|
Post by luke213 on Mar 13, 2015 14:19:38 GMT -5
You actually don't need one with a bowl shape on it, they have a tare function witch basically cancels the current weight to zero. So say you put a bowl on there, then hit tare, then put a bb in there it will just give you the weight of the BB.
Luke
|
|
|
Post by Gunny87 on Mar 13, 2015 14:24:00 GMT -5
Yup, it has to also be the case because of R-hops. And I too use R-hops or flat hops in every one of my guns these days. Which does requires the use of a heavier bb as already explained why. But, I still personally am not using anything higher than a .30 at this time. I have some .32's but they don't seem to give that much of an advantage. I have .40s myself, but those are only for the bolty....
|
|
|
Post by Tank on Mar 13, 2015 14:58:10 GMT -5
Using heavier BB's will give you a longer effective range for two reasons (both of which are directly related to wind / wind resistance).
1) Think of throwing a solid ball, versus a hollow ball. That hollow ball has the same wind resistance as the solid ball, but the effect of that resistance against the extra mass of the solid ball has much less of an effect on it. Hence the vastly different range that ball will travel.
2) The cross winds that are blowing on your BB will have a greater effect on a lighter BB, again due to the reduced mass.
Bottom line, (I hate to open this can of worms but...) the energy still left in a BB at 100 feet is different between BB weights. Even taking into account the same starting energy.
|
|
|
Post by Knief on Mar 13, 2015 15:52:26 GMT -5
But Tank, throw a bowling ball and a baseball. It's not just drag that makes it drop a few feet away. I understand the physics behind muzzle energy, drag, and effective range. My point was that on my PTW, the sweet spot seems to be .30g bbs at the limits of our standard rifle MED rules. I was wondering about the need for a heavier bb, which, all else being equal, should be past that sweet spot for any other rifle shooting with the same muzzle energy if it's not over volumed and seeing a tangible benefit by taking advantage of joule creep. It sounds like the difference is likely the R-hop, which makes sense.
|
|
|
Post by Tank on Mar 13, 2015 15:59:09 GMT -5
What I'm saying is that a gun properly volumed for the weight BB that you are shooting, will always have a greater effective range when it is set up for heavier BB's. Your hop-up being able to consistently hop that heavy BB was lacking in the past, but with the hop-up mods that have been invented, this is no longer difficult.
|
|
|
Post by Knief on Mar 13, 2015 16:17:58 GMT -5
But that's not true. If you had a sufficiently heavy bb, it won't travel as far as a lighter bb at 1.56J because it doesn't have enough initial velocity to overcome gravity over distance, regardless of the hop up and air volume. A 10lb bb with a muzzle energy of 1.56J has an initial velocity of 2.7 FPS. That's not going very far no matter how much air pushed it to that velocity or how it's spinning. The question is, what shifts the sweet spot of be weight from my PTW to a P* with the same muzzle energy. It seems like that's an R-Hop.
|
|
|
Post by Tank on Mar 13, 2015 16:20:47 GMT -5
You are seriously underestimating the effect of wind resistance Knief.
Your sweet spot is dialed in for a lighter BB. You don't have enough volume of air for the heavier BB / your barrel length. The hopup will simply only allow you to consistently hop a heavier BB.
|
|
|
Post by Knief on Mar 13, 2015 16:40:53 GMT -5
The only way drag would make a difference is if my rifle has a higher muzzle energy with .30g bbs than with .40g bbs. Remember, I'm asking for a theoretical comparison with a P* that is volumed and pressured properly to shoot a .40g bb at 1.56J. Once the bb leaves the barrel at muzzle energy X, the power system no longer matters. Hop up pushes up, gravity pulls down, and gray pushes backwards. I'm going to see if I have any .40s and run them through my chrono and compare. But honestly, I don't buy that. I'm using cylinders that are compatible with M16 length barrels. I think I have the volume to push a .40g bb the whole way. If anything, my PTW will experience joule creep compared to its chronographed 410FPS w/.2 muzzle energy while the "correctly" tuned hypothetical P* controls for joule creep. I'm shooting hotter and my .40g bb should travel farther unless one of the three forces affecting it changes. The only one that can change is the lift created by hop up.
|
|
|
Post by Gimpalong on Mar 13, 2015 17:11:34 GMT -5
Even in AEGs, the benefit of using a heavier BB isn't solely to overcome wind resistance. In fact, I'd wager the impact of wind resistance on a .20 and a .25 are negligibly different. The main reason to use a heavier BB is because even AEGs experience joule creep to a degree. Yes, hop-ups tend to work better with heavier weight rounds, but the main benefit of the heavier round is the joule creep inherent in the added weight. At some point though adding weight will absolutely result in decreased range.
|
|
|
Post by Coldwave on Mar 13, 2015 17:15:51 GMT -5
I'm curious to see that difference of 1.55 j vs say 2.55 j at 50ft in terms of "damage" to a players skin. That'd be the difference of a 0.30 gram bb at 328 fps vs 425 fps with the same weight.
|
|
|
Post by Mosin on Mar 13, 2015 17:28:31 GMT -5
I currently have all the needed materials to see that difference if you're coming out to No Limits tomorrow. Maruzen shoots 2.7j right now at a cool 540 FPS, and the PTW shoots dead on the 1.55j we're looking at if I recall correctly.
EDIT:
Hell I'd be down to just mess around at the Chrono booth for a minute and see how I could cheat it. Maybe we'd be able to come up with some new systems in place?
|
|
|
Post by Kjones on Mar 13, 2015 17:59:17 GMT -5
I can bring the camera and document the damage if someone is willing to lift the shirt and take the hit. We need real evidence.
|
|
|
Post by X on Mar 13, 2015 18:02:55 GMT -5
Even in AEGs, the benefit of using a heavier BB isn't solely to overcome wind resistance. In fact, I'd wager the impact of wind resistance on a .20 and a .25 are negligibly different. The main reason to use a heavier BB is because even AEGs experience joule creep to a degree. Yes, hop-ups tend to work better with heavier weight rounds, but the main benefit of the heavier round is the joule creep inherent in the added weight. At some point though adding weight will absolutely result in decreased range. Based on this person's results I have to disagree. www.pstartalk.com/archive/index.php/t-374.html
|
|
|
Post by luke213 on Mar 13, 2015 18:07:43 GMT -5
From what I understand the heavier BB to a certain point will carry more energy over the distance covered. So for instance a .20g at the muzzle at 350fps might be 200fps at 100ft. Where a .25 might be around 310fps out of the same gun but at 100ft. it's still traveling at 260fps.
Now these numbers are complete BS pulled out of my head but that's how I understand it from my reading basically the heavier weight pending it's not too heavy to get initial velocity will travel further than the lighter round at higher FPS at the muzzle.
Luke
EDIT: Also if your testing I'd love to see a chrono test at the muzzle and then one at 50ft. if someone has a traditional firearm chrono which should be a big enough target to hit at that distance. That might shed some light on it.
|
|
|
Post by X on Mar 13, 2015 18:22:04 GMT -5
From what I understand the heavier BB to a certain point will carry more energy over the distance covered. So for instance a .20g at the muzzle at 350fps might be 200fps at 100ft. Where a .25 might be around 310fps out of the same gun but at 100ft. it's still traveling at 260fps. Now these numbers are complete BS pulled out of my head but that's how I understand it from my reading basically the heavier weight pending it's not too heavy to get initial velocity will travel further than the lighter round at higher FPS at the muzzle. Luke EDIT: Also if your testing I'd love to see a chrono test at the muzzle and then one at 50ft. if someone has a traditional firearm chrono which should be a big enough target to hit at that distance. That might shed some light on it. I actually started doing a test like this once then for some reason abandoned it. Probably a cool video game came out or something hehe.
|
|