7mm PRC

[cohunt]

If someone other than Hornady starts making 300 PRC brass won't that also fix the only problem with the LRM?

heard that GW has new 7lrm brass on the way from a new manufacture

 

[jpndave]

heard that GW has new 7lrm brass on the way from a new manufacture

Have you verified this? Last time I spoke with them they still had a ton of the old stuff and no plans for new until that is depleted. That was after reading a rumor that they were getting some new brass from I think ADG.

 

[cohunt]

Have you verified this? Last time I spoke with them they still had a ton of the old stuff and no plans for new until that is depleted. That was after reading a rumor that they were getting some new brass from I think ADG.

Their website no longer says who makes their 7lrm brass let alone who makes any of their brass, BUT they claim "new manufacture- premium brass" that would lead us all to believe it is no longer the old manufacture--- misleading info? You tell me.

You'll notice that their 7lrm brass is NOT listed with their "new premium brass" -- I was told that after they sell out of the hornady lrm brass they have a new manufacture waiting to produce it for them, misleading info? You tell me.

 

[WahooYahoo]

heard that GW has new 7lrm brass on the way from a new manufacture

Is it still going to cost $4 a piece?

 

[cohunt]

Is it still going to cost $4 a piece?

I have no clue, but their new premium brass is .71 ea for 6.5cm,1.09 ea for 300wm, 1.44ea for 6.5prc, 2.11 ea for 28 noz, and 2.14 ea for 338lm-- so my guess would be in the $2/ea range or a bit cheaper

Currently, their 7lrm brass is 1.97 ea, but not sure if it's still hornady or not at this time.

 

[Wild Monkey]

If you necked the .300 PRC straight down to 7mm, without changing the shoulder or neck length, it would work perfect with a 3.7" magazine box. The 180 ELD is 1.54" long, subtract the boattail (0.190) and subtract the neck length (.308) that leaves around 1.042" of bullet sticking out of the case:The .300 PRC is 2.580" long, so add those two together, and you get 3.622" with the boattail/bearing surface junction seated right at the neck/shoulder junction.

If the 180 ELD touched the rifling at say 3.632" that would give the chamber roughly a 0.242" long throat. Using that same freebore with a Berger 195 in the 7mm-300 PRC, would give a C.O.A.L. of around 3.696" touching the lands and with the bearing surface above the neck/shoulder junction. Seat the Berger 0.020" off and it's at 3.676", the bearing surface is still above the neck/shoulder junction, you have full use of the case capacity, and it will reliably feed in a 3.7" mag box.

Sir that Math is terribly flawed. For example when downsizing the neck from .308 to .284 it shortens to approximately .285 less if trimmed. Also the location of the Neck - Shoulder Junction rises up the case. So when I stated 2.9" that is giving the Magazine Clearance for 195 Grain Bullets. Like I said, that is a very long Cartridge. "7-KAM" is the Best scenario for Accuracy unless you're using very short Bullets. Also would like to add there are unlimited Cartridges out there that have seen great success with the Bullet shoved way down below the Neck, it's just not my preferred way to design things.

 

[jpndave]

Sir that Math is terribly flawed. For example when downsizing the neck from .308 to .284 it shortens to approximately .285 less if trimmed. Also the location of the Neck - Shoulder Junction rises up the case. So when I stated 2.9" that is giving the Magazine Clearance for 195 Grain Bullets. Like I said, that is a very long Cartridge. "7-KAM" is the Best scenario for Accuracy unless you're using very short Bullets. Also would like to add there are unlimited Cartridges out there that have seen great success with the Bullet shoved way down below the Neck, it's just not my preferred way to design things.

WOW Poeniceltic, that's quite a post there! You might want to get your own math in order before you go calling out errors that don't exist. As to length change if necking down only from 300 PRC to 7mm, follow along...

The diameter will change from 0.308 down to 0.284. That's a difference of 0.024 (0.308-0.284=0.024). Half of that is on each side so 0.012 (0.024/2=0.012). The length change is the tangent of the angle of the shoulder times the change in length subtracted from the original shoulder (since our shoulder angle is 30 degrees using Pythagorean theorem - which is pretty well established math - times our change in diameter) so 0.012/TAN 30 = 0.020785 (rounded to 0.021 for consistency). So the new shoulder length would be the original 300 PRC neck length of 0.308 minus our change going down to 7mm as you pointed out 0.308-0.021=0.287 give or take with the brass forming or trimming. So that .285 is close.

And just for fun and to make some sense of all this in case the math is confusing. Here is a 300 PRC case with a 180 ELD-M set at the 3.9" which I assume you meant even though you typo'd 2.9" in your post above as you used the 3.9" back in post #71. (Quoted below) To get that bullet out to 3.9" would take some SERIOUS neck stretch. You can almost get the boat tail in the case - our extra 0.021" will help a tiny bit. It may not be the longest 7mm out there but it is a long 7mm bullet.

@ 3.9" Long OAL the 7mm PRC would be a Monster and way too long. The 7-KAM is perfect IMO and if you think it's under-bore Then you need the 7-300 Blaser (7-SMX).

Can we let this length issue and the "7-KAM" go, at least on this thread, please? Might want to apologize to Jud96 for running him into the ground on "flawed math" that isn't flawed.

 

[Jud96]

WOW Poeniceltic, that's quite a post there! You might want to get your own math in order before you go calling out errors that don't exist. As to length change if necking down only from 300 PRC to 7mm, follow along...

The diameter will change from 0.308 down to 0.284. That's a difference of 0.024 (0.308-0.284=0.024). Half of that is on each side so 0.012 (0.024/2=0.012). The length change is the tangent of the angle of the shoulder times the change in length subtracted from the original shoulder (since our shoulder angle is 30 degrees using Pythagorean theorem - which is pretty well established math - times our change in diameter) so TAN 30 * 0.012= 0.006928 (rounded to 0.007 for consistency). So the new shoulder length would be the original 300 PRC neck length of 0.308 minus our change going down to 7mm as you pointed out 0.308-0.007=0.301 give or take with the brass forming or trimming.

And just for fun and to make some sense of all this in case the math is confusing. Here is a 300 PRC case with a 180 ELD-M set at the 3.9" which I assume you meant even though you typo'd 2.9" in your post above as you used the 3.9" back in post #71. (Quoted below) To get that bullet out to 3.9" would take some SERIOUS neck stretch. You can almost get the boat tail in the case - our extra 0.007" will help a tiny bit. It may not be the longest 7mm out there but it is a long 7mm bullet.

View attachment 146908



Can we let this length issue and the "7-KAM" go, at least on this thread, please? Might want to apologize to Jud96 for running him into the ground on "flawed math" that isn't flawed.

Thank you for this awesome explanation. I didn't want to get into the full details and argue back and forth. My example wasn't perfect, but I feel it's pretty dang close to what a real 7mm-300 PRC would be like.

 

[jpndave]

I had to fix some of my "math" had an angle in the wrong place, LOL. Was a 0.014 difference in the neck. We needed the adjacent not the opposite on the added length. My sexy wife distracted me while I was running the numbers, came in and laughed at me for getting to carried away and my OCD kicking in. Me...Never!

 

[jpndave]

Thank you for this awesome explanation. I didn't want to get into the full details and argue back and forth. My example wasn't perfect, but I feel it's pretty dang close to what a real 7mm-300 PRC would be like.

I guess to summarize, Your "guesstimate" would be off by 0.021" so if you add that to your length theorizing it still comes in under 3.7", even if simply necked down. I still think a shoulder bump would be better setting the water capacity at ~85gr H2O. The 7mm-300 PRC could still be and easy formed wildcat. It's all just speculation at this point anyway.

 

[Coyote_Hunter]

If there were a 300 PRC and something like 30 PRC (a short version) I'd agree it was a problem. If there's only one 6.5 PRC and one 300 PRC I don't see how what confusion there could be.

You underestimate the general public.

But I agree when it comes to shooting looneys. No confusion. Do shooters confuse the 222 Remington, 280 Remington and 35 Remington? The .222 Remington Magnum with the 6.5 Remington Magnum and the 8mm Remington Magnum? The .243 Winchester, .307 winchester and .308 Winchester?

 

[Coyote_Hunter]

People here seem to forget that the PRC designs are more than just case dimensons. The SAAMI standards include chamber specs are tighter than most cartridges and include tighter twists and more headroom for longer bullets than many similar cartridges.

 

[Coyote_Hunter]

Yes I have seen and considered all of those. If a 7 PRC version is out I would look at the 7 LRM or 7 Blaser.

If Hornady comes out with a 7mm PRC on a long form factor, I have a Savage waiting for a new barrel. Would love to do a 7mm PRC if it has a COL that will fit a 3.5" mag.

At the moment I 'm waiting to do a 6.5PRC for that rifle, only because the .300PRC is too long for the mag.

 

[Coyote_Hunter]

...

• 7mm LRM - horrible brass at horrible prices, maybe a little long in the neck. With the 300 PRC brass out now and yet to come, this could be formed reasonably. Capacity/performance right there
• 7mm Blaser - Not as common in the US, decent brass but expensive and somewhat difficult to get, the improved version might be a little better with a few more grains capacity
• 7mm Practical - (similar to 7mm Mashburn and 7-300 Win Mag) ideal goal but done with a belt - so lose the belt, make it a little shorter fatter powder column but capacity right there
• 7mm Dakota - Non-standard head size, proprietary design, brass cost and availability lacking, slightly overbore
• 28 Nosler - Overbore, rebated rim, brass cost and availability
• 7mm STW - Overbore, belted case, too long with long bullets
• 7mm RUM - Way Overbore, rebated rim, length
• 7mm WSM - Short neck, rebated rim, not enough capacity
• 7mm SAUM - Rebated rim, not enough capacity
• 7mm Weatherby - Belt, Not a modern short powder column/shoulder/etc., needs a little capacity
• 7mm Rem Mag - Belt, Not a modern short powder column/shoulder/etc., needs a little capacity

Thank you for posting that. I agree with most if not all of the points made.

I've been looking for about a year for a cartridge that will fit my Savage 111 magazine and give me great down-range ballistics.

When the .375 Ruger first came out I predicted a series of new cartridges based on that case. Why? Because it ditches the superfluous belt, fits standard long action rifles and bolt heads and provides a fatter case for more consistent powder burn.

The 6.5 PRC and .300PRC will, in my estimation, be winners in the marketplace. I believe we will see other calibers follow. While I currently plan to rebarrel my Savage 111 in 6.5 PRC, a longer 7mm-PRC with a COL that still fits a 3.5" magazine would be my first choice. I'm not going to go with a wildcat and have rejected some of the cartridges you list for the very reasons you list, as well as others.