Semi auto ammo check.

Cass · 09-10-2019 2:24pm #1

So i spent last Sunday on the range with pm. and got the chance to re-zero some rifles and test some ammo.

The semi auto was my focus because i have so many different types and brands of ammo. Its a 1:9 twist and unlike Tikka and other rifles with the same twist rate that are not fussy, it is so it can be hard to get a consistent supply of the same brand and type..

I have:

Hornady 60gr TAP
Federal Fusion 64gr
TulAmmo 62gr
American Eagle 50gr
American Eagle 55gr

I also have, but never got to try:

Remington 55gr fmj
Unknown 50-55gr fmj & HP
Hornady 53gr V-max
Hornady 5grgr V-max
Remington 55gr HP

I checked the zero at 50 yards, because i use it often for comps, and most all the ammo hit centre So no problems. I then moved to 100 yards.

I started with TulAmmo (its what i use most, plus i want to finish off the last few hundred rounds i have of it). It was almost spot on at 100. So little difference as to not warrant a change in scope adjustment.

Then onto the rest of the stuff i tried. Now i had wind drift, which i ignored as there was a healthy 18 - 22 mph wind going from 9 to 7 o'clock and gusting. Might have caused a marginal amount of elevation issues, but again i'm focused on average grouping and was only using a bipod, with no back bag (have to shoot as i would in the field or in the comp).

The rest of the ammo i tried all had a surprising effect. All of it was between 1.5 to 2" higher than the Tul. I thought with my 5 yard zero it'd be lower, but then something caught my eye during a ceasefire. My TulAmmo casings were at my 4 o'clock. The perfect ejection. All the rest was at my 2 o'clock. I changed my stock and recoil spring some time back and the 2 o'clock brass placement wasn't a surprise, the fact the Tulammo was different to the others were.

I can only put it down to the propellant and speed of the Tulammo being noticeably different to the rest of the ammo. The propellant from the point of view of pressure, hence ejection of the casings, and speeds from the point of view of POI on the target compared to the rest of the ammo.

I recorded all POI and the necessary clicks required for each so i'm happy i have what i need ubt has anyone else experienced this? Has anyone ever chrono'd the various ammo and gotten hard data to compare?

cookimonster · 09-10-2019 5:36pm

Ok so, a bit vague and limited info here, so the only worth is my personal observation of what occurred.

Recently I was present at a range practice. The firearms were all identical, firing same ammo (5.56) and all shooters were in the same shooting postion as each other and all in an open air but sheltered firing line.
I was directly to the rear at about ten paces and centrally positioned. During and directly after the first detail I observed the flight of the ejected brass was not consistent with each firer. Some would eject 3 to 4 o'clock while others ranged between 1 o'clock and 5 o'clock. To me this was interesting as it was a very short range with each firer directly covering off thier target in frount.
At longer ranges fireing positions may not be perpindicular to the target with shooters on the line firing at a slight angle causing the brass to eject at various angles from the ejection way.... or so I had previously assumed! In this case all firers were directly behind targets.
I have witnessed both with semi auto shot guns and centrefire rifles that if the shooter does not properly mount / hold the firearm it can and will result in poor extraction, ejection or reload as the immovable force behind the butt is in fact 'moving'..... would this explain some what as to what I observed were 90%+ factors are the same but the persons behind the guns are just enough variable to cause different results as to brass ejection.

Also the distance the brass flew varied from firer to firer.
......plus dirty gas plug, assemblelies etc will evently change the firearms performance!

Cass · 09-10-2019 6:19pm

First off thanks for the input. Anything you can learn from is never a waste.

Secondly, and its my fault for putting in so much information but a little slim on the salient stuff, is the oddity i'm asking about is the variance in POI.

As i said above i changed my stock some time back. The new stock has a slighter shorter buffer tube and hence shorter/stronger buffer spring. All casings were ejecting at the 4 o'clock mark, but when i changed stocks they went to 2 o'clock with the same ammo. So i'm not surprised by the 2 o'clock ejection path.

The bit that surprised me was that the Tulammo was still ejecting to the 4 o'clock mark. Couple that fact with the POI of the Tul compared to any of my other ammo (all 1.5 - 2" higher with the same zero) and it leads me to believe that perhaps the Tul is slower/much slower than the other stuff and based on ejected cases the propellant is not as "hot" as the rest.

ak51535 · 09-10-2019 6:24pm

Ive been on similar ranges such as cookimonster at work in the same position and a lot of those ejection variations will be dependant on shooting position, and worn ejector springs, or build up of crud and if the gas setting is adverse or not.

But with your experience Cass the only thing I could think of would be the propellant in the Tulammo, also just wondering is Tulammo steel cased?

Cass · 09-10-2019 6:45pm

ak51535 wrote: »

........ also just wondering is Tulammo steel cased?

It is.

Don't get me wrong, this is not a problem, just a curiosity.

If i stick the old stock back on everything goes back to a 4 O'Clock ejection path (done this some months back when i first noticed the change). So i know why my casings are going out at 2.

It's just odd that in all the various types, weights, brands of ammo only the Tul still goes out at 4 when the rest are at 2.

tikkamark · 10-10-2019 12:34am

The steel case Ammo contracts slower than brass so I’d imagine that would change the speed the bolt would fly back on a semi auto thus changing where the empty’s land.
Ive heard the Americans do have some bother with steel case wolf ammo in there Ar15’s.

Cass · 10-10-2019 12:05pm

Interesting.

I had a feeling the Tulammo being different would have have been down to propellant or just being cheap. Never occurred to me that the casing being steel might contribute to the variance. I only ever think of steel case stuff as a "once fire" ammo.

I know from reloading for F-Class that different brands fo casings, different primers, propellants (hell the same brand of propellant just a different batch) can effect performance but at 100 yards i've never seen such a difference as the distance is usually too short to show it.

Grizzly 45 · 10-10-2019 11:49pm

Intresting you bring this up.I use Hornady Steel match in mine, same design ,same company,but in .308 in my case and it consistently ejects at 3 oclock.But with brass casing depending on brand,it can eject at 2 or 4 o clock,[stock notwithstanding] Hornady V MAX goes out at 2 oclock if I remember rightly So it is this a design quirk of the AR platform??

Cass · 11-10-2019 8:43pm

I'm not surprised at the Hornady. They tend to use a "hotter" propellant which creates more pressure and according to articles i've read can produce a change in ejection path. Hornady Superformance, and i've said this before, are one of the only rounds i've found (by chron-ing) are actually understating the speeds they produce.

Most other rounds overstate it.

RS98 · 12-10-2019 12:04am

Cass wrote: »

I'm not surprised at the Hornady. They tend to use a "hotter" propellant which creates more pressure and according to articles i've read can produce a change in ejection path. Hornady Superformance, and i've said this before, are one of the only rounds i've found (by chron-ing) are actually understating the speeds they produce.

Most other rounds overstate it.

Have you chono'd superformance 223 rounds? What do they come out at? I never really believed the 3465 fps they claim.

Is it actually that fast?

Cass · 12-10-2019 12:19am

RS98 wrote: »

Have you chono'd superformance 223 rounds?

Years ago along with 243 and 308 all in Superformance.

What do they come out at? I never really believed the 3465 fps they claim.

The average for the 223 was 3560 fps while the box claimed 3450
The average for the 243 was 3700 fps while the box claimed 3580
The average for the 308 was 3200 fps while the box claimed 3000

Is it actually that fast?

Faster.

The Superformance were the only factory round i've ever seen that were not only faster than the stated speeds, but gave stift bolt lifts which is a sign of overpressure. If i got the same results when reloading i'd back off the charge.

For a shot or two they were always on the ball, but in one of my rifles they would start to climb and go right after the third round. Only in the heavy barrel rifles did they hold close to a group.

All this was done in my bolt action rifles, never the semi auto. I haven't used Superformance in a few years.

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Semi auto ammo check.

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