Problem with Lapua Reloading Manual?

[OMB]

Just picked up a 7mm Remington Magnum & was scoping out loads for 184 gr Berger Hybrid with N165. Their closest load was for the 180 gr Scenar {min, max} = {44.3 gr, 53.7 gr}, which seems quite low to me and is low compared to Quick Load estimates. Looking at adjacent loads, for the 175gr SBT, the listed min, max are {52.6 gr, 62.7 gr} and for the 194 gr Berger, {54.9 gr, 60.8 gr}, both loads significantly higher.

Seems to me the Lapua load data are not correct, perhaps dangerously low at 44.3 gr when the case capacity is closer to 83 gr water.

Help.

 

[1bamashooter]

What does the Berger manual say?

 

[OMB]

Berger manual reports {58.0, 61.3} for N165 for the 180gr match hybrid.

 

[CJ6]

Manuals are "guides" to get you started. Your rifle will tell you what is best.

 

[OMB]

Do you think a starting load 10 grains under what others recommend would be safe? At 44.3 gr, the case would be only a little over 53% filled. I always thought reduced loads with slow powders were to be avoided because of the possibility of inadequate pressure to properly expand the case allowing gas into the action. An additional concern was the possibility of pressure from the primer pushing the bullet & plugging the bore before the powder fully ignites, leading to a dangerous pressure spike.

 

[1bamashooter]

I always check data from the bullet manufacturer and the powder manufacturer then go from there

 

[Nude nut]

Just picked up a 7mm Remington Magnum & was scoping out loads for 184 gr Berger Hybrid with N165. Their closest load was for the 180 gr Scenar {min, max} = {44.3 gr, 53.7 gr}, which seems quite low to me and is low compared to Quick Load estimates. Looking at adjacent loads, for the 175gr SBT, the listed min, max are {52.6 gr, 62.7 gr} and for the 194 gr Berger, {54.9 gr, 60.8 gr}, both loads significantly higher.

Seems to me the Lapua load data are not correct, perhaps dangerously low at 44.3 gr when the case capacity is closer to 83 gr water.

Help.

Did you compare their OAL nimbers between berger and lapua.

Cheers Trev.

 

[Twdmar]

I would agree that at least some of their data seems very conservative. Perhaps not dangerously low but definitely slow.

 

[Jager]

Do you think a starting load 10 grains under what others recommend would be safe? At 44.3 gr, the case would be only a little over 53% filled. I always thought reduced loads with slow powders were to be avoided because of the possibility of inadequate pressure to properly expand the case allowing gas into the action. An additional concern was the possibility of pressure from the primer pushing the bullet & plugging the bore before the powder fully ignites, leading to a dangerous pressure spike.

No, please do not load anything like a 44.3gr charge of N165 behind a Berger 184gr Hybrid Target bullet in a 7mm Rem Mag!

The biggest concern with very light loads of slow powders is the risk of secondary detonation. That is a fairly rare phenomenon but is usually catastrophic when it happens.

Not sure why you're looking at Lapua load data for a Berger bullet... but, as you note, Berger catalogs several 180gr varieties. Their 180gr Hybrid Target bullet (#28407) is dimensionally very close to the 184gr Hybrid Target bullet (#28408) you're looking at. Using load data for that 180gr pill will get you close.

If you plug the 58.0/N165 starting load that Berger lists for that 180gr bullet into QuickLoad, using your desired 184gr bullet, you get this print. That's a perfectly reasonable starting point.




What's NOT reasonable is 44.3/N165. QL predicts chamber pressure of 23,000 psi with that load... and that's a place you do not want to go.

 

[OMB]

Thanks for confirming ... I was too hasty in reviewing the Berger manual and missed the N165 load for the 180gr (bottom of previous page) ... Berger shows {58.0, 61.3} for the 180 & from my QL estimates , I was planning on starting at 58.5 or 59.0-ish. I given pause by what I think must be an error in the VihtaVuori website data for the 180gr Scenar ... until I "discovered" the Berger data, I was using the Scenar as a rough point to start.

Thanks again.

 

[Laurie]

The charges listed for all powders in the Viht online data tables are massively over-low for the 180 Scenar, not just N165. It looks like a compiling error and data for another smaller cartridge have been inserted. Either that or the lab tech who did the pressure readings had a serious hangover that day.

The N165 charges for the 194gn Berger (table below 'yours') are starting: 54.9gn; maximum: 60.8gn, those for the 175gn Sierra SBT run at 62.7gn max. You'd expect a 180, unless one with very unusual pressure generating characteristics - which doesn't apply to the 180 Scenar IME - to fall somewhere between the two.

 

[1bamashooter]

Has anybody reached out to these companies to find out why they are listing such a low charge weight? I'd like to hear their answers

 

[D-4297]

Yes , I did . The response was that they were constantly up-dating their information , but could not possibly do everything all at once . But they were working on it . Almost like talking to the White House Press Secretary , if you catch my drift .

 

[1bamashooter]

Yes , I did . The response was that they were constantly up-dating their information , but could not possibly do everything all at once . But they were working on it . Almost like talking to the White House Press Secretary , if you catch my drift .

I would think updating bad info would be a priority but I guess they will get pissaki on it

 

[Doom]

Just a thought, the Scener-L has a BC of .661 and the 184 Berger is even higher, which seems higher than the other bullets mention in the manual. The Berger is 0.055” longer than the 180 VLD hybrid. That is reducing the case capacity. The load stated has been in the manual since the 2015 edition, maybe earlier.