Tips needed for quality load development

[Bart B.]

chronograph. Target rifles and chronographs go together like peanut butter and jelly.

Target rifles need not go together with chronograph. I never used a chrony reloading ammo. Didn't need to know exact muzzle velocity; +/- 77 fps was close enough by guessing. I never owned one nor thought I needed one. Borrowed one to see velocity spread with different amounts of pressure rifle was held against my shoulder and velocity increase from clean to dirty barrel over 5 shots.

I never worked up a load for new barrels or any existing bullet-cartridge combination.

 

[kingmt]

That's been normal with everyone; me included, for few shot groups since rifled barrels were invented.

20 to 30 shot test groups stay about the same size from day to day.

I'll agree with that. But if I can shoot two 5 shoot groups & see a change of POI with .2gn increase then I don't want to waste my time there. I'm not going to load my hunting ammo or anything besides test ammo to that close of a standard. +/- .2 probably.

 

[kingmt]

Target rifles need not go together with chronograph. I never used a chrony reloading ammo. Didn't need to know exact muzzle velocity; +/- 77 fps was close enough by guessing. I never owned one nor thought I needed one. Borrowed one to see velocity spread with different amounts of pressure rifle was held against my shoulder and velocity increase from clean to dirty barrel over 5 shots.

I never worked up a load for new barrels or any existing bullet-cartridge combination.

If all your doing is coping from a manual you probably don't need one but for hand loaders I'd suggest it as a useful tool. I have powders that there is no data for until I decide what it acts like then I'll refer to the known powders data for reference in different cartages. That is until it proves me wrong.

 

[Bart B.]

But if I can shoot two 5 shoot groups & see a change of POI with .2gn increase then I don't want to waste my time there.

Several times, I've fired five 5-shot groups with the same load and powder charge weight. Each individual 5-shot group center is at a different place. Is that normal?

 

[Reloadron]

H/Roaders how are you?
My son 26 got himself a really nice all the bells and whistles remmington 700 in 7mm rem mag.
Now I have been reloading for years really good ammo 10s of thousands most for ar sks, mauser,enfield,colt,
My son wants to make the best he can with out driving me crazy. Biggest obstacle is the hour ride each way to the range. So about every two weeks we go.
So far I have primed with CCI BR and sized. Going to trim cases to fit chamber seat bullet .005 from rifling using r-22
Plan on starting mid load and up and down 1/2 gr about 5 rounds each load and see what produces the best group and load from their.
Any tips on making this any smoother?
My son is thinking way ahead for next deer season and wants to lay all the ground work for seccuss.
Thanx

Well congratulations to your son on his new hunting rifle. The 7mm Remington Magnum is a cartridge I have always liked. I have an older Ruger Model 77 in the chambering which was one of my best longer range hunting rifles. It is also a rifle which I seldom take out of the safe unless I move it around. Wasn't bad 20 years ago but my shoulder isn't what it once was. My new best friends are .308 Winchester and .223 Remington.

Anyway, the 7mm Remington Magnum is a cartridge I see more as a hunting round rather than a target round. I do not see striding for 5 shot 1 MOA or smaller groups off the bench but rather see a few shots at a few hundred yards at a nice buck. When I hunted with mine I liked Spitzer BT bullets in the 150 to 160 grain weights and the powder I liked was IMR 4350 as I recall. For hunting applications I like hunting bullets suitable for game and always had good luck with the Sierra Spitzer Boat Tails out to 300 yards or more when I felt comfortable. As to making good hunting ammunition? The usual rules apply. I always size and trim and did fine with full length resizing. I liked keeping all my loads as uniform as possible. Never saw a need to weigh each charge as my RCBS Uniflow did fine as did my standard RCBS dies. The 7mm Rem Mag case has plenty of room and using a powder like IMR 4350 there is a wide charge spread, about 51 to 60 grains give or take so you can load in 1.0 grain increments working up under a 160 grain bullet. After all, we are developing a hunting load and not a target load with target bullets. I doubt any deer will wait for a hunter to place a 5 shot group in its kill zone. I wish your son the very best of luck with this rifle and what I see as a really great hunting cartridge.

Ron

 

[kingmt]

Sounds like your trying to test my knowledge.

Depends on what you mean by a different place. If it's over a inch off from where I've zeroed & within 100 yard I'd consider it a bad load. I look for loads that shot the same every time. If it shoots well one day it should the next also. I usually don't worry about zeroing a scope until I go hunting or start shooting a load over & over. I look for groups. I don't care if they are 1"high & 5"left wheel I'm testing.

 

[Bart B.]

Are you saying five 5-shot groups at 100 can have centers within an inch of each other?

And that 25-shot composite is larger than any 5-shot one?

If so, that's good. But isn't the real accuracy the size of the 25-shot composite?

 

[kingmt]

Are you saying

No "I'm" not. Your saying that & have been for a while. I just agree with you.

Only thing you don't seem to like about my statement is I don't always shoot 20 to decide there is something I don't like about the charge.

 

[Bart B.]

OK.

 

[30Cal]

Ken Waters' and the Sierra manuals have saved me a lot of time in hunting for good loads.

Also, I'd take an adequate load with plenty of data (zero's worked out for different ranges) over a very sweet looking load where I have very little shooting data. Something to think about. It's worth just picking something and shooting it to the point where you're very familiar with it.

 

[sage5907]

I read through your original statement and what you were planning to do is exactly the way I would approach the situation. I am big fan of R 22 and the first time to the range I would load 5 rounds in each half grain increment ending up two grains below max. By the time your son shoots 25 rounds he will probably have enough shooting. If you and your son are both shooting I would load 10 rounds in each half grain increment so both of you can do the same accuracy testing. The second time to the range I would test only the two most accurate loads to see how they compared to each other, and each subsequent time to the range I would continue the accuracy testing. Bart B is a wealth of information and he may know the overall length that Sierra used for their accuracy load in the 7 MM mag. The 7 MM mag case neck is so short I wouldn't want any part of the boattail to be up in the neck. Alliant lists their minimum overall length at 3.190 for a Sierra 150 grain GameKing.

 

[Bart B.]

The 7 MM mag neck is so short I wouldn't want any part of the boattail to be up in the neck.

What problems do boattails in case necks cause?

Never heard of this issue. It's common with boattail bullets in several cartridges winning matches and setting records. All the military 7.62 NATO M80 ammo's boattails are in case necks.

 

[sage5907]

Bart B, the neck on a 7 mag is only .272 inches long. If you trim it short by .010 it is only .262 inches long. If you seat a boattail so shallow that the tapered tail is up in the neck there is very little friction to grip the bullet. That may be OK for a target shooter but makes many hunters nervous, especially if the case is annealed soft for shot to shot consistency. The owner is preparing the rifle for deer hunting and not target shooting.

 

[Bart B.]

Size case necks smaller by polishing expander ball down .001" or more in diameter. I've done that seating 200 grain BTHP hunting bullets in 300 Win Mag short necks. I've never annealed a case nor seen a reason to.

A friend shot 57 bullets from the same 308 case into 3/8" at 100 yards. Full length sizing each time and never annealed that case shooting a maximum load.