Need help, Load discrepancy Swift vs Hodgdon

[davidg8480]

I need some help here gang, I'm really confused and maybe I'm just missing something. I started loading up some 338 rum rounds using Swift a frame 275 GR. My confusion is...
In the Swift load manual, using H-4831Max.load...78gr.
On the Hodgdon website using H-4831 max load...86gr. A freaking 8gr.difference??
Can someone enlighten me why thereissuch a large difference?
Thanks David

 

[JimP]

Different manuals.

There can also be a misprint.

This is also why they tell you not to start out at the max loads.

I found a well known manual that listed some loads for a 7mm Rem mag, if you would of even started at the minimum load you would of seen over pressures. I contacted them and they sent me the correct data, but they never did anything about what was printed until their next manual came out.

 

[davidg8480]

@JimP That's kinda what I was thinking.
Thank you sir.

 

[pilar]

This is what I have

 

[shootist~]

And QuickLoad shows it roughly halfway in-between with 82.0 grains H4831 still a little under max pressure. This was using COL as 3.490" (same as Hodgdon) instead of the QL default of 3.600" COL.

Sounds like some major differences in case volume and barrel wear. My SWAG. I do not have a 338 RUM.

 

[Jefferry404]

the 3.49 OAL is correct for the 275gn Swift (their bullets are usually seated deep). And both were using Remington cases. My experience with Swift manual is the loads seem conservative.
for what is is worth:
250 gn bullet, h4831, 338 RUM
Manual max load
Barnes 84.0gn
Hornady 87.5gn
Hodgdon 90.0gn
Lyman 88.5gn (note this is for 250gn Swift A-frame)
Speer 89.0gn
Swift 83.0gn

Lyman 84.5gn (for 275gn Swift A-frame)
Hodgon 86.0gn (for 275gn Swift A-frame)
Swift 78.0gn (for 275gn Swift A-frame)

 

[AimSmall]

Sounds like the exact reason we start low and work up! Glad to see you cross-checking. Seems we never can have enough load data.

 

[Lance Hopper]

If I remember correctly, swift A-frames, use a pure copper jacket. Also, the bearing surface may be considerably longer than the bullets. The Hodgdon manual was using. This would cause a lot higher pressure than with gilding metal jackets, and or shorter bearing surfaces.

 

[Hunter4752001]

The Swift data shown doesn't list the parameters ie barrel length, twist, primer etc. Maybe that was on a different page. The parameters often affect the loads. Swift also didn't list the pressures. Maybe they take a more conservative approach. Unfortunately there's nothing unusual about published loads being very different.

Irrespective I'd start a load ladder starting at the bottom end of the Swift data and working it up a bit at a time. Your rifle and brass will always be different to what was used for testing. Ultimately, it's your hide so take the time to be safe.

 

[davidg8480]

Looking closer and deeper into everybody's input and looking at all sorts of data supplied and researched . I've come to the conclusion that maybe, combined Over all length May have something to do with the discrepancy and load charges. Apparently the Swift load book has a listing of 3.60 for c o l and all others that have been submitted and researched c o l is listed as 3.490 that is a difference of .105 inch that's a big freaking jump. WHAT DO you think?

 

[shootist~]

Looking closer and deeper into everybody's input and looking at all sorts of data supplied and researched . I've come to the conclusion that maybe, combined Over all length May have something to do with the discrepancy and load charges. Apparently the Swift load book has a listing of 3.60 for c o l and all others that have been submitted and researched c o l is listed as 3.490 that is a difference of .105 inch that's a big freaking jump. WHAT DO you think?

Wrong direction. (The pressure, per QL, goes up when you shorten the COL. (Assuming there is no other issues such as a short throat.)

 

[shootist~]

The idea of a ladder test is a good one.

Possibly one grain increments, one round each.

 

[davidg8480]

The idea of a ladder test is a good one.

Possibly one grain increments, one round each.

Good idea one round each,338 swifties are getting hard to find. My main goal is accuracy though,this load is for a crocodile hunt.

 

[Jefferry404]

Swift manual only shows the maximum Saami OAL, not what they actually load the cartridge. For me, I always load and crimp to the top of the cannelure to prevent bullet setback from recoil. The 3.49" OAL per Hodgdon is to the top of the cannelure. Swift A-frames have a wide cannelure, around 80/1000".

 

[rookhawk]

I need some help here gang, I'm really confused and maybe I'm just missing something. I started loading up some 338 rum rounds using Swift a frame 275 GR. My confusion is...
In the Swift load manual, using H-4831Max.load...78gr.
On the Hodgdon website using H-4831 max load...86gr. A freaking 8gr.difference??
Can someone enlighten me why thereissuch a large difference?
Thanks David

View attachment 591746View attachment 591747

Not speaking to you like an idiot, but a common, deadly mistake people can make is conflating different powders.

IMR4831 is not the same as H4831 and its not the same as IMR4831SC

People risk death all the time by confusing those loads. It may be that some lawyers at reloading manual companies protect themselves by publishing the lower load levels of the one powder versus the other knowing people make this mistake.

 

[davidg8480]

Yes sir .

 

[RayAtkinson]

Not to mention that the old service milsurp 4831 will give highest velocity at much less pressure than anythinh on todays market, the stuff Jack O'Conner shot 63 gr. in his 270. I have about 20 or so of that good stuff. left over from a SS 150 lb keg I bought 40 years ago and its still fresh and clean..but cuts grains terribly, I only use it in the 270 and 06 from time to time.

 

[Jefferry404]

Buried in snow here, nothing better to do...
Using Hodgdon manual and of all the load data, only the 7mm-08 has data for hornady and swift a-frame same bullet weight. Here is the data:

Hodgdon Data:7mm-08		powder	charge	vel.	psi
139 gn hyd sp, OAL=2.800, 1.157, 0.382		h414	45.5	2710	43339
140 gn swf sp, OAL=2.750, 1.115, 0.390		h414	46.0	2791	57133
139 gn hyd sp, OAL=2.800, 1.157, 0.382		h335	37.5	2585	46825
140 gn swf sp, OAL=2.750, 1.115, 0.390		h335	37.5	2647	57588

As this shows, particularly for h335, with nearly identical seating depth, the A-frame has higher pressure.

Below is Swift Data. Pressure not listed but for the exact same charge, shows higher velocity and would in resulthigher pressure.

Swift Data:7mm-08		powder	charge	vel.	psi
140 gn swf sp, OAL=2.750		h414	45.5	2813	na

Using Quickload and fitting the hornady bullet to match the hodgdon data shows:

QuickLoad Data:7mm-08		powder	charge	vel.	psi
139 gn hyd sp, OAL=2.800		h414	45.5	2709	43377
140 gn swf sp, OAL=2.750		h414	46.0	2831	55836
QuickLoad Data:7mm-08		powder	charge	vel.	psi
139 gn hyd sp, OAL=2.800		h335	37.5	2585	46710
140 gn swf sp, OAL=2.750		h335	37.5	2634	55929

The default shot start pressure for hornady is standard 3625psi whereas the default for swift is 10733!
and this accounts for the higher load pressure. A-frames are suppose to be pure copper, thick jackets and with the copper partition, looks like harder to start into the rifling.

BTW, Quickload has the same 10733 shot start for all the A-frames in its database.

Steve

 

[Nevada Mike]

Because of the partition in the Swift AF the bullets are less compressible than standard cup & core bullets. This could elevate pressures a bit.

 

[meigsbucks]

There is a difference between most manuals. However, being an owner of a .338 RUM (You have good taste), I too found Hogdon’s data high.