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Old March 13, 2012, 09:26 AM   #1
Wyoredman
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Is my chronograph wrong?

I just finished chronographing some .223 loads and the results are dissapointing. I used 25.3 gr H335 under a 55 gr Hornady SP with a CCI 400 primer. Hodgdon's manual said that the load produces 3203 fps.

Well, I didn't even come close to that velocity! The five shot average was 2875 fps, with and ES of 71 and an SD of 27!

I use a Lyman beam scale and weighed each powder charge.

My rifle is a Ruger SR556E with a 16.12", 1:9 twist barrel. I was expecting a bit slower speeds than the manual, but not 300 fps? What is going on here?
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Old March 13, 2012, 09:38 AM   #2
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You didn't use the same gun and barrel as was used for the manual.
Or on the same day, with the same temperature and humidity, or the same chrony.
Manuals are guides, not absolutes.
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Old March 13, 2012, 09:38 AM   #3
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What was the configuration of the gun used by Hodgdon to test the load data?
Longer barrel?
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Old March 13, 2012, 09:42 AM   #4
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Yeah they used a longer (20") barrel, but would those 4" make a 300fps differance? I am used to seeing around 100 fps slower speeds than the manuals, but this has me confused?

This is the max load listed in the manual for H335 and 55 gr SP bullets. Iwas hopeing to find a velocity neer the 3250 that my Nikon scope is calibrated for? Doesn't look like its' gonna happen if you guys think the chronograph is correct!
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Old March 13, 2012, 09:53 AM   #5
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Wouldn't it be easier to adjust the scope instead of pursuing the elusive extra 300 f/s?
Assuming, of course, that the scope is accurately calibrated for the higher velocity, in the first place.
Might be a silly question, but have you checked the point of impact against the scope settings, at the distances you need?
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Old March 13, 2012, 10:10 AM   #6
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Gadgets??? Begining to think they aren't what they are cracked up to be.

I have only checked the scope out to 100 yrds. Impact seems ok at that distance. The NIKON 223 scope has a Bullet Drop Copensation (BDC) reticle that is manufactured for standard 55gr factory loads at 3250 fps. That being said, I will adjust the scope, but I still wonder about the velocity differance.

With the 25.3 gr of H335, I am not seeing any pressure signs, would it be safe to work up a bit hotter loads knowing that my velocities are well off the book test barrel velocities? I would at least like to get to 3000fps.
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Old March 13, 2012, 10:19 AM   #7
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Quote:
five shot average was 2875 fps, with and ES of 71 and an SD of 27!
That tells me you have ignition problems.
Step up to a CCI-450 mag primer or even a CCI-41 (hotter still)

Second, I believe the Hodgdon Data web page (in print format) indicates 3,203fps from a 24" barrel. Figure ~25/30fps * 8" = 200/240fps slower.

You're not too far off from what I might expect from a carbine-length barrel.

Last edited by mehavey; March 13, 2012 at 10:27 AM.
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Old March 13, 2012, 10:19 AM   #8
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See if Nikon has the data available for the setup you're shooting. They may have computed it but not put it in the manual.
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Old March 13, 2012, 10:22 AM   #9
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You got answers for what might be going on. Your first question"Is my chron...wrong?" can be answered by shooting a known load/rifle into your set up and compare. Or shoot your load/rifle into another chrono for comparision.Best
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Old March 13, 2012, 10:30 AM   #10
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Thanks, fellas. Helps a ton. Back to the drawing board.
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Old March 13, 2012, 10:35 AM   #11
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Mehavey, What Extreme Spread and Standard Deviation should I be looking for as acceptable?
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Old March 13, 2012, 10:36 AM   #12
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Hodgdon 2011 manual data showed they used a 24" long barrel 1/12 twist barrel using Speer bullet and Win primer.

You lose almost 8" of barrel 300fps loss is very possible. I'm surprised you didn't see the difference working up the load over a chronograph?

I'm shooting a 223 with 24" long Kreiger 1/14 twist barrel and Hodgdon has a max load for 50gr bullets 26gr/H-335 @ 3393fps and I'm at 25.5gr/H-335 @3391fps.
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Old March 13, 2012, 10:53 AM   #13
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Roper, I did see the differance, but it got worse the closer I got to the max (25.3).

I did missread the test barrel length, I was seeing 20" not 24". Oops! Thanks for the heads up.

That does make me feel a bit better, but I am still over 300 fps slow at 25.3 gr. The SD for all loads was higher than 20. Lowest ES was 51 with a 23.6 gr load (SD 23) and velocity at 2783 fps.

I have a DPMS with a 20" barrel, I'm gonna chrony these same loads through that gun. See what happens. It appears that barrel lenght is the culprit, not my chronograph. Thanks guys.
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Old March 13, 2012, 11:03 AM   #14
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Quote:
What ES and SD should I be looking for as acceptable?
I like ES's in the 30's to very low 40s, and SD's in the 12-16 range as practical out of an AR.

I think a mag/milititary primer will go a long ways for you w/ that ball/spherical powder
(and you might also pick up another 50fps in the bargain)
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Old March 13, 2012, 11:14 AM   #15
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The Hodgdon data also uses Winchester cases and Winchester SR primers. If you use anything else you can get some serious differences. In early 2006 Charles Petty ran some .223 experiments with different primers lighting Reloader 10X under 55 gain Hornady V-max bullets. IIRC, he got 150 fps difference in MV for the same load using different primers, with Remington 7½ BR primers producing the most velocity and pressure and also the best 100 yard accuracy, but the worst velocity SD.

CCI altered their magnum primers to optimize them for spherical propellants in 1989. Some of the newer spherical propellants from Alliant and Ramshot are easier to light up and don't need special treatment, but when you're using the older sphericals like WC844 (H335), you'd do well to use those warmer primers. I've also had terrific consistency from the KVB556M small rifle magnum primers sold by TulAmmo and Wolf.

What SD you should expect depends on a number of factors, but if you seat your primers really well (err on the hard side) you can often get down to 10 fps, but there are a lot of factors involved. If the loads are accurate despite higher MV variation then you probably won't need to worry about it until you start to shoot beyond about 300 yards, where vertical stringing from the difference in velocity can start to tell.
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Last edited by Unclenick; March 14, 2012 at 01:10 PM. Reason: typo fix
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Old March 13, 2012, 11:50 AM   #16
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Much good info. Taking notes. The .223 /AR combo is a learning experience, to say the least.
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Old March 13, 2012, 07:40 PM   #17
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I have two chronographs and have never really achieved the velocities listed in manuals or by others posting on the internet. The last load I tested in a Remington 700 300 RUM was 100 FPS slower that the stated velocity on the box ( factory loaded Remington rounds ). I think all my guns have have slow barrels.
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Old March 13, 2012, 08:54 PM   #18
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Wyoredman,

During my years with a chronogaph, I have noticed three things,

First, almost all rifles are slower then the published date.

Second, there is a much smaller group that will about equal published velocities.

And third, there is very small group that will exceed published data.

Once you get over the shock, then you can enjoy watching your friend's face when he shoots his super velocity wize banger over your screens and finds his dream gun is 2 - 300 fps off the expected pace. Odds are it will happen just that way. Welcome to reality.

You will also see such things as a light load shooting faster then a load 1 or 2 grains heavier. Yep, saw it with my 45/70 summer before last, all loads being well within safe loading guide lines. Checked in on the forum and what do you know it is not the first time this has happened.

You will see loads during a test series, suddenly begin to show wide swings in Velocity even before you have reached max published load figures. Yep, it could happen and when it does it is time to back off with that powder no matter what the book says!

Enjoy that chronograph, they are great learning tools.

Keep em coming!

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Old March 13, 2012, 10:11 PM   #19
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Thanks ya' Ol' Coot! I plan on doing just as you suggest!
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Old March 13, 2012, 10:39 PM   #20
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If you would like to regain some of your lost velocity, you could drop down to a 50 gr. bullet. i know it wont gain you the 300 fps that you would like, but it would gain you some. The 50 gr bullets can be had in a boat tail too. It might be worth a try if you arent married to the 55s.
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Old March 14, 2012, 01:17 PM   #21
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I general, velocities published by ammunition manufacturers are fired in velocity and pressure test barrels. These are chambered with minimum chambers and a specified bore cross-sectional area and have a length that is within 0.010" of the specified bore length, which is most often (though not always) 24". If you don't have a 24" barrel, a tight chamber, or your bore is different in dimensions or length, you won't get a matching velocity.
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Old March 14, 2012, 01:26 PM   #22
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Wyoreman,

With the number of posts you have, I suspect you already know the following. BUT, Don't let that stop me!

There can be a fairly wide swing in velocities when changing from one powder lot to another.

For example, back a few publications of the Speer manual. they listed a velocity in the 300 Winchester Mag. that would be every velocity hounds dream.

Good luck gett'in there! The published velocity was so high, I'd guess there weren't many or even any of rifles that fall into that small group of, "fast" rifles that got there.

Of course, their test rifle/barrel was part of the picture, but very likely the lot of powder they were using played a large part.

I have seen velocities drop by 100fps or more just with the change from lot of powder to the next, and I suspect it goes the other way also.

The question comes up from time to time about the need for a chrongraph, and I'd agree they are not really needed for most of us. I reloaded for years before I had my first one.

However, I sure like having one, and almost all my rifle test loads are fired over the screens at the same time I am targeting them. I really like the additional info supplied.

Then back to my earlier post about the wide swings in velocity that sometimes happens during load development.

In the cases I recall, there were no other signs that my combination of rifle/powder/bullets etc. was not setting well at that charge level. Without the info supplied by the velocity readings, I would have not know it was time to back off and try another powder.

Do I need the chronograph? Maybe not but it will remain part of my program as long as possible.

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Old March 14, 2012, 02:06 PM   #23
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'Ol' Coot,

I purchased my reloading equipment, used, 15 years ago. I read many books, taught myself the basics and I have been reloading ever since. But not until the last year have I been trying to teach myself to HANDLOAD! This forum has had alot to do with it.

I have been upgradeing tools and buying new powders and bullets, building load work ups and the like. My new chronograph is the latest in this quest to really teach myself about firearms and ammunition.

It really opened my eyes when I shot these .223s over the screens! I have been just assuming that the velocity was close to that listed in the load books! HELLO REALITY!

This forum has pointed me in different (correct) directions many times, and for that I thank everyone!

As for my original question, I am building some new test .223 test loads with H335, but this time I seated CCI450 primers. We'll give it a shot this weekend over the chrony.

My education continues.
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Old March 14, 2012, 02:15 PM   #24
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I always look at the reloading manual velocity as 'guideline'... Not what I am going to get over the chrono. Same with what you find in magazine articles. I shoot mostly revolvers and cylinder gap, bullet, primer, barrel length, temperature, etc. all play into what your velocity is really going to be. And in actuality, 'accuracy' in 'your' gun is more important than a few fps.... If going 3000fps puts them on a 12" circle at 200yards and 2900fps puts them all on a 4" circle and 2800fps on a 2" circle ... what would you use? . That is what is called working up a load.... Not to see how fast you can go... but to see how accurate a load can be (within the min and max load data of course)!

[added] Note this only hypothetical, the groups could be decreasing as you go up in velocity or act like a bellows opening and closing...... Having fun yet?
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Old March 14, 2012, 04:00 PM   #25
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rclark,

I'd say you are 100% correct in that small groups trump high velocities.

However, I have read some posts where the poster said that they found the best groups to be at load levels below the max listed.

Not doubting their word, as I wasn't there. However, for me that has not been the rule.

Not all of the time of course, but it seems most often that my best groups show up, at or near the max published loading.

I have however, seen during a test series where the groups grew progressively smaller and then suddenly reversed and began to increase in size.

Guess that is what handloading is all about when compaired to just reloading.

Sounds to me like Wyoreman is getting a handle on it for sure!

Keep em coming!

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