Interesting chronograph results in 300WM load work up

[MallardAddict]

I recently bought a custom R700 in 300 WM with a 24" 1:10 Obermeyer AMU contour. I have about 350 of the 208 AMAX and several pounds of R22 so I decided to start there. Using hornady's data I'm consistently 200--225fps faster then their data despite them using a 25" barrel.

I am jumping the bullets .025 to start and things look good. Best accuracy in my rifle is between 71-71.5 gr of powder. Hornady states 2800fps for 71gr and I'm getting 3010fps average with an SD of 7.3 and 3/4" groups at 200 yds. At 71.5gr I'm getting 3045fps average and an SD of 5.7 and 1/2" groups at 200 yds.

I tried their max load of 72.4grs which hornady states should do 2950fps and I get 3175fps with 13.5 SD and 1" groups.

My speeds were gathered via magnetospeed and double checked against another shooters Oheler and the variance between the 2 chronographs was less then 10fps.

My brass looks great, primers are still round on the edges and extraction was super easy.

I'm still a little leary of using the 208 AMAX on game as shots may range from 150yds to well past my comfort level. Seems the 212 eld-x is unobtanium so I may settle on the 200 eld-x and hope it shoots as well.

Anyways, i am a bit puzzled by the extra velocity over book with less barrel, but nothing i can see or measure makes me feel like im pushing my gun over pressure.

Long story short has anyone seen results like these?

 

[Darkker]

You do have very clear signs of over pressure, but you are ignoring them.

This notion of being able to "read pressure signs" really needs to stop being spread among reloaders. Is it better than nothing? Certainly. Is it better than anything other than nothing? Absolutely not!!

It has been long well known and reported on, that very carefully calibrated copper crushers aren't accurate above roughly 45,000psi. With reference lots of powder, in carefully controlled chamber, barrel dimensions; will report pressure differences on the order of 20,000 psi!!
Some random reloader who bought powder off the shelf, doesn't know the alloy or tensile strength of either his cases or primer cups; can't stare at them and magically be more accurate at pressure measurement...

Alliant, and about every other powder brand name you know, caution you to drop charges by 10% when changing lots, or to find a starting load. Great! So you know that they are allowing for a 10% burning rate variance in lots of powder. You took Hornady data that doesn't list lot numbers tested nor date tested, ignored the burning rate caution from the powder company, and are surprised your results are different?

Velocity comes from pressure. Mo pressure, Mo velocity. In your case about 200fps worth of Mo pressure.
Grains aren't absolute, that belongs to death and taxes.

We've pressure tested several lots different powders. 10% swings aren't common, but have seen it.

 

[MallardAddict]

I guess I am confused with your reply, what clear pressure signs am I ignoring? Every round I have ever loaded has been exactly how the books say to load them. I always start at minimum suggested loads and work up carefully.

I started my load testing at 68grains of R22, which is the starting load for that powder in my hornady book. I worked up to the current loads in 1 grain increments until 70 grains which is mid book, after that I worked 1/2 grain increments. All loads were done in groups of 10 rounds and all shot as 5 rounds groups over 2 differnt chronographs.

In the interest of clarity I loaded: 68, 69, 70, 70.5, 71, 71.5, 72 and 72.4. In every single one of these loads 2 differnt chronographs showed I was faster then book speed by 200-225 fps.

I am not a professional, but took my time loading, prepping brass, weighed each charge, measured each rounds COAL etc. I'm not sure what else I can do as a casual shooter to be any safer.

I asked the question because the speeds seemed high to me but nothing i can see in my brass, how it chambered, extracted etc was any differnt from any other round I have loaded.

I am all for learning and advice, but please don't assume I am new to reloading or looking solely for speed. I value my life and safety too much for that crap.

As an aside I called Hornady and the tech said he has heard of many people getting 3k from R22 in a good barrel.

 

[johnnyk]

MA,
I too have a .300 WinMag that shoots faster than Hornady sez it should. Mine averages about like yours, 150-200fps faster than book.
I'm shooting the 208 ELD-M at 3092fps with a 26", stock, Savage 112BVSS. Using 77.0gn of RL26 and CCI BR2's.
I've been reloading 30 years, I know when my rifle has had enough. If I wanted a .30-06 I would have bought one! JohnnyK.

 

[Darkker]

The most obvious sign is the velocity. You are not loading them "exactly how the books say to load them", you are copying actions, but don't understand what you are doing.
Re-read your manuals load info and theory of operation, found before the load data.

Both the manual AND the powder company warns you, that each lot of powder can be different by 10%. Re-read that part.

You ignored the warning that burning rates can vary by 10%, Ignored the fact that the book doesn't say what lot number they tested, or when they tested it. Pretended those warnings don't exist, copied the charge weights as though the powder was identical. Ignored the section of the manual showing how excessive pressure gives excessive velocity, and can't understand why your velocity is high!!!???

This is fundamental reloading 101. This is the beginning half, of every loading manual ever printed.

Your powder lot, has a faster burning rate than what was tested by Hornady. Powders are NOT a single unchanging thing. They have ranges, those ranges change with time and humidity.

THAT is how your manual tells you to approach reloading. At no point, does it hint that coping grains alone is safe, wise, or even something that should be done.

 

[MallardAddict]

Holy ****, can you be any more of a condescending *******?

I didn't ignore anything listed in any reloading manual despite your best assertions that I did.

Once again genius I started at 68 grains when book max is 72.4. So gee rather then reduce 10% to start i reduced 9.4% which conviently is that listed start load. Are you really so obtuse as to claim that a book start load is over pressure since it showed the 200fps variance as well?

You keep making your ridiculous claim that my lot of powder is fast based on 1 of my rifles yet you are guessing at best. Here is a hint for you it is NOT a fast lot of powder! I bought 3 8# kegs of R22 at the same time and all of the same lot number. I say this because velocities with this same exact keg of powder in my 257Wby, 7 WSM, 280 A.I and 338 RUM all fall within norms for speed posted in several manuals and are inline with those posted by others online. I don't hotrod any of my rifles for the sake of speed.

I asked a simple question about velocity and you go on a tirade that my loads are at unsafe pressures based on velocity yet know nothing about me, my rifle or how I load my ammo. Velocity is only one indicator of pressure and is far from the end all be all you seem to claim.

Hopefully your just having an off day and aren't this much of an asshat all of the time. Good day sir.

 

[Darkker]

I'm sorry you feel slighted.
You asked for an answer, I gave you one. You said you don't understand that answer, so I repeated it, and told you where to verify what I told you; and that makes me condescending?

I am guessing based on the one rifle you asked about, that's right. And you are aiming you have the same chamber and barrel specs, and the same lot of powder a book tested. Assuming you stored the powder the same to, and no burning rate change happened.

Yes, there are many ways to ACCURATELY measure pressure, velocity is the easiest and cheapest for the average Joe. Staring at cases isn't one of them.

 

[philipbrousseau]

there are fast barrels and slow barrels. i've seen 300 win mags that were as fast as most 300 Jarretts. if you want to be sure of pressure being good with your particular brass get a micrometer to measure with and look up how to measure case head expansion. there is no guessing with this method.

 

[FURMAN]

If you do not have a heavy bolt lift and no heavy ejector marks on the brass I think you are ok. I would do drop validations at long range and see if it agrees with the chrono. I would ignore Drakker. He may be very knowledgable but his input to this topic was worthless and not constructive in any way.

 

[Nomosendero]

Holy ****, can you be any more of a condescending *******?

I didn't ignore anything listed in any reloading manual despite your best assertions that I did.

Once again genius I started at 68 grains when book max is 72.4. So gee rather then reduce 10% to start i reduced 9.4% which conviently is that listed start load. Are you really so obtuse as to claim that a book start load is over pressure since it showed the 200fps variance as well?

You keep making your ridiculous claim that my lot of powder is fast based on 1 of my rifles yet you are guessing at best. Here is a hint for you it is NOT a fast lot of powder! I bought 3 8# kegs of R22 at the same time and all of the same lot number. I say this because velocities with this same exact keg of powder in my 257Wby, 7 WSM, 280 A.I and 338 RUM all fall within norms for speed posted in several manuals and are inline with those posted by others online. I don't hotrod any of my rifles for the sake of speed.

I asked a simple question about velocity and you go on a tirade that my loads are at unsafe pressures based on velocity yet know nothing about me, my rifle or how I load my ammo. Velocity is only one indicator of pressure and is far from the end all be all you seem to claim.

Hopefully your just having an off day and aren't this much of an asshat all of the time. Good day sir.

Mallard, being from AR. I appreciate your user name. I am curious if you have taken 3-5 cases and loaded them over and over again to see what your case life and case expansion is, I know that this too may be irrelevant too but just for giggles ?

 

[MallardAddict]

Nomosendero
I enjoy all of my hunting and shooting but waterfowl and my field trial labs are my true passion.

I've only had the rifle a short time and only 4 range trips so far. I have used the same brass each trip and cases now finally need to be trimmed. Expansion of the cases has been very minimal likely due to the tight chamber job by Terry Cross at KMW Longrange.

It's still shooting the same load at 3025fps with sd's of under 6

 

[Nomosendero]

Nomosendero
I enjoy all of my hunting and shooting but waterfowl and my field trial labs are my true passion.

I've only had the rifle a short time and only 4 range trips so far. I have used the same brass each trip and cases now finally need to be trimmed. Expansion of the cases has been very minimal likely due to the tight chamber job by Terry Cross at KMW Longrange.

It's still shooting the same load at 3025fps with sd's of under 6

Interesting indeed !

 

[elkaholic]

Mallard.....I personally don't see where you are doing anything wrong, just because your results are unusual! Here is the first question that comes to my mind. You stated it is a custom rifle. What is the coal of your loaded rounds? It could very well be that the rifle has a very long throat, or even if it does not, it could be a stepped throat which would not show in coal. I am not saying it does, but this would be a good place to look and could be a plausible answer. This would definitely keep the pressure down and would be a velocity increase when loaded back to pressure up!......Rich

 

[eshorebwhntr]

I also don't see anything that you have done wrong or bad practice. You worked up safely. Nothing to this point that you've written seems unsafe to me.

I've come to the conclusion that most modern manuals state velocities on the low side as a precaution. Most companies make recommendations on what to use as guidelines to get you started but state all the standard safety precautions and disclaimers.

Case in point, some new reloader has the same mentality as the previous guy that ripped your *** and thinks his gun should reflect the manual and a given cartridge-powder-bullet combo should produce a certain velocity. Using the mentality that the best way to ascertain pressure indicators is by velocity readings and not by "staring at cases" he starts 10% low, works up, and has an over pressured load that is low on velocity. He then keeps upping the charge trying to get to book velocity and ignores the fact that he has flattened primers, heavy ejector markings on his case heads, and a sticky bolt lift.

Looking at only one side of the equation to me would be a bad idea- spent case condition or velocity readings. The good news is you looked at all factors objectively (brass condition, primer condition, bolt stiffness, and chrono readings) and seem to have a safe load.