I've been working with a new M70 Featherweight .243 Win., and finally got the chance to setup the Chronograph. Hornady's max load with 70 gr. bullet and RL-15 is 40.2 for about 3400. I got 3164 with 40.0 and the 70 gr. TNT. Hodgdon lists 39.5 of H4895 with the 70's for 3477, I got 3260 with 39.0 and the 70 TNT. Hodgdon lists 40.5 Varget max, while the Speer goes to 42.0 in a Ruger M77. I worked up to the 42 gr. load with no apparent pressure signs and got 3420 with the same TNT's. 1st off there seems to be a wide variation in max loads for the manuals, and my barrel seems slow in comparison(not that unusual). Question is should I work (carefully) up to close to the velocities given with the 22" barrel in the Speer manual, or go with the lower listed max loads that are considerably slower in my rifle. I started with a fresh battery in the Pro Chrono, and tried my Ruger .22-250 sporter with 39-H4895-50TNT as a check. Got 3613 fps out of that one. Much closer to published velocities.
Edited to say, I should have added that I'm getting fairly large ES, and SD which makes me think I'm not up to optimum pressures.

The truth tends to create a lot of difficulty for the folks who believe a Chronograph is infallible. No problem at all shooting over it while "developing loads" as long as you don't fall into the trap of thinking a particular Velocity "indicates" a specific Pressure - it doesn't as you just saw. That is the biggest misconception concerning chronographs. It only tells Velocity.
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Since you asked, I'd recommend you shoot a box of factory ammo through your rifle, while recording the Pressure Ring Expansion(PRE). Average the results and write it on the box. You now have a Comparative Benchmark Standard(CBS).

P-FLR those exact same cases and load a series of individual Test Loads (0.2gr apart fot the 22-250Rem and 0.3gr apart for the 243Win) beginning with Starting Loads in your Manual and fire them into a single target at 300yds. Be sure to document the Impact points as you will be eventually looking for "Clusters".(You've just performed the never improved upon Creighton Audette Load Development Method.)

Compare the PRE of your Test Loads as you fire them to the CBS and when you reach it - STOP. That will mean you have reached a Load that is "equal in Pressure" to the CBS.

Hopefully it is on a good Harmonic(cluster of shots) at that point. If not, go back to a lower level Load and find where the best Harmonic(cluster) occurred. Then load another Series of Test Loads at that level while varying the Seating Depth to fine tune the Load.

Now is the time to break out the chronograph and see what the Velocity happens to be. Then once you know, there isn't much it is good for. You can use it to speculate on some Drop Rates. But it is always best to actually shoot the Final Load at the distances you feel comfortable shooting at Game, to generate a Real Drop Chart.

Best of luck to you.

As Hot Core points out, a chronograph will not measure pressure. It puts you in the ball park, but it cannot give you pressure directly. (Of course, PRE only puts you in the ball park as well.)

Any substitution in componenets -- bullet, brass, and esp. primers -- can lead to large changes in pressure and velocity. Unless you're using the componenets shown in the loadbook, you can't assume anything about the velocity you'll see on the chronograph.

Pressure barrels are made to SAAMI minimum specs, in an attempt to insure pressures in your gun will be no higher than that found in the lab. In general, factory barrels will give lower pressure and thus lower velocity.

There are differences in powder lots and pressure barrels and this partly accounts for differences in performance reported in load books. A fellow who often posts here has found, using a strain gauge rig, that barrel temperature has a noticeable effect on pressure and velocity, and that probably accounts for other differences in load books (ie., how much time did the lab tech. take between rounds).

The writer Barsness has access to a piezo set-up. From his tests, he feels it is safe to work up to the fps shown in a load book if the other components are the same (ditto barrel length). This allows one to compensate some for a slower batch of powder.

One thought: do you really need that last 100 fps?

If you go to http://stevespages.com/table1.html you will see some of my favorite loads.

For comparison I listed what I measured with my chrony at 15' from the muzzle, compared to what several reloading manuals "forecasted" as well as what QuickLoad "predicted".

There is significant difference...

Thanks guys. I don't really need the extra 100 fps, just a bit "underwhelmed" at 3042fps from a 75 gr. bullet out of a .243. I was in a hurry when I typed that post and it didn't explain things too well. I'm having a time getting this gun to shoot as well as my Rugers and Rems. The only consistant ly under MOA load is 39-RL-15-75 sierra hp, seated to the lands. I broke out the chrono to check velocity variation and there is more than I'm used to. 42-Varget-70TNT gives very good ES, and SD, but always patterns with two shots touching or nearly so, and the third an inch or more away, not in any particular order of sequence. The gun has been glass bedded, and I've played with the action screw torque. Because of the flyers, I polished the crown this afternoon. 1st three shots out of the cold clean barrel with H4895 went into one slightly oversize hole, the next three with RL-15 went into a slightly smaller oversize hole. Thoght I was getting somewhere, but succeeding groups went back to the normal 1.25-1.5". Guess I need to try taking more time between shots and cleaning more often.

Here is my unwritten rule:

IF A MANUAL STATES THAT THERE VELOCITY IS "XXXX FPS", THEN YOU CAN BANK ON UP TO 100-250 FPS SLOWER. I'm speaking in general but I've never achieved equivical loads as they are published in a manual, at least not to my recollection, in terms of velocity.

There is a good reason why the manuals vary as much as they do. Of course this is due to a varitey of reasons, from different copper jackets to the exact bore that manufacturer used while developing loads, etc.

When I've picked a bullet for a task, and a powder, those are the 2 books open on my bench while developing a load. I sometimes reference stevespages or who else, YOU guys.

ole_270,

I'll second hot cores suggestion to buy and chronograph a box of factory loads similar to the reload you are attempting to make. This will give you a good comparison on velocity. 1st compase the chrono reading to the velocity the manufacturer claims. Then compare your load.

I wanted a reload for a 270 using the 150 SGK so I bought a box of PMC silver line 150 SGKs. The velocity was said to be 2,850 at muzzle - I measured 2,817 at 10' and was able to reproduce that load. However, some times neither your load nor the factory load will go as fast as the manufacturer claims.

quote:

Originally posted by RaySendero:
...I'll second hot cores suggestion to buy and chronograph a box of factory loads similar to the reload you are attempting to make. This will give you a good comparison on velocity. ...

Uuuuhh Ray, I believe you mis-read my post. Actually, I don't have a lot of use for a chronograph at all. I do have access to them, but rarely waste my time with them.
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Hey ole_270, The powders you listed seem a bit on the "fast" side to me. That doesn't mean they won't work for you though.

One of the most accurate Loads I have for a 243Win uses a Federal Primer, 75gr Sierra(#1510) Flat Base Hollow Point and H380. You can get the starting loads from Hodgdon and work up to a load your rifle likes if you are so inclined.

The load I settled on is plently accurate for my shooting. One of my best memories with it is after I'd fired a 3-shot group and let the barrel cool, a buddy asked to shoot it. He put another 3-shot group into the same target and the combined 2-man 6-shot group was in the 6s. Probably couldn't do it again today, but it is a fine Load in that rifle. Had a very difficult time prying that S&S M7 out of his hands.

Sierra also makes a 0.243" 70gr HPBT(#1505) which shoots fairly well for me too. But I just like the 75gr weight better simply because I've used it a whole lot more on all kinds of varmints.

When working up a new 175-grain load for my 7mm Rem. Mag. using IMR 7828, with ONE SPECIFIC powder charge, I got average velocities for three different brands of bullets as follows:

175-grain Remington PSPCL = 2875 FPS @ 10';
175-grain Sierra PSPBT = 2950 FPS @ 10'
175-grain Nosler Partiton = 3050 FPS @ 10'

All three bullets produced acceptable accuracy results, and since I was developing a load for elk hunting, I was just tickled pink at the Nosler Partition bullet performance!

But this just shows once again how much difference can be caused by a component change.....

quote:

Originally posted by Hot Core:
Uuuuhh Ray, I believe you mis-read my post. Actually, I don't have a lot of use for a chronograph at all. I do have access to them, but rarely waste my time with them.
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Hot,

Sorry to mis-quote ya. Meant to point out that the velocity of any chrono may be relative. And that could be ole_270's probable. By establishing what it will read out of the same rifle on a known factory load similar to the load your working-up you can judge the performance of the reload.

Your quite right about chrono not measuring pressure and offered a good way to do that. But since the Pressure Ring Expansion(PRE) only estimates peak preasure, I use both the PRE and relative chrono velocity to evalute my reloads. For example if you can't duplicate the factory load velocity at similar PRE then its probably time to look for a more appropriate powder. If my time allows, I'll usually keep looking for a powder that will better the factory load - Most times I don't find it but did with that 270/150 SMK combo.

Along those lines - Why do you not use a chrono more?

Hey guys, thanks for the responses.
Hot Core, just kind of curious. If my bore or chamber was oversise, causing the low velocity by way of low pressure, wouldn't the factory loads be correspondingly lower on pressure?
Just tried the gun again this evening, but at 95 degrees, I didn't get too much shooting in, mostly cooling. I added a pressure point to the end of the forend and glassed that, and a short section under the chamber. The first 3 shot group from the squeaky clean barrel went into .61. While waiting for it to cool, I got out the .223 ADL, and put 3 into less than half that. Thinking this was going to be a good range session! The next 3 from the Win. was 1.05, then .65 from the Rem. the last group I had time for with the .243 went about.88.
I think the added glass really helped this barrel, but I have really noticed how much more difficult it is to get the featherweight steady on the bags compared to the ADL or my Rugers.

quote:

Originally posted by RaySendero:
...Meant to point out that the velocity of any chrono may be relative. And that could be ole_270's probable.

Hey Ray, I agree.

quote:

By establishing what it will read out of the same rifle on a known factory load similar to the load your working-up you can judge the performance of the reload.

That is true depending on the Primer, Powder and Bullet used in the Reload as you obviously know.

quote:

...But since the Pressure Ring Expansion(PRE) only estimates peak preasure, I use both the PRE and relative chrono velocity to evalute my reloads. For example if you can't duplicate the factory load velocity at similar PRE then its probably time to look for a more appropriate powder.

Excellent method - the way "you" are using both Methods together.

The basic problem with a chronograph is it can be very mis-leading to a Beginning reloader. I'd encourage you to take a close look at the threads where people typically mention a chronograph (or one of the totally worthless non-calibrated Home Strain Gauge System fiascos) is the way to be able to get good reloads. Look at it from the perspective of a Rookie and think about it. You will normally see nothing mentioned about how a change in Primer, Powder, or "brand" of Bullet will have any effect at all on the Velocity. Think about that, and from your post, I believe you will understand how mis-leading to a Rookie that can be.

quote:

...Along those lines - Why do you not use a chrono more?

I do on occasion use one, but it is normally after any Load Development is finished. (That is no slam on the method "you" used.) I believe the last Loads I chronographed were for a 140gr Nosler B-Tip and a 140gr Nosler Partition in a 7mmRemMag. I'd noticed I could use a bit more Powder with the Partition than the B-Tip and was curious about the difference in Velocity between the two. And I feel sure I wrote it down on the Load Development Sheets I keep.

Now with this particular 7mmRemMag, it reaches a SAFE MAX Pressure 4gr below the previous 7mmRemMag I had when using the exact same "Lots" of cases, primers, powders and bullets. The old rifle would go above most Reloading Manuals MAX Loads because of slightly larger Bore dimensions. But the new rifle would not reach most Reloading Manuals MAX Loads without being "over Pressure".

So, had I simply gone by using a chronograph as most of the threads go(even using the correct components), I would have been under-loading the first rifle and over-loading the second rifle when using Velocity as the "only" criteria.

That is one example.
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Here is what I normally see in the old "I need a Load for a xxx." threads.

In response you will see, "I keep adding "Ole StumpBlaster Powder" until it reaches 3200fps in my rifle with a 150gr bullet. Really safe and accurate.

How many shots per case before the Primer Pockets are too large? Uuuuh, don't know, but it is SAFE and goes 3200fps with a 150gr bullet.

What bullet did you use? Well..., all of them!!!

Or maybe the response was, "Most accurate and safe Load in the World is 50.239182gr of GeeHaw Powder for 3202.491587fps at exactly 57,982.01346psi(M43)."

What kind of bullet?It was a perfectly concentric 150.00004gr EyeOfTheNeedle bullet.
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Seriously though, let's say I decide to chronograph a Load and it indicates the Velocity is 3000fps. And I do what with it?

If done the way you(Ray) are doing it along with PRE, I agree it could provide one additional verification of a SAFE Load. I'm happy using CHE and PRE because I've used them so long. So even when I know the Velocity, I really have no actual "need" for it.

Drop Rate? The argument begins that you can use Velocity to determine Drop Rate. No, you can "estimate" Drop Rate, but Velocity can't determine it. Since the proper way to determine the real Drop Rate is to shoot the actual Load and measure the Drop at distance, Velocity just doesn't have any real use.

Retained Energy? Or the argument, you need Velocity to determine how much Retained Energy you have down range. In this situation, I sit down with a few Manuals prior to buying the particular caliber and determine if it will have the Retained Energy at the distance I intend to use it. If it does and I like the cartridge and rifle combination, then I get it. I just don't believe the time to determine this is after you purchase the rifle.
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So, other than using it with PRE to determine your Loads, what do you do with Velocity? Perhaps I'm overlooking something and am willing to learn.

quote:

Originally posted by ole_270:
.... If my bore or chamber was oversise, causing the low velocity by way of low pressure, wouldn't the factory loads be correspondingly lower on pressure? Just tried the gun again this evening, but at 95 degrees,

Hey ole_270, You would normally think so. But then you mentioned 95deg and as you know, that can crank the Pressure right back up.

I prefer Developing Loads at 90-95deg because that is the kind of weather the Season Opener generally has where I prefer to hunt. And since there is little chance the Powder we use to reload with is the same as the Canister Grade used in the Factory Ammo, I like to do the comparisons under the "worst case" situation.

Once you get a good Load at 95deg, it might not be as good at lower temperatures. This seems to be less of a problem today than it used to be due to the current crop of excellent Powders available to us. Easy to check with a couple of shots as the weather drops though.

The temp extremes for "me" would be 60-70deg at most, cause I just don't hunt in the cold weather that some folks do. But if I did, I'd really like to have a Load Developed in colder temps than "my" current Loads.

quote:

I didn't get too much shooting in, mostly cooling. I added a pressure point to the end of the forend and glassed that, and a short section under the chamber. The first 3 shot group from the squeaky clean barrel went into .61.

Now that is the kind of groups I like too for my hunting rifles. Congratulations. A person gets lots of confidence in a rifle/load combination that shoots that well.

When it is really hot I like to remove the bolt, lightly wet the Bore with Hoppe's BenchRest and set the rifle so the muzzle is pointed "up". The chimney effect really helps speed the cooling, but I do have to remember to wipe the Chamber real well to remove any of the Hoppe's that eases back into it.

I like to take a few rifles to the Range too. Really enjoy shooting off-hand out at 100yds on soda cans with a 22LR. That seems to help me focus my concentration better than anything else I do.

quote:

While waiting for it to cool, I got out the .223 ADL, and put 3 into less than half that. Thinking this was going to be a good range session! The next 3 from the Win. was 1.05, then .65 from the Rem. the last group I had time for with the .243 went about.88.
I think the added glass really helped this barrel, but I have really noticed how much more difficult it is to get the featherweight steady on the bags compared to the ADL or my Rugers.

Absolutely great shooting with the 223ADL. About the very best I can hope to shoot any more is the 4s with a great Load in a HEAVY M700VLS. Everything working against me, but it is great to see someone out there can still get in the 3s with a regular rifle.

My 223Rem is a S&S M7 and it is fairly light too. But I enjoy it so much more than the Hornets I had for 35 years. By the way, have you tried any of the 50 or 55gr Rem PLHPs? These were made for years and noted for their accuracy because the Jacket is "Plated" to the Lead similar to a Speer Gold Dot. Then Remington quit making them for a very long time. And finally began making them again.

I can "normally" get the 50gr Rem PLHPs to shoot in the 8s with H322 or H4895. Haven't tried them with Benchmark, but I need to. Not quite as accurate as the 50gr B-Tips in "my" rifle, but plenty accurate for carrying during the off-season for the various Varmints I run across.

Agree that the "lighter" rifles are more difficult to get steady. Not sure if I can help you with that other than to recommend you just have to focus on rifle position from shot to shot, shooting form and concentration. Even though that is also true for the heavier rifles, the effects seem to be magnified on the nice light rifles to me. Any little mis-alignment in the shoulder or cheek, wrong tension on the grip, or mind drifting shows up right quickly in wider groups for me.

Sounds like you have a great start on some fine Loads.