Help with Groups from M305

I'm working with a new Norc M14 rifle right now and am seeing similar results with a single flier in each 5 shot group (details here: http://www.canadiangunnutz.com/foru...roups-I-show-the-symptom-you-tell-me-the-cure)

I was thinking bedding is the key, but now reading your info I'm not as confident about that. I've got more experimenting to do and will try your idea of grouping the #1, #2, #3 etc, shots so see what I learn.

I haven't started reloading yet as I was hoping tio establish baseline accuracy with factory and see how much reloading could improve groups. But, now I've stumbled onto this flier issue and it has me intrigued/distracted from my original plan.:rolleyes:
 
Hey guys - Thanks for the comments. The groups were shot using commercial Hornady ammo. Reloading is in my future for both economic and accuracy reasons. Very interested in getting started and need to make space and find a press (Lee, Dillon, hmm...)

While I understand that a heavier barrel will change the barrel harmonics and dampen the barrel temperature effects, I'd think that the primary accuracy increases from this mod would be due to improved barrel concentricity and the fit of the chamber. The required chamber reaming would also allow precise headspacing even if one were to choose to continue using the Norc bolt. Anyway, this mod is off into the hazy future for me - end-of-summer at the earliest if ever. If I can continue to get predictable 1.5" groups from a hot, dirty barrel I'll start to play with the barrel tensioning system of the Blackfeather to see if this has any effect and also experiment with hand loads to find some accuracy nodes.

Since no one has chimed in, I'm assuming that I'm on the right track with my flyers being due to barrel temperature. I'd appreciate hearing from the folks who regularly get 1 moa from their rifles in service rifle or other competitions. What do you do to control for temperature effects? Time your shot intervals?

I'm still kinda surprised that even the small cooling intervals such as going up to change targets, or reloading a mag, can result in significant POI changes - after all, the barrel never got less than uncomfortably-warm-to-the-touch throughout the course of the 40 rounds of my test. Recall that I had shot some rounds before to warm up the bore.

Baron - I hope that you post your results to see if there is any consistency with my observations. I know that others have posted on this issue as well, with some seeing last-round flyers instead of first-round (lack of pressure from the mag follower was theorized as a potential cause). No doubt there are many potential causes of flyers depending on the rifle.

Anyway - good fun. What would be the fun in buying an out-of-the-box tack driver for masochists like us?
 
Have you tried not shooting the gun empty i.e. reloading the mag (carefully) or switch to a full mag with the last shell in the chamber, then continue to shoot after an interval.
This could help to determine if manually cycling the bolt causes the first shot issue.
I had an FN that would group manually cycled rounds 2" outside the normal grouping.

Dan
 
Your grouping looks good, I will bet as the fliers are on your first shot, the problem could be one of a couple of things.....
Your trigger pull on the first shot or barrel temp. Try shooting a few rounds then load up on a hot barrel and see what happens on your first shot. Then let the barrel cool off then try again....


Pr589 said:
Thanks guys.

Yo - That link was a good find. Searched the M14 forum but couldn't find what I wanted. Google is better than the search engine on the site.

After reading the M14 forum post and 45ACP's I'm now wondering about the effect of the magazine. I tried holding low for the first round on one of my strings but wouldn't you know, the rifle shot exactly where I was aiming on that string :(

At least I know that this isn't necessarily inherent in the platform, there is likely something happening with my rest, my mags or me. I think I'm going to try an AIA 10 round mag to see if a longer string, or change in mag has an effect.

See the groups below just for interest.

2013-01-13142419_zpsf17a8c4e.jpg
Click to expand...
 
Dan B said:
Have you tried not shooting the gun empty i.e. reloading the mag (carefully) or switch to a full mag with the last shell in the chamber, then continue to shoot after an interval.
This could help to determine if manually cycling the bolt causes the first shot issue.
I had an FN that would group manually cycled rounds 2" outside the normal grouping.

Dan
Click to expand...

Why would the manual cycling of the action affect the grouping or trajectory of the projectile?
 
Pr589 said:
Hey guys - Thanks for the comments. The groups were shot using commercial Hornady ammo. Reloading is in my future for both economic and accuracy reasons. Very interested in getting started and need to make space and find a press (Lee, Dillon, hmm...)

While I understand that a heavier barrel will change the barrel harmonics and dampen the barrel temperature effects, I'd think that the primary accuracy increases from this mod would be due to improved barrel concentricity and the fit of the chamber. The required chamber reaming would also allow precise headspacing even if one were to choose to continue using the Norc bolt. Anyway, this mod is off into the hazy future for me - end-of-summer at the earliest if ever. If I can continue to get predictable 1.5" groups from a hot, dirty barrel I'll start to play with the barrel tensioning system of the Blackfeather to see if this has any effect and also experiment with hand loads to find some accuracy nodes.

Since no one has chimed in, I'm assuming that I'm on the right track with my flyers being due to barrel temperature. I'd appreciate hearing from the folks who regularly get 1 moa from their rifles in service rifle or other competitions. What do you do to control for temperature effects? Time your shot intervals?

I'm still kinda surprised that even the small cooling intervals such as going up to change targets, or reloading a mag, can result in significant POI changes - after all, the barrel never got less than uncomfortably-warm-to-the-touch throughout the course of the 40 rounds of my test. Recall that I had shot some rounds before to warm up the bore.

Baron - I hope that you post your results to see if there is any consistency with my observations. I know that others have posted on this issue as well, with some seeing last-round flyers instead of first-round (lack of pressure from the mag follower was theorized as a potential cause). No doubt there are many potential causes of flyers depending on the rifle.

Anyway - good fun. What would be the fun in buying an out-of-the-box tack driver for masochists like us?
Click to expand...

Your assumption about barrel heating is correct - as the barrel heats it gets longer changing barrel whip.
I have found variations of P.O.I. impact affected by when the gas cylinder is tool tight at 6pm through to 5.30pm, and also ferrule lip pressure from 5lbs. all the way up to 40 lbs.
A barrel tensioning screw also affects the variation of flyers.

The best system I have used to control and minimize cold hot barrel variation P.O.I shift uses the barrel tensioning screw principle but with 4 spring loaded variable tension ball bearings top and bottom (it allows the barrel to stretch when heated but not whip).The system was designed after extensive testing (not by me) of the situation you describe.
It places shots closer to the first shot flyer and shrinks groups significantly - especially on long strings of fire.


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Flyers caused by manually cycling the bolt seems unlikely though I haven't tried loading a fresh mag with the last round in the chamber. I'm not knocking the thought but in my test I was using the bolt release which should have minimized the effect.

Also, looking at the patterns from the sequential shoot (1st round in 1st target, 2nd round in 2nd target, etc.) you can see the drift in POI in target 1 to approximately the POI of the other rounds. This seems to imply some sort of gradual effect like barrel temperature.

That said it wouldn't hurt to try to eliminate manual cycling of the first round. Something to try next time I'm at the range.
 
chopper 1 said:
Your assumption about barrel heating is correct - as the barrel heats it gets longer changing barrel whip.
I have found variations of P.O.I. impact affected by when the gas cylinder is tool tight at 6pm through to 5.30pm, and also ferrule lip pressure from 5lbs. all the way up to 40 lbs.
A barrel tensioning screw also affects the variation of flyers.

The best system I have used to control and minimize cold hot barrel variation P.O.I shift uses the barrel tensioning screw principle but with 4 spring loaded variable tension ball bearings top and bottom (it allows the barrel to stretch when heated but not whip).The system was designed after extensive testing (not by me) of the situation you describe.
It places shots closer to the first shot flyer and shrinks groups significantly - especially on long strings of fire.
Click to expand...

My initial reaction to your comment was skepticism however after running some numbers I found that the barrel length can change a surprising amount. So to geek out on you guys, the linear thermal expansion coefficient for chromoly steel can vary from 5.9 to 7.5 10exp-6/deg F. So if we use some conservative numbers...7.5 x10exp-6 x 22 inches x 400 deg F = 0.066 inches.

So assuming that the barrel heats evenly over it's length (it's going to be colder near the receiver, and anywhere there is a boss) and that it heats by 400 deg. F (will produce a burn but is not cherry red) the muzzle tip would "grow" by 66 thousandths of an inch. More than I would have thought but enough to affect barrel harmonics...hmmm? Raises an interesting question about the effect of the Blackfeather Op. Rod guide which rigidly attaches the barrel to the stock. The fact that this attachment point is half way back on the barrel reduces the barrel growth at this location but 33 thousandths would still be significant given the tight tolerances of the stock.

I still am somewhat skeptical that 66 thousands of an inch in length would materially affect the harmonics of the barrel. I could more easily believe that other factors related to linear thermal expansion have an effect but ya never know. I would have thought that thermal effects would have affected bore diameter (friction/velocity), linearity (especially if the barrel hasn't been stress relieved), before the harmonics. Anyone interested in doing some finite element analysis?
 
Groups are fine for m14 (norc), dont get to anal about groups its a $400 rifle not a precision rig.

Don't get upset i have been there and spent the money, 2-3 moa is fine for m14.
 
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F55 has a good point, if you want to put the money in to an m14 then go for it, but based on what iv seen it takes a custom bolt, custom heavy barrel and good reloads or match commercial ammo to deliver 1" groups consistently. Your better to spend your money on a precesion.

If you can get 1.5" that is pretty awesome! I don't really buy the idea of the first round loading different from the magazine. If you are pulling the bolt to the rear and let it fly with out riding it forward. It's the same spring that pushes the bolt forward. The only difference I would think would be the added pressure of the rounds pushing up as .45acp stated.

The the OP, are you shooting off sand bags front and rear, and have you tried dry fire pulls on an empty chamber, to see if you might be pulling your rounds at all? No offence ment at all but I found when I started to shoot precesion rifle that on my trigger pull the cross hairs would jump half a mil. It maybe some thing stupid but worth a try.
 
yomomma said:
because the bolt would not be seated by the same force, nor would this force be applied at the same point.
Click to expand...

I'm still not tracking.

The return spring (op rod spring) returns the bolt to full battery. What difference would it make wether you compressed the spring and released it by hand as opposed to the gas compressing the spring? How does this result in affecting the accuracy or trajectory of the projectile after the hammer slams the firing pin? No offense but that sounds pretty ridiculous.

How can anyone say that this would in any way affect the consistancy of a projectile leaving the barrel? Maybe I'm wrong but it sounds pretty far fetched.

I get the same issue with my M14, different trials have shown that it must be due to the cold barrel. It's always my first shot that goes off the main group. If I shoot 2-3 rounds down range and then shoot a 5 round group from a warm barrel, I don't get the "flyer" anymore.
 
From the looks of those groups, if you start handloading, I bet you could easily get a load that will let you shoot around 1.25 MOA consistantly.

If you're going to put money into anything, I recommend a reloading setup.
 
Folks - Thanks for for the input.

I'm anxious to start reloading and am waiting for some gear. At this point it's kinda useless to keep tweaking until I start reloading. Every time I buy high quality commercial ammo, it's a significant percentage of what a reloading setup would cost. The only saving grace is that at least I get brass. Shot 80 rounds of MFS the other day to see what effect the BF tension screw would have and was lucky to get a 3" groups at any setting - bah, waste of time without better ammo!

Logically, I know that investing in a precision rifle is the most economic way to improve groupings but what does logic have to do with shooting or any hobby :) For me part of the game is just continuous improvement and part of it is the attractiveness of having an MOA, non-restricted semi (in addition to having a precision rifle in 223 or 260 Rem - must resist). If they would only non-restrict the AR platform... There are a few threads on CGN about how to build a sub-MOA Ruger 10/22 for $1500+ or buy a Savage or CZ for under $500 - similar issue.

If nothing else the thread kinda documents my journey down this well traveled, potentially expensive road, and helps others to make decisions. Will update thread for my first reloaded rounds.

Buzz - I'm shooting off bags front and rear. Regarding my trigger pull, While shooting .22 at 100 I can frequently get 1 MOA that is with a different trigger with a much lighter pull. I'll have to try dry firing.
 
I'm anxious to start reloading and am waiting for some gear
Click to expand...

Don't mean to sound harsh, have not read this entire thread, but If you are not reloading, the whole M1A accuracy thing is pointless.
Don't care what mods or by what guru built you're rig, it's all for not.

With a stock rig, bi-pod + quality reloads I noticed a 50% increase (having said that, I had quite a bit of reloading experience)
No bull####, occasional sub 1 MOA, mostly 2-3 MOA.

Years later, same reloads, 2K+ in mods including a rock solid JAE rig, and the only difference I noticed was CONSISTENCY.
Now it's a consistent 2 MOA rifle, no matter what the conditions (and I mean TRUE MOA, any condition, all the time, no flyers)
-20 snow squalls to +30 humidity, it will deliver. Even when the retarded owner is hung over :confused:

You want the largest gains, you go reloading. That's where you'll get it.

Reloading = improvement on accuracy
Mods = improvement on consistency

Hope you take the advise, start reloading and go from there....

Rob

If nothing else the thread kinda documents my journey down this well traveled, potentially expensive road,
Click to expand...

It's a frequently traveled road and previous M1A addicts acknowledge your journey. I wouldn't be sharing my knowledge with you otherwise.
 
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TACTICAL111 said:
Don't mean to sound harsh, have not read this entire thread, but If you are not reloading, the whole M1A accuracy thing is pointless.
Don't care what mods or by what guru built you're rig, it's all for not.

With a stock rig, bi-pod + quality reloads I noticed a 50% increase (having said that, I had quite a bit of reloading experience)
No bull####, occasional sub 1 MOA, mostly 2-3 MOA.

Years later, same reloads, 2K+ in mods including a rock solid JAE rig, and the only difference I noticed was CONSISTENCY.
Now it's a consistent 2 MOA rifle, no matter what the conditions (and I mean TRUE MOA, any condition, all the time, no flyers)
-20 snow squalls to +30 humidity, it will deliver. Even when the retarded owner is hung over :confused:

You want the largest gains, you go reloading. That's where you'll get it.

Reloading = improvement on accuracy
Mods = improvement on consistency

Hope you take the advise, start reloading and go from there....

Rob



It's a frequently traveled road and previous M1A addicts acknowledge your journey. I wouldn't be sharing my knowledge with you otherwise.
Click to expand...
This post should have been posted in the "bible" stickies forum!
LoL!!!
 
Mine used to have not a single flier but the last 2 in mag. A 3 and 2 group.
Don't know now as I've done some tightening up of the gas systems after a Hungry clinic (Thanks again Hungry!!) but I'm curious.
 
Perforator said:
Mine used to have not a single flier but the last 2 in mag. A 3 and 2 group.
Don't know now as I've done some tightening up of the gas systems after a Hungry clinic (Thanks again Hungry!!) but I'm curious.
Click to expand...

Hey Perforator - I remember you handle from the Burlington clinic - fun session. Get out and shoot and let us know if your fliers have vanished.
 
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