Reloading .308 - Strange Issue - Help!

[roscoe53]

Well, just when I thought I was headed down the right road. Here's the problem - I have been working up 100 yard loads for .308 and settled on Sierra 168gr MK, 43gr Varget, CCI 200 with a .005" jump. These rounds have produced groups of .207" & .250". I wanted to begin same on 300+ yard work up and started with the following - Sierra 175gr., 43gr Varget and a .005" jump. Keeping the jump the constant I began bumping up powder at .3 per 5 shot group. My first 5 shot group at 300yds was crazy wild - maybe 5-6" and the second group was about same. Nothing was even close to a group - holes scattered all over paper. At this point I don't know what to correct next! Should I keep powder at 43gr and start varying the jump .010" - .020"? Very strange - never had such a variance before. The loads were as good as I can make them - Powder throw no more than .1gr var / runout was no more than .002". SD was 9fps and ES was 19. Anybody have any ideas about what I should do next? Thanks in advance for your help.

 

[ballisticdaddy]

Looking at the load data on the Hodgdon website the starting load for 175 grain projectiles is 42.0 with maximum being shown at 45.0 grains. What is the length and twist rate for your barrel and what kind of MV were you achieving with the established and new loads?

 

[roscoe53]

Rifle is Ruger Precision Rifle - 1-10". Hope this helps!

Sierra 175gr. HPBT MK Tipped
Varget (+/- .1 grain)
CCI 200 Primer
Federal FC (fully prepped)
O.A.L. 2.233" (Ogive)
.005" Jump
Series	1	Shots:	4		Varget 43.0gr
Min	2565	Max	2584
Avg	2572	S-D	9
		ES	19
Series	Shot	Speed
1	1	2565	ft/s
1	2	2584	ft/s
1	3	2566	ft/s
1	4	2576	ft/s
----	----	----	----
Series	2	Shots:	5		Varget 43.3gr.
Min	2578	Max	2599
Avg	2589	S-D	9
		ES	21
Series	Shot	Speed
2	1	2584	ft/s
2	2	2578	ft/s
2	3	2599	ft/s
2	4	2598	ft/s
2	5	2588	ft/s
----	----	----	----

 

[djarecke]

How does your 1/4" group ammo shoot at 300 yards? That seems to be a known, so I'd try that to see how I shot.

 

[roscoe53]

I should have taken some with me to use as a known standard. Will do next trip for sure.

 

[NukeMMC]

M852 is a military match ammo essentially made for shooting CISM 300m rapid-fire rifle. It is rated at 2550fps at 78ft with a 168gr SMK. I have chrono'd different batches and they are very consistently 2560-2570 fps 20ft from a stock Remington 700 SPS-V ("lawyer-leade long throat). Same rifle on the same day shot FGMM 168gr at 2623fps. Same lot M852 shoots 2675fps over a Magnetospeed V3 in a WOA 20" AR10 with a 308 Match chamber. The 168SMK is quite adequate for 300yds, so unless you plan on reaching out past 600, there is no reason to shoot 175s. Save them for >600yds. I have had good luck with 41.5-42.0gr Varget behind 168s in LC Match brass in M14s. I normally used 41.5gr of 4895, though. As always, LC brass runs about .5-.8gr less powder than a commercial case.

 

[roscoe53]

Beginning to learn that I may have created my own problem. Staying with 168's out to 600 yards may be the best way to go. I may have made something more complicated than necessary. Thanks for your help.

 

[fxdrider]

http://optimalchargeweight.embarqspace.com/

If you're not familiar with OCW (Optimum Charge Weight), it might help to read this rather lengthy article. Whenever I try a new bullet, I do an OCW test. The OCW test, or even a ladder test are (I believe) the best ways you can be sure you're getting the best powder weight for your rifle/bullet combo. Every rifle/barrel is different, as it every bullet model. It's definitely a tedious process to go through for each new bullet I try, but it's the only way to be certain you've got the best load for your rifle with that bullet. As the article says, once you've decided which is the optimum charge weight, then you can begin experimenting with different seating depths to tighten groups to the best possible.

 

[roscoe53]

Fxdrider, I will read that tonight. Always looking to improve my system, thank you. I've been reloading shot shells and pistol for a long time - finding out rifle is a whole new level in handloading. Much more science than just stuffing a casing and pulling the trigger. I'm loving it - handloading is almost as much fun as shooting. Thanks for your help.

 

[918v]

If you want to shoot 175's with Varget "the" load is 44 grains and it is too much for FC brass. You should get a lighter case with more capacity like Lapua or a Hornady or Remington.

 

[fxdrider]

Fxdrider, I will read that tonight. Always looking to improve my system, thank you. I've been reloading shot shells and pistol for a long time - finding out rifle is a whole new level in handloading. Much more science than just stuffing a casing and pulling the trigger. I'm loving it - handloading is almost as much fun as shooting. Thanks for your help.

There are SO many different facets to shooting in general, and rifles in particular. Definitely challenging.

 

[roscoe53]

918v, your comment is interesting. Had no idea, but that helps me understand some other articles that I have read related to that. Funny how you can read something and it didn't mean much until someone puts it into perspective. Have some Lapua and Hornady that I will try next time out. Thank you!

 

[NHPiper]

I have owned several 308s and with the first two I wasted a lot of reloading components shooting groups at 100 yards with small increases in powder charges. This is a great way to go through bullets fast and powder too. My recommendation, do the ladder test. With a new gun, I will load up 20-30 rounds of a mid-high charge (with my newest .308 it was 44gr of Varget under a Nosler 175 Customer Comp in Lapua brass and a standard Federal Primer) to first sight the gun and have some fun. Then I do a ladder test at 200 or 300. It is going to immediately tell you what charge range you should work with.

Coincidently the 44gr of Varget under a 175 Nosler shoots like a dream from my 18" Bartlein tied to a Surgeon action.

 

[GhengisAhn175]

Roscoe, sounds like you want to do load development at 300 yards and have access to a chrono.

what type of chrono?

you can do the ladder test (another load development version)
the ladder test is basically shooting one round per "string" going up in incremental charges until you see clusters.

the clusters indicate a node window and from there you work the middle of it with seat depth.

example would be:
42.0 grains to 44.0 grains in .2 grain increments

A= 42.0
B= 42.2
C= 42.4
ETC.....until you get to the last load of 44.0

load two of each charge and have a tall cardboard target with a prominent target near the bottom 1/3. Your POA is always the target and just shoot 1 of each. The idea is the hotter charges shoot up higher from your POA and your POI looks like a vertical string of shots.

Again youre looking for "clusters" so say F, G, H (43.0, 43.2, 43.4) clustered together. I would take G (43.2) and start a seat depth test.

** here's another thing: I always keep a minimum 20 thousandths jump, never closer. Then I only seat deeper in 5 thousandth increments, up to 50 thousandths.

The seat depth test would be 3 shot groups at 100-300 yards. One should shoot real well and all you need to do from there is verify your best group with a chrono.

unless you have a screen chrono like an Oehler or labradar , you can't chrono from start to finish (ie magnetospeed)

 

[flyright]

If you're getting .25 moa at 100 - then you should be getting at least (in theory.25) .5 moa at 500 - if your sd's are low. Not always the right math but you all know what I mean. However, you have to stay with that load and not even consider any "interpolation". When I shot BR we always looked at 100yds then went straight to 300yds (same load) and then 600 or 1000 to see if the moa was consistent. Sometimes it would stay identical (moa wise). Sometimes it would blow out horribly - even with low sd's. And, seldom, it would improve - like touching holes or .25 @ 600 - I emphasize- seldom. And sometimes with crappy sd's - like 40 fps - it would make tiny groups. We used to say "just let the paper be the judge". There are many variables - welcome to shooting - especially long range...

 

[zeroz]

Take the 168 load out to distance. With those velocities that load should be stable out to 900. If it shoots great at distance stick with it. That exact load has rung many a 12" steel plate at 1000. If that load gives you sub minute out to 800+ run it until that distance gets boring. No reason to mess with a good thing. Ive gone crazy with a rifle trying to get it to shoot heavies and it just wanted the 168's. Not that your rifle is in that boat but worrying about a load for heavies for 300 yards in unnecessary. If you start shooting way out there and want to develop a new load go from there.

 

[1J04]

Agree wholeheartedly with the above regarding the 168's to at least 600. Since you want a 175gr load I'm curious if you've tried a box of FGMM 175's and how they shot if you did. If you haven't shot any yet I'd give it a whirl and see if that gets you going in the right direction, so to speak.