IMR4451 7rm

[sixonetonoffun]

Looking at Hodgens site I see IMR 4451 giving some really impressive velocity with 160gr pt's. I have typically used IMR 7828ssc for 175's and IMR4350 for everything lighter. 4451 sits right between. H4350 & IMR4350 on the burn chart.

Their data appears to give about 100fps edge to 4451. Is this believable? I know I can get the same velocity from 4350 but it is most likely at or above 61,000 psi.

http://i1259.photobucket.com/albums/ii554/sixonetonoffun/Mobile%20Uploads/Screenshot_2015-08-25-22-28-14-1_zpseffbgf39.png (http://s1259.photobucket.com/user/sixonetonoffun/media/Mobile%20Uploads/Screenshot_2015-08-25-22-28-14-1_zpseffbgf39.png.html)

[wbm]

Is this believable?

Hard to say. In their particular test rifle or barrel under their controlled conditions it may well be but that does not mean that it will be "believable" in your firearm. One way to find out.

[darkker]

Yes, it is easily believable.
Few things to remember.
WHO is making that powder isn't the same as the old days. General Dynamics is making that new powder now. They are a MASSIVE defense contractor with some very juicy contacts. The original 4350 patent date is VERY old, so current technology Vs. 1930's era.....

I haven't seen our been able to Pressure test then yet, but suspect given some progressive burning curves I've seen from them; easily possible.
A progressive powder burns with a very flat shaped top, providing a longer push. Classic powders burn curves are very peak like. I've posted a few examples from Pressure testing on this before If you search my name

[yobuck]

Im assuming your referring to the 7mm rem mag?
Weve been using 162 gr Hornadys, both the bthp match and the amax for many years.
In the 7 rem mag we use 65 gr h 4831 which produces velocities of close to 3000 fps in a 24" barrel.
We also use imr 7828 in the 7x300 Weatherby, it being a balistic clone to the 7 stw.
I will say the 7828 produces very good velocity in the 7x300. But ill also say its not a very easy powder to work with
in my opinion. Be very carefull when approaching max charges because the door slams very abrubtly.
Also be carefull when ammo sits for awhile and the bullets sieze onto the case when using near max loads with that powder.

[sixonetonoffun]

Your right on that!

Was mostly asking because have been following some threads where 7977 has been tested and consensus is the 7rm would need 28-30" barrel to reach the tipping point where velocity gains can be made vs 7828 rl22 from a 24-26" barrel. Making it a poor choice for the mid weight bullets in my 24" barrel at that.

The hodgen 7rm data with 7977 for whatever reason appears exaggerated significantly. With compressed loads yielding 100-300 fps less there.

As the 4451 is a little more $ then the 4350 I thought I'd ask if anyone can confirm the lower pressure higher velocity vs 4350 which I have a good supply of.

Adding 100fps without raising pressure could in my estimation get to that next higher node just out of reach with I4350. Which would be imo worth the effort and cost.

The node I am on now sits around 2920-2950 in line with premium factory 160 ammo.

Based on the above lines of reasoning I am skeptical of the published numbers vs my own results and the likelihood the 4350 data published is probably older and doesn't align much with my actual results.

Making a direct comparison of published data virtually useless.

Hence the question.

[acj7382]

Your right on that!

Was mostly asking because have been following some threads where 7977 has been tested and consensus is the 7rm would need 28-30" barrel to reach the tipping point where velocity gains can be made vs 7828 rl22 from a 24-26" barrel. Making it a poor choice for the mid weight bullets in my 24" barrel at that.

The hodgen 7rm data with 7977 for whatever reason appears exaggerated significantly. With compressed loads yielding 100-300 fps less there.

As the 4451 is a little more $ then the 4350 I thought I'd ask if anyone can confirm the lower pressure higher velocity vs 4350 which I have a good supply of.

Adding 100fps without raising pressure could in my estimation get to that next higher node just out of reach with I4350. Which would be imo worth the effort and cost.

The node I am on now sits around 2920-2950 (tel:2920-2950) in line with premium factory 160 ammo.

Based on the above lines of reasoning I am skeptical of the published numbers vs my own results and the likelihood the 4350 data published is probably older and doesn't align much with my actual results.

Making a direct comparison of published data virtually useless.

Hence the question.

im running 61-62 grains of IMR 4831 under a 160 flat base Speer sp. I just bought chrono last weekend and five shot average out of my 26 inch Remington 7 mag was pretty much dead on at 2980 to 3000 fps. Hornady Brass and Remington 9.5 magnum primer. I use same load in 150 ct Noslers but didn't have any loaded to check speed.

[yobuck]

While ive not used the imr 4831 i do believe it is a little hotter than the Hodgen 4831.
I also believe 4831 to be better than 4350 as a 7 rem mag powder for velocity.
At least in factory legnth barrels.

[sixonetonoffun]

darkker you bring good info as usual. I'll just have give it a chance.

Yobuck I have h4831sc on hand will have to add that to the list. I had it in my mind as 270 powder and hadn't really run it in the 7rm. Tried it for 260 rem but went back to 4350 there.

I do know exactly about the door slamming shut on 7828 I am about 1.6 gr's short of it with my 175gr load and toss brass after the 6th firing just to be on the safer side.

acj7382 one of these days I'll do the same and just get the longer barrel 24" is what I have to work with right now. Like I said on a node just like to see if I can step it up to the next one.

[darkker]

Six.
The extra speed isn't from extra pressure per se, the curve is the kicker, especially with the short barrels.
Here are some traces to illustrate the difference in burn curves.
This is "normal"
http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2014-12-26-14-36-09_zpsv6lwcels.png

This is progressive
http://i78.photobucket.com/albums/j84/Darkker13/Mobile%20Uploads/Screenshot_2015-01-11-13-59-58_zpsgm1lkctj.png

At least from testing in the Creedmoor, an extra 100fps will cost you about 10,000 psi with about any powder. So as you can see above you are less than 100 fps slower at @ 10k less pressure.
So is the speed you ask about possible? Certainly possible. Another question to ask, if they would answer you, is testing date and equipment. Many times data doesn't get tested often, and is simply reprinted. Depending whether or not the equipment was modern (strain gauge) they may back down data to be safe. The example is copper crushers. They don't accurately report data above around 45,000 psi. The same reference load shows swings on the order of 20,000. So to be safe, may back there loads down.

[sixonetonoffun]

Interesting how the curve appears very tight on your 4350 load. Yet the superformance has a looser appearing start and ends tight for an es about half of the 4350. Facinating illustration.

[Scott Evans]

Enduron powder, 4166 burned too darned dirty for me to use. Sassy dirty, coal mine in 20 shots.

GD bought the IMR factory in Canada. Just like St Marks (all the ball powders made in the US) in FL. Same places its always been made.

[sixonetonoffun]

I don't mind some residue for this purpose. Aside from changing the load and needing to work it up, this barrel only see's +- 20 rounds a year.

Freebore is a bit tight so I have to go slow with increasing charges. But I also believe it contributes to the accuracy consistently being just a little better then the Remington guys I hunt with. My son included is chasing a new stock and barrel for just this reason.

[darkker]

The residue is an interesting argument.
Many of them are due to the additives, specifically for copper fouling; but is related to operating pressure. The Extreme series looks clean, but causes hard carbon fouling. Comes down to stuff you can see and easily remove, or what you can't see, or remove.

The Traces were for illustration purposes, then Superformance loads were my very first loads. So they weren't tight, since I had done no development.
The IMR plant of GD was totally re-built this last summer.

[sixonetonoffun]

So I tried to chrono some quick loads today. It was cloudy so not sure of accuracy of the results.
All 160 pts.
Went up to 65gr of h4831sc fps 2718.

Magpro went up to 70.9 gr fps 2940.

WM Fed Deerthug 160gr bonded for a baseline of 2724 fps. Advertising 2900. This is consistent with previous results.

Ran my 175gr cor-lokts that were @2860+- last fall got 2782avg today. Hot n humid.

Looks like Magpro is closer to book velocities so far. The h4831sc is well over and shows no signs of being hot. But a long ways from 2900 yet. Will keep going up with it on a better day.

No 4451 yet but would still like to give it a shot.