.300 Win Mag Accuracy "issues"

[aebhunter]

More of a lurker than a poster on here, so bear with me...
A little background first-I have a Remington Sendero SFII in a .300 win mag that is mostly stock. I have a timney trigger, APS Painkiller Brake, and it has been skim bedded by APS as well. It has a Vortex HSLR scope with Nightforce rings and bases. I shot the rifle in stock form last year and it actually shot about everything well, if not really well. I would routinely print sub MOA groups with handloads with 190 Berger VLDS, 210 Berger VLDS, and 200 grain Nosler Accubonds. I went through a quick load development last year and ended up going with the 190 grain VLDs shooting about 3050 FPS for my hunting load. I have been experimenting with the heavier 215 Berger Hybrids as well as the 190 Nosler ABLRs lately and have been having some "issues". I am putting "issues" in quotes because I know there are so many variables involved in this little hobby. I want to be clear that I am not implying that the gun doesn't shoot well now since I have had the work done to it, it actually shoots my load from last year very well.

I guess the main crux of the issue is that other than the 190 grain vlds I shot last year, the gun really doesn't even come close to performing like it used to. I have gone from shooting 1/2-3/4" groups at 100 to 1-1.5", if I am lucky. So far I have tried about 8 different loads, with mediocre results at best.

I am shooting the 215 grain hybrids under both Retumbo and H1000, and have gotten better accuracy and velocity with the Retumbo. I am shooting different seating depths that range from about .010 off the lands to about .040. Charge weight has been between 76.5-77.5 of Retumbo and 74-75 grains of H1000. The H1000 loads are really slow and not accurate.

190 ABLRs are being shot under H1000 solely. To be quite honest I am really trying to make these 215s work, and am more interested in them.

Any ideas on where to start? Here are some of my thoughts:

Keep playing with seating depths on the 215's
increase/ decrease charge weights by .5 grains
Switch powders

Wondering how much adding the brake and bedding the gun actually affects its performance?

Is there a regimented way to find an accurate load? Right now I am just trial and error and it is costing me some serious gas money

Sorry for the rambling post...any help is much appreciated.

 

[Broz]

In regards to the 75 gr H-1000 and 215 load, what is really slow?

What chronograph?

Have you cleaned the rifle since you tried all these different brand bullets? If so with what?

If the rifle is capable, and lets say it is, I have seen many 300 wins shoot sub .75 moa with 215's over 74 to 77 gr of H-1000 with a Fed GM 215M primer seated between .005" and .040" off the lands. They were no where near slow across an Oehler 35 or a Magneto Sped V2/

How many shot groups?

Are two ever touching or close?

Jeff

 

[aebhunter]

In regards to the 75 gr H-1000 and 215 load, what is really slow?

What chronograph?

Have you cleaned the rifle since you tried all these different brand bullets? If so with what?

If the rifle is capable, and lets say it is, I have seen many 300 wins shoot sub .75 moa with 215's over 74 to 77 gr of H-1000 with a Fed GM 215M primer seated between .005" and .040" off the lands. They were no where near slow across an Oehler 35 or a Magneto Sped V2/

How many shot groups?

Are two ever touching or close?

Jeff

Jeff,
Thank you for the response, and please excuse my rather spartan knowledge. Still just getting into this long range game...

On the speeds, they are recorded over the notorious chrony...I know.
My chrony results were showing average of 2620 fps with the H1000, Retumbo was closer to 2800-2850. In the past I have used the chrony to at least get me close, then I validate out in the field as needed.

I clean between groups with Montana Exteme products and a Tipton carbon rod..

I did actually shoot a very promising 2 shot group this am (touching), then I called a yank on one and then touched off what I felt was a good shot with a solid follow through and strung one low and right, my hopes were high. The wind started to bellow at a good clip and I called er a day. I am going to reload that particular load and see what happens next. I did start very low with my H1000, I might try and up the powder charge on that one and see how it does. I don't really care too much about velocities, I had a Lazzeroni Warbird (been there, done that).

I am not eliminating shooter error out of the equation, but I generally am able to shoot some pretty good groups.

Thanks again,
AEB

 

[Broz]

Forget the shooting chrony for now. I highly doubt that a 75 gr load of H-1000 under a 215 was 2620 fps. 26" barrel right? I have seen 2900 plus from 77 gr in a 26". Lets not worry about fps right now.

What brass?

Jeff


PS: stop cleaning for now until you change bullets again. and don't oil the bore.


..

 

[aebhunter]

Gotcha. Nosler Brass is what I have been using. Seems like it is pretty decent.


One thing to note is that I have seen zero signs of pressure through any of these loads...

I will play a little more with the H1000 and see if that yields some better results...
I really want to give these 215s a try.

 

[Broz]

Yes, it sounds like you could go higher if the rifle will let you. I just wanted to make sure you were not using RWS brass as it has a lower case volume and maxes out at lower charge weights.

I would try the H-1000 and work between -.040" off and touching. Most of them have shot there.

Jeff

 

[aebhunter]

Thanks for the help. Happy hunting this year.

 

[Broz]

Thanks and you are more than welcome. Let us know how it goes.

Jeff

 

[aebhunter]

Jeff,
Took alot of your advice, and things improved dramatically. Switched to mainly increments of H1000 and ended up with a very, very, accurate load at 75 grains of H1000. O.A.L. was 3.671. All shots were touching, inside 1/2 MOA. Funny thing is that once I switched to H1000 instead of retumbo ALL my groups got smaller. I am showing zero pressure signs whatsoever, so I am going to work up in .5 grain increments and see how it shoots.

 

[artemistrad]

Hi, I have the same caliber. Had issues too. Can only talk about Barnes LRX bullets, found out that because of the solid-cupper bullet it needed a lot of bulletjump to get accuracy and I found out that when I shoot less then the speed I have now (so by less powder) the accuracy left me too dramatically.
I use for my Barnes LRX 175gr bullet compressed 80grain H1000 and shoot with my standard barrel 0,3"groups at 100meters. And the load is very temperature stable. So think that your bulletjump is the issue not the powder or maybe even to less of it. Gr Mark

 

[aebhunter]

Quick Update....
Did find a nice seating depth for accuracy, the guns seems to shoot every powder charge I put through it sub moa. I have ran through .5 grain increments of H1000 form 71.5-77. I am not really experiencing any signs of pressure that i can see. No extractor marks, bolt lifts very easily. Primer looks a little flat, but they all look the same from 71.5 up...

My only problem now is that I have no idea how fast the **** thing is moving. I had readings all over the place on my chronograph tonight, so I can't really rely on the data it's spitting out. So I said hell with it and impulse purchased a magneto speed chronograph from this site. Hopefully it gets here soon.