Home Forums Reloading Big Game Rifles working up to maximum loads with limited information to go on.....7x64

Here's my project: I wanted a light, efficient long range big game rifle to compliment my current .308 and 35 Whelen. I did not want a belted magnum, and thought the .280 would be a good choice. I found a nice old Brno 21h 7x64, with a 23.5" barrel. I thought "Eureka!" and brought it home.

Load data seems scarce for the 7x64 Brenneke. Most US data says "use 280 loads" but a lot of 280 data is very moderate, SAAMI holds the 280 to lower pressure than the 270 or 7mm RM for instance. Factory loads were unavailable, so I started loading with new components.

The max. load in some Swedish data showed V160 at 57.3 gr. for 2903 fps. Some other European data showed up to 57.4 grains of N160 for 2850 fps as max. load.

I did find one bottle of Vihtavuori N160 powder, and worked up a 160 gr. Nosler Partition to 2800 fps. 57 grains did the trick in Norma cases. It seemed like a good load. So at least I had one good benchmark to work from.

I wanted to use a more common North American components, and so I chose IMR4831, Remington cases, and Remington 9-1/2 primers.
Speer, IMR and other US data sources like LoadData showed 54 grains max. with 160 gr bullets for about 2650 FPS. I worked up to that with 160 gr. Speer MT and 160 Nosler partitions, and velocity was as expected, only 2600 when checked on my Chrony. If I could be satisfied with 2600 I would just keep shooting my .308s with 165's.

I kept going, and reached 2850 fps at 57 grains of IMR4831 with no flattened primers, no sticky bolt lift, and good accuracy. That was the velocity I was looking for. But the 2850 fps was way above what US data sources said I should stop at. So to see if repeated firing would loosen primer pockets I shot off three shells, reloaded with the same stiff load and shot off again, and did this a total of three times.

All three primer pockets seem just as tight after four firings, when seating primers with a Lee hand prime tool.

After working up that load, I finally found some factory loads to compare with. A box of German RWS was loaded with 177 grain bullets. I chronographed them, and found they averaged 2706 fps. A pretty hot load for a heavy bullet. I also found some American made Hornady 160 gr SST that were only going 2660.

I cannot find any Remington factory loads to compare case head expansion or velocity with my handloads.

So, would the more experienced loaders here say about the load I came up with, is it safe for MY rifle?

CNB--can't recall which manual but I'm pretty darn sure I have an older one around the house that has info for the Breneke in it. I'll take a look around and see what I can'find.

Also, seems to me that Waters had it in his book as well?

Dober

I just did a little reverse engineering and extrapolating of Hodgdon's data for the 280 using 160 grain bullets with H4831, a slightly slower powder than the IMR you're using.

It looks like you would need around 58.9 grains of H4831 to get to 2850 fps. The problem is the pressure looks to be a bit above 58000 CUP. That's CUP mind you, not PSI. A certain conversion suggests that's a little over 70000 PSI.

The IMR4831 is a quicker powder than the H, so if my H4831 numbers hold any water it's pretty certain you're running a hot load.

I'm not telling you with certainty you're running hot, pressure signs or no. What I am saying is I wouldn't keep doing it without more info if I were in your shoes.

Please be careful.

thanks Dober & Mathman
Mathman, I'm paying attention to your calculation, and 58,000 CUP is scary. I just don't know about extrapolating data like that. I realize I'm in somewhat uncharted territory here. I don't need to shoot off the loads I have on hand. (It's not hard to pull bullets!) But I'd hate to be limited to Finnish powder and Swedish cases, if only because they are hard to find and expensive around here. And I have 150 Remington cases on hand. I could always use them for loading plinkers I guess.

A bit more information that I forgot to mention:
I'm loading to 3.3" OAL and the rifling starts .33" from the case mouth.
Norma cases weigh a little less than Remington, 183 grains vs. 191. With all the other components the same, the difference in velocity was 45 fps less for the Norma case loads, but I only compared three shots each if I remember right.

Try this link for data for the 7X64

http://www.accuratereloading.com/764brenneke.html

More Data
Caliber: 7x64 Brenneke


http://www.robsoft.nu/databaser_en/laddata/showloads.asp?MainID=4


Also Hornady #3 Has data for 7X65R

Thanks for the links RNF. But loads on the "Accurate" site don't come close to the factory loads from Europe. I am looking for long range loads better than the .308, which should be quite possible in this case with 160 grain bullets. The robsoft site does not work with my browser, or there's some glitch.

I'll ask another way. Has anyone else loaded the .280 Remington with IMR 4831 and 160 grain bullets to a safe 2800 fps?

Or does anyone have an opinion about an otherwise "over max" load that shows no sticky bolt, no excessive primer flattening, and can be loaded and shot four times without the primer pocket becoming loose?

I'll offer this up to you. Measure case capacity in water filled to the top of the case. Then extrapolate between the 280 Rem, 280 AI, and the 7mm SAUM. My assumption is that it falls somewhere in between those values. The bonus is that while 280 data is limited to 50KCUP or 60KPSI, the 280 AI and 7mm SAUM are not, 65KPSI for 7 SAUM, looks like the 280 AI is 60+KPSI as well. If you tell me how much water it holds, I'll run it through my Powley spreadsheet, and give you some ideas on what to expect based on my experiences with the 280 and 7 SAUM.

For the record, my 280 cases hold 68 grains water, 7SAUM hold 74. I think the 7 x 64 is in the same ballpark.

cast&blast

The 7X65R is a rimmed 7x64 if you want I can send you the data for it from Hornady #3

The top loads give 3100 fps with 120

3000 fps with 139's

2900 fps wwith 150's

and 2700 with 175's

I also own a Brno 7x64, a 22F carbine with 21-inch barrel and set triggers. I have been acquiring a variety of factory ammunition to see how it shoots and to chronograph each one.

I have gotten a lot of personal loads from other 7x64 owners in Europe, but many of them use common IMR, Hogdgon, and Reloader powders. VV and Norma powders are to hard to find, so I have not messed with those yet.

I will run short report from my reloading database later today and post some of the handloads, and a separate one of factory loads in a 23.5 inch metric barrel, which they use as their standard. I can tell you the Norma 154-gr is hot.

Norma's data for the 7x64:

http://www.norma.cc/sortimentladd.asp?Kaliber=7x64&Lang=2

They only show Norma powders but at least it will give you some guidelines as to what velocities are possible.

-Bob F.

I would back off a bit when the weather gets warmer and work back up. Cant be too warm where you are right now. Just a thought before you yank the thing out this summer and go shooting.

Well, this is interesting, I have a 284 win that has about 1 grain more water capacity than the 7x64, and about 1 gr less than the 280 Rem. I've been using 7X64 data off the Norma site with Norma URP (supposedly similar to RL-17), as a data point for my 284 with that powder. Hodgdon has excellent data on their site for H, IMR, and WW powders. Their 284 win data for 162 gr BTSP bullets reveals that H4831 lists a max of 2816 fps, and Hybrid 100V gives their max velocity of 2864 fps on that site - again this is 284 win data. I think you can reference that site to at least give you a ballpark starting point, and go from there. If you can find some URP - Graf's has it - Norma's site shows 2779 fps with 160 gr A-Frame and that powder. Good luck, and be cautious as always.

For the 7x65R (which is the rimmed version of the 7x64), Hornady #4 shows 55.6 grains of IMR 4831 as the max load for a 154 grain bullet. Book velocity is 2900 fps, so it sounds like you may just have a slow barrel. By comparison, it also lists 53.6 grains of IMR 4831 as the max for a 175 grain @ 2700 fps.

Just for giggles, here is a picture of the 7x57R and 7x65R:



I just love those long necks....

I just realized that in my original post I did not state a key fact, obvious to me anyway - I was looking to shoot 160 grain bullets...
"The max. load in some Swedish data showed V160 at 57.3 gr. for 2903 fps. Some other European data showed up to 57.4 grains of N160 for 2850 fps as max. load." Sorry for forgetting to add bullet weight.

Thanks for all the additional information everyone!

bwinters -I will try to measure the water capacity tonight.

Hawk Driver- I agree that winter and summer results can vary. We just came out of 25 consecutive days of temperatures that never rose above daytime highs of -25C. Some kind of record I hear. When working up max. loads in winter I keep cartridges in my pants pocket until just before firing and also keep my rifle warm in the truck cab. Firing conditions probably simulate a cool fall day, but hard to know for sure.

rnf and rbmcmjr:
My understanding of the 7x65R is that it is loaded to somewhat lower pressure than the 7x64. Similar to the lower pressure loads the factories specify for for the rimmed versions of the 7x57 and 8x57JS. So I think ( without much good data) that I should be able to load my 7x64 to a little bit higher pressure than 7x65R data and still be within industry standards. Am I wrong??
I would like to see the new Hornady data by the way.

here is the data on water capacity: fired cases with primer

Remington: 196 grain empty, 68 grains water
Norma: 189 grain empty, 68 grains water
RWS: 204 grain empty, 67 grains water

I've a 7x64 bbl. for my Sauer 202. Its petload (5 in .5 MOA) is the 160 Sierra GK* / N 160 / 56.0. So far,this load has accounted for 24 heads of game with complete satisfaction. I presently use a .30-06 bbl. and so far, hasn't seen any difference in killing power between both calibers (the 7x64 shoots a bit flatter, though).


* Depending on the game I might encounter (roedeer or wild boar) I switch bullets between the Sierra Game King 160 BTSP (softer) and the 160 BTHP (harder). They're loaded the same, shoot as accurately and to the same POI.

Andre,
That is one FINE looking firearm!

cast - that is identical to my 280 Rem cases. I don't think you're going to do much better than 2850 with a 160.

As a guide, I'd feel comfortable exceeding 280 Rem data, known pressures tested data only, by 2-3 grains. 2-3 grains should gain you 75-100 ft/sec over 59-60K psi data. Looking over my manuals, esp Hodgdon's website, their 280 loads top out at 2700 and change at 49K CUP (note CUP is significantly different than psi). Nosler is the only data source I have that breaks 2900 and then only with MagPro. Plus, I've struggled to reach Nosler's velocities most of the time.

I'd look strong at my go to's for velocity: MagPro, IMR 4831, IMR 7828, RE 22. You also might be able to cram enough RS Magnum and/or RE 25 into a 280 case as well.

I'd also look at 280 AI data - and not exceed it in any way, shape or form. Hodgdon show 280 AI data with pressure testing. They show IMR 4831, 55.5 for 2847 at 62K psi, IMR 7828, 58 for 2849 at 61.3K psi. I'd look over more 280 AI data to look for do not exceed limits - I'd also evaluate if the author of the data held it to the 280 Rem pressure standard of 60K psi or not. I see that Nosler AI data and JB's 280 AI article exceed Hodgdons and Sierra's by a bit and suspect they ran pressure up to 65K psi in their 280 AI loads. I'd back off couple of grains from Nosler and JB's load data in the regular 280 when trying to determine 65K psi loads.

I think I'd use MagPro, RE 25, RE 22, IMR 7828, IMR 4831, Magnum, load using 280 data to start, stop adding powder when I hit 2850. If you can get enough RE 25 and Magnum into the case it may do 2900. I would not exceed 280 AI data.

I ran the numbers through my modified Powley and it suggests 57.6 gr of a powder a bit slower than IMR 4831 for 2894. This is in line with the empirical book data as well. Understand that these powley numbers are idealized with the perfect powder - reality dictates 2894 is ideal - 2850 again looks like a wise limit.

Good luck.