolt that is a decent fit--I'm currently reviewing a very nice one in fact (cocker with delrin bolt and no O-rings, that is), and--
I have routinely removed all the O-rings except the one behind the gas thru port on all sorts of bolts with no problems whatsoever--
and there are quite a few aftermarket bolts now that dispense with all or most of the traditional O-rings
hi yuh.
we made the bolt with o-rings so u can use with or without, u have the choice, where as most of the other delrin bolts dont have them.
basicaly, as baba said, if the bots is a good fit, and you are not geting lots of gas up the feed tube then you gas use the bolt with no o-rings. been trying this on my Evo x and seems to work fine.
if you use o-rings u'll need to oil the bolt and also clean it at least 2-3 times in a days play and re-oil.
i found that it made me be able to up the BPS on my race having the new bolt, the new delrin pin we makin does the same as well
soooooo much lighter aint it
we made the bolt with o-rings so u can use with or without, u have the choice, where as most of the other delrin bolts dont have them.
basicaly, as baba said, if the bots is a good fit, and you are not geting lots of gas up the feed tube then you gas use the bolt with no o-rings. been trying this on my Evo x and seems to work fine.
if you use o-rings u'll need to oil the bolt and also clean it at least 2-3 times in a days play and re-oil.
i found that it made me be able to up the BPS on my race having the new bolt, the new delrin pin we makin does the same as well
soooooo much lighter aint it
yes it is . why can't u make them in a nice shiny colour thought cos everyone know's shiny = faster!!
hmm, dont think they make shiny delrin
yep, no o-rings is ok as long as you arnt getting much gas go up the feed tube when you fire
No o-ring/delrin info,
As for any bolt, if you want a to have it seal without o-rings you need to have a very close tolerance fit. Say you have a .689 breech, then you need a .684-.685 bolt. With a .003-.004 tolerance you get little to no blowback.
With a aluminum bolt, with these tolerances, you can get some serious wear. So, most bolts made in aluminum are made to .680-.683 tolerance, and then o-rings are added around the valve for a better seal. A tip o-ring seems to have problems if it swells, catching on the feedneck.
With a delrin, because it won't wear out the breech, you can run the tolerances closer.
But, to make a bolt that will fit any breech you will run into a problem with some breeches being tighter than others. In a cocker I have measured breeches between .689 and .696. So, getting a bolt that will fit all of these is hard, and most are build to fit the normal .689-.691 breeches that are the fit for 90% of the guns.
Having a choice of O-ring or not, on the Evo bolts is how they compensate.
On a side note, due to breech differences I have designed the Mutant Bolt. If you are curious (I don't want to blatantly advertise) check out the link on PBNation, it includes a bit more info on breech fit:
http://www.pbnation.com/showthread.php?s=&threadid=144829
Josh
As for any bolt, if you want a to have it seal without o-rings you need to have a very close tolerance fit. Say you have a .689 breech, then you need a .684-.685 bolt. With a .003-.004 tolerance you get little to no blowback.
With a aluminum bolt, with these tolerances, you can get some serious wear. So, most bolts made in aluminum are made to .680-.683 tolerance, and then o-rings are added around the valve for a better seal. A tip o-ring seems to have problems if it swells, catching on the feedneck.
With a delrin, because it won't wear out the breech, you can run the tolerances closer.
But, to make a bolt that will fit any breech you will run into a problem with some breeches being tighter than others. In a cocker I have measured breeches between .689 and .696. So, getting a bolt that will fit all of these is hard, and most are build to fit the normal .689-.691 breeches that are the fit for 90% of the guns.
Having a choice of O-ring or not, on the Evo bolts is how they compensate.
On a side note, due to breech differences I have designed the Mutant Bolt. If you are curious (I don't want to blatantly advertise) check out the link on PBNation, it includes a bit more info on breech fit:
http://www.pbnation.com/showthread.php?s=&threadid=144829
Josh