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> 7prc or 7saum??
7prc or 7saum??
@ 05:44 pm (GMT) |
Jack DunrossI'm currently tossing up between 7prc or 7saum for my next rifle. I'm going to build my first custom rifle, so I have intentions of keeping it till the end of my days and then handing it down.I'm on the fence between 7saum and 7prc. The main pros I see for either is that the 7saum will have better barrel life and can be a little bit shorter and handier in a short action, but the 7prc will have better availability of brass and factory ammo as time goes on, plus a bit more velocity. I've been trawling forums and Facebook pages just trying to suss out the perfance of both and people are able to get very good velocity with the 180 class projectiles out of relatively short barrels and short actions in the 7 saum, using Alliant reloader powder, which we can get here in Western Australia, but it's less common that the adi powders. I guess my main question is: if you can boost the velocity in the smaller saum using fancy powders, do you still get the better barrel life, or would it end up burning through a barrel just as quick as the 7prc? Negating the main benefit of the saum in the first place. I don't really see the long action as being a hindrance over the short, but there is something cool about a stumpy little magnum in a handy short action rifle. |
Replies
@ 07:14 am (GMT) |
Nathan FosterRe: 7prc or 7saum??Hi Jack, I don't know if this is the sort of thing other people should weigh in on. I would also be very careful using the internet these days, so many thoughtless, self centered opinions.I will try to offer some thoughts that may or may not help. Regarding the fancy powders (i.e. Alliant double base), yes it is possible to achieve higher velocities in a number of cartridges than can be achieved with ADI powder. However, the entire industry is under pressure at the moment as a result of military (war) and civilian buying including ADI (See also FAQ page of Alliant). So at this time of writing, I would not hang my hat on one powder. I don't know why but many hunters seem to be in some kind of la la land regarding the current logistics of the industry. As I wrote in the Cartridges book, try to back work your project including the range you wish to shoot to and also which bullet weight is going to be best for your intended game. The SUAM is a nice cartridge but do keep in mind the OAL's are a bit on the long side if using the 180gr. Might pay to have a bit more than the standard 72mm short magazine box. A .280 or .280 AI would likely be easier to build for similar velocities, works OK with both ADI and Alliant and with fairly good barrel life. These cartridges are also slightly more economical than the larger magnums regarding potential powder shortages. I will go out on a limb here and say that the .280 in particular, is possibly (statistically) one of the most effective cartridges at this time regarding powder availability and powder consumption versus extended range kill probability, though its a bit too much to go into here sorry (also fails to address game weights / easy to misconstrue etc). Its hard to say how long a magnum will last. Some folk will burn out a magnum within a year or two so not the greatest heirloom if thats your goal. But it will be fine if you are OK replacing barrels from time to time. My only advice here is - if you go with the 7mm PRC, adopt a 9 twist as opposed to the factory 8 twist. It will make the rifle a little less finnicky, especially in WA temps. As I wrote in the book series, a hack and magnum combination can also be useful if one can afford it. This can also help us to get through shortages and also extend the barrel life of a magnum. Others might prefer just the one do-all rifle. It is really up to you and what you think will suit you best. It is good to remain practical but we do need to allow ourselves to explore and gain new experiences. |
@ 08:17 pm (GMT) |
Jacob MSRe: 7prc or 7saum??HI,I recently visited a large ammunition manufacturer in the US. They showed me a scrapped test barrel (Bartlein) in 7PRC. The barrel had 810 rounds through it and was cut it open so you could inspect the throat and and the beginning of the rifling. There were no rifling at all the first 5-7 cm (2-3 inches). When they test shoot magnums they shoot 5 shots at let the barrel cool down to ambient temperature before firing a new 5 shot group- so it has not been belt fed or tortured at all. This specific barrel was probably worn out already after 500 rounds if it was sitting on a precision LR hunting rifle. Best regards Jacob |
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@ 02:52 am (GMT) |
Jack DunrossRe: 7prc or 7saum??Thanks Nathan, sorry for the slow reply. I've been marinating on your advice for the past few weeks.I've decided to rebarrel my 308 win to 7mm SAW, due to having heaps of 2208 and 2209 powder and also having 308 palma brass and most of the components I need. I had already purchased a 22" 7mm ibi 1:8.5 twist barrel before I posted the original question. So I'll be using that, which hopefully won't be too finicky. Here is a link to some info on the 7mm SAW https://westtexordnance.com/7mm-saw/ and also here https://westtexordnance.com/7mm-saw-general-faqs/ Pretty interesting little cartridge! I have chosen the SAW, because of the reasons stated above, but also because I have already had a Wyatt's baney box installed on my Remington 5R, with a 3.1" available coal, which should work well for the long 180 eldms. 308 win brass is also maybe the easiest brass to find here in WA and being able to choose between small or large rifle primers gives me more options, as primers seem to be harder to come by than powder. The rifle range I normally practice at is 800m long, but I have places I could shoot up to 1km. For now though I'd like to keep my max range as 800m. I'd like to hunt up to elk (being the largest game), but that would require an overseas trip. I'd mostly be able to hunt fallow deer pigs, kangaroos and goats and maybe red deer. I would really like to run a magnum and a hack as you suggested, but I think due to my limited available time for shooting due to other life commitments I would be best served with one long range rifle for now. Also the upcoming gun law reform here in WA might throw a spanner in the works, so I'll wait until all the dust settles before getting a magnum later in life. Thanks for all your advice Nathan, it really is helpful. And thank you Jacob! That's very interesting about the 7prc barrel life. I'll be curious to see what other people report in the future. When I get the saw up and running, I'll make a post with some of my load development info. Cheers! |
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@ 07:51 am (GMT) |
Nathan FosterRe: 7prc or 7saum??Hi Jack, the 7mm-08 is a wonderfully effective and efficient cartridge - but also and especially with regards to supply issues and restrictions. The SAW is about what you would expect using small primer pocket brass and loading to higher pressures.For comparison, here is an example of a standard 7mm-08 I put together with 24" barrel / 162gr loads / SAAMI standard freebore .119", seated just off lands at an OAL of 75mm / 2.953" (Tikka long magazine) Accuracy load: 42gr 2208, 2694fps. Upper accuracy node: 43.5gr 2208, 2792 - near max / reduced case life. Groups open up at 44gr (.590") - near max / reduced case life. 44.5gr Max (2856fps) - max, reduce load. |
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@ 01:47 am (GMT) |
Jack DunrossRe: 7prc or 7saum??Thanks Nathan, so going off the average velocities for the 7 saw on the WTO website, it looks like they're able to utilise the upper accuracy node that the 7mm-08 is getting, but with good brass life? I'd be pretty happy with that kind of performance!I'm most interested in being able to launch the 180 eldms over 2600fps. That seems like a pretty potent upgrade from my 308. |
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