Home Forums Reloading Big Game Rifles Trusting a chronograph

I just got into hand loading last fall and managed to build a decent inventory before things got out of hand. Took my time studying up and started putting together loads over the winter but didn’t have a chance to get out with them until spring. Spent one day at the range with a .270 and .243 Win and then got busy with spring and summer stuff. Fall’s coming so it’s time to get loading again.

So here’s where I’m at. Before shooting any hand loads I ran a few rounds of factory ammo over my Caldwell chrono just to get some sort of starting reference. Loads were both Hornady American Whitetail, 130gr .270 listed at 3060 fps and 100gr .243 at 2960. Speeds for the .270 were 2973, 2924 and 2918. For the .243 I had 2969, 2869 and 2875. Both rifles are Rem 700’s, the .270 with a 22” barrel and the .243 with a 24” tube. Results were as expected, close to the box numbers but a bit slower.


With the .270 I worked up using H4831sc from 56.0 to 59.5gr in half grain increments wiith Rem cases, CCI 200’s pushing the same 130gr Hornady Interlock. My best group by far was right about an inch with the 59.5gr load at speeds of 3046, 3042, and 3048. Book max I have is 62.0gr @ 3100. This seemed normal to me although it appears I’m getting good velocity numbers compared to the book.


For the .243 I used W760 starting at 37.0gr and worked to 39.0gr in half grain increments as well, in Win cases with CCI200’s and Speer 100gr bullets. The rifle shot groups right around an inch with 37grs, 38.5 and 39.0. Thing is book max I have for those components is 40.5 grains at 2828fps. At 38 grains I was getting 2865, 2805 and 2827.
At 38.5 I had 2863, 2891 and 2886. Ran at 2939, 2884 and 2941 with 39.0. There were no pressure indicators that I could tell even though I was getting speeds over the max load with some room to spare charge wise.


Now I understand there are many variables involved and my sample sizes are small. My intention was to just get feeling for the process and get a baseline started. I’m not looking for max velocity, my end goal is for decent hunting loads without necessarily leaving too much on the table. Since I’m going to be building on what I’ve done so far I’m looking for input on what’s next. I’d rather not hit the point of pressure signs but I’m not sure how much to trust a fairly cheap chrono either. The only real odd reading I had was with the .243 and one of my 37.5gr charges that went 3057. The other two went 2813 and 2916. Pretty bad spread. No idea if that was something I did or the chronograph. Everything else seemed consistent and expected.


That’s a fair amount of info to digest but details are important. Thanks in advance for any suggestions, might be a couple days before I can check in.

I think you’re good and would trust your numbers. Anomalies Happen but overall your stuff looks spot on.

Thanks. I felt pretty good with the .270 results and will bump up a little and see what happens. The .243 was giving good results so I may quit while I’m ahead and just repeat the last loading to verify.

Looks like you're on track to me.

That is where the problem starts.......a Caldwell chrono, not as bad as a Shooters Chrony. but I would trust my adulterous exwife before the numbers off these two piles of crap

Had the chrono long before buying reloading gear, got the kit for archery when Gander Mtn went out of business. Figured for $60 it was worth trying.

I think your numbers are probably pretty close to what you’d get with any other chronograph. My last range trip I used IMR 4831 with a 130 gr. SST. My fastest load on the load test was 55.9 grains at 3048fps. I’m using a Magneetospeed Sporter. I’m probably settling on 55.3-55.7 grains as I got a nice Velocity plateau in the high 2980’s, and I can definitely live with that speed.

You're getting a baseline with factory ammo which makes sense and it's how I start too.
I sometimes experienced odd speed variations when using the little translucent shields on my chronographs. I finally put a 2' wide and 3' long sheet of cardboard taped over the top, problem solved.
You're on the right track, a spreadsheet or log book will help to make sense of the data.
Data helps so good loads can be duplicated and bad loads only get loaded once.

Congrats on becoming a Handloader!

Thanks as well guys.

I’ve been keeping records right along and will continue to do so. I’m being extra cautious as I have two teenagers who will be using my stuff eventually. We shoot a bunch of .22lr but the centerfires have run in spurts, stocked up enough to change that but I’m trying not to waste components in the meantime. Just using every tool available to avoid mistakes.

I'm not buying that 62.0 as a good max to use - I've seen it listed in the new Hornady manual though.

I consider 60.0 as max and it will usually get you right around 3,100 fps in a 24" bbl. It's the JO'C load.

You're right where you should be for speeds in a 22" barrel - I wouldn't push it.

MuskegMan,

A couple of points:

The latest H4831, whether short-cut or "long-cut," tends to be slower burning than the original H4831 mil-surp powder that O'Connor used. Though that powder did vary from lot to lot, since it was cranked out during WWII in a hurry. I can say this with confidence after having tested both H4831s in a number of cartridges, often side-by-side. (Yes, I still have a supply of "mil-surp" H4831, which has not changed in burn-rate over the years.)

Second, Hornady bullets tend to develop less pressure than some other bullets. The prime example is the Interlock Spire Point--but Hornady also engineers their other bullets to all result in about the same pressure. This is explained in their recent manuals. It's a handy deal, and has proven to be pretty much true in my use of all Hornady bullets from the Spire Points and SSTs to the GMXs.

However, I would NOT go directly to 62.0 grains with other brands of 130-grain .270 bullets.

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Glad you checked in sir. Looking at the BB of GG you have that combo of powder and bullet listed for 61.0 grains @ 3008. That’s part of the reason I asked this here.

Sounds like you have gotten your answers. I`ve used "cheap" chrono`s for years to develope loads for my various cartridges. I`m also lucky enough to have a 600 yrd range close by to varify come-ups from the velocities provided. So far, I`ve been happy with the results.

On a given day, if I am suspicious of the numbers, I shoot a few standard velocity 22lr rounds to verify. They are pretty consistent in my experience.

Some of those extreme spreads are too big to believe easily. I think it's probably likely the chrono has problems.

Borrow a magnetospeed or labradar from someone for a point of comparison...

Question is how do you get any reliable or even valid ES or SD on 3 shot groups?
Velocity average maybe but still too damn small of a sample.
It’s not the chrono, his average for all the numbers are in the park.

The nice thing about ES is that you know it'll never get smaller shooting more shots. He's got an ES of over 100 ft/s with a factory load. It's possible the factory ammo is that bad, but I would definitely want a confirmation from an accurate chrono before proceeding.

I’m getting better feedback than expected, plus this thread might help others who may be wondering the same thing.

I have a few types of .22lr ammo that I can use, I also have swapped scopes on a couple rifles that need sighting in. I’ll bring the chrono along next time out even if I’m just shooting factory stuff. Battery was brand new to start by the way.


I was setting COAL to book specs using a micrometer, I’m thinking a comparator would be a wise purchase. Brass was trimmed to specs as well, I kept everything within book recommendations. Charges were thrown light using a Lee Perfect and trickled up on an Ohaus 505. I actually did each load one at a time after priming brass.

Basically the factory numbers didn’t surprise me but the velocity of the hand loads both came in higher than I expected. I do have back up rifles in both chamberings that I can compare with. Sounds like I’m in good territory where I’m at so far.

Best way to know is to run two chronographs. If the numbers agree, it is likely a good number.

The Oehler 35 P has three screens. It gets a speed from Screen 1 to Screen 2 and a speed from Screen 1 to Screen 3. Therefore, it is just like running two chronographs.

I've used many different chronographs. All will look you square in the eye and lie to you if you get careless. Doubtful that two will tell the same lie.

That's why I'd use a system that makes multiple measurements or two chronographs.

Just a FYI, I have had just as bad ES than his factory when blowing out brand new brass.