Question about reloads tested .223

[Tubs]

I'm shooting a Tikka T3 lite with 20" barrel and 1 in 12 twist ,my reloads are 50grn V max with 22.2grn of powder N 130 ,and 52grn Amax with 21.8grn of the same powder both group fairly well at 100mtrs once barrel is fould say 5 shots.My question is why would the heavier bullet group higher at this range when it uses less powder and a heavier bullet.

[MrCetrizine]

A heavier bullet has to overcome more inertia which creates a higher initial pressure and thus a higher muzzle velocity. Coupled with a slightly less filled case which also increases initial pressure.

 

This is a guess based on a slightly above amateur knowledge of physics and a well below expert knowledge of reloading.

[onehole]

Even bullets of similar weight can group in slightly different places ,,,,they could equally have grouped differently to the left or right just as easily. Another reason may also be that the slower bullet is exiting the muzzle slower and the rifle has more time to recoil thus sending the heavy bullet slightly higher on target,,,bit of a long shot but you would see this more likely with a bigger weight difference..Shouldn,t scratch your head too much over this one,,,,regds,,,,O

[bully]

Maybe it leaves the barrel at different times of the barrel whip.

[247sniper]

Revise barrel harmonics. There will be your answer.

 

Steve

[gbal]

As above professors.

Barrels are vibrating,different bullets move at different speeds within the barrel,so exit muzzle at different times/with muzzle in slightly differnt places in it's period of vibration.Not a big deal-if consistent load used.

 

Steve gives the homework reference..

 

Have a look too at barrel/muzzle tuners used by competition 22 rf shooters,to optimise bullet exit (and yes,there was a cf system-Browning/Winchester Boss,but it never caught on,probably not needed,once a consistently load is used.)

 

gbal

[Tubs]

Ok thanks for the replies that makes more sense now about barrel harmonics and loads, both loads group 5shots @100mtrs inside a 5p most of the time as long as I do my part.

[gbal]

Ok thanks for the replies that makes more sense now about barrel harmonics and loads, both loads group 5shots @100mtrs inside a 5p most of the time as long as I do my part.

You're pickin' up good vibrations.....gotta keep those good vibrations a-happening........(Beach Boys Pet Sounds go Ballistic, 1966)

 

g

[VarmLR]

Sounds like you've found some accurate groups with those loadings. They sound very conservative though...almost at the bottom of the load ladder. Nothing wrong with that as long as you're getting proper obturation but I've found that V-max accuracy improved with increased velocity in my rifle.

 

The Lee reloading manual shows a starting load with N130 of 22.1 grains for a 50gr jacketed bullet, very close to your load. If you haven't tried a few loads half-way up the recommended range or between half and 3/4 way, it might be worth it depending on what ranges your intend to shoot at (with the usual caveat to work up in sensible increments). The 50gr is a relatively lightweight bullet with a low BC and more easily affected by wind than say the 60gr version, so driving them out a little bit quicker helps a little at 200 yds, and even at 100 yds depending on conditions.

[Chanonry]

You're pickin' up good vibrations.....gotta keep those good vibrations a-happening........(Beach Boys Pet Sounds go Ballistic, 1966)

 

g

 

 

the nights are in and the whiskey is oot....

[Tubs]

Varmlr i have tried the 50grn V max up to 22.6grn of powder as the Hornady manual states max load of 22.9grn but for me they never grouped as well in my gun, from 109yard zero to 200yards i dial up 5 clicks and its bang on for height they have a MV of 3127fps but could be more if maybe i had a longer barrel and the A max are just for 100mtr paper targets,But you are spot on with the wind factor. Thanks again for the help and replies.

[gbal]

Tubs: SAAMI spec comparisons,commercial ammo,drop/drift inches at 100 ,200 and 300y ; 400y; 200 zero,10 mph:

 

Black Hills 50 V Max BC .242 @3300 +1.3/1.1 ; 0/4.7 ; -6.8/11.4 ; -21.1/21.9

 

Black Hills 60 V Max BC .260 @3100 +1.6/1.1; 0/4.6 ; -7.7/10.9; 23.5/20.8

 

not a lot in it- bc balances mv pretty much.

 

Umax 50 Nosler BT BC.238 @3100 +1.6/1.2; 0/5.2; -8.1/12.6; -25/24.4.......this shows the velocity efffect,compared to the very similar BH BC .242 Vmax BC @3300 (above)

 

Umax 60 Nosler Partition BC .228@ 3100 +1.7/1.3: 0/5.5 ; -8.3/13.3; -25.6/25.8 .......shows the BC effect compared to the BH

60 VMax BC .260 @ 3100 (above)

 

again,not a lot in it, until both BC and MV start to have increasing noticeable effects with after about 350y

 

Of course,with those drift effects 400y is pretty much out of reach for 2moa targets (wind error reading of 20% - 2mph-is a 5 inch miss on it's own....let alone group etc).

 

gbal

[VarmLR]

Varmlr i have tried the 50grn V max up to 22.6grn of powder as the Hornady manual states max load of 22.9grn but for me they never grouped as well in my gun, from 109yard zero to 200yards i dial up 5 clicks and its bang on for height they have a MV of 3127fps but could be more if maybe i had a longer barrel and the A max are just for 100mtr paper targets,But you are spot on with the wind factor. Thanks again for the help and replies.

 

If it groups well, and you don't need the distance, then it sounds like you've found some good loads. Have you had a play with seating depths yet?

[gbal]

Tubs, take Varm's advice to heart and head.

Given that velocities are in the general accepted range for the cartridge/bullet weight (and this effectively means in the range given in the loading manuals-perhaps nearer max than min-but balance accuracy) and are giving acceptable accuracy for purpose (remembering more velocity does NOT equate to more accuracy) then yu might well be done testing,and can start shooting! (seating depth might well squeeze a little more precision).

I gave the drop/drif data for two very comparable BC bullets in the low 50+ g range...have a close lookk....200 fps more reduces d/d about an inch at 300y.....click....it may/not be more accurate.

The obsession with max velocity is usually correlated with ballistic optimism with very little corresponding accuracy data (and I put that a little kindly)....for ultimate LR (1000y+ shooters ) even 50 fps might offer an advantage...so they check it out-their problem is how to assess precision with a wind blowing bullets about so variably.For short range,accuracy wins hands down (given,as said,velocities in the cartridge envelope- and the evidence is pretty clear. It's basically,the laws of physics :-)

Just enjoy decent performance... if the bullets are going through the same hole,does it matter how fast?

gbal