Newb reloader has a go at fiddlin' with seating depth... A few questions...

[ScottyD]

First, a HUGE thanks to TresMon for all the good info in those stickys above. I can't even begin to tell you how helpful that info has been! I found that 42.4g's of H4350 put me right in the middle of a big node with my 140g A-max's in my 25" barreled 6.5cm. I'm right at 2810fps. Today I loaded up enough rounds for 1 five shot group at each of the following seating depths: .010 jammed, right on the lands (I think!), .010 jumped, .020 jumped, and .030 jumped. Here's what I got:



Of course, I'm all excited about that group in the upper right. That is the smallest group I've ever shot! I'm thinking the next thing I'm gonna do is load up 25 more at that seating depth and see if I can do that again! But while I'm waiting to get back to the range to do just that, I'm beginning to wonder: I kinda think I'm a .5 to .75 moa shooter at best right now. Over-all this target is about the same as I usually do with factory loads. A typical target for me with 5 groups will have a few nice ones (to me a nice 5 shot group is anything sub .5 moa), a few sloppy ones (.75 to 1moa)...Do you guys think 1 five shot group at each of these seating depths is enough to be significant? In your experience, have I definitely found my sweet spot for seating depth? -Or does this target simply tell me that seating depth doesn't really matter, the gun is shooting as well as the guy driving is capable of, and I just got lucky and landed one random nice looking group? I kind of expect that next time I go out, I won't see another group that nice, and I'll start doubting my seating depth choice again... Then what? Exactly how much shooting do you guys do to lock in on a seating depth? Part of me wishes I could lock the gun in a vice for this test, and take myself out of the equation. Any advice, wisdom, or recommendations from you guys would be most appreciated...

I also did the same test with my .223 trainer as well today (69g smk's and 22.6g of RL-15). I can't decide if I should keep working on my loads or if that's all my cheap rem SPS (20" 1:9) is ever going to be capable of. The only factory load I've seen shoot well in my .223 is FGMM w/69g smk's... Here's one target with a group of FGMM in the center (about typical with that ammo -ALL other factory stuff I've tried, including Black Hills, is much worse) and then 3 groups with my loads at the same "length to Ogive" (1.87") as the factory FGMM:



Then I shot groups with a bunch of other seating depths (.010 jammed to .030 jumped again):



If you're still with me: the gun ususally shoots .5 to 1 moa with the factory stuff at 2765fps. To get my loads anywhere near those groups, I had to drop down to 2550fps. And now it does look like my loads at 1.87" to Ogive length are my best bet... But those groups still kinda suck! Is it time to accept the factory barrel on my .223 sps isn't ever going to stack 'em for me? Or should I try something else? And if so what would the next step be? I can definitely shoot a little better with my sweet AO custom 6.5cm... So maybe the horrible .223 groups are NOT my fault...?

Thanks in advance for the help...

 

[JGorski]

With your 6.5CM all you can do is load more of the "jammed' rounds and go for it and see what happens, just shoot when conditions are calm or near calm, or shoot at longer range.

 

[No1]

Now load up 20 or more of the 'on lands' load and go shoot. Looks like that bullet doesn't like to be crowded or jump.

 

[Beluebow]

The 6.5cm load looks like a good start kissing the lands.Load some more and go shoot at longer distance like 300 or more and look at your vertical.You may end up tweaking .002-.003 increments one way or the other till it really comes together.Not telling you anything you probably dont already know but groups that are tighter than a frogs ass at 100 doesnt always translate to good groups at distance.

The 223 looks off on the powder charge at 10 off and 30 off.If your not seeing any pressure signs you might try bumping the powder charge up .2-.3 of a grain at each those seating depths. Shoot and see how she does.

 

[ScottyD]

The 6.5cm load looks like a good start kissing the lands.Load some more and go shoot at longer distance like 300 or more and look at your vertical.You may end up tweaking .002-.003 increments one way or the other till it really comes together.Not telling you anything you probably dont already know but groups that are tighter than a frogs ass at 100 doesnt always translate to good groups at distance.

The 223 looks off on the powder charge at 10 off and 30 off.If your not seeing any pressure signs you might try bumping the powder charge up .2-.3 of a grain at each those seating depths. Shoot and see how she does.

Thanks to all three of you guys for the advice. Sounds like I need to load up some more 6.5 and go longer with the range. Will do.

Interesting, Beluebow, that you may see potential in the 10 off and 30 off .223 groups. Thanks for mentioning it. Pressure is good so I do have some room there. I'll bump up the powder charge and give it a try as you suggest. Finding a load for that .223 has been a real pain so far. I'd be thrilled if it happens that you're onto something there....

THANKS!

 

[oldfatguy]

A lot of folks have found jumping further then 0.03" gives better results. Might want to try increasing your jump a little and see what happens.

That 6.5 group kissing the lands is awesome. Definitely go shoot some more of those. Kissing the lands turns into chasing the lands as the round count goes up, but if it repeats, well worth the effort.

OFG

 

[ScottyD]

A lot of folks have found jumping further then 0.03" gives better results. Might want to try increasing your jump a little and see what happens.

That 6.5 group kissing the lands is awesome. Definitely go shoot some more of those. Kissing the lands turns into chasing the lands as the round count goes up, but if it repeats, well worth the effort.

OFG

Thanks OFG! Yeah, I noticed the factory A-max loads shot pretty well and they were about a .095" jump according to my math. The factory .223 are also a huge jump... A lot of variables to play with... First thing I tried was matching the factory loads before anything else. If "kissing the lands" ends up being my spot, how often would you say I'll have to check and see if its time to start chasing? My 42.4g of powder doesn't seem to be a particularly hot load... I have no idea how long that sweet spot will last? Can you give me a ballpark guess as to how many rounds I might get before it's time to look at seating depth again?

Thanks!

 

[oldfatguy]

Can't really give you a good number. Barrels are all different and your load has a big influence on throat wear. Might want to pick a number of rounds and measure at that increment.

OFG

 

[1lnbrdg]

In my .308, I've found that the 190gr Noslers like to jump .080 or more, .050 and more with the 155gr Noslers.

For my .223 with the 80 Amax, I'm jumping .040.

A lot of bullets like to jump and I'd try to find one that does. It's really tough to load and chase the lands. The lands are always moving further away as the barrel wears.

 

[Boxerglocker]

OP you never mentioned how your R700 SPS is set-up. What stock do you have it in?

I load a 69 smk backed with Varget inside Lapua brass with a Fed BR4 primer for the same gun R700 SPS tactical 20 inch 1-9. 25.5g which is max depending on the manual, but no pressure signs and a .030 jump is silly accurate at 2850 fps 10 feet from the muzzle out to 600 yards. I recently scored a 198-11x in a 500 yard prone string with it. I also have a 50g Vmax varmint load using LC brass and TAC which is sub half MOA consistently, and shot a personal best .187 for 5 shots at 100 yards. That load is at 2.20 OAL so a huge jump.

 

[Captain Kirk]

One thing I have found about finding the accuracy "node" is it has a lot to do with bullet seating depth which can greatly effect pressure AND velocity. If you are at the bottom of a node, getting into the lands will increase pressure/velocity and you will think you are there, what you may be doing is increasing pressure and jumping into the node you were just below. Its a balancing act, but from the looks of it, you have found a good accuracy node with the first batch of targets. I see some patterns that could very likely be induced by the shooter such as fliers and vertical/horizontal stringing. Practice will reduce group size, and I see a few groups that strongly suggest your doing a lot of things right, from the loading bench to behind the rifle.

Keep it up!

Kirk R