Why Flyers?

[fourarmed]

I recently came into some 7mm 150 GC boolits from Leadheads for the cost of the alloy. I am trying to work up a load in 7BR for a MOA Maximum pistol for silhouette. I have had two range sessions so far. At the second one, I fired two 5-shot groups each of 6 different loads at my 70 yd. bench range. The groups ranged from one inch up to around 2.5 inches. I was using a 7x Burris scope which was just recently overhauled by the factory.

On two of the groups I got flyers that were around 6" out of the group. I am satisfied that if I had been responsible, I would have known it. I did not call any shots that bad. The two wild shots came from different loads. One was from 15/2400, which was responsible for the 1" group. The other was from 21/Re-7. Between that load and 20/Re-7, I got 3 of the best 4 groups I shot.

I know a lot of people moan about shots that make a 1" group into a 2" group. I think most of the time, that simply means the gun and load and shooter are capable of grouping at the 2" level. This pistol has repeatedly shown itself to be a consistent 1-2 m. o. a. (hence the name?) shooter with jacketed bullets, with me shooting it. I think around 2" is the capability of this combo. So what are the most likely sources of wild shots?

I have 40 more loaded to try. I went with 20.5/Re-7 and 4 different OALs.

[Phil]

What twist rate is the barrel?

Have you weighed a quantity of the bullets to determine how consistant they are?

Are the bullet holes in the target round?

Is the nose section of the bullet a tight fit in the bore?

Does the base section of the bullet fit the throat?

Sounds like you are on the right track and its time to start tweaking things.

Cheers,

Phil

[Bass Ackward]

Fourarmed,

Your only running about 25,000 max. Stick a pistol primer up that pipe and be done with it. Then you can have a 1MOA combo. :grin:

[44man]

I have the 10" MOA and I found the 7BR is VERY picky about powders. I haven't shot cast yet and no longer shoot IHMSA. Cast is a future project.
I use only 4759 with 154 gr bullets but 322 works with 175 gr bullets. I have shot many 3/8", 5 shot 100 yd groups and many below 1" to 1-1/2" at 200 meters from bags with a scope.
I wanted to get the 120 gr SSP bullet shooting for deer but nothing worked, they sprayed the 50 yd target. I had Varget so I contacted Hodgden and they told me it wouldn't work in the BR. I worked loads anyway and was blown away with the groups I got with the little bullet that doesn't match the rifling. The powder burns clean and velocity was very good. It is the ONLY powder that will shoot the 120 gr. Don't ask, I know it is supposed to be too slow!
Here are my loads and you can most likely use them OK with cast;
Hornady 120 gr SSP, 32.5 gr's Varget. Velocity is 2175 fps. (Reduce and work up for the 150's)
Hornady 154 GR, 18 gr's SR 4759. This load shot more 40's then I can list.
The strange thing is both powders also work in my 7R Witchita with the same bullets. Just takes a tad more powder.
Personally, I would try 4759.

[VTDW]

Why Flyers?? That is easy to answer...to keep us humble.:mrgreen:

[Shiloh]

Fourarmed,

Your only running about 25,000 max. Stick a pistol primer up that pipe and be done with it. Then you can have a 1MOA combo. :grin:

How does this help eliminate flyers?? :???:

Shiloh :castmine:

[Freightman]

I can almost call a flyer before I look in my spotting scope, most are my fault. I do the same with a bow it just seems different.

[Bass Ackward]

How does this help eliminate flyers?? :???:

Shiloh :castmine:


Shiloh,

Cause just about any brand of pistol primer is WAY more consistent than a rifle primer. And when a rifle primer is off, it usually is WAY off to the high side with some brands having higher percentages of errors than others. With the lower resistance of cast, this shows up much more quickly than with jacketed because primer force can put the bullet well into the barrel.

Read some real good testing by a fella that measured one flat of every primer available about 5 years ago now. The set-up this fella made was similar to a strongman event at a carnival where the guy tries to ring a bell by hitting a pad with a sledge hammer. You could visually see and measure the strength of each primer.

With one particular box of CCI standard rifles that was measured, this error rate was 10 percent, and the wild ones were hotter than the average for Fed 215s. Now I don't know if or what fourarm was using and my intent is not to discredit a brand. I suspect from reading the testing that you could substitute a certain batch of primer from any make and get better or worse results.

Bottom line, any brand of pistol primer was much more consistent in these tests.

If you have a small enough case capacity to run a cooler primer, and you are staying below pistol maximums like 40,000 psi, and the powders he mentioned shouldn't require it to ignite, using a pistol primer to let the powder start the bullet moving forward instead of the primer, also tends to show enormous advantages.

Might not be the actual cause, but that was my best guess. :grin: I am sure fourarm will come back with his solution.

[fourarmed]

The second set of targets - all 20.5/Re-7/150 GC at various lengths - did not show any of the extreme flyers noticed in the first batch. There were some that enlarged the best 4-shot group by factors of 2 to 4, however. I adopted the method of measuring the 5-shot group, then measuring without the worst round. In one case I got 2.7"/0.8". There were groups, however, where the two measurements were virtually equal. Those were always over 2". I suspect that this boolit just doesn't fit the throat of this barrel well enough to group MOA consistently. The nose is a firm press fit at the muzzle, but I can't get it to touch the rifling in the throat.

I have prepared more loads to try the effect of different primers. The second trial indicated that an OAL of 2.32" (second shortest of the series) gave the best results, so I have loaded 10 rounds each at that length using Fed 205M, CCI-550, and Winchester small pistol. I was using new cases, and the CCI small pistol magnums were quite a tight fit in the pockets.

My main worry is that I will shoot all these boolits up before I get a good load. I guess if that happens, then they weren't going to work anyway.

[Shiloh]

Why Flyers?? That is easy to answer...to keep us humble.:mrgreen:

Boy, isn't this the truth.

How many times has a 100 yd, sub 2" group been spoiled by
the cursed flyer?? :roll:

Shiloh :castmine:

[HORNET]

For those interested, I think the primer tests that Bass referenced might be the ones on the Cabine Tree website ( http://www.castingstuff.com ). I've been hoping that he'd run some tests on the small rifle/pistol primers....[smilie=1: :roll:

[fourarmed]

I shot the loads with different primers yesterday after work at 100 yds. The dispersion was mostly vertical, with the WSP being the worst at 5-6" high by 2-3" wide. The best was the Fed 205M at 3-4" high by 1" wide. My usual primer for this pistol is the CCI-400, which shows no tendency to string vertical at 70 yards. I may try some SRM primers, or go back to the drawing board on powders. I didn't try 4227, which is what I use with 139 grain Hornadys. I haven't tried anything slower than H322 either.

The state IHMSA bigbore match is a week away, so I guess I will put this project on hold until after that.

[Jon K]

You are right about the boolit not fitting the barrel, if the bore rider is too big for the bore. Do not seat the GC below the neck, the Throat in the gun may also be too short to shoot cast Boolits.
Although the boolit is my personal favorite for 7mm- it is the RCBS Silhouette 145 gr, mine weghs in @154 gr w/GC & lube.
Try H4227 18 gr/ Fed 205 primer(good enough to shoot 40)

Have Fun Shooting,
Jon
:castmine:

[Scrounger]

Some powders simply won't shoot with powder charges that are too far under maximum, and changing primers will make some difference but very little. And if this is the case, changing to a hotter primer would help more than than going the other way. Another clue is that you got improvement when you seated the bullet deeper, thereby raising pressures a bit. You're shooting 20.5 grains? Go to 22.0-22.5 grains.

[joeb33050]

So what are the most likely sources of wild shots?

I have 40 more loaded to try. I went with 20.5/Re-7 and 4 different OALs.

First, wild shots are the nature of cast bullets.
Second, on average, if one shoots 5 5-shot groups and measures each, the largest group will be twice the size of the smallest. Not every time, on average.
Third, some of the suggestions made by others here may reduce the AVERAGE group size, but the "twice" average size will always hold true.
joe brennan