Good range to confirm 175 SMK 1,000 load at?

[CK_32]

Ok so I think I have some results from my last OCW for my 600 to 1,000 yard 175 SMK load.


Question is at what range should I test the window of charge weights in my suspected load?


I'm thinking maybe 300 yards? 200? I cant make up my mind whats a good distance to show enough evidence on how each load will preform at 500 - 1,000 yards.
But not go too far out where my shooting limit or elements will be too great and alter results.


What do you guys do or think is a good range to confirm nodes for a 1K load?


Load Specs:

Bullet: 175 SMK HPBT
Powder: Varget - 45.2, 45.5 45.7 46.0 46.2
Brass: Winchester Nato once fired
Primer: CCI 200

Rifle:

Rem SPS tac 308 20" 1:12
Bushnell 3200 Tac 5-15x
Eagle Stock Pack
B&C A-3 stock
Harris 6-9 (Plan on shooting off pack tho)

 

[CK_32]

reserved for more info

 

[Asperly Aimless]

600 yds. Do your best to read the conditions and shoot accordingly.

 

[Bear24]

I confirm my loads at 400 yards. I ignore most the horizontal and just concentrate on the vertical so environmentals are not really a factor. Those are some really stout loads you are working with, what kind of velocities are you getting?

 

[Sako man]

If you want to test long distance then you should have a kestrel and all your altitude pressure data. But I find it best to chrono with a magneto speed chronograph at 100 yards, just get your MV data then you should be able to calculate everything out from there. The idea is to eliminate as many environmental variables as possible.

A ladder test with group measurement at 100 usually is great.

Yeah, I dont' think I have ever gone over 45.2 grains of varget with my Sako action which is much stronger than a R700. The primers were starting to flatten somewhat at that pressure, and thats on Lapua brass which is strong. Now if you were shooting 155 Scenar or SMKs then your ok but a 175?

 

[scudzuki]

Quickload predicts a pressure of 63,208 PSI from 45.2 gr Varget under a 175 SMK and 46.2 gr yields 67,849 PSI.
WAY hot.
Wear glasses shooting those.

Joe

 

[Asperly Aimless]

A ladder test at 100 yds really doesn't show you much. A ladder at 300 followed by a 400 yd ladder would be better.

Once you have conducted your ladders start shooting for groups. Don't ignore the conditions. While a Kestrel is nice, it is not necessary. You can get the majority of your needed info from Google before you step off. All you'll really be lacking is accurate wind speed.

If you are shooting far, conditions (wind) can/will change with distance. Stick some wind flags out at intervals and see what is going on.

Once you finish your load development, start shooting for "score", and record everything. That'll get it done.

 

[CK_32]

As for the grains I'm using this is a factory untuned/blue printed 700 SPS tactical. Chamber will not be as tight as customs actions.

Also I OCW'd all the way up to 47.0gr of varget behind these 175s with no primer or bolt stick issues.

I don't have a chrono but plan on using one when I get the chance and trying for some MV once I get my loads closed in and a starting point before I collect a ton of data on throw away loads.

 

[Sako man]

As for the grains I'm using this is a factory untuned/blue printed 700 SPS tactical. Chamber will not be as tight as customs actions.

Also I OCW'd all the way up to 47.0gr of varget behind these 175s with no primer or bolt stick issues.

I don't have a chrono but plan on using one when I get the chance and trying for some MV once I get my loads closed in and a starting point before I collect a ton of data on throw away loads.

A magneto speed chrono should be a must on the list if you really want to gather data, I assume your looking for accuracy and a good MV in the load. You want to be able to reach out to 1000 accurately.

I suggest the kestrel if your shooting long distance as it gives you accurate data for where your standing. If you go out shooting long distance to test the load without doing a 100 yard first might result in you wasting some ammo.

Your correct a loose chamber will ease the pressure but seems really hot as in unnecessarily, faster is not always better. You can loose accuracy with speed. Once again your job will be to keep the projectile from going subsonic past 1000, I assume.

Then again you did not really post your objectives beyond testing your load.

 

[damoncali]

I do everything at 100. No point in adding wind to complicate things. Variations in velocity may not show up, but if you chrono, you should be good. If things fall apart at 1000 for a good 100 yard load, start over.

 

[CK_32]

Again I'm working on using a chrono. Not in the budget to pick one up for my self. Does me no good to pony up for the chrono but not have funds to shoot due to me spending on the chrono. I'd love one but think money wise it would be smarter to find one to rent or borrow for a few shots. I feel although yes it will help greatly it is not completely necessary to find data and basic load characteristics with out it.

So I should still run a 100 hard group test then push out to farther to confirm? I just thought 100 wouldn't show me much but again why I'm asking for advice on where to go from this point. But I have no issue confirming at 100 if that will show me results.

My nodes for this rifle were around the 43gr range and the 45.4 range. From gathering data and notes from other SPS Tac shooters I was told for 1,000 shots the 43gr window probably wouldn't be sufficient at those ranges. And that some in these factory shelf rifles usually end up around 44.5 to 46.0 gr ranges. Some even at 47.0 gr but I feel that to be wa

Dan quoted me that usually from his knowledge 44.5 - 45 gr should land me around 2,600 to 2,700 FPS MV and stay trans around 1,000 from a 20" but I know that is just an educated guess but still helpful as a optimistic range for my self.

My main goal is for longer range desert plinking and occasional local match loads for 600 - 1,000 where my cheap factory plinking 147gr loads usually end up being nothing short of 20" groups past 600 yards on a good day.


So in short main goals are to dial in a good load for 600 to 1,000 shots and below. Aiming for the higher node to keep the transonic window around 1,000 or at least close.

To which will play off my 168gr load for 100 to 600 I will work up after this which will hopefully allow my self to use my rifle to its full potential.


Again thank you for all the replies and helpful info. Keep it coming. Planning in going out this Saturday to do my next round of testing. Still pretty new to this OCW process beyond the initial testing.

 

[dustinoif3]

2600 is pretty close. I'm getting an average of 2581 with bh brass, 44.5 varget, 210m and 175smk out of my 20" sps tac.

 

[dustinoif3]

I've tested that load to 700 so far. Did okay. Held right around 7". Had bad conditions and was hurried but they hit tip first which what I was really after.

 

[harley_jeff]

Use a chrono if you can.... Factory Federal SMK 175's are going 2719 fps (average of 5 shots) out of my 24 inch gun. The MV was measured with a magneto speed and verified with data to be true at 890 yards.

 

[CK_32]

2600 is pretty close. I'm getting an average of 2581 with bh brass, 44.5 varget, 210m and 175smk out of my 20" sps tac.

I've tested that load to 700 so far. Did okay. Held right around 7". Had bad conditions and was hurried but they hit tip first which what I was really after.

Yea my testing showed a node at 43.8 to 44.6 and a scatter between my next node at 45.5 to 46.2. I figured the 45.5 window would get me better velocities and be a better 1k load around 2,600 to 2,700 average. Kinda like Jeff's 24" spitting the Fed SMKs.

Or is 2700 goal too fast?

 

[damoncali]

Even without a chrono, I would do load development at 100. Verify at 1000 after you know it's good at 100. If 1000 isn't practical, you should be able to see signs of problems at 5-600, but do the majority of development at 100.

 

[CK_32]

Even without a chrono, I would do load development at 100. Verify at 1000 after you know it's good at 100. If 1000 isn't practical, you should be able to see signs of problems at 5-600, but do the majority of development at 100.

Realistically this will probably be a majority 650 to 800 yard load for my self. But of course like everyone I'd like to work it out to 1,000 maybe further.

I was trying to hit a 15" steel plate I had at 615 yards with a WWB 147 gr and I was lucky to hit the 5ft rock it was against.

Since then I've upgraded the stock and trying to cook some pills to take the bullets and little bit of rifles limitations away and let me work on dinging at 600 consistently then move out farther. But those 147s weren't cutting it.

So I'll do a 100 yard test today at those weights and then confirm at 300 or 400 after. Again I just figured 100 test aside from OCW would be a waste of led

 

[damoncali]

Don't over-think it. I would argue OCW is a waste of lead because you aren't shooting enough to learn anything. Instead,

Pick a good powder based on recommendations of others for your caliber (and availability, these days)

Pick a suitable bullet (e.g. SMK, Amax, whatever match-grade HPBT you want to use)

Load up 15 rounds each of 4 powder charges 0.5 grains apart (60 total). Use smaller changes for smaller cartridges, bigger for big magnums.

Shoot 3 five shot groups of each load at 100 yards off a bench in calm conditions.

Measure them properly. (outside edge to outside edge, then subtract the diameter of a bullet *hole*).

If you don't have a reasonably well shooting 100 yard load staring you in the face, something else is wrong. Chances are good that it's also a good 600 yard load, but go ahead and load some up and try it out. Worst case you'll spend an afternoon dealing with some vertical stringing, but not much.

You will probably see some trends with the group size. If you feel you can do better, you'll know where to start investigating.

 

[dustinoif3]

Yea my testing showed a node at 43.8 to 44.6 and a scatter between my next node at 45.5 to 46.2. I figured the 45.5 window would get me better velocities and be a better 1k load around 2,600 to 2,700 average. Kinda like Jeff's 24" spitting the Fed SMKs.

Or is 2700 goal too fast?

2700 is a good speed but the problem with a 20" rifle is the charge you have to stuff in the case to get there. Your brass life would be shortened greatly. I think the 2600 range will be fine and it won't to be to HOT of charge. Itll be close to book max but that's a guideline as you know. I read in the op that you got really high on your charge with no issues. My sps had a hard bolt at 45.3

 

[Pinecone]

OCW is designed to work at 100 yards.

I followed the directions and the load developed is good enough for hits at 1200 yards if I do my part.

 

[Skigolfmike]

The SPS tactical I have pretty much stopped gaining velocity at 44.0 gr of Varget with the 175 SMK. It shoot sub moa at 100 and runs at 2560. 11.8 mil to 1k, 5.0 mil to 600. Hits transonic right before 1K, but I have hits to 1165 with it.

I tested on a chrono about 2 years ago starting at 40.0 gr in .5 increments all the way to 46.0. Never saw any pressure signs either, but the velocity pretty much stopped increasing after 44.0. I figure the bullet is out of the barrel before all the powder can burn.

 

[Graham]

Lots of guesswork and speculation going on here, and dressing it up as advice doesn't make it more valid.

OP, if it shoots well at 300 it will probably shoot well at 600. If it shots well at 600 it will probably shoot well at 1000.

It's a .308: forget about learning much about your loads at 100 yards and forget about sixty-round computer generated load testing. If that rifle doesn't shoot well with 45 Varget you have other problems.


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