Sunday, February 10, 2013

Praxis Help Request: Tightening groups on a POF .308

A reader asks in a Praxis help request:
Finally scraped together everything to finish my modifications on my POF 308. Pics attached. The first target is 20 rounds at 100 yards, the last two are 10 rounds each at 200 yards - not quite as accurate as I was looking for. Any suggestions as to how to tighten this up? What I want to do is be able to make good hits at 600 yards. I can tell by my 200 yard targets that I need more skill.
Any suggestions?


Anonymous said...

How loose is the fit between upper & lower? If there's any shake at all (side to side & front to back), there are shims that can be bought and installed to tighten the fit.

B Woodman

Anonymous said...

Looks like holding the weapon too tight, or breathing irregularities.

Your trigger control looks fine, otherwise you wouldnt have a group at all.

Relax, get in the zone, breathe right.

That's all I can offer.

Edwin III

Anonymous said...

the upper to lower must be 100% tight. the .308 seem to be more sensitive to play than the smaller AR-15 frame. and youll probably hear alot about premium ammo being needed but i have found found the bullet jump to the rifiling is more important. the shorter the gap the better

Anonymous said...

The first thing i would do is look at my ammo .What grain of .30 caliber, is it 146 or 150 grain or 168 or even 175 grain ? You will see a differance between the two .Mine likes the heavier grain bullits .I buy top notch commercial ammo for it, shoot it, see the results then handload as close as i can to that bullits speck and i have received great results at a cheaper price . Make sure you also full length resize when you reload and stick to the recommended overall length.Id stick with Hodgdon powders to, seems to be more stable when you have differant weather conditons, like heat .

Robert Fowler said...

With groups that size at 200 yards, I think your six hundred yard groups will be acceptable to make killing hits on man sized targets.

whitestone said...

Check what ammunition you're using... those groups look about right for surplus military ball ammo. Try to find some M118 or equivalent commercial match grade and see if that doesn't help.

Anonymous said...

What ammo? I'd start with a premium load like FGMM and IMHO the 175gr does better in the shorter POF barrels...

Looks like its a nut behind the trigger issue (YOU) you not stringing them vertically or horizotally..they are just all over the place...if there was an issue with the rifle it would be repetitive, stringin the rounds in one way or the other...

Get more ammo, practice more then worry about it...

Capt Beach

Hefferman said...

Do you have the time and money to spend a week on a range?
The best thing to improve you shooting, is shooting with someone working with you.
Here is a video showing what we taught in the Corps.

That is the basics. Master them and you can build on them to become a good marksman.

PS don't stress over the weapon, most weapons can out preform the shooter.

Anonymous said...

Breaking in a barrel is essential for success. All the high quality manufacturers suggest this and Douglas, Kreiger and Lilja have their processes posted on their sites.

If you have already started shooting you may get better groups by reworking the barrel, just start from scratch after you chemically clean the barrel. Always check you headspace, even the factory rifles can be off. Broach cut is usually more precise than button cut. The exact ammunition will affect the outcome of course.

You want consistancy, keep your ammo consistant, length of case, powder charge, primer and bullet of course. I have found factory loaded bullets out of spec. by .005 in some ammo. Nothing like the bullet wallowing down the bore to make awful goups.

When in doubt load it yourself, try reloader 15 with 168 Grn Serria BTHP Match and match primer. Cases do stretch and become, thinner cases make different chamber pressures and accuracy changes. Somewhere on the web you can search for Military Match Loads. A fellow researched and wrote an article that list all the match recipes that the military has ever used. Good info...

Longbow said...

You haven't told us what load you are shooting. If you are shooting regular ball like Americal Eagle red box, your groups aren't bad at all. If you are shooting de-linked G.I. machine gun ammo, then your groups are pretty good indeed! That information is critical. A match grade bullet and a cafefully measured powder charge will do wonders. Also, you should know how far you bullet is jumping before it is hitting the lands in the rifling, so cartridge overall length is critical too, but remember, you still have to fit them in the magazine and have the weapon function reliably.

More information, please!

Anonymous said...

It's either your load or the fundamentals of your position.

In other words, either your ammo, your skills, or both may not be up to the task.

For help with your shooting skills try to attend an Appleseed Shoot or begin shooting High Power Rifle matches.

For your ammo, if you reload, try to duplicate standard M852 match ammo as a starting point and tweak it from there as necessary to tighten your groups. You may also wish to consult Handloading For Competitiion by Glen Zediker. He also has a web page (google it).

Good luck, Sir.

Anonymous said...

With the exception of a couple of fliers, Thats good shooting. I call those fliers "heartbeat" shots. I can see my scope move if my heart rate is to high. Go out and shoot again same exact everything. But this time no coffee or caffeine if you had any before shooting. You wont be able to tell if its an ammo issue until you bump it up another 100 to 200 meters more. Its all about practice, practice, practice. Took me ALONG time & lots of sore shoulders & lots of ammo before I could group at 400+ meters. Thats a long damn ways. I do know for me. No coffee the day I was shooting. Good luck you have nothing to complain about. Thats good shooting.

Razor in the Benewah

Historian said...

I know nothing about this platform or manufacturer, but 3" groups at 200 is respectable for any gas gun. (I am assuming that these groups were shot from prone with the bipod.) There isn't enough information for a diagnosis; how good is the shooter? What ammunition is being used?

If this is ball, I'd say that the owner is getting all the accuracy one could expect, although the group shapes are somewhat indicative of some variance in hold and trigger squeeze, especially the first and third targets, which show the characteristic oval shape of groups fired from a rest/bipod.

The flyers may indicate a need to work on his trigger squeeze a bit, or they might indicate the sort of variance one expects in ball; this goes back to who the shooter is, although I expect that from the group shape the shooter could use a bit of practice.

Now if this is Federal GM Match, or other high quality match ammo being fired by a high power Master, then there may be room for improvement of the rifle system, but I would shoot several hundred rounds of break-in ammo before doing anything else.

Given my total ignorance of the system, my comments cease at that point.

Miles said...

1 Practice more

2 What are you shooting through it?
If M80, try different ammo. Most M80 ball isn't all that accurate. It's designed for belt fed MGs.

3 Possibly learn hand loading

4 Practice LOTS more.

It's possible that the barrel/upper receiver isn't torqued to spec, or the bolt/barrel extension fit isn't within tolerance, but I've got an M14 that'll shoot 1 MOA with Portuguese ball and 3 1/2 MOA with 'Good Lake City'.

There's a reason that really accurate ARs in 7.62 are so damned expensive.

Roger said...

What ammo are you using? If its factory fodder, (except for the special stuff like Fed GMM etc) that's about as good as you're gonna get. If its FMJ stuff, your groups are pretty darned good.
41 gr (+/-) of IMR 4895 & a Sierra 168 HPBT match bullet seems to be a popular load in Fed or RP brass. It shoots lights out in my LR308.

Liberty or Death said...

What ammo were you using? What is the RoT? That's not a terrible group there for a semi-auto. Most are intended to be in the 2 to 3 MoA range for accuracy standards and it looks like you are there. Your groups are not all over the place, so it looks like your barrel is properly torqued in and the scope is solidly mounted. You have a couple of fliers in there but almost all of those are attributed to shooter error. If you are not behind the scope exactly the same every time, you will get the oddball flier in there. Most likely just more practice is all that is needed especially since this is a new build. More time on the trigger is always good anyway. If that doesn't help tighten up the groups, try different ammo or loads.

Anonymous said...

Note that a lot of the shots are in the middle of the target with only a few further out - that is why you have a 20 round mag ...

So you can keep firing till you hit!


Anonymous said...

It appears that you are shooting 4 MOA. At 600 yards, that's 24". Practice your steady hold factors and trigger 'squeeze' and you should tighten up. measure your own distance from shoulder to shoulder and see how many inches that is. Practice will get you tighter, but sub 4MOA will be effective out to 600 yards.

Gunny G said...

Looks good @ 200.

The fliers can be attributed to anticipating the shot. Try to make every shot a "surprise" when the weapon fires.

Anonymous said...

Not buying a POF rifle in the first place would be my suggestion. If he wants good groups with a 308 AR, then stick to the LMT MWS for an affordable rifle, or the KAC for twice the price of the LMT. Or get something with proven reliability like the SCAR 17 that can still group at 1.5 or less inches at 100 yards.

Anonymous said...

Here's a hint I read once and was able to demonstrate the effect to my own satisfaction. It hasn't been mentioned here yet and wasn't mentioned at either of the Appleseed shoots I attended. Not knocking Appleseed. There's only so much they can cram into your skull in a weekend.

Just after you eat a meal your stomach is going to demand additional blood flow to work the digestion process. This naturally increases the pulse in your abdomen. You will notice this more if you're shooting with a scope especially at higher magnifications. Because you will be laying on the offending organ it is most pronounced in prone. The guy who wrote the article noticed his pulse moving his crosshairs up and down more after eating lunch in the middle of a match. His fix was to skip eating before and during a match and substitute Carnation "Instant Breakfast". Apparently your stomach see's it as something not needing digestion and doesn't shift into overdrive. I tried it and it worked for me.

The other point that needs to be considered, and already has been somewhat in earlier comments, is that your groups are affectd by many variables, some easily controlled and some not so much. But in general they can be broken up into three categories: shooter skill, rifle accuracy, and ammo quality. Every one of those areas have been touched on already. But I would suggest that, based on what has been seen in the Appleseed program, you probably don't shoot as well as you think you do. In two days, Appleseed will show you how to read your targets (targets will never lie!) and what part of the fundamentals you need to work on to correct what your targets are telling you.

Their goal is to enable every American shooter to be able to put 20 rounds into a man sized target at any range up to 600 yards in 60 seconds using a rack grade rifle and milsurp ammo.

I think we can assume that your rifle is probably way better than rack grade. Milsurp ammo generally is good enough to stay in the black. That leaves it up to the shooter.

Appleseed! Appleseed! Appleseed!


Practice! Practice! Practice!

Anonymous said...

Have the barrel "Lapped" by a qualified gunsmith or "Fire Lap" it yourself.

Anonymous said...

Spend more time on your brass prep. Trim the flash holes inside the brass case, removing any leftover brass flakes from the manufacturing process. Make sure that the bevel inside the case mouth does not scar the bullet when your press it in. Weigh your bullets before loading. Use only bullets that are within 1 or 2 hundredths of a grain of the same weight. Weigh your powder load carefully and slowly, don't use volume loads. Seat your bullets so they are about 20 thousandths off the lands. You may not be able to do this on an auto-loading rifle, as per the bullets fitting into the magazine. Use Varget gunpowder. It's preferred by competitive long range shooters. Use Sierra HPBT Match Kings in the 168 grain range.

Practice, Practice, Practice! And if you don't already have a good two stage trigger, get one and install it.

More info. If your shots are 'stringing' vertically in the paper, it's a sign that your bullets are either not the same weight, or your powder detonation if being hindered by something, like interference from extra brass flakes around the inside of the primer flash hole, or your powder charge is inconsistent.

If your bullets are stringing horizontally on the paper, the wind is gusting downrange from the sides or you are not performing a good smooth trigger pull. This is, of course, assuming everything else is perfect.

Once you start producing your own radically consistent ammunition, then it's just a matter of your learning to become a better shot.

Anonymous said...

To me the shooter is the significant question. If he is a seasoned high power guy that can punch tacks at 500m with a Garand then we can look at the ammo. On the other hand if he is a more casual shooter then there may not be any issues with the gun at all.

Next I would look to ammo. The comments that if this is generic ball the groups are good but if it is premium match grade stuff it's not so good are on point. To get beyond what I would call 'service grade' accuracy of 2-3 MOA you probably need to go to match grade ammo or take the time to find a load that works with the gun.

I suspect the gun is just fine. If it was shooting 6MOA at 100 meters or failing to keep a zero there is an issue. If we have a seasoned shooter using match grade ammo then maybe it is time to look at the gun.

In any case let us extrapolate these (call it 3.5in) 200 meter groups. Assuming a perfect world that makes 7" at 400m and about 10.5" at 600m.

Assuming a seasoned shooter using match grade ammo I would still think about whether there is a need to do anything and what the return on investment is going to be. The difference between service level accuracy and match accuracy is a lot of little things that get expensive in a hurry. Does the shooter think it's worth $500 to make a 3.5 in group at 200m into a 3 in group? What about a grand for a 2.5 in group? It depends on his finances/ disposable income and what he really wants the rifle to do. For many concepts of use the current level of accuracy is sufficient.

Well that's my .02 on that.

Anonymous said...

Group 2 has a vertical component that is typically associated with breathing. Every shot should be taken during a pause following exhalation. When soothing prone, pull your trigger knee up as far as possible to get your diaphragm off the goring and tighten your torso muscles.

Group 3 has 3 shots low and right. most likely due to either "dragging wood" as in some part of your trigger finger is contacting the side of the stock as you squeeze the tigger, or possibly some trigger snatch, vs. squeeze. If your rifle is not supported by a bipod or a rest, make sure your support arm is directly under the rifle and if you are using a sling as a shooting aid, make sure it is snug. The other seven shots in that group look reasonable, so it is likely a consistency thing more than anything else. Focus on position fundamentals, respiratory pause, and hooking your trigger finger while squeezing the shot off and holding the trigger back after each shot. My two cents.

WarriorClass said...

First of all, I'd like to thank everyone for the great advice. All three targets were shot with Prvi Partizan 168 grain HP BT Match, which for some reason performed better in this gun than the Black Hills 168 grain Match. Before that, I tried American Tactical 150 grain ball since it was the cheapest ammo but the POF didn't like it at all.

The comment about the heart beat makes sense to me because I noticed the movement with my heart which was hard to overcome. I could see my sight picture move with my heart beat. There were wind gusts of about 15 mph which were irritating, but I didn't think enough to blow me off target since it was mostly from behind.

One of my first thoughts was to go to a 175 grain bullet, but now those have disappeared and would be cost prohibitive anyway.

All three targets were shot from the bench, so I would have done a little better from prone. For some reason, I do a little better from prone than the bench, but I'm not sure why.

Hopefully with this additional information you guys can give me some additional advice that will save me from too large an expenditure on ammo, which is really hard to find right now and very expensive.

Thanks again Threepers!

WarriorClass III

Anonymous said...

Are you sure your scope base and rings are tight? Is the scope a decent one? Cheaper scopes can tend to be a little loose internally. In all honesty, 1.5 MOA is acceptable.

Anonymous said...

i recommend closing your eyes when you pull the trigger; that way you won't know if it is a bad shot.
looks like the rifle can deliver one minute of bad guy. good enuf!

Anonymous said...

Well sooprise sooprise sooprise.
Make a "drone" target. We need to familiarize, as the day has come. My prediction happened on the same day I predicted it.

quote:’”Yesterday, as a task force of 125 officers, some riding Snowcats in the rugged terrain, continued their search, it was revealed that Dorner has become the first human target for remotely-controlled airborne drones on US soil.”unquote

Well folks, buckle up. Here we go..and it ain’t gonna be a nice ride. Who's next?

The day of "capturing" are over. We have arrived.
Lord help us.

Historian said...

I have no comments on smithing your stick, as I know nothing about that weapon or it's maker. However, I would ensure that I had a crisp, glass rod break on the trigger. I suggest you practice your trigger squeeze; dry practice can be very helpful with this, as long as you are honest with yourself about when you get a good break.

A switching gusty wind from front or back can be very hard to dope and can have a surprisingly large effect. Steady cross winds are relatively easy to deal with, but the fore and aft gusty winds humble even high masters.

Other suggestions-

Start rolling your own, and experiment with seating depth. Some rifles like their bullets almost on the lands and others like them back a bit. Different makers have different ogives, and I have found a shorter tip to datum point distance, while not necessarily providing the best BC will allow seating the bullet closer to the lands. This can be important in some rifles. Both Hornady and Sierra offer worthwhile projectiles.

I find Hogdon's Extreme IMR powders to be very consistent across a wide temperature range. In .308 gas guns I have had excellent results with both Varget and H4895.

I stick with the harder primers for gas guns, and I make sure that all such ammo is primer pocket reamed to reduce the likelihood of slam fires. You should do a slam fire check with the dies, brass and primer that you use, and any time you change any of those, check for primer dimples. I always FL size for a gas gun.

For longer range, case sizing and prep become critical. Neck alignment and runout are very important and having a gage to check this is essential for LR accuracy.

Anyway, I hope this is of use.

Anonymous said...

Two things I didn't see mentioned that may help a lot, Warrior: DRY fireing (use a Snap Cap to save firing pin concerns), and- almost touched upon by a couple, is your heartbeat.
Do lots of dry firing, even in your living room.
Once you feel you're getting a good release, do a few pushups to get your heartbeat up.
Now that you have a noticeable heartbeat, do as we did in Biathlon training: learn to squeeze off your shot between the heartbeats. You can time them with your sights/scope (is more noticeable w/scope).
Get a good sight picture, breathe, relax, aim and watch the beat while holding the picture. The scope/barrel will rise with the beat, and drop when the heart relaxes. Hold the picture on the relaxation aprt, which is when you want to squeeze off the shot. (Hard to explain, but you'll get the idea fast when you try it.)
Your groups look pretty good, really- to me, anyway. Not 'great', but good for a new rifle. Stick with the ammo that gave the best groups for now, then look for better reloads once you're familiar with the rifle and it's familiar with you.

WarriorClass said...

Thanks Anonymous @ February 10, 2013 at 5:29 PM. I'll try these things. This was only my second time at 200 yards and the first time with this rifle. The last time was a couple years ago but I thought that with a good rifle it would be easier.

The scope is a Bushnell Tactical 5X15X40mm and seems pretty solid. I took a lot of time with the rings smoothing them out and mounting to make sure it was done right, but it was the first time I mounted a scope, so I read everything I could find and bought a kit with a torque wrench to do it right, and I think I got it.

So, I'll do a lot more dry fire as you suggest and then go back out and see how it goes. My concern now is that I am using ammo I may not be able to replace for some time. I don't have a reloader and have never reloaded before anyway.

Thank you all for your help with this. Hopefully I'll get there without wasting too much ammo.

WarriorClass III

Dakota said...

One thing I haven't seen mentioned is, how fast are you firing your shots. Heat is a great enemy of barrel life and accuracy. If you fired 20 rounds in say 5 minutes your barrel was getting hot to the touch. Also as mentioned barrel break in is very important to future precision shooting and easy clean up. THe more time you spend finding the "pet" load for that rifle the sweeter the groups. There are no short cuts and handloading is the only real way to precision shooting.

However if you plan to use it to shoot "varmints" your heart rate will be high and you will be lucky to shoot as good as the targets you have shown so do your homework and practice your snap shooting. Can you hit a pie plate at 200 within 2 or 3 seconds of sitting up at the bench? That is the real world of owning your property out to 600 ..... good luck.

jim said...

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jim said...

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jim said...

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Willorith said...

Project Appleseed will teach you the correct way to shoot a rifle. It is the best riflery instruction anywhere on Earth outside of the U.S. Marine Corps.

JudgementComes said...

I am surprised that no more has been mentioned about optics. I love my Horus Vision Falcon.

I also agree that each weapon has a load that it prefers. Find the load that consitently gives you groups that are sub-MOA at 100 yards. You will be surprised at how the subtleties like first shot fouling will effect your groups.

Is it a cold barrel?

Is it a dry barrel?

But once you find your load at 100yards. Practice shooting that load at the greater distances. You will get more accuracy by shooting more than tinkering with minutia.

And do not ignore the higher BC of the 175 grain bullet. It is more stable period. It is a more significant factor at greater distances.