.308 long range load development results

[Nature Boy]

I’m continuing to work on my load knowing that the 180g SMK doesn’t have the best BC, however, it’s still very accurate, easy to tune and consistent. I keep coming back to the 185g Berger. The Berger has a BC of 560 vs. the SMK BC of 496



To find the best load I’ve been using the “Cortina Method” as its called over at the accurate shooter forum. Here’s the link http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

Basically, you start your load testing at 100 yards using 0.5 grain powder increments shooting 3 shots at each target dot at each change in charge weight.

Here’s my test for the 180g SMK



The way I understand it, you look for the least amount of change in vertical in comparison between adjacent groups. That is your node. You tweak from there by making small changes to powder charge and seating depth. As you can see from the target above, theres very little change between 42.0 and 43.0. I think that’s one reason this combo shoots so well because it has such a wide node.

So here’s the test I did for the 185 Bergers



From my perspective the node for this combo is between 42.5 and 43.0. I added 0.2g to match the velocity I was getting from the SMKs

So today I headed to the range to shoot 20 of each at 500 yards. Here’s the results. The Bergers on the left and the SMKs on the right.



Here’s the data on these two groups. Not a lot of difference, with one exception. The berger’s require less elevation, which I assume is due to its higher BC.



What do you guys think? Which would you shoot?

 

[dgod]

1st off, Good shooting. 2nd, I would choose the Bergers, excluding the 2 flyers, it is pretty tight.

Just my $0.02
dg

 

[Nature Boy]

I really want to try the Berger 200x20 or the new Sierra 200g Matchking. Both have BCs in the 700 range. My chamber isn't throated for these long bullets but I'm wondering as the throat erodes if it might allow me to run them now.

I have ~1,500 rounds through the barrel now and the throat has advanced 0.060. It's making it difficult to chase the lands with these 185 bergers and still have enough bullet in the case. No problem for the SMKs. They like 2.825 OAL and don't care where the throat is.

 

[WelshShooter]

Both groups look great, so you can't really make a bad decision. I think if you're shooting out to 1,000 yards the 185gr Berger's will be more forgiving for a bad wind call, but they are also a fair bit pricier than the Sierra's (I'm assuming this is true in the US as it is in the UK?). The big question will be if there is a noticeable difference at 1,000 yards with these two loads.

 

[Nature Boy]

Both groups look great, so you can't really make a bad decision. I think if you're shooting out to 1,000 yards the 185gr Berger's will be more forgiving for a bad wind call, but they are also a fair bit pricier than the Sierra's (I'm assuming this is true in the US as it is in the UK?). The big question will be if there is a noticeable difference at 1,000 yards with these two loads.

Wouldn’t the 185s also be more forgiving if you missed a wind call at 600?

I got a little practice in on Saturday at 1,000 yards using the 180g SMKs. The wind was 5-10mph switching from 9:00 to 12:00. I had a heck of a time staying on target. Very humbling

As to cost, the Berger’s are more expensive that the Sierra’s in the states too, ~$15 more per 100. If we’re talking about informal paper punching I’ll go with what’s cheaper. If its for a match, I’ll pay up for even modest marginal improvement.

 

[WelshShooter]

Wouldn’t the 185s also be more forgiving if you missed a wind call at 600?

I got a little practice in on Saturday at 1,000 yards using the 180g SMKs. The wind was 5-10mph switching from 9:00 to 12:00. I had a heck of a time staying on target. Very humbling

As to cost, the Berger’s are more expensive that the Sierra’s in the states too, ~$15 more per 100. If we’re talking about informal paper punching I’ll go with what’s cheaper. If its for a match, I’ll pay up for even modest marginal improvement.

Ah sorry, following from the start of this thread I thought this was for the intention of 1k yards only In which case yes, it will also help at 600!

 

[Nature Boy]

I got some of these new Sierra 200g SMKs to try.

I have a feeling they may not work too well.

Sierra recommends a 1:9 twist for these and I have a 1:10

OAL touching the lands comes out to be 2.881. That puts approximately 0.516 of the bullet’s 1.395 length into the case which might keep me from getting enough powder in there to achieve acceptable velocity. I’d like to get something in the mid 2,600’s

I will do some load development anyway and see what happens. I might be surprised.

180g SMK / 185g Berger / 200g SMK


P.s. I think I’ll use Varget first unless someone has a better idea

 

[Nature Boy]

Got up early before work and loaded up my first test. Changed my mind on powder and stuck with H4895. It has been making more speed with less powder than Varget. If it doesn’t play nice I’ll try Varget.

Load range 39.5 to 42.0. OAL 2.875 or 0.015 off the lands

 

[Nature Boy]

Having loaded rounds + range on the way to work x minimal self control = this....



Again, not looking for group size. I’m looking for adjacent groups with the least amout of vertical deviation. It would seem that’s 41.0 and 41.5

Questions:

Will the speeds indicated be enough to take advantage of the higher BC of these 200g bullets? Do any of you see stability issues from the above (would they show up at 100)?

Next steps:

I didn’t see any pressure issues at 42.0 so I may go up 42.5 and 43.0. I think I’ll also run this again with Varget. I’ll pick the best nodes from this and shoot 20 at 500. I have enough data from the 180g SMKs and 185g Bergers to know if these 200 SMK will be better or not

Feedback please

 

[Klint Beastwood]

Once I've got the load dialed in everything has been in the 1/2 MOA range
View attachment 764435

The problem I mentioned in the original post is that what worked at 100 fell apart at longer ranges. Not sure why that's the case but I think I'll re-start the 185 bergers with a different powder and see if I get a different result. There's no reason they shouldn't be good at 500 or 1,000. In the mean time 180 SMKs are good.

I don't have other photos of the 1,000 target. What I posted was the last 5 rounds I shot yesterday after a bit of practice and scope dialing and shooting different loads. I started with what the ballistics app said and it was high. We're on a hill and I'm sure that had something to do with it, but I was a full mil off

Do you latter test when doing your load development?

 

[Blue68f100]

No, He's using the OCW method.

 

[Klint Beastwood]

No, He's using the OCW method.

Ah, very well
Thanks.

 

[Nature Boy]

I realized I’ve made an error. These are the old 200g SMKs not the new ones. I inadvertently ordered the #2230 not the #2231

Oh well, I’ll finish with these and ses where they go while I wait for the others to come in

 

[bikemutt]

Nature Boy, I've been struggling lately with the OCW method you are using.

Do you load more than 3 per charge weight in the event you pull one?

Do you chronograph at the same time?

Do you shoot the groups round-robin?

I apologize if you answered these already elsewhere, I didn't read the entire thread.

 

[Nature Boy]

Nature Boy, I've been struggling lately with the OCW method you are using.

Do you load more than 3 per charge weight in the event you pull one?

Do you chronograph at the same time?

Do you shoot the groups round-robin?

I apologize if you answered these already elsewhere, I didn't read the entire thread.

This isn’t the standard OCW method. It’s a method developed by a guy named Erik Cortina. He lays it out on the Accurate Shooters Forum in this thread. He’s an accomplished shooter and knows his stuff.

http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

It’s simple and intuitive. I’ve had good success with it. You load 3 per charge weight in 0.5g increments and shoot them in order, not round robin, looking for adjacent groups that are close to each other in the vertical

Anyway, read his thread on it.

 

[bikemutt]

This isn’t the standard OCW method. It’s a method developed by a guy named Erik Cortina. He lays it out on the Accurate Shooters Forum in this thread. He’s an accomplished shooter and knows his stuff.

http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

It’s simple and intuitive. I’ve had good success with it. You load 3 per charge weight in 0.5g increments and shoot them in order, not round robin, looking for adjacent groups that are close to each other in the vertical

Anyway, read his thread on it.

I've seen the post, one more question; how many times do you run the test to confirm it's validity?

 

[Nature Boy]

I’ve done it twice on one load combo and they were very close. If I could find where I put the first dang target I’d post the pics.

 

[bikemutt]

I’ve done it twice on one load combo and they were very close. If I could find where I put the first dang target I’d post the pics.

No need Nature Boy, from what I've seen so far the OCW methods serve good shooters and good hand loaders well. My thought is when we combine a very small sample with an average shooter and perhaps average hand loading equipment and skills, the result is less useful.

I haven't given up on OCW, just skeptical for now.

 

[Steve S.]

I would say that you have talent that is being waisted; how about we slap a uniform on you, issue orders for a field promotion to (say) E-6 and ship you, your talent and your rig to Libya where those Bergers might change the world. “Sargent Nature Boy”, it has a nice ring to it!

 

[Nature Boy]

No need Nature Boy, from what I've seen so far the OCW methods serve good shooters and good hand loaders well. My thought is when we combine a very small sample with an average shooter and perhaps average hand loading equipment and skills, the result is less useful.

I haven't given up on OCW, just skeptical for now.

I never could get the standard OCW method to work either. This “Cortina” method does help me find the accuracy node.

It is a prerequisite to have a minimal amount of consistency in reloading, shooting technique and rifle accuracy in order for any of these methods to be meaningful. A discussion about that would probably be worthy of its own thread.

 

[bikemutt]

I never could get the standard OCW method to work either. This “Cortina” method does help me find the accuracy node.

It is a prerequisite to have a minimal amount of consistency in reloading, shooting technique and rifle accuracy in order for any of these methods to be meaningful. A discussion about that would probably be worthy of its own thread.

I'm going to look into the Cortina OCW more, so far just from a cursory read I see plenty to like

 

[Nature Boy]

Shot my 3rd F-TR match this morning and chose to use the 185g Berger load. My score improved again and I shot a 592 / 28x. I was only one dropped shot from shooting clean at 300 yards.



Wind this morning was nil during 300 and 500 but once the clouds cleard and the sun came out so did the mirage making 600 a challenge.

I think the improvement in score has less to do with this load being better and more to do with my recoil management improving

 

[hps1]

Shot my 3rd F-TR match this morning and chose to use the 185g Berger load. My score improved again and I shot a 592 / 28x. I was only one dropped shot from shooting clean at 300 yards.

View attachment 777128

Wind this morning was nil during 300 and 500 but once the clouds cleard and the sun came out so did the mirage making 600 a challenge.

I think the improvement in score has less to do with this load being better and more to do with my recoil management improving

That's some hard holding, NB. Do they use the same targets used in NRA XTC matches in F class (6" x and 12" ten ring)?

Regards,
hps

 

[Nature Boy]

Do they use the same targets used in NRA XTC matches in F class (6" x and 12" ten ring)?

Not for F Class. There’s a different target at each distance where the 10 ring is 1 MOA and the X ring is 1/2 MOA. The sling shooters have a bigger target but I’m not sure of the dimensions.

That X ring is hard to see, regardless of distance. I may be under scoped in comparison to what others are using. It was impossible to see the X at 600 when the mirage got bad. I used the shot spotter from my previous shot as my aiming aid.

 

[hps1]

Not for F Class. There’s a different target at each distance where the 10 ring is 1 MOA and the X ring is 1/2 MOA. The sling shooters have a bigger target but I’m not sure of the dimensions.

That X ring is hard to see, regardless of distance. I may be under scoped in comparison to what others are using. It was impossible to see the X at 600 when the mirage got bad. I used the shot spotter from my previous shot as my aiming aid.

Right; I forgot to mention the dimensions I posted are for the 600 yd. target shorter ranges + smaller scoring rings in XTC as well. Makes sense the F class would have a smaller target.

I only tried F class once or twice. Never got the hang of shooting from a bipod....always shot better scores w/coat and sling, but was trying same technique for F class that I used w/o rest. Another problem I had was too much power on scope. Had fixed power 20X scope and the mirage is horrible down here. Scoring rings looked like amoebas and the aiming black way too big to quarter @ 20X; hard to concentrate.

Shooting iron sights @ 600, I could actually see a 5" spotter in my target and if it was not a cartwheel, my shots always drifted toward the spotter. Never did quite figure that out, but started requesting a 3" spotter @ 600 as I lost points to the 5".

Have posted before, but kinda proud of this spotter even if it did cost me a couple of rounds due to the fact the 15th shot hit the wooden spindle and splinters blew a hole big enough that they had to reface the target face and conditions changed.


Regards,
hps