7.5 Swiss

[Andy]

Note that Hodgdon did not provide pressure data - that's because they didn't take any, because in this case it was guesswork. I already stated that I shot 25 rounds with 45.0 grs of H4350 and my average MV was 2100 fps. 46.0 is not going to give me 2550. My chrony works fine.

Look at Hodgdon's data for the 30-40 Krag - a round that is 10% smaller in capacity than the 7.5x55 and has a very similar SAAMI pressure limit. Hodgdon states 46.0 grs of H4350 (more than for the larger 7.5x55) and state an MV of 2110 fps - 450 fps slower than they state for the 7.5x55. The 30-40 load is believable, but again they don't provide pressure data because they don't have it.

There are many other examples like this on the Hodgdon site. Those that cling to published data are stuck with it.

GP11 contains about 49.5 grs of powder. I bet its Burn Rate is right beside H4350.

[dogtag]

I have a 1911 and the Lee dies work just fine.

[Andy]

178gr Hornady Amax, 2.900" OAL

44.0 grs IMR4064 - avg MV of 2575 fps. Very consistent, very accurate, and a max load IMO

50.0 grs H4350 - avg MV of 2525 fps. Very consistent, accurate, about 3 grs below max IMO (i.e. 2650 fps).

These two loads closely mimic GP11. The listed Hodgdon loads must be estimates, and poor ones at that. The 7.5x55 is just a bit lower in capacity than the 30/06 and has the same bore size, yet Hodgdon lists loads for the 7.5x55 with almost 10 grs less than the 30/06 in some cases.

[Andy]

178gr Hornady Amax, 2.900" OAL

44.0 grs IMR4064 - avg MV of 2575 fps. Very consistent, very accurate, and a max load IMO

50.0 grs H4350 - avg MV of 2525 fps. Very consistent, accurate, about 3 grs below max IMO (i.e. 2650 fps).

These two loads closely mimic GP11. The listed Hodgdon loads must be estimates, and poor ones at that. The 7.5x55 is just a bit smaller in capacity than the 30/06 and has the same bore size, yet Hodgdon lists loads with 7 fewer grs in many cases.

[gunner]

I use for my G 11

167grs. Lapua Silver Scenar
44,0 grs. VV N140
CCI BR 2
OAL 2.97"
2418 fps.

The load has a good accuracy ( around 40 mm )

[tony549]

I have the following for one 7.5x55 unfired brass case manufactured by Ruag:
Brass wt = 12.3 grams.
Water wt = 4.15 grams [64.0 grains](full to top of case neck).
or = 58.2 grains [corrected to base of case neck].

I managed to scrounge up an old Hodgden Load Data Manual No. 26. It implies that that their loads for 7.5x55 are ~40,000+ CUP. The muzzle velocities are quoted for a barrel length of 31 inches, which could explain the velocity differences seen above [180 gr bullet, 46.0 gr. H4350, 2566 ft/sec]. Hodgden stated that their loads are appropriate for 1911 S-R rifles.

On another website I saw a copy of the CIP data page for 7.5x55 GP31, dated 6/14/1984. It listed a Pmax of 3800 bar [~55,000 psi (transducer)].

Vihtavouri's max load for 7.5x55, with 167 gr Scenar, is 45.7 gr VV N140, for a MV of 2493 ft/sec [23.5 inches barrel length]. I recall that VV used CIP max pressure limits.

In my opinion Gunner's or Andy's loads appear to be good to go as reload data guides and I will use them accordingly for my K31's.

[gunner]

Hi tony549 !

I have also a load for the K31 that i use.

170grs Lock Base Lapua
43.2grs VV N 140
OAL 2.97"

The Load is very accurat in this K 31 ( at least if work great on the rifle :-) )
I use it with a scope so the shot group is around 18 - 25 mm at 100m.

gunner

[Andy]

.....I managed to scrounge up an old Hodgden Load Data Manual No. 26. It implies that that their loads for 7.5x55 are ~40,000+ CUP. The muzzle velocities are quoted for a barrel length of 31 inches, which could explain the velocity differences seen above [180 gr bullet, 46.0 gr. H4350, 2566 ft/sec]. Hodgden stated that their loads are appropriate for 1911 S-R rifles....

Thanks - that explains it I think. The Hodgdon loads are max for 1911 rifles (e.g. pre-K31) and the MV's are listed for a 31" barrel. You'd expect 200+ fps less with the K31's 23.5" barrel, and a higher Max load in the stronger K31 action. They either don't have pressure readings, or left them out for their own reasons.

[andiarisaka]

3800BAR = 55,114PSI The method used was transducer and this is for the GP11 ammo. Andy your loads appear to be more in line with my thinking, on the various Swiss rifle sites, I thought they were posting some pretty weak data. One site even removed the CIP pressure from the data sheet. I think many are afraid someone will use data for the K31 in the older and weaker rifles. Considering the capacity of a case once fired in a K31, I imagine even your 50gr, of 4350 is mild pressure-wise. N140 has a burn rate similar to 4064 so your data is good there as compared to VV's max, remembering there's 11gr more bullet.

[Andy]

3800BAR = 55,114PSI The method used was transducer and this is for the GP11 ammo. Andy your loads appear to be more in line with my thinking, on the various Swiss rifle sites, I thought they were posting some pretty weak data. One site even removed the CIP pressure from the data sheet. I think many are afraid someone will use data for the K31 in the older and weaker rifles. Considering the capacity of a case once fired in a K31, I imagine even your 50gr, of 4350 is mild pressure-wise. N140 has a burn rate similar to 4064 so your data is good there as compared to VV's max, remembering there's 11gr more bullet.

What has happened is a common phenomenom. A guy named "St Pierre" was an early poster of load data, and it has been copied ad nauseum on various Websites and Forums, in the process taking on an aura that it is "Gospel". A dearth of other load data, and what Hodgdon has posted, only adds support for it.

Anyone who dares to challenge it, is pointed back to other posts (all with a common origin) that supposedly refute them. Cries of "unsafe, unsafe" abound, and the heretic is silenced. To be fair to many reloaders, they are "cookbook reloaders" who don't really understand things like pressure, powder burn rate and the like, so they rely on "safe" (read published) loads. It's the "experienced" guys who put out the challenge.

To be fair to St Pierre too, I have never seen him claim that they are max loads, just that they are accurate in his guns. I don't always use max loads, but like to know what they are, as accurate loads are often max loads - the case with IMR4064, but not (for me anyways) with H4350.