Home Forums Reloading Big Game Rifles Best accuracy tweaks

I read the long range accuracy series stickied at the top of this forum - which got me to thinking about accuracy tweaks for hunting rifles. What are the best accuracy tweaks to get the best accuracy - in the most efficient manner.

In most of my rifles, I can find a load that shoots 1.5" at 100 yards consistently with hunting components, namely Nosler Partitions. My goal is always 1.0" net at 100, so I'm fairly close from the start. I always weigh my cases and shoot batches that weigh within 2 grains of each other, trim all the same length, use perfect bullets (visual inspection). I always start seating depth at 0.020" off the L&G, and that fit into the magazine. I usually shoot a bunch of powders and charge weights, striving to optimize velocity and accuracy and hoping to find a non-temp sensitive powder combo that meets the accuracy/velocity goals I'm looking for. Once I find a load combo that appears to have potential, I usually load 3 cases with 0.5 grain increments on either side of the load to see what it does. I usually repeat the 0.5 grain increments 3 times to check for repeatability.


I normally do not play with seating depth or charge weights finer than 0.5 grain.

What do you guys do when you get a load that is close to what you're looking for? What is the order of accuracy tweaks for hunting rifles, from most beneficial to least?

Seating depth is what typically rings the bell.

How much do you vary the depth? Suppose I load 3-5 of a specific charge weight, how much do you vary seating depth to get an idea of what works? 0.005? 0.010?

I'm going to try this but could use a bit of guidance. I have several loads that are at 1.5" that usually shoot 2 touching and one out an inch opening the group to 1.5".

Curious Steelhead, do you start at or into the lands and how much change at each relay? I've seen guys going in .005 increments and others at half a turn on the seating stem (roughly .018).

I ain't that silly, I typically have some loaded up before the rifle even arrives and go about .020" at a time after that, give or take.

Kind of my thoughts, if the sweat spot is narrow enough that .015 or so skips it I'm not sure it's worth chasing in a hunting rifle. I'm not into target games or extreme long range so I don't go overboard with load prep.

http://www.longrangehunting.com/for...acy-berger-vld-bullets-your-rifle-40204/

Pretty good read.

Found that earlier today. Have changed my thoughts based on the article. I'm going to try 0.020, 0.040, 0.060, 0.080 off L&G for several loads in the 7mm and 300 SAUM's for next weekend and will report back what I found. Am really curious at this point........

+1 on the seating depth.

After the rest of the tweaks you mentioned (OP), go to a different bullet. A different weight, different ogive, different style and so forth.

You can tweek a load till the cows come home with one bullet and just run into an accuracy wall. That is, until you make a bullet change.

Higbean,

Thanks for the reference. Man those are some serious jumps (as much as 0.130 off lands). But it confirms an experience I had a few years ago with a Sako in 7-08 that I could not get to shoot handloads. I was a fairly new handloader and steeped in the idea that best accuracy was found near the lands. I drove myself nuts trying different things to get this rifle to shoot. In desperation, I tried some Federal factory rounds with the 140 grain Ballistic Tip. These had a big jump in my rifle, but shot well. Time has dimmed my memory, but it was a REALLY big jump. Thereafter I loaded both Accubonds and Ballistic Tips with a similar jump and the problem was solved!

Al

I found that in my 257 Weatherby, the 100gr TTSXs shot better with a deeper seating depth. jorge

Originally Posted by bwinters

Once I find a load combo that appears to have potential, I usually load 3 cases with 0.5 grain increments on either side of the load to see what it does. I usually repeat the 0.5 grain increments 3 times to check for repeatability.


I normally do not play with seating depth or charge weights finer than 0.5 grain.

What do you guys do when you get a load that is close to what you're looking for? What is the order of accuracy tweaks for hunting rifles, from most beneficial to least?

After almost 50 years of seeing "THE" most accurate loads with muzzle velocity coming in #2, I've learned that the "SWEET SPOT" in the amount of powder used is sometimes less than .5 of a grain wide.

Therefore, if you're using .5 of a grain increments, you might sail right 'passed "THE" Sweet Spot and never know it.

Examples in real life: All groups shot at 50 yards off a solid bench-rest using Lyman rifle rest and four sandbags.

Rifle used: 23� inch, heavy-barreled Sako in .222 Remington with 6-24x50mm scope set on 24x. VihtaVouri N-130 powder, 50 grain Sierra "Blitz" bullet. SWEET SPOT = 21.6 to 21.8 grains inclusive (3 grains wide). Best group = 21.8 grain, 5-shots into .0911 inches (1st four bullets through the same .224" hole). MV 3200 fps.

From 21.6 gr. to 21.8 grains (3 grains wide), the 3 sets of groups were all less than .15 inches, at 21.9 grains, the group opened up slightly to .24 inches. At 22.0 grains (Max. Suggested Book load = 22.1 grains), primer began showing pressure signs and group opened up to .35+ inches... therefore, didn't try the max load.

I've had similar experiences with a Ruger #1 International (aka "RSI") in 7x57 and a Model 99 Savage in .300 Savage caliber as well as a pre-'64 Model 70 Winchester in .338 Win. Mag.

Rifle used: Ruger #1 in 7x57mm with 20-inch barrel & full Mannlicher-style stock with Kepplinger single-set trigger using set trigger (6 oz.) with a 4-12x40mm A/O scope set on 12x.
"THE" Sweet Spot was from 47.2 grains to 47.6 grains inclusive (5 grains wide) of H4350 powder with a 3-shot groups @ 47.2 grains measuring .176 inches and the 47.6 grain group measuring .179 inches.

Rifle used: Savage Model 99 (lever-action) with a 24-inch barrel in .300 Savage with 3-9x scope set on 9x.
"THE" Sweet Spot was from 41.3 to 41.5 grains (3 grains wide) of the "old" (prior to Hodgdon buying IMR out) IMR4895 with a 150 grain Nosler Ballistic Tip bullet. The best 3-shot group (41.3 grains) measured .112 inches. The 41.4 grain group measured .221 inches. The 41.5 grain group (max. book load) was 2nd. best measuring .191 inches.

As you can see, most "Sweet Spots" weren't 5 grains wide. Can't remember the .338 loads, but I seem to recall the "Sweet Spot" was 4 grains wide (IMR4350) @ 100 yards with 3-9x scope set on 9x. Best groups was slightly less than 1-inch... something like .877 inches (3 shots).

When trying to find "THE" Sweet Spot on a new load or a new rifle, I use either .2 grain or .3 grain powder increments once I'm within 5% of the maximum load. The amount of the increment depends on the case capacity of the cartridge. With larger calibers (and generally larger cartridges), I use 3 grain increments.

Once I find "THE" Sweet Spot, let's say 40.0 grains, I switch to .1 increment loads and load a set of 3 rounds at 39.8 grains, 38.9 grains, 40.0 grains, 40.1 grains and 40.2 grains. Then I shoot the rounds and measure the results.

If, for example, I'm getting the smallest groups at the upper powder charges and the smallest group is at 40.2 grains, I will try loading a few increments higher... example: 3 rounds at 40.2 (to re-check that amount is still giving me very small groups), at 40.3 and at 40.4 grains as long as these loads do NOT exceed the MAXIMUM book load.

Then I verify "THE" smallest group by loading five 3-shot groups of loads at that single loading point (let's say 40.3 grains) in order to insure that load yielding the smallest group wasn't a "fluke".

If the 5 loads all prove out to yield very small groups, THAT is my "accuracy load" for that rifle and that powder, bullet, primer, cartridge case combination along with that bullet seating depth.

Incidentaly, I've usually found "THE" most accuracy was having the bullet "jump" from 10/1000ths to 30/1000ths. I never push the bullet up against the lands and groves. This can cause high chamber pressures which was why Roy Weatherby (and a few others like Sharpe & Hart in their 7x61mm cartridge... a 7mm magnum without the "magnum" name) "free-bored" their rifles in their magnum calibers.

With "free-boring", bullet "jump" can be considerable (up to several hundred thousandths) before the bullet is allowed to contact the lands & groves. This allows the rifle to safetly operate at much higher chamber pressures than a rifle without free-bore.

That said, don't be afraid to seat that bullet deeper in the case if that gives you good accuracy (as round-nosed bullets often do when seating deep) and fits in your rifle's magazine and feeds ok.

Good luck with your "project"...


Strength & Honor...

Ron T.

Thanks for posting Ron.

I can buy that the sweet spot may be less than 0.5 grain. My initial loads are spaced 1 grain apart. I see if the gun likes high end or low end, concentrate only on the high end loads, then start tweaking. Frankly once I hit an inch or less, I'm good to go - but the load must repeat the performance for me to call it good.

I'm down now to tweaking powder charges and seating depth.

If your going to tweak loads for accuracy then start with the rifle first. Adjust the trigger and bed the action, then start working up loads.

Done and done.

The most efficient way to get great accuracy with a hunting rifle is to toss the factory barrel and have a match grade barrel properly fit. I'm not trying to be a smart alleck, but you can waste alot of time and money trying to find the magic load for a so/so barrel, or you can just save your time and money and get a barrel that won't be finicky. I figure if you put any value on your time, 3-4 range sessions will pretty much pay for a new barrel.

That said, I just haven't had that much trouble getting factory barrels to print 3 shots into 1" or less with a couple of range sessions, if they gun will shoot. If it won't shoot, I just won't waste my time on it. That said, I've not found nosler partitions to be terribly accurate bullets, so I'd either go with a different bullet, or a different barrel.

The gun will shoot. It will shoot less than an inch with Re 22, Re 25 and H4831. The Re 22 and H 4831 loads are not speed demons (2875 and 2905, respectively with 160's). My fall back is the Re 25 load but the Magnum shoots ~ 1.5" at 100 but always groups 2 touching and a third out and inch or so.

I wanted to play with seating depth to see if that is some kind of ballistic magic I hadn't played with before. It'll cost me ~ $20 in bullets/powder to try.

I don't care what distance from the lands any bullet is because it doesn't matter as long as the OAL fits into the magazine and chambers well.

Here is what I do.

The shape of the group tells all. If the groups is a large equilateral triangle, seat the bullets out a 1/4 turn on the die and repeat until the group shrinks. If the group is 2 together with the 3rd out there, seat the bullet deeper in the same manner, a 1/4 turn at a time and the group will shrink.

John

I do 0.005" at a time. Assuming you can shoot, some of your 1" guns will do 0.5" if you'll take the time to experiment with seating depth.

AGW - I have several powders loaded using that exact method. I'm shooting them tomorrow and will report what happens.