pokey Posted August 24, 2015 Report Share Posted August 24, 2015 Why if you were shooting ladders, would the bullets impact lower with higher powder charge? Before you ask, it was the same case, powder, primer, and bullet. The only thing that changed was the amount of powder. As the powder charge increased the point of impact lowered. This was true with two different rifles with four different tests. I expected the opposite. I know everything was correct, didn't load the rounds in reverse order (the heavier loaded rounds were on the bottom of the mag), or anything like that. Positive of the order they were fired in. What gives? Pokey. Quote Link to comment Share on other sites More sharing options...
sketch Posted August 24, 2015 Report Share Posted August 24, 2015 Im no expert just learning? What range are you sighted in at and what range were you shooting?Is the bullet gn in the test the same as sight in?im just asking hope these are the right ?'s sshop will know? Quote Link to comment Share on other sites More sharing options...
pokey Posted August 24, 2015 Author Report Share Posted August 24, 2015 One rifle sighted in at 200 yards, and the other at 100 yards. Both tests were done at 100 yards. No they weren't sighted in with these bullets. The rifle sighted in at 200 was a .308, and the other rifle sighted in at 100 was a .223. Quote Link to comment Share on other sites More sharing options...
DNP Posted August 24, 2015 Report Share Posted August 24, 2015 Higher velocity maybe. The range you are shooting is before the peak of the trajectory. They reach the target faster and therefore at a lower point? Just guessing. I know nothing. Quote Link to comment Share on other sites More sharing options...
DNP Posted August 24, 2015 Report Share Posted August 24, 2015 Naw. That wouldn't work thinking about it. Quote Link to comment Share on other sites More sharing options...
Cali_Ed Posted August 24, 2015 Report Share Posted August 24, 2015 Higher velocity maybe. The range you are shooting is before the peak of the trajectory. They reach the target faster and therefore at a lower point? Just guessing. I know nothing. im leaning towards this answer as well. if the projo is going fast maybe it doesn't have enough time to lift? w heavy was the projo? Quote Link to comment Share on other sites More sharing options...
sketch Posted August 24, 2015 Report Share Posted August 24, 2015 (edited) I ment to ask was the test projo the same weight as the sight in? Edited August 24, 2015 by sketch Quote Link to comment Share on other sites More sharing options...
pokey Posted August 24, 2015 Author Report Share Posted August 24, 2015 No. The rifles were sighted in with 150grand 55gr. The ladders were run with 168gr, and 69gr. Like I said, they were .308 and .223. It just seems really backwards. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 24, 2015 Report Share Posted August 24, 2015 You say the rifles were sighted in with 150 gr. & 55 gr. Bullets respectively to caliber , then you shot 168 gr. & 69 gr. Bullets respectively to caliber ? Heavier bullets will impact lower than lighter ones , if thats the case. Even if you match the Velocity's at the Muzzle . Another thing can be spin drift , right hand twist , depending on other factors can push a Bullet down, or up , for that matter , depends on many factors . Quote Link to comment Share on other sites More sharing options...
shepp Posted August 24, 2015 Report Share Posted August 24, 2015 You say the rifles were sighted in with 150 gr. & 55 gr. Bullets respectively to caliber , then you shot 168 gr. & 69 gr. Bullets respectively to caliber ? Heavier bullets will impact lower than lighter ones , if thats the case. Even if you match the Velocity's at the Muzzle . I was thinking the same thing but I've never reloaded so I wasn't sure, makes sense to me? Comes out faster but Gravity is pulling harder on it Quote Link to comment Share on other sites More sharing options...
blue109 Posted August 24, 2015 Report Share Posted August 24, 2015 He's not questing the Bullet drop between the 155 and 168, he's questioning the drop between the 168 and 168 with higher powder charge. Seems the hotter load should mean higher velocity meaning higher poi to a certain point...Unless you hit a point where you are not getting efficient combustion anymore. Chrono would probably solve this one for you. How many shots of each load did you make to confirm POI? did the gun rest and cool between strings? Quote Link to comment Share on other sites More sharing options...
planeflyer21 Posted August 24, 2015 Report Share Posted August 24, 2015 He's not questing the Bullet drop between the 155 and 168, he's questioning the drop between the 168 and 168 with higher powder charge. Seems the hotter load should mean higher velocity meaning higher poi to a certain point...Unless you hit a point where you are not getting efficient combustion anymore. Chrono would probably solve this one for you. How many shots of each load did you make to confirm POI? did the gun rest and cool between strings?That's the way I read it: powder weights with the same bullets, identical in weight for each caliber.I was thinking it may be barrel harmonics, how the barrel vibrates/whips differently with each powder load but it seems odd that higher powder loads in each caliber both impact lower than lighter powder loads, seeming to indicate that a powder load's effect on barrel harmonics may be predictable.Mikedaddy!! You have a new assignment! Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 24, 2015 Report Share Posted August 24, 2015 Well , those post were hard to follow , is why I asked about the Bullet weights . You also don't say how much the loadings were increased & spin drift & as was mentioned , Barrel whip , to some extent may effect Bullet impact , not to mention Barrel heating , unless they are all cold bore . There are a lot of factors involved & some more info is needed . Barrel spec's ?Same COL ?What were the charge weights & how were they weighed ? How much lower did the different loadings impact ?Bullet Manufacturer ?All the same case trim length ? & what were they trimmed to ? Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted August 24, 2015 Report Share Posted August 24, 2015 What's the twist rate for these barrels? With the extra velocity, might be overstabilizing the heavier rounds? Quote Link to comment Share on other sites More sharing options...
GreyGoose Posted August 24, 2015 Report Share Posted August 24, 2015 (edited) Well , those post were hard to follow , is why I asked about the Bullet weights . You also don't say how much the loadings were increased & spin drift & as was mentioned , Barrel whip , to some extent may effect Bullet impact , not to mention Barrel heating , unless they are all cold bore . There are a lot of factors involved & some more info is needed . Barrel spec's ?Same COL ?What were the charge weights & how were they weighed ? How much lower did the different loadings impact ?Bullet Manufacturer ?All the same case trim length ? & what were they trimmed to ? I think SurvivalShop is on the right track here given what we have to work with up to this point.The different loads produced different nodes and anti-nodes along the barrel, and as the barrel harmonics changed the whipping of the barrel changed as well and your ladder group reflected that.Ladders are what we all grew up with I know, but you might check out out Dan Newberrys work, he's the guy who came up with the "Optimal Charge Weight Load Development" system. I've run through it a few times and was happy with the results, I know a lot of long range guys use it, its really quite simple and it really does tune your barrel in and help you find the best load for consistent accuracy.Hope that helps. ;-) Edited August 24, 2015 by GreyGoose Quote Link to comment Share on other sites More sharing options...
pokey Posted August 24, 2015 Author Report Share Posted August 24, 2015 Yes, all testing was done with the same bullet weight. No, it wasn't cold bore. The .308 was a 20" with a 11.25 twist. The .223 was a 16" barrel with 1/9 twist. The tests were done at .2 grains at a time. 100 yard distance. The .223 was on a lead sled. .308 on a regular rest/sand bag, because I thought the lead sled may be affecting something. Quote Link to comment Share on other sites More sharing options...
Sisco Posted August 24, 2015 Report Share Posted August 24, 2015 (edited) When you load a round with a specific powder load and projectile, and fire it, that bullet will follow an elliptical parabola that is unique to that combination. Adding powder to that charge might very well be doing two things: Flattening out that parabola because of the extra energy, and shifting it downrange a certain distance from your firing point. If you are sighting in at a distance where the projectiles are still ascending, which I believe they are at both 100 and 200 yards, this will cause the larger charge projectile to impact lower. Once they reach the maximum height, or apogee of the parabola, the larger charge should be furthur downrange. As they start to drop, eventually they will cross paths Edited August 24, 2015 by Sisco Quote Link to comment Share on other sites More sharing options...
Sisco Posted August 24, 2015 Report Share Posted August 24, 2015 When that happens, the smaller charge projectile will impact lower and drop off more dramatically s far as bullet drop. Quote Link to comment Share on other sites More sharing options...
survivalshop Posted August 25, 2015 Report Share Posted August 25, 2015 So much can change when an even small charge wt. change is made , the fact that the Bullets impacted lower then the lighter charge wt. is just what happened with your loads , your Barrel/Chamber . If you had some Chronograph readings , they might surprise you . Since I started using a Chrono. for re-loading , it simplifies the process of finding the right combination of charge weight to a specific Manufacturers Bullet/ wt.. Everything else comes from testing them . Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 25, 2015 Report Share Posted August 25, 2015 What's the twist rate for these barrels? With the extra velocity, might be overstabilizing the heavier rounds?You can't overstabilize a heavy round. You can come in under, though, on a heavy round, and not stabilize it. Slow-twist barrel.You can overstabilize a light round, and it'll fragment long before it reaches any target. Shoot a 5.56 36-grain Barnes Varmint Grenade through a 20" 1:7" twist barrel... Quote Link to comment Share on other sites More sharing options...
pokey Posted August 25, 2015 Author Report Share Posted August 25, 2015 Thanks for the replies. I suppose the higher than normal scope height as compared to say a 700 Remington may have played a role also. All rounds were the same over all length, trimmed to the same length, and powder trickled. The drop difference was about 2" . No chronograph readings, hey I'm a poor boy! Looks like I may buy one soon. The .308 is a 20" barrel with 11.25/1. The .223 Is a 16" barrel with 9/1 . Quote Link to comment Share on other sites More sharing options...
98Z5V Posted August 25, 2015 Report Share Posted August 25, 2015 No. The rifles were sighted in with 150grand 55gr. The ladders were run with 168gr, and 69gr. Like I said, they were .308 and .223. It just seems really backwards.5.56 shiit here, and I've got tons of experience with those...1:9" twist is great for 55gr. 1:9" twist does okay up to about 62gr. The max a 1:9" twist can handle is 68/69gr, and it's just above it's capabilitiles for precision shooting. Will it get it done? Yeah, it can, but it comes down to the barrel manufacturer that that point. Most times, not optimal, though. You hit that peak shooting 69gr in your 1:9" barrel, that was sighted with 55gr ammo... That's what got you, with your recent tests.I have 3 stainless match barrels for 5.56 guns that are .223 Wylde chamber, 1:8" twist. one 16", one 18", and one 20". Those bastards are WICKED with 68/69gr match projectiles. Fucking ridiculous. They won't outshoot the 20" YHM steel-barreled 1:7" heavy barrel gun with 75/77gr ammo though, for distance. That thing is a freak with 75s and 77s. Total freak, all the way to 800 yards - yes Ed, you just read that... Pull that shiit with a 5.56 gun, stud. The Hornady 75 BTHPs are slightly more accurate over the Sierra 77gr OTM/BTHPs through that gun.The 18" Wylde chamber 1:8" twist is the best overall performer, though. That rifle eats anything, with ridiculous accuracy. I've got 55gr Hornady FMJ-BT loads that hit just as well as the 75gr Hornady BTHP loads do, at 100 and 200. Fucking stupid accurate rifle - but it's all about the barrel.For you, pokey, it's all about the barrel - and twist rate. Quote Link to comment Share on other sites More sharing options...
ChaseFan9 Posted August 25, 2015 Report Share Posted August 25, 2015 You can't overstabilize a heavy round. You can come in under, though, on a heavy round, and not stabilize it. Slow-twist barrel.You can overstabilize a light round, and it'll fragment long before it reaches any target. Shoot a 5.56 36-grain Barnes Varmint Grenade through a 20" 1:7" twist barrel...My bad, had it backwards. I gotta stop posting schit before work.... Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted August 25, 2015 Report Share Posted August 25, 2015 Need to stick to two or less variables.Let's see what I can find. Quote Link to comment Share on other sites More sharing options...
MikedaddyH Posted August 25, 2015 Report Share Posted August 25, 2015 Couple charts... The Ballistic kind. Quote Link to comment Share on other sites More sharing options...
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