Federal GM210M vs CCI BR-2 LR Primers

[Bart B]

[ QUOTE ]
I'm with Roy, group size is only half of the equation.i'm more partial to ES. And Roy says: If you're shooting longer than 300 yds the primer producing the smallest ES and SD would be the selection.


[/ QUOTE ]I'm not with either of these guys.

I and many others have shot 20-shot groups at long range using ammo producing the lowest spread or standard deviation in both muzzle velocity and peak pressure only to have its groups three times as large as ammo having medium spreads in these two internal ballistic elements. This all happened with different barrel weights and tapers. If the name of the game is accuracy, that's all that counts.

Folks testing the ammo thought that something was happening to the bullets from that ammo with very uniform internal ballistics when fired that caused poor accuracy.

[Jimm]

Yupp! ,

I've seen that very thing myself. Daaaang Bart ! we are on the same page on something [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img] [img]/ubbthreads/images/graemlins/smile.gif[/img]

On the serious side I appreciate your freely exchanged and hard earned experience.

Jim B.

[royinidaho]

GeeWizz I finally get in tune with Dave and fall out of grace with Bart and jimm. Gloom, disspare and agony on me.... [img]/ubbthreads/images/graemlins/blush.gif[/img] Sorry Dave I just can't help myself at times.....

Here's my experience.

two rifles and maybe 400 total shots through both. 100 through the 270 and 300 through the 338 WIN.

The 270 WIN w/27" lilja barrel spits the 140gr bullets out at +/-5 FPS for the most part (average)always less than 9 FPS extreme spread. Note that's for 3 shot groups as I am impatient enough to not go to 5 shot groups due to barrel heat. But as I logged a greater number of 3 shot groups the numbers maintained the average SD and ES.

Time after time the 640yd milk jug was dead on the first shot (I cheated and shot on only low wind days.) This rifle is capabable of 200yd groups less than 50% in size of the 338 Win groups which hung around 1/2MOA.

The 338 extreme velocity spreads were on the order of +/- 20 FPS and greater. Standard deviation of a number of groups was double digits.

Overlaying several338 Win 200 yd groups resulted in a somewhat but really definite eliptical/oval shape narrow at top and bottom. But hey groups way small so I was happy. Really impressed the neighbors.

When I stuck the steel yote out in the area of 800yds I was chasing shots up and down and never hitting. When I put 5 shots in a large paper target at that distance the group spread was all vertical sufficient to make hitting a 6 inch yote chest a game of chance. A deer would have been difficult to make a good shot on at that distance.

Short range accuracy on both rifles was similar. The major difference was that one rifle exhibited terrible extreme velocity fluctuations which I couldn't correct.

That's all I have to go by.

I'm willing to listen and learn though.

[jwp475]

I agree with you Roy, as the ES spread widens so does the vertical dispersion at long range.......

[Bart B]

[ QUOTE ]
Short range accuracy on both rifles was similar. The major difference was that one rifle exhibited terrible extreme velocity fluctuations which I couldn't correct.

[/ QUOTE ]A very common problem when firing pin springs get weak and they all do over time. If the spring's over 3 years old, it may need replaced. I'd replace the firing pin spring with a new one and see what happens.

Many rifle's factory springs aren't strong enough to smack primers hard enough to detonate them uniformly One with at least 10 to 20 percent stronger preload force will usually reduce muzzle velocity spread. For example, Winchester 70 factory springs are rated about 23 pounds when cocked. I use 26 to 28 pound ones and get much better muzzle velocity spreads and accuracy.

Another cause of large spreads in muzzle velocity is the firing pin doesn't stick far enough out of the bolt face. It should be between .055- and .060-inch for large rifle primers.

[Mysticplayer]

Never an absolute answer when it comes to reloading. Just use the items that shoot best in your rifle...PERIOD.

I use both primers and will test any rifle with both primers. My 7Mystic only shoots the Fed 210M. Other rifles, the CCI BR2.

I can say that the CCI is the milder of the two but that is greatly affected by the type of powder, cartridge pressure and barrel.

You are also likely to find differences in lots of the same component so if you find a combo that works for you, buy a bunch so you don't need to tweak all the time.

Temp has a pretty profound affect on primers just as it does many powder. Test under the conditions you are going to hunt/compete.

As to testing over the chrony, sure it is a great aid and can help to narrow down loads or catch when things get too toasty. However, no one scores our chronie, only the holes on paper. So ultimately, that is what matters.

Always keep in mind that the average chrony has a mechanical error of at least 0.1% to 0.5% (just ask the manf). At 3000fps, the error in the chrony is......3 to 15FPS plus or minus for a total ES of 6 to 30FPS.

Not so good when the measuring device has a built in error equal or larger then the amounts you are trying to measure. Just give your manf a call and ask for their reading error specs...All optical and timing devices have one.

I use the chronie alot to catch really gross errors. However, I use the target to fine tune any load/rifle.

Jerry