February 17, 2008 at 5:32 am #1544garytexParticipant
I am thinking of getting some powderburner bore barrels made up for my Condor, the object being to be able to shoot higher B. C. lead bullets.
The barrels will be profiled at the Douglas factory, my smith has a connection there. I am considering .224, .243, and .257 cals. I will pull exterior dimensions from my existing .22 & .25 cal airrifle barrels and request those dimensions, and just buy barrel bushings from Airforce.
I will buy cast lead bullets & size them in a Lee sizer.
Any advice on any part of this scheme from the experienced would be greatly appreciated.
GaryFebruary 20, 2008 at 4:14 pm #34474vincentvangervenParticipant
nobody? thinks this is interesting and am curious too 🙂February 20, 2008 at 4:17 pm #34475voltar-1Participant
If it was me a straight barrel works fine for these guns. So perhaps 16mm is a good size.
I like the Track of the Wolf barrel liners as they are light, beautiful rifling and perhaps not as deeply rifled as PB barrels.
A Douglas barrel would be sweet for sure!
Walter….February 20, 2008 at 5:25 pm #34479walkonkingParticipant
I personally like ready about this kind of work, but have no experience doing it.
I am content just spitting out my .22 pellets. But really enjoy reading about the conversions and what these airguns are capable of.February 20, 2008 at 6:51 pm #34488airtrampParticipant
Gary, I have zero experience with big bore AG (unlike Walter) so take my comment as just something to trigger your thoughts/more questions.
I read that barrel harmonics actually have a bigger effect on AG than PB due to the long resident time of the projectile i.e. enough time for all kind of standing waves etc. to form and the higher the power, the more pronounced the effect. Our choices are limited by the OD of AG barrels available because there are so few suppliers.
If you are going to start from scratch, you might as well start with a bigger OD like 18-19mm and see what happens. I think the ID of the frame is around 25mm. It’s easy to remove material afterwards and by all means, don’t limit yourself to the AF bushing locations. Experiment with moving the front bushing to near the end of the frame. I think the free floating concept as an end-all is over sold. It may be empiracal engineering but what the heck – as long as you are having fun. Don’t forget : nothing ventured, nothing gained.
Looking forward to updates of your project and best of luck.February 25, 2008 at 4:02 am #34843garytexParticipant
Van at Airhog has done the PB barrel thing, and reports that with the much taller lands, that engraving forces eat up so much energy that power is low with PB barrels and full bearing surface bullets. This brings us back to the bore riding double diameter pellet swaged from a Corbin die, or bought from FMG airbullet (ignoring little difficulties like So. Africa is a 26 hour jet flight away, and that production quantities may be relatively small.)
Alternatively one can seek shallow rifleing bores. I am re-barreling one of my PB rifles to take off a Shillen .270 WBY. barrel The concern with the .270 WBY barrel is that it has extremely shallow rifleing, and in less than 100 rounds the throat (origin of the rifleing) has moved forward about 80 thousands. The rifleing is so shallow that it will barely turn a cleaning rod with a tight patch. It shot about 200 fps faster than it should, however, probably due to low engraving force losses. The barrel was bought out of a lot of rejects and overstocks from Shillen several years ago. Ought to be just the ticket, as soon as I get that one back from still another smith. The ouchies that I can anticipate are: 1) Profiling off the chamber end, 2) Bushing up the too small muzzel end to fit into my shroud, 3) Cutting flat spots on the sloping contour of the barrel to fit bushings, and 4) building a replacement breech large enough to slide over the larger barrel. I could really use some help from someone who knows the how to figure dimensions for the proper breech O-ring sliding fit. Additionally, there may be other things required that I don’t know enough to anticipate, any help from folks who have done this sort of thing before would be appreciated.
Additionally my gunsmith will ask the his friend at Douglass to see if they have any shallow rifleing rejects. He is also lineing me up with an aspiring apprentice to do some of the machining, as he is too busy with his regular business to respond to my foolishness in a timely way. (he is a nationally known shilouette competitor and gunsmith and very busy)
We will see how that all works out.
I have this nagging suspicion that I may in retrospect decide that it would have been less trouble and cheaper to just buy the Corbin dies to make their already proven heavy projectiles for my existing barrels which are already the right profile, and choked, etc.
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