Powder Test 7mm Rem Mag

[Varmint Hunter]

Do you remember when you tested ? Was it hot out ? I read a thread where someone said IMR was temp sensitive. This is what I was concerned with.

It was a rather balmy 75 degrees when I was testing IMR4350 in the Creed.

 

[baldhunter]

The difference in velocity between the three 4350 powders has a lot to do with the cartridge case capacity fill and the bullet weight.The three powders are different in weight volume per grain of powder.The A4350 is the lightest and takes up more case space,followed by IMR4350.It falls about right inbetween A4350 and the heaviest H4350.Here are some examples of what I have loading all three the same.
308 Norma Magnum 168gr Nosler Ballistic Tip
H4350 69.0grs 3148fps
IMR4350 69.0grs 3111fps
A4350 69.0grs 3125fps (70.0grs 3168fps)

308 Norma Magnum 180gr Nosler Ballistic Tip
H4350 69.0grs 3028fps
IMR4350 69.0grs 3103fps
A4350 69.0grs 3065fps
I ran this test years ago in my 30-06 A4350 was the fastest,followed by IMR4350,about 10fps slower,followed by H4350 being the slowest by about 25fps slower than the fastest.All the powders grouped about the same.

 

[baldhunter]

I think the 4350 powders work well in the 7mag with the lighter weight bullets like 150gr or less.It will work for heavier bullets,but seems to reach pressures quicker with those.That's where the slower burnrate powders are a better choice because they work well with most all bullet weights.I like Reloader-22 or Reloader 26 the best in my 7mags.Those two powders have made it very easy to find a good load in multiple 7mags.
Not a 150gr TTSX bullet,but my Remington 700 Long Range did really well with the 150gr Nosler Ballistic Tip with 65.0grs of A4350.

 

[cajun]

Everyone assumes you need a slow powder with the 7 mag. Unless you are shooting 160 plus the 4530 burn range is perfect for 140-150 class bullets. A 150 gr ballistic tip and Imr 4350 is a classic 7 mag load.

 

[VinceMule]

61g of IMR has worked well with the 160g Sierra BTSP in some rifles @3000 fps.

 

[baldhunter]

Though this load was accurate,the pressure was way up there.I'd drop down probably 1.5-2.0grs with 160's.

With Reloader 26,I still could have gone up a bit more.

 

[hemiford]

153 / 154. As far as burn rate goes they are essentially the same. Typically we don't get big swings in temperature here on the Gulf Coast of TX. 30 - 100 vs sub zero to 100 in NW New Mexico (for instance).

Most of us here in TX would be adamant that jacket weather starts at 50 degrees because that's when water freezes in Texas


View attachment 481736

Thought I would post another burn rate chart, this one supposedly compiled this year, it is different than the above chart.

 

[Mike6158]

I did the fine powder test for the IMR4350 today. Temps peaked at 104. I got there early but by the time I got the targets up, LabRadar, rests, etc it was 10-ish and in the 90's. I got thru the test before we hit 100. I fire formed 100 rounds of .220 Russian to 20 PPC in the high temps. Joy...

Here's the results. The 8th and 9th data points look similar because I... well... I charged both at 61.8 gr. I thought I might have done that when I was loading them but now I know that I did.

61.6gr is pretty... I wonder what it will do in cooler weather. Whatever that is.

 

[VinceMule]

Mike, H4350 is to be found if you look. In your weather, it may pay big dividends,

 

[Mike6158]

I found some. Powder Valley has been pretty good with in stock powder and primers lately. I need that 61.6 ES node to be wider...

 

[VinceMule]

Mike, if you can, work up groups at 300 yards, 200 at a bare minimum if possible.

 

[Mike6158]

Mike, if you can, work up groups at 300 yards, 200 at a bare minimum if possible.

I normally shoot the "final" test at 200. If I ever get to a final. This one was a powder charge test. I was looking for low ES. I shot at a target (100 yards and the groups kind of tracked ES. I don't have the targets here in front of me so I could be wrong about that. The mirage is really bad in the afternoon right now. So is the wind. 200 is about the max for groups and, for hunting loads, it's about all I'd be willing to shoot at except for hogs and coyotes.

One thing I've noticed, after cleaning and lubricating the bolt. plus changing the firing pin spring to a 28# Wolff spring, the weird vertical flyer I used to get seems have gone away.

 

[Buckys]

Mike, I'm just skimming your posts here but are you planning to hunt year round with these loads (I'm presuming primarily in Texas)? If so then I would not necessarily only do my load work at ~75F as was suggested earlier ... if you want to know what's likely to happen when you reach out more than ~200 yards, you're likely going to want to know what will happen when you're pig hunting at 95+ degrees on a summer night all the way down to the coldest temps you can imagine hunting in during Jan-Feb at the end of our Texas deer season and beyond into feral hog/exotics post deer season.

Keep in mind that you can get some idea what colder temp behavior might look like if you're doing something to control the temperature of your ammo up to the point you chamber it and pull the trigger. e.g., a friend with a range setup off the backporch of the ranch will have his ammo inside the house at ~75F, walk inside, grab a round and shoot it and not be too concerned that its 105F on the back porch.

Likewise, he can stick another box of ammo in his refrigerator to test ~35F. That gets tricky with the humidity, though.

 

[Ronald W Schaefer]

I stumbled on a load using RL-25 and 160 gr federal trophy bonded bullets, fed 215 primers...it really rocks, small group size and great velocity. I use it exclusively now in 7 Rem Mag and .257 Wby mag. Ironically both use 68 grs of RL-25.