Help me with my loads... lousy accuracy

[Afy]

Just back from the range...

Fired off a load of Sierra MK 190Grs sepated over VV N165 powder.

Loadings from 71 Grs to 74.5 grs...

Best five shot group was a little over 1.5 inches using 72.5 Grs... very disappointing.

I typically get under 1 inch at 100 meters using federal 180 gr game kings...

Barrel is 24 inches with a 1 in 10 twist.

Also began seeing flattened primers at 74.5 grs (Max load listed is 75.3) and a group of over 3 inches...

 

[Walkalong]

Back off a tad on the powder charge and see if your groups tighten up. Just because something is max in a load book, doesn't mean it is max in your rifle, despite all the care the powder companies take to publish safe loads.

 

[Afy]

I have actually tried the entire range from 68 grs up to 74.5 in .5 gr increments.

2 groups of 5 at each level. 1-2 mintues between shots and 5-10 minutes between groups..

I think my rifle might not like 190 grain bullets...

will probably load up some more between 72.5 to 73 grs in .1 grain increments...

dont know what to make of it...

 

[ForneyRider]

300 Win Mag?

N165 is pretty close to RL22 in burn rate. I never used the VV brands.

Must be fun testing. I got a fist-sized shoulder bruise from testing 7mm Mag recently.

Have you experimented with OAL? When I set mine way out, like single-shot length, my groups really tightened up with same load as factory lengths.

http://www.lapua.com/fileadmin/user_upload/esitteet/VihtavuoriInternationalReloguide2008.pdf
Says max load is 77.3gr with 190gr Sierra at 2893 fps, COL 3.339in.

 

[Vern Humphrey]

I typically get under 1 inch at 100 meters using federal 180 gr game kings...

Switch back to Federal 180 gr game kings.

 

[Afy]

Ammo is very expensive about 30-40 Euro's for a box 20.
Plus was hoping for better accuracy with handloads...

Is it Ok to go over COL of 3.339 if I do not want to use a magazine?

 

[cracked butt]

Is it Ok to go over COL of 3.339 if I do not want to use a magazine?

Absolutely. Most people load with longer COLs in order to get the bullet closer to the lands in the throat to shorten the jump the bullet needs to make before it engages the rifling. Only caveat is that if you seat the bullets long enough to engage the rifling, you need to start at the bottom end of the powder charge and work back up because pressures will be increased.

I'm not familiar with the VV line of powders- you might have to switch powders. Often times one powder will not shoot well while another will with a certain rifle/bullet/cartridge combination. The other option is to try a different bullet.

 

[cracked butt]

Also if you want a shortcut to burn through less bullets and powder to find a load try the Audette/ladder method.

http://www.washtenawsportsmansclub.org/groups/cba/downloads/incredload.pdf
http://home.earthlink.net/~dannewberry/dannewberrysoptimalchargeweightloaddevelopment/index.html

 

[Walkalong]

Some rifles can be very picky about the bullets they like. Try another good bullet.

I typically get under 1 inch at 100 meters using federal 180 gr game kings...

Sounds like a good one to start with.

 

[Afy]

My current inventory of .308 bullets are as under:

1. 180 gr Strela FMJBT (Sellior Belloit)
2. 150 gr Strela FMJBT
3. 180 gr Sierra MK
4. 190 Gr. Sierra Mk
5. 185 gr Lapua Scenar
6. 168gr Lapua Scenar

So far have tried the 180 gr Strela (only two loads) and the 190gr SMK's

Will load up the Scenars, and 180 SMK's and see what happens

 

[John4me05]

Try a different powder with a tad slower burn rate... When i develop a load ill use 2-3 powders the first loading... If it doesnt go sub 1" with 1 of them ill try another powder...
If you dont want to do that try to trade the bullets for something that you want or works...
Not every gun will shoot every bullet made for that caliber accurately...
Just the nature of the beast... It all has to do with barrel harmonics...

 

[dagger dog]

AFY,
Just looking at the Sierra bullet poster and that 190 grainer is very long, you may be encountering a twist rate problem, check yours against a twist rate chart or formula.

Those longer bullets , and the 190 looks quite a bit longer than the 180, take quicker twist rates.

I can't relate to the .300 Win Mag, as I shoot a .308 Win most are standard with 1-10 which is not fast enough to stabilize the longer,heavier bullets, 180gr is right on the cusp.

 

[Afy]

Well

am switching to 180 SMK's for the next load, in conjunction with the Vectan Tubal 5000 and 8000. Which are simillar in performance to H4350 and IMR 4831 respectively.

Have also ordered some N160 which is supposedly good with Win 300 accroding the VV.

Though I do think the slow 1 in 10 twist is behind my issue with the 190grs..

Also noticed that the OAL was around 3.28 on some of the 190's left over from the lot. So some bullet pulling... or should I just use them for fouling shots?

 

[Mal H]

Have also ordered some N160 ...

Good, that's exactly what I was going to recommend, but I saw you ordered some in your last post. N165 may be just a little too slow for that small a magnum (small in comparison with the .358's and .458's). It was designed for heavy bullets in large magnums.

What primer are you using?

 

[Afy]

I am using the CCI Large Rifle Magnum primers.

 

[DaveInFloweryBranchGA]

Try this link, should help you figure out what bullet sizes your rifle will be happy with:

http://www.uslink.net/~tom1/twistrate.htm

Berger lists recommended twist rates for their bullets on their website, it should help you a good bit:

http://www.bergerbullets.com/

Those two websites should get you going.

Dave

 

[JJ Junior]

Try an RCBS Precision Mic for your bullet seat depth problems. It will help you find the lands of your rifle. You can then make rounds that sit -.010, -.020, and -.030 (or any variation for that matter) off the lands and find out what YOUR .300 likes best. It worked well in finding my best COAL/bullet seat depth for my .223. The freebore tool is somewhat of a pain but there are ways around that. The mic itself works well and also gives you headspace information.



http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=302361&t=11082005

 

[dagger dog]

Afy,

I'm not fimiliar with the Scenar bullet shape in any of the .30cal. weights, but if it's close in design to the Sierra MK you got a winner. If you want the max. sd. and and bc. for that 1-10" twist go with the 175gr. Sierra MK #2275

 

[R.W.Dale]

You can go crazy trying to get a rifle to shoot a bullet that it doesn't like. In my case my Winchester M70 30-06 hates! 168grn BTHP match bullets literally pukes them at the target like your rifle. Yet I can feed it a cheap bulk Remington 165g flat base SP and it'll shoot really close to MOA out to 300m:banghead: