8x57JRS 200gr Nosler Partition

[Gun Barrel Ecologist]

An odd question;

Given you are loading for break actions the recoil force that normally applies to push bullets back in to cases does not apply, as the bullets are sitting with an empty barrel in front of them.... BUT in both combos and doubles there is the potential for a projectile to move under the recoil of the other barrel.....
So, do you crimp?
And perhaps the more intriguing question, If you do crimp, do you notice any increase in velocity due to the extra pressure that is presumably built up by having greater resistance to initial bullet movement?

[stokesrj]

Crimping can improve or degrade accuracy, velocity, or extreme spread of velocities. It depends upon the relationship of the case neck and bullet alignment of the cartridge with and without crimp. Optimum is proper neck tension with no crimp provided the bullet is seated with enough of the bullet in the case neck to promote optimum alignment until the bullet has engaged the rifling before leaving the case mouth.

So, there is no answer that fits all situations. I've found that often the Lee Factory Crimp will improve accuracy, velocity consistency, and alignment if other parameters are not optimum. There is no reason to crimp in a Kipplauf other than improving accuracy other than also improving velocity consistency if long range use is intended.

If you have .003" of neck tension that is about optimum, .001" or .002" is too delicate and must be handled carefully to avoid bullet set back. More than .004" will usually result in a greater variance in velocity as the grip on the bullet becomes more variable. To measure this simply measure a sample of case mouth outside diameters before and after seating a bullet. You can also feel this as bullets are seated. If you're getting sometimes hard seating, sometimes soft, then a LFC die will usually help. But it is better to troubleshoot the problem and correct it.

[Gun Barrel Ecologist]

I knew it was a “how long is a piece of string” type question, however it occurred to me as a means of creating a minor change in pressure with the same powder charge - handy if the “goldilocks zone” of desired velocity or accuracy is between two tested chargers.

Also under the impression that second try’s load if for a BBF, do the bullet movement under recoil of the other barrel is possible, and not in the same direction a experienced with bolt guns

[secondtry]

Also under the impression that second try’s load if for a BBF, do the bullet movement under recoil of the other barrel is possible, and not in the same direction a experienced with bolt guns

It's an interesting question GBE. I haven't used my BBF (12g) enough to comment.

Perhaps Charles has fired repeated 12g loads from his BBF with an unfired 7x57R in the rifle barrel and can comment ?

[secondtry]

Good work. Keen to see outcomes of larger woodies

Me too, but we will both have to wait . I am trying to get the 200NPs sorted (nearly there) for some High Country trips in Spring (read - now !). Should hopefully have the 220 Woody load sorted by Christmas, but unlikely to put one into meat in 2017. Wouldn't it be nice if the 220 RNs had close to the same POI at 100yds as the 200NP ? Even a bit lower than the 200 would work for me.

The POI with the 200s BTW is around 4" higher than with the RWS factory ammo and perfectly in line laterally.

[secondtry]

Just updated the details of my load on page 2 of the thread.

Very pleased with the results

[stokesrj]

Looks like a great load.

[secondtry]

Looks like a great load.

Thanks Bob. I think I might need to temporarily retire the 7x65 from hochsitz duty so that this load can get some use on sambar.

[stokesrj]

Hope to see some sambar autopsy photos soon