Would lengthening a loads oal effect bullets horizontal impact?

[cath8r]

Wondering if anyone has noticed this. Lots of fellas with alot more years doing this than me. Would love to hear a response from someone who knows. Thanks Rob

 

[Cleftwynd]

If it is enough to change the internal volume it could possibly reduce pressures and velocity.


PS: I know your user name is supped to be cat hater, but can't help reading it as catheter. Lol

 

[Juster]

It will change pressure if there is more space behind the bullet, and therefore affect velocity and the vibration of the barrel, which could affect horizontal impact.

 

[jamesharrison]

If you mean vertical (up & down), then yes. Essentially because you are changing the combustion chamber, which affects the pressure your load is generating..

If you mean horizontal, it shouldn't. That's the wind.

 

[cath8r]

Thanks. I bumped out an oal of a load I've been working on. I think group size shrunk but I need to get a chance to shoot on a day that isn't so breezy. I felt the amount of drift was more than the wind would account for. Need to load up some more and try shooting in a calm spell.

 

[stubblejumper]

Anytime you change the load, it can change the harmonics, which can cause the point of impact to move vertically or horizontally, or both.

 

[Juster]

If you mean vertical (up & down), then yes. Essentially because you are changing the combustion chamber, which affects the pressure your load is generating..

If you mean horizontal, it shouldn't. That's the wind.

Not entirely.

Anytime you change the load, it can change the harmonics, which can cause the point of impact to mover vertically or horizontally, or both.

Yes indeed.

 

[rral22]

Changing the COL may well change the load's POI due to a variety of variables that will have changed, but there is no way to predict what that change will be. You can only shoot it and see what happens.

 

[cath8r]

Thanks guys. Loaded up 5 more and waiting for a calm day to test at 300 yards. I worked up a load gor my .22-250 with 55 gr vmax at 2.355 oal. I was thinking I would add the length of the plastic tip to the oal, since it still git in mag and didn't touch rifling. So, plastic tip was .140". 2.355"+.140" =2.495. I chickened out and went 2.460" oal and feel group size may have shrunk a bit when I shot it at 200 to start. Went an even 1". Going to see how it does at 300 when calm.

 

[dero338]

Did it on 2 300WM. Throted 0,100" deeper and load 200 accubound at 0,050 from riflings. In a 28" benchmark 5R, got 5 grains more capacity and the go average 3035 fps at the more acurate load. [ H1000 ]
Yet, never needed a second shot with this bullets

 

[BCRider]

In addition to changing the case volume and thus the pressure altering the OAL also changes how close to the rifling the bullet rests when chambered. And by all accounts having the bullet seated so it is extremely close to or even is lightly pressed into the beginning of the rifling aids the accuracy. So if you're getting better groups then this may be why.

But if you're going to do this keep in mind that due to slight variations in chambering shapes between rifles even of the same caliber that rounds set up for one rifle may not work as well in the other rifle.

Another technique that is found commonly but only used for loading singles is to deliberately not crimp the bullet and rely only on neck tension to retain it. And not even that strong a neck tension either. And with the bullet seated long the idea is that when you chamber and close the bolt on the round that you seat the bullet at closing so it's resting on the leade of the rifling for the very optimum fit.

But such rounds don't have the neck tension needed to safely be used in a magazine where recoil from firing can cause the bullet to seat more deeply while in the magazine and end up too short when fed into the chamber. This "loose neck fit" trick is only for single loading.