375 H&H Mag Reloading for Encore

[pcpharm]

Hello Everyone:
I just purchased and Encore 375 H&H Mag barrel with Lee Pacesetter 3-die set and Lee Neck Sizer 2-die set from someone on the Nossler reloading website. Not sure what I intend to hunt with this caliber, but to good of a deal to pass up. I already own 308 and 30-06 calibers in Encore and reload for these. Note, everything I hunt in East Tennessee is susceptible to 30-06 and 308 calibers and I do not have the opportunity to hunt out West. However, I am uncertain where to begin with reloading for the 375, and not just because it is a “belted” magnum. I have found that with the Encore just neck resizing is insufficient as the case will continue to lengthen and eventually loose the 0.001-0.002 inch clearance between the case head and rear breech face. On the SAAMI website there are clear datum lines and diameters listed for the 308 and 30-06 calibers (1.634/0.400 inches for 308) and (2.0256/0.375 for 30-06). So I occasionally full-length resize all my 30-06 and 308 cases taking care to make sure I am not pushing my shoulders back beyond the above datum lines. My experience in the past with the Encore has been that pushing the shoulders back beyond these above datum lines results in head failure. I see no such information for the 375 H&H Mag on the SAAMI website. So the question is what is a good datum line and diameter to start with for the 375 H&H Mag caliber when full-length resizing? I have read that some use 2.464 inches with 0.420 diameter as a starting point. Comments?
PCP

 

[Timmypage16]

I am not sure about the datum data but I am consfused/curious why you said the brass grows out of spec when neck sizing. I have an encore and plan on buying a rifle barrel for it, so I am really curious about reloading for the encore.

 

[WYOMan]

The reason for the differant information is because the rimless catridges headspace on the shoulder, where the 300 and 375 H&H headspace at the belt.

 

[pcpharm]

To my understanding, the datum line is the point on the shoulder from which the "headspace" is measured.

I am theorizing in that the break-open encore does not have the stiffness of a bolt action chamber and the case continues to expand toward the breech. I have found that after multiple reloading, depending upon the load, the case will eventually become flush to the breech surface, I am unable to place a 0.002 feeler guage into the breech with a cartridge in the closed chamber. I remedy this by either full-length resizing occasionally or use Forester bushing bump neck resizing dies
http://www.forsterproducts.com/store.asp?pid=36223

 

[bfoosh006]

Blemished bullets IM sent.

 

[Legion489]

Case necks grow (stretch) and need trimming, so trim your case when you first get them (after sizing) and after every third/fourth firing. The belted cases are SUPPOSED to headspace on the belt, but seem to be reamed quite freely as far as the belt goes, so if you can, headspace off the shoulder (what there is of it) on the case. This will give you much longer case life for ANY rifle, and especially the Encore.

 

[R.W.Dale]

Case necks grow (stretch) and need trimming, so trim your case when you first get them (after sizing) and after every third/fourth firing. The belted cases are SUPPOSED to headspace on the belt, but seem to be reamed quite freely as far as the belt goes, so if you can, headspace off the shoulder (what there is of it) on the case. This will give you much longer case life for ANY rifle, and especially the Encore.

The h&h rounds have no shoulder that's sufficient for control of headspace. Just a long tapering body.

Headspace on the belt will be required.

 

[GooseGestapo]

Because of the taper of the H&H case, you'll need to partially full-length resize every time. Just size them enough to allow the action to close easily. Keep the loads "modest", and the case stretch will only require retrimming every 5rds or so.
For bullets for Tennessee, try the 235gr Speer Semi-point. I've taken deer with it and at ~2,800fps it performs much like the 180gr RN from the .30/06...
For powders, the bullets 250gr and lighter do really well with Reloader 15. For bullets 270gr and heavier, use IMR4350..
.375H&H in an Encore ????? Ouch!!!!
My .375 is a .375Ruger in the Ruger M77MkII "African". I cut the stock 1" and installed a Pachmayer "Old English" "Decelerator". It matches the rifle and noticeably reduced the felt recoil... I actually "enjoy" shooting this rifle... Quite accurate and recoil is about like my Rem. 12ga 1187 SP with "duck loads"...
Not as bad as you'd think.... for an "elephant" gun...

If the shoulder on the .375H&H is "to small" to properly headspace...... Then the .30/30 will never make it as a "popular" cartridge...... When "reloading" it isn't neccessary to headspace on the belt. And it's isn't neccessary to crimp for the single-shot "Encore"...

You're way, way over-thinking the issue. Forget the "datum" points from the SAAMI site. This is for manufacturers making tooling to cut chambers, dies', ect...
Lee has already done the "homework" for you in cutting the dies. If the "sized" brass will easily chamber, you've done enough.... Headspacing the reloaded ammo off of the belt will result in brass that will fail within 3-5rds/loadings.... Use data from a "Reloading" manual such as Lyman #49, Nosler #5, Speer #14, ect, ect, ect...

 

[pcpharm]

Thanks everyone for the information.
Ouch indeed for an Encore in 375 H & H mag, we'll see.
Ditto on the Lyman 49th.
I already have around 200 bullets that were part of the setup I bought from the previous owner (Nosler 300 grain & Barnes 235 grain). I was thinking about developing a light load with IMR 4064 and the Hornady 225 grain. I already use the IMR in my 30-06 and 308 (150 grain Hornady). I was however considering add Reloader 15 to my list of powders.

 

[R.W.Dale]

If the shoulder on the .375H&H is "to small" to properly headspace...... Then the .30/30 will never make it as a "popular" cartridge........

Do I need to point out that 30/30 has a rim on it for the same reason. H&H cartridges have a belt?

Modern belted mags have a belt purely for aesthetics. But the belt was originally developed for cartridges that needed it.