Need help, Load discrepancy Swift vs Hodgdon

[sgt_zim]

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

GRT shows same starting pressure for swift, talked to them about it on their discord channel because my MVs weren't anywhere near what GRT and QL say it should be, like a couple hundred fps slower than predicted

10k starting pressure is just wrong. My LD with A Frames shows them with an initial pressure of every other jacketed bullet I've ever worked loads for - 3625 psi

10k should be expected from monolithics, not from jacketed bullets.

 

[Jefferry404]

GRT shows same starting pressure for swift, talked to them about it on their discord channel because my MVs weren't anywhere near what GRT and QL say it should be, like a couple hundred fps slower than predicted

10k starting pressure is just wrong. My LD with A Frames shows them with an initial pressure of every other jacketed bullet I've ever worked loads for - 3625 psi

10k should be expected from monolithics, not from jacketed bullets.

Well, as the saying goes "a man with one watch knows what time it is but a man with 2 watches never knows" or as Bob Vyne of Motorola used to tell me as a young engineer "who's who in the zoo".
below is the data from the Hodgdon Manual No. 27 that I used:

for the same h335 load, swift shows higher pressure and velocity vs the Hornady.
below is the Saami data for the 7mm-08

and you can use the CUP and PSI to convert the Hodgdon table to PSI. Doing this,
shows the Swift has 8329psi higher pressure and higher velocity 62fps.
If one fits QL to the Hornady load and adds the 10733psi shot start pressure, then
QL Hornady load shows 2630fps and 58550psi which now compares to the Swift load
Hodgdon published data 2647fps and 58419psi!
If one then uses the Hornady fitted QL and runs the Swift bullets (with the higher shot pressure), the QL results: 2627fps and 59118psi
compared Hodgdon manual 2647fps and 58419psi.

So, is the QL shot start pressure a convenient way to model the Swift bullet or does it actually take more start pressure for it to engage the rifling?

PS
The Hodgdon data is based upon physical measurements, not simulations, so I would bow to their
authority.

 

[sgt_zim]

My understanding of at least the way GRT calculates IP is a function of 3 things

• bearing surface
• jacket composition - copper is softer than copper/zinc
• core composition - lead is softer than copper, gilding, and way softer than steel

What I have learned from both GRT and QL data is the importance of ladders. I do either 15- or 20-shot ladders in 0.2 gr increments for small bore, and 10-shot ladders in 0.5 gr increments for anything larger than 308 Win.

I wasn't aware that Hodgdon did actual physical pressure measuring. That certainly seems to be a better way of doing things.

 

[davidg8480]

Well, as the saying goes "a man with one watch knows what time it is but a man with 2 watches never knows" or as Bob Vyne of Motorola used to tell me as a young engineer "who's who in the zoo".
below is the data from the Hodgdon Manual No. 27 that I used:

View attachment 596754
for the same h335 load, swift shows higher pressure and velocity vs the Hornady.
below is the Saami data for the 7mm-08
View attachment 596755

and you can use the CUP and PSI to convert the Hodgdon table to PSI. Doing this,
shows the Swift has 8329psi higher pressure and higher velocity 62fps.
If one fits QL to the Hornady load and adds the 10733psi shot start pressure, then
QL Hornady load shows 2630fps and 58550psi which now compares to the Swift load
Hodgdon published data 2647fps and 58419psi!
If one then uses the Hornady fitted QL and runs the Swift bullets (with the higher shot pressure), the QL results: 2627fps and 59118psi
compared Hodgdon manual 2647fps and 58419psi.

So, is the QL shot start pressure a convenient way to model the Swift bullet or does it actually take more start pressure for it to engage the rifling?

PS
The Hodgdon data is based upon physical measurements, not simulations, so I would bow to their
authority.
View attachment 596756

You guys are on such a different level than I am when it comes to reloading ,so I kind of keep my mouth shut my ears open. Sort of.

Now, going back to my original post, now I see why there might be such a wide discrepancy in published load data; in a nutshell, ( hodgdon / swift) actual measurement / simulation. Maby ?

 

[Jefferry404]

Davidg8480,
actually, I compliemnt you for questioning! Your question stirred my interest and I generated the info in this thread from my study. Thanks
For now, my working hypothesis is that due to the thick copper jacket and copper partition, the Swift needs higher pressure to engage the rifling. This powder combustion peak barrel pressure adds to shot pressure and hence there is higher velocity.

below is cros-section of the swift and hornady. Clearly, there is a thicker copper jacket and the substantial copper partition (which to Mr. sgt_zim point regarding mono-bullets)

sgt_zim,
I checked my reloading notes and for my 338 winmag and 375HH using Swift A-frame was 100-150fps slower than expected. My QL file had app 4150psi shot pressure and my notes say was the default (2 years ago). I recently updated and now see the 10775 pressure and will use this going forward until more info. I do have an email into Neco regarding the Swift shot pressure.

I have moved away from ladders and have been using OBT (optimum barrel time) with good success. I modified that concept for hunting purpose. It takes 3 calibration shots and then usually 3 more to verify. If there might be interest in this, can post more info. thanks
Steve

 

[Rule 303]

A reloading manual I have lists 86 grains of AR2213SC as max load for a 275 grain bullet. No mention of what make.

AR2213SC is rebadged by Hodgdon to H4831SC and IMR4831SC. If the powder does not have the SC (Short Cut) and is branded H4831 this is AR2213. The SC is a slightly different powder. The strands of powder being shorter, hence Short Cut. Do not substitute one for the other.

 

[FlyGuy]

@David G,
Really good Swift A-Frame loads take time.
Most of your other data points to higher loads than the manual with H4381but,
I’ve found that Swift bullets respond well to old school, load development methods that result in excellent accuracy.
Start at 0.020 / 0.030” off the lands or magazine length.
Start low (75gr) and work up in 0.6gr increments for a case like a 338 Rum.
Ladder/pressure tests at 300 to look for accuracy windows or pressure signs.
Group tests around the charges identified in the ladder test at 100 yards.
Fine tune seating depth if needed.

 

[Graham Hunter]

My friend had the same problem with Nosler load data in his 416 Rigby. Way to hot.

 

[Rule 303]

My friend had the same problem with Nosler load data in his 416 Rigby. Way to hot.

That would take some massive mistake to make the 416 Rigby to hot as the manuals have it loaded to produce around 2400 FPS with a 400 grain bullet. Yet it can safely be loaded to near 416 Weatherby velocities of 2700FPS

 

[Rule 303]

@David G,
Really good Swift A-Frame loads take time.
Most of your other data points to higher loads than the manual with H4381but,
I’ve found that Swift bullets respond well to old school, load development methods that result in excellent accuracy.
Start at 0.020 / 0.030” off the lands or magazine length.
Start low (75gr) and work up in 0.6gr increments for a case like a 338 Rum.
Ladder/pressure tests at 300 to look for accuracy windows or pressure signs.
Group tests around the charges identified in the ladder test at 100 yards.
Fine tune seating depth if needed.

You blokes like burning out barrels in load development. I take we are talking hunting accuracy not benchrest. Just try a couple of different powders with the bullet seated so that it will feed without problems and take the load that gives you the tightest group and go hunting.

I learnt from experience. Too much time at the range and not enough out hunting.

 

[FlyGuy]

You blokes like burning out barrels in load development. I take we are talking hunting accuracy not benchrest. Just try a couple of different powders with the bullet seated so that it will feed without problems and take the load that gives you the tightest group and go hunting.

I learnt from experience. Too much time at the range and not enough out hunting.

The sub 0.5” load work up I did for this hunting season, took less than 30 shots to accomplish.
Used a powder and cases that I know well. The rest was easy.

 

[Rule 303]

The sub 0.5” load work up I did for this hunting season, took less than 30 shots to accomplish.
Used a powder and cases that I know well. The rest was easy.

You already had a head start by using known components in a rifle you knew. Some times you strike it lucky and get what you are after quickly. Great when that happens.

 

[davidg8480]

Never too much time at the range.

 

[Jefferry404]

from the Swift Manual #2:

Good to know loads are based upon measurements.

 

[Inline6]

Never too much time at the range.

How many barrels have you burned out?

 

[TXTad]

I have moved away from ladders and have been using OBT (optimum barrel time) with good success. I modified that concept for hunting purpose. It takes 3 calibration shots and then usually 3 more to verify. If there might be interest in this, can post more info. thanks
Steve

I am very interested in hearing about this.

 

[davidg8480]

How many barrels have you burned out?

Maby #6
Why you ask ?

 

[Jefferry404]

I am very interested in hearing about this.

below is link for optimum barrel time paper.

http://www.the-long-family.com/OBT_paper.htm

It boils down to the speed of sound in steel (that how vibrations travel).The vibration wave
from the Pressure pulse travels back and forth down the barrel until it dissipates. When the
travelling wave hits the end of the barrel, there is a slight distortion at the muzzle and then it is
reflected back towards the action, etc. If the bullet is timed to exit the barrel between these reflections, there is no distortion and the bullet has the best change to exit to the same point of impact.
You need a ballistic program that estimates the bullet travel barrel time, I use Quickload.
All my barrels are integral with mostly the same actions, wood stock, perhaps one reason OBT
working good for me.
Steve

 

[Inline6]

Maby #6
Why you ask ?

Range time mean different things to different people. I spend time on the range, it's usually shooting matches.

Load development is not something I care to burn up barrels and components with. Most barrels will take between 150 to 200 rds to get to a break in point where you can actually figure out what is truly going to happen with your barrel. Unless you are chasing benchrest accuracy, most hunting rifles will do .5 MOA or better if the shooter is capable. No need in trying get every .001" out of it.

Then I know some people that build custom rifles that will burn a barrel out in 500-600 rds. To each their own. Most people can use more practical shooting i.e. off the sticks or field positions vs off a bench chasing groups.

 

[FlyGuy]

How many barrels have you burned out?

Burn out as many barrels as you can, I say…
Shooting is enjoyable, so it doesn’t matter if it’s chasing small groups at the range, developing multiple loads, shooting competitions or filling refrigerated trucks with venison. When the barrel is cooked, screw in another one and keep going.

Globally, most of the youngsters today couldn’t care less about hunting and shooting, so why leave them a safe queen in pristine condition with a hardly used barrel?