mysteries of 22lr--part2

[tangolima]

I finally got some Norma tac-22 to try. Without retuning my poor man's barrel tuner (shaft collar) it shot similar to, could be a bit better than, Aguilar super extra HV. It will probably do much better if I retune.

I had to crank up the elevation to compensate for the slower MV, about 8moa extra at 150yd. The longer TOF may be a good time to have. It extends the equivalent center fired distance for my training purposes.

-TL

Sent from my SM-N960U using Tapatalk

 

[Unclenick]

The drop of a standard velocity (1070 fps) bullet at 80, 125, and 265 yards is within an inch or so of the drop of the Sierra 0.224" 77-grain MatchKing at 200, 300, and 600 yards from my 20" AR match rifle, though the wind deflection is about 150% of what the MK sees. But good training is scaling the standard service rifle targets down by 60%, setting them at those ranges, putting your .22 LR training adapter in the rifle, and practicing your positions, wind reading, and trigger control, and remembering your come-ups.

 

[FrankenMauser]

Interesting.
With Blazer 40 gr RN / CCI Mini-Mag 40 gr RN, I am only down ~4 MoA, or so, under CCI Standard Velocity (1,073 fps) at 150 yd -- 11.xx vs 15.00 MoA.
(Blazer advertised at 1,235 fps, but I have not been able to get a full string to read across a chronograph yet, from any of our match rifles.)

 

[Unclenick]

When the bullet starts out at just above Mach 1, it is in a disproportionately high drag circumstance, so the velocity advantage is quickly dragged down to standard velocity behavior. It has the effect of being a standard velocity bullet fired at a bit shorter range.

 

[tangolima]

4-5moa more sounds right. Initially I put in 6moa, observing the new round's tendency to hit low. It actually still hit several inches low, so I jacked it up to 8moa and held a little low to hit. Probably 7 - 7.5moa for real.

They are different bullets. HV is 38gr copper plated hollow point. Subsonic is 40gr solid lead round nose. BC could be different.

Unclenick. I'm rather surprised to learn the difference in drop is within an inch even out 600yd. The MV is more than double so the drop would be more than 4x. I can't wrap my head around this one.

Training here is mostly for ability to read wind. Using TOF equivalent, the HV is about 400yd with center fired. The subsonic probably extends it to 500 - 600yd.

I probably will revisit Aguilar subsonic with barrel tuner. It may be close enough. It costs less.

-TL

Sent from my SM-N960U using Tapatalk

 

[stagpanther]

When the bullet starts out at just above Mach 1, it is in a disproportionately high drag circumstance, so the velocity advantage is quickly dragged down to standard velocity behavior. It has the effect of being a standard velocity bullet fired at a bit shorter range.

There's a nuance there that while (maybe?) implied is not directly mentioned. That is (IMO) that the relatively inefficient ballistic characteristics of the better 22 RN bullets going 1050 to 1,150 fps +/- will sort itself out or avoid altogether the destabilizing effects of transonic transition at or near the muzzle. It's a game of seeing just how fast the bullet can be launched without getting degraded by transonic transition. The other game is trying to find a super that can somehow make that transition and remain as consistent as the subsonics, I know people keep saying it has been done but I haven't experienced it yet.

 

[Unclenick]

Since the speed of sound goes up with temperature, just go out on a 91°F day, and it will be 1150 fps!

 

[stagpanther]

Since the speed of sound goes up with temperature, just go out on a 91°F day, and it will be 1150 fps!

That's almost exactly what RWS R-100 gets. I think by using the long barrel on my CZ jaguar it slows the bullet down a bit by the time it exits the muzzle

 

[FrankenMauser]

One of my rifles launches CCI Std at an average of 1,104 fps. During the winter, they're supers. During the summer, they're subs.

I missed most of the deep freeze matches this year, but did note in April that many shooters with 22" and 24" barrels were objecting loudly to "random" flyers during sight-in and the first couple stages of the day. Tenex, Midas+, and CCI Std were the most represented types of ammo. Shooting started with the temperature at about 20 F (with ammo coming from warm vehicles), and the match ended at about 42 F (with ammo having had time to cool).

Gotta keep an eye on that moving trans-sonic zone, sometimes.

When the bullet starts out at just above Mach 1, it is in a disproportionately high drag circumstance, so the velocity advantage is quickly dragged down to standard velocity behavior. It has the effect of being a standard velocity bullet fired at a bit shorter range.

Indeed.
But it is still a big enough difference to keep 375 yards within the limits of the scope's adjustment, rather than dialing just shy of max* and then using a bottom-of-reticle hold.

*I never dial to max. I hate having sensitive devices sitting on a stop - or simply jammed at max travel, with no actual stop.

 

[stagpanther]

But it is still a big enough difference to keep 375 yards within the limits of the scope's adjustment, rather than dialing just shy of max* and then using a bottom-of-reticle hold.

*I never dial to max. I hate having sensitive devices sitting on a stop - or simply jammed at max travel, with no actual stop.

Even with 100MOA in elevation in the scope sitting on a 15 MOA rail I have to dial up to near max at 350+ yds if I still want some down elevation for closer shots. That difference in velocity of +/- 50 to 100 fps at even just 350 yds can make a dramatic impact on bullet drop in my experience.

 

[tangolima]

Even with 100MOA in elevation in the scope sitting on a 15 MOA rail I have to dial up to near max at 350+ yds if I still want some down elevation for closer shots. That difference in velocity of +/- 50 to 100 fps at even just 350 yds can make a dramatic impact on bullet drop in my experience.

I believe that. Out of the 100moa adjustment range, only half of it is useful, so you actually have 65moa for up elevation. The TOF for 350yd is over 1 second, probably 1.5s ish. The downward speed of the bullet is pretty high. The 15moa extra from the rail probably buys you 25yd more.

Scope manufacturers should recenter their designs to put more adjustment range on the top side. More body needs to adjust below the axis.

Having said that, nothing wrong with holding over. With good reticle, it is even more preferable to dialing it in.

-TL

Sent from my SM-N960U using Tapatalk

 

[FrankenMauser]

The 'problem' rifle for us sees a difference of about 12 MoA.
That is, obviously, not a huge difference. But it is enough for my son to be able to dial and hold, rather than using a holdover where there are no references in the reticle.

Though, he should be able to dial right to a dead-hold.
I should double check that base. I am wondering if we got a 20 MoA base by mistake. The other 10/22s have 30 MoA bases and about that much more elevation available.

 

[tangolima]

With plain cross hairs, holding over is hard (still doable if you try hard enough). Even with simple duplex reticle, it becomes practical. Now I have to have at least mildot of moa hatch in any new scope I will buy. Christmas tree is great, but it is a bit too busy.

-TL

Sent from my SM-N960U using Tapatalk

 

[tangolima]

Tried Aguilar subsonic today. It is not as good as tac-22. Hit rate drops by half. It drops less though, probably it has slightly higher speed. TAC-22 then. 2-3 cents more per round. Doesn't sound a lot, does it? It is 30-40% up. But it doubles the hits. I got some of my money back, I suppose.

I still have some Aguilar HV to burn through. I will wait.

-TL

Sent from my SM-N960U using Tapatalk

 

[stagpanther]

Tried Aguilar subsonic today. It is not as good as tac-22. Hit rate drops by half. It drops less though, probably it has slightly higher speed. TAC-22 then. 2-3 cents more per round. Doesn't sound a lot, does it? It is 30-40% up. But it doubles the hits. I got some of my money back, I suppose.

You could recover the difference by recycling your can targets.