Eley Subsonic Ammo Testing

A simple day of sight in turned into some ammo testing we weren’t really expecting.  Brad brought over his threaded CZ 455 to tighten up before his suppressor arrives for squirrel season.  The last time we shot this rifle the groups opened up and we couldn’t understand why.  Our goal was to tweak this 455 until we could achieve some consistency.  It had recently been pillar and glass bedded to free float the barrel.  Barrel is threaded and length is 20 inches.  Our testing would be at 50 yards, which is typical sight in for our squirrel rifles.  With some information from the great folks over at www.rimfirecentral.com we re-torqued the barrel screws in at 30 inch pounds, and both action screws were torqued at 24 inch pounds.  This actually was the combination we would end up sticking with.  Gotta love it when you can get it right on the first go.

Little back story here, I’ve had a chronograph for around 6 years and I’ve never used it.  It was vital in our sight in process.  I’d always been told when testing loads you build for centerfire rifles that a chronograph is key and I found that out this weekend.

08-03-14 CZ 455

I’ve done so much shooting without the chrono that for the first two, 5 shot groups I was so focused on the grouping that I completely forgot about the chrono.  The third group I fired was the group that would start our “experiment”.  When I started firing the third group I was making sure I had constant technique:  Center the crosshairs on the target, take a deep breath in, (crosshairs would move down on the target) as I released the breath the crosshairs would settle back the the center of the target.  From here I would stop the breath and start the trigger press.  The trigger on this rifle is set around 1.5 pounds.

Eley SS HP 2

Here is the break down of feet per second for the 5 shots:

1.  1041

2.  1043

3.  1041

4.  1043


08-03-14 CZ 455 chrono

This last shot had a huge impact difference on target, as is should, it was on average 125 feet per second slower.  At first I thought it could have been me, and the shooter is most likely the weakest link in the shooting process.  There are plenty of other variables to account for though, ammo, temperature, equipment and so on.  Ammo was the problem here and without the chrono we would have been left guessing.  It’s a great piece of equipment to utilize if you have access to one.  This is also one of the shots that would have you scratching your head in the squirrel woods.  When all is right with the shot and you miss like this!

08-03-14 CZ 455 Flyer group

So from here Brad and I decided we would weigh out the rest of the ammo on a digital scale, in grains.  Now the variance in weight could be the actual bullet, brass, or powder charge.  We felt though that we could find a consistent weight and shoot for a group.  Let’s examine some groups with chrono results.

The most consistent weight for Eley Subsonic Hollow Point 40 grain was 51.5 grains for the total cartridge.

08-03-14 CZ 455 Eley weigh process

51.5 grain 7 shot group chrono results

1.  1039

2.  1021

3.  1069

4.  1057

5.  1060

6.  1069

7.  1055

Average was 1053 fps.  Technique was good and group was fantastic.  Every shot here brings a squirrel out of the tree!

08-03-14 CZ 455 51.5gr 7 shot goup

I did fire one other group before the rain set in.  I have the chrono numbers but no photo.  The results were interesting as the weight was lower at 51.2 grains, but the average feet per second was higher at 1058.

1.  1061

2.  1065

3.  1053

4.  1066

5.  1068

6.  1036

I’d say in conclusion that weighing rounds out doesn’t necessarily guarantee that you won’t have a flyer of some sort, but I think you could possibly weed one out that could result in a miss.  I still would love to have known what the 917 fps round weighed, but it’s too late for that.  I do think that by weighing ammo out that you can find your most consistent weight for the particular ammo you are sighting in for.  I’m certainly gonna look much closer at this before squirrel season starts.  I really don’t like missing, and when I do I want to know why.  Hope you found this information useful, and it is by no means meant to be scientific, just a fun and interesting test.

[phpzon keywords=”Shooting Chrony” num=”3″ country=”US” trackingid=”squihuntjour-20″ templatename=”columns” columns=”3″ paging=”true”]

(Visited 10,826 times, 1 visits today)

9 thoughts on “Eley Subsonic Ammo Testing

    1. Yes my zero is 50 yards with optics that are above 10 power. Any scope 9 power and under I sight in at 35 yards. If I have 50 yard zero then my 35/25 yard shots are 1/2″ high. My 15 yard shots are generally low, maybe 3/4″ to 1″ and are due to how high the scope is above the center of the bore. I have a couple of videos on the subject, so if my description isn’t clear enough the videos may help! https://squirrelhuntingjournal.com/sighting-squirrel-rifle/

  1. FWIW, I have found that segregating rimfire ammo by measuring the rim thickness produces more consistent groups than segregating them by weight alone and, better yet, if segregated by rim thickness and then sorting those groups again by weight. This process is time consuming, but it does improve the potential for shooting smaller groups with lower grade ammo. I don’t think that it is worth spending time to sort higher grade ammo, Eley/RWS/SK, except for shooting formal matches.

  2. good read nate. looks like again the sweet spot is that magical 1050 fps. 1070-1040 is the “zone” you wanna be in. i just did some testing today myself on my new 452 16″ threaded american both w/ and w/o suppressor. to my absolute joy adding the suppressor did absolutely nothing in relative terms to poi change. like you and everybody else said that the suppressor would “tighten things up a bit” was so true. as soon as i have time i’m gonna post up the pics over in the cz subforum at rimfirecentral for the folks to critique.
    keep at the testing and posting up nate,

    1. I bet a great many have. I usually blame myself as the weak link, but the ole chrono called my flyer this time. Gives me some confidence back, and helps educate me to be able to call my shots.

Leave a Reply

Your email address will not be published. Required fields are marked *