Frustrating differences in 7RemMag data...

[FiveInADime]

I bought a box of 162gr SST along with another box of 150gr Sierra MKs today.

I've got two cans of Accurate 4350 and Hornady 8th lists a max of 58.4 grains for the 162 bullets (~2900fps out of a 24" Rem 700).

Accurate's data shows a max of 63.4 for 2890fps (162 A-Max). What the heck? A FIVE-GRAIN discrepancy!!! 63.4 seems like a lot but I've been told to trust the powder manufacturer data over the bullet manufacturer data.

My rifle:

Winchester M70
1:9.5" twist
26" barrel

Using:

Winchester cases
CCI BR-2 primers


Anyone have experience loading with 4350 powders and 162gr bullets?

 

[Jimro]

It isn't a discrepency, it's data.

The SST and the Amax may look similar on the outside, but they are consctructed a bit different, especially in the jacket.

That difference in construction shows up in barrel friction differences between the two. The Amax will have less friction because it has a thinner jacket that is more easily deformed by the rifling, so you can use more powder to get the same pressure levels as a bullet with the same weight (mass) but has more friction because of a thicker jacket that takes more energy to deform in the rifling.

This shows up a lot, and you can usually see it most easily with boat tail verses flat base cup and core bullets. The flat base bullets have a direct line of gilding metal all the way across the base that resists deforming a lot more than a boat tail that only has to deform lead.

I hope this helps.

Jimro

 

[ligonierbill]

And the only data that really counts is the data from your rifle. My 700 7 mag doesn't like those 162 SST. I have no idea why. Use the manufacturers' information to set a starting point and work up your load.

 

[Bart B.]

There are several things that easily cause a 50 fps difference in muzzle velocity for a given cartridge, bullet, powder and primer combination:

Powder lot to lot differences.

Barrel's bore and groove diameters; smaller ones shoot bullets out faster.

Case neck grip on the bullet; more causes higher velocity.

How rigid the rifle's held; tighter causes higher velocity. A 75 fps spread across a few people shooting the same rifle and ammo is normal.

Bullet's jump distance to the rifling.

---------------

Depending on how much of each of these variables adds up with you and your stuff, a 100 to 150 fps difference is possible for a given set of components used by several people in different rifles. I've never owned a chronograph but borrowed one a few times out of curiosity.

 

[FiveInADime]

It isn't a discrepency, it's data.

The SST and the Amax may look similar on the outside, but they are consctructed a bit different, especially in the jacket.

That difference in construction shows up in barrel friction differences between the two. The Amax will have less friction because it has a thinner jacket that is more easily deformed by the rifling, so you can use more powder to get the same pressure levels as a bullet with the same weight (mass) but has more friction because of a thicker jacket that takes more energy to deform in the rifling.

This shows up a lot, and you can usually see it most easily with boat tail verses flat base cup and core bullets. The flat base bullets have a direct line of gilding metal all the way across the base that resists deforming a lot more than a boat tail that only has to deform lead.

I hope this helps.

Jimro

Hornady lists the same data for all the bullets of a weight range. I guess they just list the max charge for the bullet that has the most friction in it's weight range? Still 5 grains difference is A LOT in my mind.

What velocity should I shoot for with the 162 SSTs in my gun?

There are several things that easily cause a 50 fps difference in muzzle velocity for a given cartridge, bullet, powder and primer combination:

Powder lot to lot differences.

Barrel's bore and groove diameters; smaller ones shoot bullets out faster.

Case neck grip on the bullet; more causes higher velocity.

How rigid the rifle's held; tighter causes higher velocity. A 75 fps spread across a few people shooting the same rifle and ammo is normal.

Bullet's jump distance to the rifling.

---------------

Depending on how much of each of these variables adds up with you and your stuff, a 100 to 150 fps difference is possible for a given set of components.

I was more concerned with Accurate's max load for the A-Max being 5 grains more than Hornady's listed data. Not so much the useless listed velocities.

63.4gr is more A4350 than I can find as a published max for 150gr bullets.

 

[FiveInADime]

And the only data that really counts is the data from your rifle. My 700 7 mag doesn't like those 162 SST. I have no idea why. Use the manufacturers' information to set a starting point and work up your load.

I had some disposable funds to spend on bullets and powder. Figured I would try a new bullet and it was between the SST and the cheaper 162 SPBT Interlocks. Just couldn't talk myself into buying a box of Bergers at $46. Maybe if those SSTs don't work out.

 

[SonOfGun]

A FIVE-GRAIN discrepancy!!!

Really??

Accurate and Hornady would have to use the exact same equipment and components to achieve the same results.

Different test, different results.

I am sure somewhere in those manuals it will state that MAX loads was for their equipment. It will also state to start low and work up for YOUR load development.

 

[FiveInADime]

Really??

Accurate and Hornady would have to use the exact same equipment and components to achieve the same results.

Different test, different results.

I am sure somewhere in those manuals it will state that MAX loads was for their equipment. It will also state to start low and work up for YOUR load development.

I know. Sorry about the hyperbole. I still think 5 grains is a lot with this relatively fast powder for this cartridge.

I just wanted some people to post their opinions and maybe some experience with similar loads.

 

[Clark]

I average 3023 fps with 180 gr Berg VLD and Re22
I average 2970 fps with 162 gr HNDY SST 62.8 gr H4350 [wimpy load]
I average 3356 fps with 150 gr Nos BT and H4350
I average ~ 3400 fps with 140 gr Nos BT and H4350
I average 3633 fps with 120 gr Nos BT and H4350

 

[FiveInADime]

I average 3023 fps with 180 gr Berg VLD and Re22
I average 2970 fps with 162 gr HNDY SST 62.8 gr H4350 [wimpy load]
I average 3356 fps with 150 gr Nos BT and H4350
I average ~ 3400 fps with 140 gr Nos BT and H4350
I average 3633 fps with 120 gr Nos BT and H4350

Thanks Clark.

I will probably work up to 63 grains with the A4350.

It seems to me that 7mag data is really scattered all over the map. If I get your velocity I will be perfectly happy with that.

 

[Bart B.]

5inaDime, what velocity should anyone shoot for with any bullet in their gun?

I think that's the backwards way to develop loads unless you're going to shoot them in several rifles with the same sights. That way, the sight dope for different ranges with each rifle won't change. Such was life at Lake City Army Ammo Plant developing loads for 30 caliber match ammo used in thousands of M1 and M14 rifles with the same sights. They get virtual equal accuracy in a 1 grain (or more) spread in charge weight but adjust the charge to get the fps +/- 30 of the ammo's spec.

Use a near or at max load that gives best accuracy. It doesn't matter if each lot of powder produces some fps number within a 30 to 60 fps spread. I used the same charge weight for different lots of powder in different barrels for the same bullet for the same cartridge and never saw any change in accuracy, but I know the average muzzle velocity had a 50 fps spread as long range elevation zeros changed a bit.

What difference does it make that matters if an accurate load's 25 or 75 fps different in speed in your rifle compared to what some load recipie lists?

 

[FiveInADime]

5inaDime, what velocity should anyone shoot for with any bullet in their gun?

I think that's the backwards way to develop loads unless you're going to shoot them in several rifles with the same sights. That way, the sight dope for different ranges with each rifle won't change. Such was life at Lake City Army Ammo Plant developing loads for 30 caliber match ammo used in thousands of M1 and M14 rifles with the same sights. They get virtual equal accuracy in a 1 grain (or more) spread in charge weight but adjust the charge to get the fps +/- 30 of the ammo's spec.

Use a near or at max load that gives best accuracy. It doesn't matter if each lot of powder produces some fps number within a 30 to 60 fps spread. I used the same charge weight for different lots of powder in different barrels for the same bullet for the same cartridge and never saw any change in accuracy, but I know the average muzzle velocity had a 50 fps spread as long range elevation zeros changed a bit.

What difference does it make that matters if an accurate load's 25 or 75 fps different in speed in your rifle compared to what some load recipie lists?

Thanks Bart,

I don't expect my results to match any one else's I just more or less wanted to see what others were getting and how much powder it took to do that.

More or less I just post on here to pacify my itch to be shooting until the next range trip, lol. I really do like figuring things out myself.

 

[GeauxTide]

Having owned and loaded for several 7mags over the years, one thing is constant - there is a GREAT variation in load data and performance. Example, a load I used in 1969 that I considered a working max was blowing primers 20 years later in a different rifle. Powder has changed, too. FWIW, I've never had success with any bullet at 160 or better with anything faster than H-4831. I've had the best success with Hornady 154 and 162 with IMR7828.

 

[FiveInADime]

Having owned and loaded for several 7mags over the years, one thing is constant - there is a GREAT variation in load data and performance. Example, a load I used in 1969 that I considered a working max was blowing primers 20 years later in a different rifle. Powder has changed, too. FWIW, I've never had success with any bullet at 160 or better with anything slower than H-4831. I've had the best success with Hornady 154 and 162 with IMR7828.

Thanks for the response. If I can't find an accurate load with A4350 and 162SSTs I'll try out a slower powder like 7828 or RL22.

Isn't IMR-7828 slower than H-4831?

 

[hooligan1]

5In a dime, dont you have a "burn rate"chart? It would be a necessary part of any handloaders tool box..

FWIW, I use IMR 7828 for two bullets and my 7mm rem mag, the 160 grain Accubond and the 168 grain Berger VLD hunting bullet,noy even max and very consistant, although haven't shot over my chrono so dont have the velocity...

 

[std7mag]

Hmmm, my Lee manual doesn't even list A4350 for either of those loads.
Neither does my Nosler Manual (powder for bullet weight).
Nor does my Sierra manual (albeit it's the 2nd edition)

My Load data book (yes, I know, it's old data) in the Accurate powder section is showing 61.0gr. for a Sierra BT
For the 160gr. Nos SP it lists 57.0gr.
Those are the max loads listed.
The Sierra section does not list A4350 at all.
And the Hornady section lists the 162gr. A-Max at 58.4gr. A4350 at 2900FPS.


I knew there was a reason that I use RL25 for the Rem Mag.

 

[GeauxTide]

OOPPPSSS

Thanks for the response. If I can't find an accurate load with A4350 and 162SSTs I'll try out a slower powder like 7828 or RL22.

Isn't IMR-7828 slower than H-4831?

I should have typed FASTER than H-4831. Very sorry.

 

[FiveInADime]

Hmmm, my Lee manual doesn't even list A4350 for either of those loads.
Neither does my Nosler Manual (powder for bullet weight).
Nor does my Sierra manual (albeit it's the 2nd edition)

My Load data book (yes, I know, it's old data) in the Accurate powder section is showing 61.0gr. for a Sierra BT
For the 160gr. Nos SP it lists 57.0gr.
Those are the max loads listed.
The Sierra section does not list A4350 at all.
And the Hornady section lists the 162gr. A-Max at 58.4gr. A4350 at 2900FPS.


I knew there was a reason that I use RL25 for the Rem Mag.

I have a very mild and accurate load with IMR-4350 and the SIERRA 150gr HPBT already. It's at 7mm-08 velocities and recoil, however.

We'll see how the A4350 works out with the 162s probably on Friday. If I can't get accuracy at near max loads I'll go with a slower powder for those.

 

[FiveInADime]

5In a dime, dont you have a "burn rate"chart? It would be a necessary part of any handloaders tool box..

FWIW, I use IMR 7828 for two bullets and my 7mm rem mag, the 160 grain Accubond and the 168 grain Berger VLD hunting bullet,noy even max and very consistant, although haven't shot over my chrono so dont have the velocity...

I do have a burn rate chart in each of my loading manuals. You'd have to read the post I quoted to understand why I posed that question.

He said he wouldn't use any powder slower than H4831 for 160gr+ bullets, but he meant faster.

 

[hooligan1]

Now that I have re-read his reply, I gothca fiveinadime...carry on man...