ball shape/bore affected by gradual barrel bore

[QUINCYMASSGUY]

OK, my next technical question and of course input from the usual suspects who have time and time again proved to me they know their stuff (AThomas, The Electrician, and more) would be appreciated.

How would this scenario affect how a ball shoots/the efficiency of it?
-Ball is loaded into a Cocker barrel by the bolt pushing it and the marker gets ready to fire(so closed bolt functionality) and the ball is fired. The start of the barrel is .685 or .687 and the rest of the barrel is .689 which is the bore fit for the paint. If the section of tighter bore was only 1-2 inches long and the rest of the barrel (8-12 inches lets say) was the larger and more accurate bore of .689, how drastically would this decrease efficiency or risk ball breakage? I take it it would mean the ball would be squeezed in a little but that's the idea. So what would the negative effects of this idea be?

My idea is a pre-barrel 2nd breach for cockers that let the ball be queued up in a sense without risk of it rolling out if it happens to be a little smaller (paintball inconsistency issues would be reduced as no detent holds a ball in with cockers once it's chambered and this would resolve it). However issues with paint-to-barrel exist and even though such an idea may actually improve this for cockers and further fuel the idiots who think cockers shoot further than any other marker, I want to make sure no issues arise due to paintball physics.

Part of this idea would involve a thin aluminium sleeve being inserted into the barrel to make a smooth transition, do you think alumium could be tempered to .002-.004 accurately and be strong enough to not be bent too easily?

Your input would be appreciated, thanks guys!

[the electrician]

the idea is alrady applied with the OTP G series barrels. they were the first ones to have breech sizers. I have an OTP G-1 barrel that shoots great.it has sizers that are about 3/4' long and have the very same purpose that your speaking of. the rest of the barrel is a nice two piece barrel, stainless back. the only thing is that it's fairly large bore. it has to be for it to work. it's like .691 and the ported length is .695. there are 5 sizers from .681 to .691.

if you use a breech sizer or insert, on any of these barrel systems, that is too tight of a fit to the paint, it can turn your suction into blowback, and sometimes cause barrel breaks. the better the paint, the more true,or round it is,the tighter the sizer you can use without it having problems.

I tend to go more for a little too big, than a little too small. it's just less of a problem. I'd rather have an occasional weak shot than the occasional barrel break.

I'm thinkin' come up with a breech design that doesn't use a bolt that pushes the ball up.

[QUINCYMASSGUY]

electrician

Please, definitely elaborate on your idea. I think I get it but I'd love to hear the details.

Up a bore would work, but wouldn't it have break issues then flying down the barrel? I did a little looking on the OTP thing, if it really is only 3/4" of tight bore and then goes up to .691, my other idea just reopened. If the bore change would cause problems my idea would be shot. I couldn't find much on the barrel but one report saying its pretty accurate and consistent. A .689 to .695 drop would work? Would it absolutely kill efficiency? Ideas are a'brewing! So you'd use .689 bore paint in that setup right? Or am I wrong.

Thanks again electrician, you keep impressing me!

[the electrician]

Yikes!
sorry about the mis-information. my OTP G-1 is actually .693" in the back and .697 in the front. and the breech sizer is actually only .515" long. I should have measured before I spoke! the G-3 is different. it has threaded sizers that actually are like lapco sizers in a way. only they are left hand threaded into the barrel and are about 2 or 2.5" long.

the main thing I don't like about the G-1 is that it is really big bore. most paint around here is on the small side, so it loses some accuracy unles you use .687 or bigger. the solution is to only buy good, big paint. it is a great barrel. extremely quiet and consistent.

here are some pics of the barrel and some pics of stuff I made.
http://home.kc.rr.com/theelectrician/OTP%20G-1.jpg

http://home.kc.rr.com/theelectrician...eupthreads.jpg

http://home.kc.rr.com/theelectrician/G-1spacer.jpg

here's an electrococker made for a friend:
http://home.kc.rr.com/theelectrician...rosideview.jpg

http://home.kc.rr.com/theelectrician...osideview2.jpg
http://home.kc.rr.com/theelectrician...lectroguts.jpg

here's my old electrococker:
http://home.kc.rr.com/theelectrician...ersideview.jpg
http://home.kc.rr.com/theelectrician...rontblock1.jpg
http://home.kc.rr.com/theelectrician...cockerguts.jpg

here's a pneuma-assisted mag:
http://home.kc.rr.com/theelectrician/magsideview.jpg
http://home.kc.rr.com/theelectrician/magclose-up.jpg
http://home.kc.rr.com/theelectrician/magsideview2.jpg

[RRfireblade]

Re: ball shape/bore affected by gradual barrel bore

Originally posted by QUINCYMASSGUY
My idea is a pre-barrel 2nd breach for cockers that let the ball be queued up in a sense without risk of it rolling out if it happens to be a little smaller (paintball inconsistency issues would be reduced as no detent holds a ball in with cockers once it's chambered and this would resolve it).

Lapco,available in 3 sizes,I think.

jay.

[hitech]

Glenn Palmer hones the center of the barrel larger than the front/back. In other words, it starts out small get larger and then smaller again.

BTW, it won't affect accuracy at all. What it will affect is efficiency and consistency. I have no hard data, but it appears that a tighter barrel is more efficient (less air "leaks"?) and a looser barrel is more consistent (excess pressure escapes past paintball?).

[athomas]

From what I can figure, a larger barrel id is more consistent because all balls are smaller than the id of the barrel. A small bore barrel will shoot a perfectly fitting or loose ball fine, but could have a velocity change if a tight ball is chambered.

From my expereience I have noticed that a barrel that is too tight, does not appear to have the accuracy grouping either. I don't have any data to support this though. The only thing a tighter barrel was used for years ago was to keep the balls from rolling out the end of the barrel.

A large ball may break when forced into a barrel that is too tight. This is quite often a combination of the bolt force and speed and the sudden slowing of the ball when it gets jammed into the barrel. Even the mighty level 10 would have trouble with this since the fat part of the ball doesn't enter the barrel until after the bolt is getting up to full speed and power.

Ideally we want a perfect match, but since paintballs are not perfect we accept the best compromise. Many players are willing to sacrifice a bit of "accuracy" to achieve consistency and minimize ball breaks. This is especially important in the tournament arena where a sudden hot shot can cost you a big penalty. So, a large bore barrel is used. The better, more consistent your paint is, the tighter you can get your barrel to the size of the ball without danger of getting the odd "tight" fit.

The ball sizers are designed to make a large bore barrel fit your paint so you have a snug fit to keep the paint from rolling forward while waiting to fire a shot. It is still advisable to not use a size that is too small for the paint or you will get barrel breaks.

Efficiency is affected by the size of the barrel. A barrel that is too tight increases the friction and decreases the efficiency. A barrel that is too loose lets too much air get by the ball while firing and is inefficient. So, again we try to get the best fit we can for best efficiency, compromising a bit for whatever perceived effect or problem we are trying to overcome or enhance.

Sorry for being long winded. Its hard to get all the stuff I want to say into a post and keep it short and readable.

[QUINCYMASSGUY]

bah

Bah, longwinded is sometimes what gets the job done. See my posts sometimes? Yours explained exactly what I wanted to hear, I always thought with larger bores you would keep having balls bouncing side to side and breaking against the inside walls of the barrel but I guess a .01 difference wouldn't risk that.

Cool, like I said I have an idea that has actually evolved beyond just being a way to hold the paintball before firing like this started, but I am not releasing specs yet as I want to have the fine details honed out and some manner of being able to fabricate it if I proves highly probable.

Thank you again for the valuable technical information, paintball involves so many pneumatic and electronic principles and I learn a little more each day.

[hitech]

Originally posted by athomas
A barrel that is too tight increases the friction and decreases the efficiency.

That has not been my experence. My experence has been that as the bore gets tighter the better seal more than makes up for the increased friction. However, I have done no testing to prove this.

And just to add my two cents worth. For shots AT THE SAME VELOCITY paint to barrel match does NOT affect accurary at all. Pretty bold statement, huh?

[athomas]

I agree, a good fitting paint will give a good seal and have the best efficiency. Unfortunately the deal with paint is that you can't consistenly get a good fit.

As the ball gets tighter in the bore the seal gets better and the efficiency gets better to a point where the friction overcomes the extra force the good seal makes. A barrel that is too tight is not good.

As a barrel gets too loose for the paint the excess space allows too much air out around the ball. This causes major inefficiencies as well.

This test was done on a pump gun (not a real test, but a good observation).:) Both barrels were 12" and the same manufacturer. Both had no porting.

The accuracy I did observe between barrels (observed, not measured) indicated that the larger barrel was more accurate. I qualify that statement noting that the large barrel id was .6925 and the ball touched on two sides. The same ball shot out of a .6875 barrel was touching on all sides and there was a noticable increase in cocking pressure required to chamber a ball. I had a velocity drop off when I installed the smaller barrel indicating efficiency was better with the larger barrel. I also noticed a tighter shot grouping with the larger bore barrel. The shots were more eratic with the smaller bore.

[QUINCYMASSGUY]

barrel talk

LOL, we're open an old can of worms with this topic... ok, so here is my next fifty cents for this topic:

First, so what would be the ideal, an optimally tight fit 80% of the time with the other 20% being too tight a fit, or 60% of the time a looser fit that lets some air out around the edges but the other 40% being the optimally tight fit?

Second, what do you think is the most drastic change a barrel can have before it's so much it's just way to inefficient and inconsistent? Like .689 to .699 would be way too much right? What do you think IS the threshold where it becomes pointless?

[redlaser666]

A bit off topic but here goes.
the electrician in your friends electro cocker how does the sear get pulled? Does it even have a sear?
Thanks.

[the electrician]

yeah, it's the same as mine. direct solenoid actuated sear.
the solenoid is in a "cartridge". it is below the sear. it pulls the sear down. it is about the size of the solenoid in the racegun frame.