Load Development Question .308 - Fliers

[Will Henry]

Ok, are we talking about 3 shots at 3/4 MOA or 5?

Can you be more specific on follow through and bag error?

Thanks

When I talk about a 1/2moa rifle, that means I can, if conditions are decent, produce a 1/2 moa or better group on demand. I generally refer to 5 shot groups.
I squeeze the rear bag to establish elevation. This works fine but it is important to maintain the alignment after the trigger trips. I have on occasion caught myself relaxing when the trigger broke. This caused a flier high. If I tensed at the shot, the shot would go low. This is especially critical with a 308. The lighter the rifle, the more critical it is. This is not a flinch per se, just a bad habit manifesting itself in a flier.
I have not shot a suppressed 308, nor one with a muzzle brake. My feeling is that the effects are much the same since the effect of the brake or suppressor doesn't take place until the bullet exits the muzzle. The flier is caused by what happens before the bullet exits.
Of course, if the rifle is mechanically flawed in some way, that's a whole different matter. WH

 

[bulletpruf]

You should think about bringing your own. Doesn't need to be expensive or complicated to start. A piece of Surveyors Tape on a stick about 4' off the ground at 50 and 100 yards is better than nothing to begin with. You'll have an idea about what is going on at the bench if you just notice.

I definitely need to do that on the range that's completely open.

The other range I shoot at is below ground level (cut into a hill) so there's no crosswinds, and only very minor headwind or tailwind.

Thanks

 

[bulletpruf]

When I talk about a 1/2moa rifle, that means I can, if conditions are decent, produce a 1/2 moa or better group on demand. I generally refer to 5 shot groups.

A 1/2 MOA 5-shot group on demand (i.e., on a consistent basis) sounds difficult to achieve. That's my goal, but I don't know if it's a realistic one.

I squeeze the rear bag to establish elevation.

Same here.

This works fine but it is important to maintain the alignment after the trigger trips. I have on occasion caught myself relaxing when the trigger broke. This caused a flier high. If I tensed at the shot, the shot would go low. This is especially critical with a 308.

Gotcha. I have not paid attention to this at all.

The lighter the rifle, the more critical it is. This is not a flinch per se, just a bad habit manifesting itself in a flier.

My rifle is not a lightweight; has an M24 profile 22" barrel and a can.

I have not shot a suppressed 308, nor one with a muzzle brake. My feeling is that the effects are much the same since the effect of the brake or suppressor doesn't take place until the bullet exits the muzzle. The flier is caused by what happens before the bullet exits.

Understood.

Of course, if the rifle is mechanically flawed in some way, that's a whole different matter. WH

I wouldn't think that would be the case, but I've done all the work on the rifle myself (trigger swap, barrel removal and swap, scope install, stock install) so it's certainly possible.

Thanks

 

[bulletpruf]

One other data point that just hit me. 43.0 is the lightest load that I've shot, and it's also the first one I shoot every time I go to the range; I start with the mildest and work my way up to the heaviest (46.0).

So, when I first get to the range, it's usually when they open at 10 am, so the sun is lower, the temps are cooler, wind generally not blowing as hard as it will later in the day, less distractions, I'm not rushing, barrel is cooler, etc. That might not explain the flier, but it may explain the generally tight groups that come with the flier.

My plan from here is to shoot 2 five shot groups of the same loads that I haven't ruled out - 43.0, 44.2, 45.1, 45.4, 45.7, and 46.0 - but perhaps change the order so I'm not always shooting 45.7 and 46.0 when it's warmer, windier, sunnier, and more crowded, and see if that makes a difference.

I also want to remove the swivel studs from the rifle so I won't have to worry about those catching the front or rear bags. Someone here mentioned that in a private message and I think that's a good idea.

Also, if anyone has any recommendations on good videos to watch on bench rest marksmanship, please let me know. I've watched a few, but I still feel like I have a long way to go.

Thanks

 

[Doom]

From what I can tell, most folks are recommending about .020" off the lands, and that's why I'm at 2.860". The FGMM is 2.800".

You post a question about your load having an issue and post another of a target using the same bullet, with a similar powder (Probably AR-COMP) and same case mfr and because some recommend 0.020" off the land you think that's the number to stick with?

I don't know squat about 0.020" but I do know if you if you shoot the 168 SMK with Varget (or IMR 4064) at about 43-43.5 gn at 2.800" and you have a problem it's the rifle and not the load. This mimic's or equals past FGMM loads.

 

[jrh84]

Is your parallax set correctly for 100 yards? Not just according to the dial, which is almost never correct. If this isn't set correctly, small changes in head position can alter where the crosshairs appear, meaning it can appear that you're lined up on target, but may actually be a small distance off. When set correctly, you can move your head around within the eyebox, and the crosshairs won't move on the target.

Just a thought as to why you have 4 solid shots and 1 outside the rest if the group.

 

[bulletpruf]

You post a question about your load having an issue and post another of a target using the same bullet, with a similar powder (Probably AR-COMP) and same case mfr and because some recommend 0.020" off the land you think that's the number to stick with?

I did a fair amount of online research and the recommended recipe for an accurate .308 load for a bolt gun was 45 or so grains of Varget under a 168 gr SMK .020" off the lands. I did the ladder with powder, starting at 43.0 and going up to 46.0 at .3 grain increments, but I didn't want to change the COAL or CBTO until I settled on the powder. Just doesn't make sense to me to change two things at one time.

I don't know squat about 0.020" but I do know if you if you shoot the 168 SMK with Varget (or IMR 4064) at about 43-43.5 gn at 2.800" and you have a problem it's the rifle and not the load. This mimic's or equals past FGMM loads.

I really don't think the rifle or the load is the issue. I think it's the shooter. I did 26 years of Army active duty and always considered myself a very good shot with an M16/M4, but the Army really just teaches you about sight picture, breathing, and trigger squeeze, and we don't shoot off a bench, so I think more research and more practice is in order.

 

[bulletpruf]

Is your parallax set correctly for 100 yards?

Damn good question. I paid attention to the setup when I installed it on the rifle, but that was a year ago and I haven't thought about it since then.

Not just according to the dial, which is almost never correct. If this isn't set correctly, small changes in head position can alter where the crosshairs appear, meaning it can appear that you're lined up on target, but may actually be a small distance off. When set correctly, you can move your head around within the eyebox, and the crosshairs won't move on the target.

Just a thought as to why you have 4 solid shots and 1 outside the rest if the group.

I'll double check. Thanks for the tip.

 

[jrh84]

Damn good question. I paid attention to the setup when I installed it on the rifle, but that was a year ago and I haven't thought about it since then.



I'll double check. Thanks for the tip.

It's bitten me far more times than I care to admit.

 

[Doom]

I really don't think the rifle or the load is the issue. I think it's the shooter. I did 26 years of Army active duty and always considered myself a very good shot with an M16/M4, but the Army really just teaches you about sight picture, breathing, and trigger squeeze, and we don't shoot off a bench, so I think more research and more practice is in order.

Thank you for your service. It's definitely a different ball game. I never served but the first time the ROTC instructor put an M16 in my hands I thought this can't be for real! Now 50 years later I'm trying to to handle the M4. Different mindset all together.

I'm doing 5 shots at each load at the same target and then moving on.

That helps with consistency of the shooter. I went back through the posts and looking at it from a little different perspective of it being a shooter issue (which is hard since I can't watch). I would suspect that there may be an issue with either cheek weld or some inconsistency with the right hand pressure torquing the rifle on recoil. It only takes about 0.006" movement difference in muzzle alignment to get a 1" shift in POI. It may not be the issue but just something to watch out for. .

 

[Homerange]

@bulletpruf
I can't help thinking your shooting technique is the main issue when you can place 4 shots in near one hole but not five.

Shooting precisely is an art and my advice learned from the diminutive 5.56/223 where recoil isn't an issue is to change your bench setup to hold the forend on top of a bag to better steady the shooting platform against recoil.
This of course removes the cross arm technique and any ability to squeeze the rear bag so bag setup becomes important but with a forend hold you also have some elevation control with grip modification.

I've always shot my best groups this way in sporter weight platforms, suppressed or not and always wearing muffs.
Try it, you might be surprised.

 

[NF1E]

How about dropping a couple of gns and starting a new ladder. I shoot a ton of 169 and 175 smk in Lapua brass. Using 41.9 of Varget for the 168s and have no problem keeping 10 shot groups in well under 1/2 moa. GMM 168s run very well at 2600 muzzle. Try it, you might like the lighter powder charge. I use a lowly Savage with a 24" X-Caliber barrel in 1-10. Whatta Hobby!

 

[bulletpruf]

Thank you for your service. It's definitely a different ball game. I never served but the first time the ROTC instructor put an M16 in my hands I thought this can't be for real! Now 50 years later I'm trying to to handle the M4. Different mindset all together.

That helps with consistency of the shooter. I went back through the posts and looking at it from a little different perspective of it being a shooter issue (which is hard since I can't watch). I would suspect that there may be an issue with either cheek weld or some inconsistency with the right hand pressure torquing the rifle on recoil. It only takes about 0.006" movement difference in muzzle alignment to get a 1" shift in POI. It may not be the issue but just something to watch out for. .

I think my cheek weld is fairly consistent, but I've recently changed right hand pressure and grip slightly. However, I had some fliers before I changed my pressure/grip, and some after.

Thanks

 

[bulletpruf]

@bulletpruf
I can't help thinking your shooting technique is the main issue when you can place 4 shots in near one hole but not five.

Shooting precisely is an art and my advice learned from the diminutive 5.56/223 where recoil isn't an issue is to change your bench setup to hold the forend on top of a bag to better steady the shooting platform against recoil.
This of course removes the cross arm technique and any ability to squeeze the rear bag so bag setup becomes important but with a forend hold you also have some elevation control with grip modification.

I've always shot my best groups this way in sporter weight platforms, suppressed or not and always wearing muffs.
Try it, you might be surprised.

I think I'm going to stick with my current shooting position, at least for now. I''m always wearing muffs, even when I'm shooting suppressed and subsonic.

Thanks for the input.

 

[bulletpruf]

How about dropping a couple of gns and starting a new ladder. I shoot a ton of 169 and 175 smk in Lapua brass. Using 41.9 of Varget for the 168s and have no problem keeping 10 shot groups in well under 1/2 moa. GMM 168s run very well at 2600 muzzle. Try it, you might like the lighter powder charge. I use a lowly Savage with a 24" X-Caliber barrel in 1-10. Whatta Hobby!

10 shot groups under 1/2 MOA is impressive!

Thanks for the recommendation.

 

[NF1E]

10 shot groups under 1/2 MOA is impressive!

Thanks for the recommendation.

Have been competing in the 1/4" 10 dot challenge on the M14BR forum and have managed 9 out of 10 with a flyer 1/8" out at 2 oclock with a .223 Savage and 8 out of 10 with my .308. The 8-9 score indicates the first 8 shots were hits on the 1/4" dots , then a miss on shot #9 and back in the groove for #10. Give it a try, it can be quite humbling but a blast. Whatta Hobby!

 

[steve210]

I definitely need to do that on the range that's completely open.

The other range I shoot at is below ground level (cut into a hill) so there's no crosswinds, and only very minor headwind or tailwind.

Thanks

There is almost always some wind, if you set flags you will see. That said i think your issue is gun handling. Since the shot appears to go random places, i have no idea what the issue is. Have someone watch you shoot or video yourself and that may provide some answers.

 

[Doom]

There is almost always some wind, if you set flags you will see. That said i think your issue is gun handling. Since the shot appears to go random places, i have no idea what the issue is. Have someone watch you shoot or video yourself and that may provide some answers.

When it comes to gun handling one thing I've learned from other shooters is working with the lowly 22LR when things go awry. Because the bullet is in the barrel so long it highlights issues with gun handling. It also helps when being spotted by someone else when because almost all movement is non recoil related. Sometimes it helps to put the ego in the uncase for awhile!

 

[Doom]

@NF1E, Thank you for your service.

 

[S Miller]

Many great suggestions here. I would add being careful not to load your bench with body pressure. Not sure what you’re shooting off of but many benches move alittle. I think I would be looking at table manners, (follow thru) flags, and parralax. Good luck!