Help with rediculous es and standard deviation

[jaycoux]

Today I was messing with loads for a 25-06. Before I get into it let me describe the rifle. This began life as a 270 win. It is a pre-64 model 70 winchester. The original owner ruined the value by blueing the barrel and altering the stock. I had it rebarrelled to 25-06 and put a new stock on it. Barrel is a Benchmark 24 inch 1 in 10 twist. All bedding and accurizing work was done by Hill Country Rifles. It shoots about .4 to .5 inches at 100 yards with loads it likes.

I decided to load 115 gr Berger vld's. It shoots best with 59.6 gr Retumbo with a cci br2 primer. Bullet is .09 jump which it likes best. Brass is Nosler custom. While doing Ocw tests I noticed some really large velocity variations. Some charges exhibited close to 100 fps spreads. Most 3 shot groups had 2 shots that were close and another that was way off. Even factory loads show a 50 fps variation (HSM with berger). Temp during testing was 50 degrees F. Chrono was oehler 35p. Never had any issues with it.

Could there be something wrong with the rifle? I could chg primers but if I see the same thing with factory loads what's the point? Any ideas?

Thanks,
Jay

 

[Victor N TN]

Re: Help with rediculous es and standard deviation

Try standard Winchester large rifle primers, weigh your powder charges and make sure the case necks are clean inside. I prefer 10 shot strings for more even numbers.

 

[jaycoux]

Re: Help with rediculous es and standard deviation

Thanks. I have considered using wlr since they are hotter and varget is so slow. Brass was meticulously prepped, cleaned and charges were weighed on 2 scales.

 

[jaycoux]

Re: Help with rediculous es and standard deviation

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jjaycoux</div><div class="ubbcode-body">Thanks. I have considered using wlr since they are hotter and varget is so slow. Brass was meticulously prepped, cleaned and charges were weighed on 2 scales. </div></div>

Sorry- meant to say retumbo is so slow. I will try bigger string but I was doing ocw test this time. It seems to be. The norm regardless of what I try though.

Jay

 

[kyreloader]

Re: Help with rediculous es and standard deviation

In my .25-06, I found a good load with Retumbo with 110g BIB bullets with BR2s. I then loaded up 5 shots with Fed210M, BR2, and Fed215M. The group tightened up with the Fed215M and the ES was significantly improved.

 

[BOLTRIPPER]

Re: Help with rediculous es and standard deviation

my read on the tea leaves is.......

bullet seating depth.....
trigger let-off is .......lacking consistancy
the verticle stacking is a result of inconsistant powdr weight/charge

 

[BOLTRIPPER]

Re: Help with rediculous es and standard deviation

prolly ought to complete your profile also......



maybe some one local to you can hold your hand and guide you better than most here on the interweb

 

[flashhole]

Re: Help with rediculous es and standard deviation

I think you are on the right track with the hotter primer. You might even try a magnum primer, expecially if you are getting sooty necks. I shoot a lot of Retumbo in my 25-06 with bullets weighing between 100-120 grains. The heavier bullets allow pressure to build up a bit more. If you are getting good and repeatable accuracy at 300 yards or so I wouldn't worry too much about the numbers. Another thing you could try is a crimp. It will have the same affect as a hotter primer.

 

[jaycoux]

Re: Help with rediculous es and standard deviation

kyreloader, that is a very interesting bit of info there. Of course, it doesn't prove anything statistically but it does warrant more investigation.

I am checking out similar loads with wlr primers. I backed off on charge a little to compensate and I'll try working up in the morning. Hopefully the velocities will look better. After that I guess I'll try the magnum primers and go back to the drawing board.

Funny, I always thought running magnum primers in a non magnum cartridge was likely to worsen es and std dev....

 

[jaycoux]

Re: Help with rediculous es and standard deviation

Flashhole,

What is the big deal with soot on the neck? I always thought it was ok as long as it wasn't anywhere else.

jay

 

[jaycoux]

Re: Help with rediculous es and standard deviation

So today I shot 115 bergers with retumbo and wlr primers. I backed off and started at 57, 58 and on to what I thought would be my money loads. Turned out 58 grains clocked in at 3100 and 59 was at 3200, a little too hot for my nightforce hv reticle. It took over 60 grains of retumbo to achieve 3100 with the cci br2's. Clearly, the wlr's are a bit hotter. Noticeably absent were the wild velocities that plagued my previous loads with the br2's. es was around 20 fps with the wlr's which is acceptable in my book. I think I might also use imr 4350.

jay

 

[kyreloader]

Re: Help with rediculous es and standard deviation

I am glad the primer change helped out things. How did it shoot?

 

[jaycoux]

Re: Help with rediculous es and standard deviation

Hard to say just yet. I loaded one round at 56, 57 and 58 just to be safe since I was changing primers. I loaded enough to shoot a group of 59 and 59.6. 58 was as fast as I want to shoot-3100. The 59 grain charge went at 3200 which is too fast for my nightforce velocity reticle. I did not elect to shoot the 59.6. It was 35 deg with a front blowing through with 25 mph gusts. The 59 charge shot about a .75 inch group and was affected by the wind. Its hard to tell whether it was any good or not but irrelevant since it is too fast. I'm going to try lower retumbo charges and imr 4350 next week. Let you know then.

I did have some hsm loaded bergers that shot well in that wind out to 500. I was pretty excited about that!

Jay