Minimun bullet in case?

[PaperSniper999]

I'm developing a new load using Hornady 40 gr V-Max BT bullets for a new to me Cooper in 223 Remington. I've loaded very few short, 40 gr bullets in ANY of my guns in this caliber, so while I have experience reloading in general these tiny 40 gr bullets are driving me nuts!

The Cooper is a slow 1 in 14 twist with a comparatively short throat.

I usually do my initial loads putting the bullet's ogive fairly close to the lands: for instance with this rifle and 55 gr bullets I used about 0.005 jump. However, if I try to be that close to the lands with the 40 gr bullet I'd end up with almost no bullet in the case!

I remember an old rule of thumb: 'Keep about the diameter of your bullet inside the case to provide decent 'pull' on the bullet when it's fired'. Now, if I put .2 in my 223 cases I'll have a huge,to me) bullet jump to the lands.

I have settled on these numbers with the tiny 40 gr Hornady bullet. I welcome any comments you might have!


> Hornady 40 gr BT V-Max,everything below is in inches)
A. I measure 1.89 length to the ogive with the bullet touching the lands for this rifle.
B. Length to the bullet ogive I chose for my seating depth: 1.865
C. Estimated bullet jump to lands,A-B) = 0.025,farther than I use with heavier/longer bullets)
D. Estimated bullet/case contact length in case: 0.12 - 0.15,doesn't include the BT non contact part of bullet in the case)

Since these rounds will be shot in a single shot bolt action rifle I figure I don't need the full 'bullet diameter' in the case. I just have to be careful handling the loaded rounds so the seating depth doesn't change. I know one thing: if these 40 grainers work okay I will not use BT bullets as they require too much bullet in the case! I'll have to find some flat base versions........

I have not shot any rounds in this rifle yet..........maybe this coming week.

 

[fdshuster]

PaperSniper999: I know exactly what you're talking about, only my problem was with an older Sako L-46 factory chambered in 222 Rem. Magnum and it had a 16 twist barrel with a very deep throat. Anything heavier than 40 gr. would not stabilze and with the bullet just barely 'holding on' to the case mouth, jump was almost .210'= 5 shot 'groups',more like clusters) at 200 yd. were laughable. That combination no longer exists. I've had excellent results with the longer 50 gr. V-Max in my 14 twist barrels, 222 Rem & 22-250. I've also heard the 'bullet dia./ length of neck contact', and try to use it as a guide: works for me.

 

[PaperSniper999]

Well, FD, I will try those little 40 grainers once just to see how they work out. Who knows, they might be very accurate in this gun, you can never tell! I figure I'm okay with 40-55 grains in the Cooper with its 14 twist, so at least load development won't take very long, eh? I strongly suspect this rifle will do much better with 50-50 gr bullets.

I have a 250 count box of these forty grainers. I got them several years ago for a slow-twist 22-250, but have only shot about 50 of them in it....it too has a very long neck like your Sako. I forget the barrel marker, but the action is a beautifully converted 1940 era Mauser in a beautiful laminated stock. A very pretty rifle, but in a caliber I don't shoot much. It's a hunter, and I'm not. It's accuracy at 100-200 yrds is okay, but not what I like in a bench gun.

 

[fdshuster]

PaperSniper999: Regarding a 1-14,22-250 in my example): could not get the 55 gr. V-Max to stabilize, 53 gr. hollow points like the Sierra #1400 seemed to be near the maximum to stabilize, but the 55 V-Max at .810' OAL were in the 'sometimes' category. Tried the shorter,.710' OAL ) Sierra 55 gr. HPBT GameKing #1390 and they are outstanding: my standard bullet for the 22-250 now. Proving once again, bullet length is critical.

 

[JRinCo]

When I bought my first box of 30 grain Berger Varmint bullets for my .223 Rem., I had the same concerns. I thought what the heck and loaded up a few with .200 of bullet into the neck. They shoot great in my 1 in 12' barrel at 4000 fps. The red mist is terrific.