Horrible velocity spread with new Lapua brass

[Domestique]

I need some tips here. My previous load was as follows:

175 SMK
42.5 grains of IMR 8208 XBR
Federal Brass
CCI BR2

I bought some Lapua brass because I was getting poor case life with the Federal. Some of you may remember my thread about the neck tension being too much with the virgin Lapua brass, and I was told just to seat the bullets and shoot, which is what I did. The only thing I changed from my old Federal load was I switched to regular CCI primers instead of the BR2's. Now, with the old Federal load, I was easily getting .5 MOA all day long with an extreme spread of about 20 FPS. It was a great great load. I loaded up 15 rounds (5 at 42.5, 5 at 42.7 and 5 at 42.9 grains) in order to find the "sweet spot" again and compensate for the change in case volume. However, when I took this new load out with the Lapua brass, I was getting extreme spreads of several hundred FPS and horrible (approaching 2 MOA accuracy). I was pissed and went out and bought a new scale that night thinking that was the problem.

Well, today I went back to the range after having loaded another 15 rounds with my brand new RCBS Loadmaster scale, the same thing happened! Horrible ES (several hundred FPS) and piss poor accuracy. I even took care of the neck tension problem this time by running an expander ball through the cases and then following it up with some polishing of the inside of the neck. I'm at a loss as to what has happened!

 

[gcoulsey]

Re: Horrible velocity spread with new Lapua brass

Try working up from 41.5 grns, lapua brass has less volume, so starting at 42.5 you might already be past your sweet spot?

 

[Downzero]

Re: Horrible velocity spread with new Lapua brass

If you have ES numbers of several hundred FPS, your chrono is lying to you or you have some sort of serious problem with your primers or, most likely, powder.

 

[jrob300]

Re: Horrible velocity spread with new Lapua brass

I agree with GfunkUK (although the neck tension thing may yet prove to be a factor). My load for Federal/Nosler brass is 76.2gr. For Winchester brass it's 77.2. (300WM... irrelevant but for illustration).

When I was in load development, I got advice that said that 77'ish gr. shot the lights out. But for me it was over pressure. Why? Case volume. Others were using Win. when I was using Federal.

Case volume can have a HUGE impact (LC vs. commercial 5.56 brass).

I'd start low and work up slow and find that new sweet spot. .5gr too much and my rifle shoots like a 12ga.

John

 

[jrob300]

Re: Horrible velocity spread with new Lapua brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Downzero</div><div class="ubbcode-body">If you have ES numbers of several hundred FPS, your chrono is lying to you or you have some sort of serious problem with your primers or, most likely, powder. </div></div>

Sorry, missed the "several hundred FPS" part. Something is very wrong. (obvious statement is obvious.

)

John

 

[Domestique]

Re: Horrible velocity spread with new Lapua brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Downzero</div><div class="ubbcode-body">If you have ES numbers of several hundred FPS, your chrono is lying to you or you have some sort of serious problem with your primers or, most likely, powder. </div></div>

Powder is of the same lot that I used for my Federal loads. I dont think the chrono is lying, as it was dead on just a few weeks ago, plus the accuracy is shit, lending to the idea that my velocity is FUBAR. I'm going to try some Federal GMM primers I have and go from there I guess.

 

[High Binder]

Re: Horrible velocity spread with new Lapua brass

I'd say double check your charges or shield your chrono from the sun/change the angle the chrono is in, in relation to the sun.

 

[Tangodown911]

Re: Horrible velocity spread with new Lapua brass

I also say the powder or primer is fucked. But also make sure that you are visually inspecting for consistant case volume when you drop the powder. Don't always trust the scales. I think the brass is the last thing on the list to cause such a cluster.

 

[arborpro]

Re: Horrible velocity spread with new Lapua brass

I hope you don't judge advice on the # of posts made. I do a lot of looking and little replying until I see some thing I can offer advice on.
Never heard Of IMR 8208 is it fast or a slow burn powder?
I have shot a lot of Highpower and Palma; here is what I'm looking for in a reload:
1) Bolt manipulation or ease of bolt use
2) groups - both 1&2 must be top priority
3)velocity
But when I do my prep, I start backwards. I want the best velocity I can get with ease of bolt use and of course the groups it shoots at the distance I'm shooting. A great load that blows primers or needs a hammer to open the bolt doesn't help anyone. Some great groups don't always produce the best spreads in velocity.
So, I start with case volume. I use the 85% rule of powder capacity of the case that offers the velocity I’m looking to obtain with pressures that are safe: this is key.
So how do I start. Use whatever case that means something to you, Lapua, Winchester, Lake City etc,. to me, I use the cheapest. So I would use Winchster. Whether factory or new brass, shoot 3 or 4 rounds and bring the brass back for analyisis. Do not size the brass. Weigh the brass on a scale, digital or beam, digital is easier. Jot down the weight. Then fill the case with water and weigh again. You should have some type of gauge to measure case length with bullet to lands. I use a stoney point guage. I’m not stating you need to put bullets into the lands; but, you need to know what that distance is though. Factory barrels will suck and have a lot of leade because of laywer issues. So, if you are shooting a factory barrel, you will need to consider the box max lentgh as your starting point If you want to load from the box. In some cases, you may find the bullet will be completley out of the case to touch the lands on factory barrles. On a custom barrel, this should not be a problem because you tell your gunsmith “I want to shoot 175SMKs box length etc.”.
Weigh the unresized, fired case on your scale. Fill the case with water to the mouth of the case. Then use your fingers to insert the bullet to your specified depth. Remove the bullet ,wipe any excess water from the outisde of the case and weigh again. The difference in the weight is the case’s water capacity. Multiply the figure by 0.85 to get a starting powder charge wieght. Refer to any modern handloaders book for a powder selection near that weight. Now that you have a weight for that case , look in your book that shows a velocity close to your liking for the bullet you want to use. You will likely see it’s nearer toward the bottm of the page as the slowest buring powders are near the bottom and the faster powders are at the top. Fast powder to me means more pressure. More pressure means sticky bolts or blown primmers. Smooth bolt operation means less pressure. Now you have a starting point and you can print your loads on paper. Now shoot for groups. Try at least 300 yrds for analysis and watch your vertical. Don’t concern yourself with side to side. If you have a chronogragh , great ! If not, don’t worry. Pessure and velocity are generally close with what you see in the book. The professionals have sophisticated equipment so if you are at the velocity listed in the manual for max, you are close to the pressure for max- so be careful and look for pressure signs.
So, now its all about groups. You can work up or down , change powder charges or primers to dial in your load. But belive me, you will be very close with the 85% rule with some small adjustments . Now if your chrono shows good spreads, that’s your load.
You want your vertical to be less than MOA; so at 300 yrds, you want your max vertical spread under 3 inches. I would want that for 600yds; so maybe 1 ½ or under would be satisfactory @ 3.
The finale: if you are a master at your trade and can call all your shots, then by all means, weigh each bullet, mold the metplate on each bullet, trim your necks, separate your brass - this is because you can read the wind within 1 mph and know the the clock values. Under 1 o’clock means wind @ ½ value. 1> o’clock = .7>value , 2 o’clock = .8>value and 3 o’clock = full wind value . Remember @1000yds the tricky shit is at 1 to 2 oclock. Full value for 1 mph is close to 1 moa. The question is - Can you tell the difference between 1 and a 2 mph wind because if you can’t @1000 yds it’s a 9.
Good Luck
Arborpro

 

[ChadTRG42]

Re: Horrible velocity spread with new Lapua brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Downzero</div><div class="ubbcode-body">If you have ES numbers of several hundred FPS, your chrono is lying to you or you have some sort of serious problem with your primers or, most likely, powder. </div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: gfunkUK</div><div class="ubbcode-body">Try working up from 41.5 grns, lapua brass has less volume, so starting at 42.5 you might already be past your sweet spot? </div></div>
Try both these 2 options.

 

[longebow]

Re: Horrible velocity spread with new Lapua brass

Extreme spreads of "hundreds" of FPS is very unusual. Are you shielding/shading your sky screens? I have gotten odd values with my Oehler if the lighting was "just wrong" (glint?).

Never used IMR 8208 before. In .308, have had good luck with 3031, 4064, Varget, Data 2520, Win 748. Since trying VV N140, have NEVER looked back.

CCI BR2 primers are good. Fed 210M are my favorite.

I like to do my load development at the range. I look at the velocity, point of impact, and then watch for "clustering" of bullet holes (the sweet spot). This is the Creighton Audette method. Use good components, seat the bullet to work in the magazine (or 0.010 off the leade), and enjoy! 300 yards is better than 100, but use what you have. I use a Redding RB3 powder measure (with baffle), and just increase the powder in "increments" to obtain the velocity range that I expect. Should get 2600--2700 fps for the 175 (individual mileage will vary, and be careful for signs of pressure).

 

[Domestique]

Re: Horrible velocity spread with new Lapua brass

Thanks for the help guys, but I'm not new at reloading. I switched over to my Federal GMM primers and its shooting bugholes again. I'm not sure if the primers are bad or the XBR powder just doesnt like the CCI primers. Strange since the CCI BR2's worked wonderes with this powder before.

 

[dar1246]

Re: Horrible velocity spread with new Lapua brass

I had better luck with the FGM 210 primers combo with IMR 8208 XBR powder. I normally shoot BR2 primers but not with that powder. I think the BR2 primers are a little hotter.