Home Forums Hunting & Shooting Ask The Gunwriters "Reading primers" - why NOT???

Apparently a wise move these days!

I have seen rifles go from no conventional signs to a bit scary more than once and so have most of my 'Old Timer' friends who have taken the time to help teach me many things concerning the rifle.

If chronograph readings are a more reliable indicator of safe pressures you can rest assured that is what I'll be teaching my children or anyone that I call a friend for that matter.

Really good info!

Shod

In my experience, if you use a chronograph correctly you rarely run into conventional "pressure signs." Except, perhaps, for flattened primers.

I don't get why some people are surprised that max loads vary by two grains of powder. First of all, you have the lot to lot variation in the powder, which according to a tech at one of the powder companies, is roughly in the percentage range that a couple of grains of powder would amount to in a 30/06 size case. Then, you have the variations in chamber size from one rifle to the next. Then, you have the lot to lot variations in bullet size, plus differences in bearing length. The, there is the variation in case capacities from lot to lot, and then the fact that not all loads are worked up using the same brand of cases. And then there is variation in bore diameters, and on and on. I have even read somewhere that different technicians will get different pressure results running the same load over the same equipment.
I also don't understand with the cheap chronographs available why anyone that frets very much about their handloads would load without a chromo. Apparently, it's the safest way to develope loads. You work up to the velocity given for a particular recipe, CHANGING NOTHING, and you are good to go.

You are right, of course. But you owe me a new keyboard.

It is surprising to hear a hand loader talk about the cost of having a tool to check pressure. A crony is around 140 bucks. Bullets are 29 a box in most stores. Powder is 29 a lb around here. Not to mention the fee for the finer things on the reloading bench.
Just doesn't seem like that much to get a fair idea of how hard the bullet is being pushed.
If you are not in a position to buy one, then it seems to make sense to hang in the under max range area of the load tables till your wallet allows you to make an investment in tools.

Bob B257
That is a good answer. Unfortunately, it's too logical and too simple to be popular.

I have a friend who went without a chronograph for years, while ordering a custom rifle for at least a couple thousand bucks every year or two. I finally persuaded him he could afford $100 for a chronograph after the primer pockets in his expensive .270 Weatherby brass wouldn't hold primers after one firing. Turned out he'd used data from the Hornady manual to work up the load with Hornady bullets, then substituted Nosler Partitions without any change in powder charge. Velocity was 200+ fps higher with the Noslers--as MY chronograph showed him.

Another reason handloading data varies somewhat is that a few companies (thankfully very few) work up loads in poressure barrels, then shoot them for velocity in factory rifles, in order to show "typical" results. Of course, there is no such thing as a typical factory rifle, since they tend to vary even more than pressure barrels. A few years ago this resulted in one manual showing higher velocities for the .308 Winchester than the .30-06.

Ah, further proof of the "inherent speed" of the .308.

I am usually a few grains if not more under books listed max load so I don't worry about over pressure loads, but all this talk about chronographs,no one has mentioned that they will vary in readings by how much and what type of light they are used in.

This might be though because I only own one of the F1 Chronys and not a more expensive model

This is not surprising, I routinely exceed .30-06 velocities with my .308.

I just keep adding powder until the primers are flat......

I was loading a 225 gr accubond in 338/06 I used to own last year.

At 2866 fps it started to show flattened primers but that was all.I'm sure that load had to be way over max pressure.

I'm glad I was using a chrono because the excessive velocity did get my attention.

Friend of mine was shooting his 8 mm mouser through the chrono and his load recorded a consistent 2450 ish just like it always had so I am confident the chrono was working correctly.

I'm thinking that this experience may be one reason at least for myself of why to not trust reading primers alone as an indication of pressure. I can see myself still looking the primer over for possible indication of a head space issue or the slight chance of a chrono working incorrectly.

However, in light of personal experience and what Mule Deer and others have confirmed I will not show up at the range again without the very useful tool, the chronograph.

Shod

saddlesore,

In my experience Chronys are more light-sensitive than any other brand of light-screen chronograph, but they still beat the heck out of guessing. There are, however, other inexpensive brands that work pretty well in varying light.

I had a friend who passed on 20 years ago. Jacques was the only amateur member of the Ohio Pyrotechnics Guild. They did a poll once and the average number of fingers was 7.5. Jacques had a full compliment. The guy who wrote the Reloading Primer that got me into this hobby had hooks on the ends of both arms.

I do not claim to be a great whiz at reloading, but I've been doing it for 15 years and I haven't blown my face off yet. I still have all my fingers. If that makes my opinions worth reading, so be it.

One of the things I started doing early on was downloading most all of my rifles. I have a 308 WIN that shoots like a 300 Savage. I have a 35 Whelen that shoots like a 358 WIN. My 25-06 is downloaded to 257 Rob levels. I'm not missing anything in performance, because . . . well, if I want to do a full-house 30-06 project, I would start with a 300 Win Mag and work down.

I realize this is philosophy that is foreign to a lot of people and it is probably anathema to many, but it makes sense to me and my shooting requirements. It is also pretty cheap to do, because it generally saves powder and is easy on brass. I had twenty years of shooting before I tried reloading, and I have been reading on all this since I was small child. For all that, I just could not see why folks wanted to make a 30-30 shoot like a 30-06, when the reverse seemed so much more workable.

One more quick story, and then I'll leave you. I had a roommate in college that was a bit of an eccentric. Everybody played pinball. There were half a dozen machines in the dorm. We all played. Pat's style of play was different. Instead of trying to get the high score, he'd play to a certain goal-- usually something higher than he got before, and then he'd walk away from the machine and leave the remaining balls for somebody else. Pat was a pinball master. He'd get way up there on the first ball and then while the lights were flashing and bells ringing, he'd walk. Nobody understood Pat's method of play, but we all enjoyed taking over for him and we all respected his pinball mastery. I suppose having Pat as a roommate left a lasting mark. With that thought, I will leave you.

A chronograph is an excellent tool for load development. I highly recommend it. At the same time, there are a few precautions you should take:

1. Carefully control barrel temperature. If you do your shots on a day that you can maintain your barrel close to 70F, then it is meaningful to compare your MV with the book MV. If your barrel is more than a few to several degrees different from that, then not so much. For some common powders, a difference of 30F is equivalent to a grain or so of powder.

2. My chronograph is somewhat sensitive to lighting conditions. If I leave the diffuser in place, and shoot under cloudy skies, I get a distinct drop in registered MV. My rule is that I do my measurements on sunny days or on days where the clouds are thin enough that I can see the shadow of my tripod. Then, with temperature control, I get very consistent results from day to day.

3. Shoot a series of shots with different charges to ensure that you are getting an orderly progression of MV with increasing charge. I'll usually do 4 or 5 pairs of shots with half grain increments. Once in a great while, you'll start to find that MV does not increase linearly. Adding powder after the MV progression slows is pretty much a waste of money. Switching to a magnum primer will sometimes bring the MV back to where it should be.

Here's a 2520 load that I tried in my 223 that showed this problem. Switching to a magnum primer brought the 26 grain load up to where it should be.

Shaman, less powder does not always produce less pressure.

Reload manuals show between what ranges a powder is stable. Go to high or to low and the rifle can overpressure and blow up.

I prefer any accurate load as long as it is withing the intended parameters.

Shod

I have often wondered what the range of error in a chronograph is. I suspect it varies from one brand to the next.
Also, what if you took the same rifle with the same chronograph and choreographed the same lot of ammo the first Monday of the month for a year, what the range of readings would be.

Well, we never learn from those who think the same as we do, and that was the reason I posted my OP. I understand and fully appreciate that primer indications are NOT a very good indicator of pressure, but as I intended in my OP, I do still think it's advisable as a check that CAN keep us out of territory where sensible loaders don't really want to know, whether they understand that or not.

One instance was a friend whose '06 loads he'd made produced very flattened primers. His load was a published one, or so he avowed, and I finally helped him solve his problem. Turned out his chamber was longer than std. and it was a headspace problem. I told him how to adjust his sizer so it wouldn't shorten the boltface to shoulder on fired brass, and he got much better results, but soon sold the rifle anyway. He just didn't understand how those things work, and wasn't comvortable with a rifle he didn't understand or trust, so .... somebody else wound up with it.

There are other instances where knowledge of the potential causes of primer flattening CAN be a good thing, like MD's and others' citing of the simple differences between bearing surfaces of different bullets, their construction, core hardness, etc. The point is, primer appearance CAN tell us if there's SOMETHING that needs to be attended to, or if we can't find or guess the reason with confidence, that load should be relegated to the past, and not loaded any more. Very simple. Not every reloader takes up the practice with a passion, and most only want viable loads at a lesser price than factories, or they want to be able to recreate "their load" at will, since it's really hard to find the load we used last time on the shelves these days. Something that will fit, probably, but likely not the load you're sighted in for, and that necessitates checking the sights again - something many resent doing, and all too often won't do, with predictable resullts.

Didn't mean to imply that "reading primers" should EVER be the ONLY thing considered by those of us out here who don't have pressure guns, but .... no harm done, and maybe someone got a good lesson herein about the subject, so .... all's well that ends well.

As an old fart now, I'll continue to pay attention to primer appearance because it's all I've got, except for my chrono (Pact I). I want the BEST load I can get, NOT the hottest. Like I said before, it just doesn't take all that much to kill a deer, and even long range shots are best done with the most ACCURATE loads, since a few "extra fps." amounts to practically nothing at range. It's the nut that squeezes the trigger that'll always be the vital factor there, along with a good, ACCURATE load.

I'm quite aware of that. I tend towards powders like H4895 that are not as prone to those situations. You're quite right in bringing it up; a fellow needs to research everything he does before he starts pouring powder down the neck.

My point here is to say that there are other ways of looking at this. A reloader does not HAVE to squeeze the highest velocity out of a given project. You can optimize for recoil, accuracy, cost-- anything you want. For what I choose to load, primer deformation is the least of my worries. My overall suggestion to folks is the best way to handle their goals may be to start with a larger chambering and work their way down rather than taking the smaller chambering and try to push the envelope. When you have to start worrying about the primers in a big way, that envelope IS being pushed. I would much rather have a light shooting 45-70 than a barn-burning 44 Mag. N'est pas?

In this thread its implied or even stated outright that a chronograph is useful for helping determine chamber pressures, as pressure correlates to muzzle velocity, or vice versa. Is that a fair statement?

If so, I have a question regarding a handload and its MV: rifle is a.264 win mag, 26" Lilja #4 contour barrel w/8" twist on a M700 magnum long action. H-S Precision stock, action bedded, barrel floated.

Load is 68.0 gr Retumbo, never fired Nosler brass, Federal magnum primers, 140 gr NPT. MV = 2780.

this velocity is ~250 fps slower than Hodgdon load data at their max of 63.5 grains, same bullet, 26" test barrel.

Based on the LOW MV I'm getting, can I safely assume chamber pressure is also LOW? And should I reasonably expect to slowly increase the charge, using MV as a guide to maintaining safe chamber pressure?

Hodgdon's max load for the 140gr NPT and Retumbo is 3026 fps with 63.5 grains, resulting in 63,000 psi.

Can I assume that (all other variables being equal) I'm below 63,000 psi as long as my MV is below 3026?

Thanks!