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Help with concentricity issues........


jam1e
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When I first started reloading I was advised to give barrel a good clean before doing the testing. So off I went with my first loads, sure enough the groups tightened up, usually the hottest load (I never exceeded a grain before max) was the best group. I loaded up 20 of the best, check zero and the first group was rubbish ( I always clean my barrel) The groups had not been getting better due to powder quantity but the fact that the barrel was getting dirty. Now I load a few extra of the start load, just to get the barrel dirty. Once properly tested through a dirtyish barrel I had much better and consistant results. I still clean my barrel each time I use the gun and I know that the groups will tighten up by 1/4 inch to a ragged hole after a few rnds but my main aim (sorry bout the pun) is to have an accurate first shot from a cold barrel. Because of this simplest of facts I played around with the load, oal,and neck tension trying to get a consistantly accurate load,of course it wasnt going to happen, god knows how many bullets I got through. If your foundations are good you have something to build on.

 

You cannot replicate a certain degree of dirtyness, you can replicate totally clean. Nuff said!

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You cannot replicate a certain degree of dirtyness, you can replicate totally clean. Nuff said!

A clean barrel is only clean for one shot kent and I'm sure if you 'totally clean' your rifle, making sure all oil is gone from the bore between each shot then it will be more accurate than shooting through a dirty barrel. Afer using a cleaned barrel at the start of each zero session on a new load I experieced discrepancy's that I eventually ruled out, through my experience I have found new load testing to be much more simple and accurate by firing a two or three homeloads and then letting the barrel cool down.

Heres an interesting fact for you, my brother in law was in the forces and shot for the WGG rifle team. After each practice session the barrels were fully cleaned, but if they were about to shoot a competition the rifles were put away, very carefully with dirty barrels. Saying that I hate the thought of any my rifles or shotguns sat in the cabinet dirty so I always clean but through testing I know were the first shot through a clean cold barre will go.

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I think it's got to be right, the bullet goes up the barrel straight doesn't it?

If i have a choice, which i obviously do. Then i want as little run out as possible.

Surely if a bullet hits the lands badly off centre, (Or as bad as it could) then surely it may damage it causing a loss of accuracy??

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Yesterday i managed to get out and try a few home loads.

The weather was cold, with a slight breeze.

I was lay on a ground sheet in a cold muddy field. Not the most comfortable of positions!

I set-up my Chrono but it was showing a fault code so i couldn't get any readings. A right pi***r as i wanted to see how accurate my loads were.

I obviously had a clean barrel to start with but decided to put 4 rounds through it before i started. I used factory Hornady .24gn NTX Superformance.

Interestingly, the 4 rounds only achieved a group of 1.42" (cold) Yet previously, In similar conditions i achieved .806".

My frazzled memory may be wrong but i think the barrel was dirty and warm when i achieved the .806".....

Much to my chagrin i had a few "flyers", which really affected a couple of what would have been quite tight groups! :mad: (For me anyhow!)

The list below is in chronological order, and the barrel was only left to cool for as long as it took for me to reload the magazine. Granted thats not the best idea, but it was very uncomfortable and cold!

 

CZ 527 American in .204 Ruger calibre

 

5 rounds at a distance of 100 yards.

Sierra .32 Blitzking bullets

Hornady Brass

Magtech Primers

Chronograph not working.

O.A.L - 2.236 (Some rounds slighlty shorter)

Weather was cold with a slight breeze.

 

IMR 8208 XBR Powder

27.5 grains - 1.25” group

28 grains - .429” group.

28.5 grains - .440” group. With 1 flyer = .787”

29 grains - .606”

HOGDONS BL © 2 Powder

28.5 grains - .930” group

29 grains - 1.19” group

29.5 grains - .70” group.

30 grains - .408” group. With 1 flyer = .829”

 

I'm quite chuffed with the results. Although i know i need to be looking at numerous groups of the same load to get a real consistant idea of that loads performance. I'm just glad i've gone down from 2"!

Edited by jam1e
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On a nicer day with bipod and bags, and letting the barrel cool down between groups you would shave off a bit but in all honesty that aint bad at all. Congratulations,now you have something to play with, though what you have, if consistant, will be more than good enough for hunting, you just have to do your bit.

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Good result Jamie - The 8208 powder in the 28 grn range looks like you're getting somewhere and I would stick with the same bullet for now. You'll hear a lot about sub 1/2 inch groups but you won't actually see many, especially 5 shot groups shot consecutively so well done. I would load up another few of the 28-28.5gn load exactly the same and see if the results repeat. If they do and if the velocity gives you enough for what you want to do then you could call it a day and say thats good enough. One school of thought seems to run - it's good enough for hunting why bother with looking for more accuracy.

 

If you can repeat the sub .5 groups then thats the place to start tweeking and fine tuning the load - every 10th below .5 is hard work but the .2 and .3's will soon start to show up.and that will make you smile.

 

How about posting some photos of the groups - the pictures might also tell a story.

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Good result Jamie - The 8208 powder in the 28 grn range looks like you're getting somewhere and I would stick with the same bullet for now. You'll hear a lot about sub 1/2 inch groups but you won't actually see many, especially 5 shot groups shot consecutively so well done. I would load up another few of the 28-28.5gn load exactly the same and see if the results repeat. If they do and if the velocity gives you enough for what you want to do then you could call it a day and say thats good enough. One school of thought seems to run - it's good enough for hunting why bother with looking for more accuracy.

 

If you can repeat the sub .5 groups then thats the place to start tweeking and fine tuning the load - every 10th below .5 is hard work but the .2 and .3's will soon start to show up.and that will make you smile.

 

How about posting some photos of the groups - the pictures might also tell a story.

 

Cheers 1066.

I'll get some pics sorted. The targets are abit muddy and have my scribble on them but should give an idea.

If the results are consistant then i'll leave it at that for now as haven't done much vermin control as the reloading took over for a while.

Although, when i've been out and cleared some more vermin i do intend on abit of fine tuning with the best group by 0.1, 0.2 of a grain and so on.

 

I forgot to mention last night that i had a few rounds, (maybe 5 out of 50 odd) that were slightly stiff to cycle. The trouble is i don't recall if it was when loading them into the breech or unloading them?? I know it has to do with expansion but not certain why it's happened to so few?? Any idea why?

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Cheers 1066.

I'll get some pics sorted. The targets are abit muddy and have my scribble on them but should give an idea.

If the results are consistant then i'll leave it at that for now as haven't done much vermin control as the reloading took over for a while.

Although, when i've been out and cleared some more vermin i do intend on abit of fine tuning with the best group by 0.1, 0.2 of a grain and so on.

 

I forgot to mention last night that i had a few rounds, (maybe 5 out of 50 odd) that were slightly stiff to cycle. The trouble is i don't recall if it was when loading them into the breech or unloading them?? I know it has to do with expansion but not certain why it's happened to so few?? Any idea why?

 

If it's when loading then it's usually a sizing problem, this is why I would advise to full length resize every time. There is a theoretical accuracy improvement in only neck sizing and minimal working of the brass is desirable but many top paper punchers full length every time, in fact I read only yesterday that the new F/TR European Champion, Tim Stewart, F/L sizes every time.

http://www.gbfclass.co.uk/index.php/component/content/article/20-interviews/147-interview-with-tim-stewart

 

It's much better to have a rifle/ammo that is reliable. Rather like having a Skoda or a Farrari. If the Farrari won't start when you want it to then you're better off with the skoda.

 

If it's when unloading then this requires thinking about before you load up some more. This could well be a sign of over pressure. Post some pics of your cartridge head so we can see if there are signs of over pressure there.

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It shouldn't be when unloading a fired round as the case should swell to fit the chamber and it can't swell any more then as it cools rapidly you get a slight contraction. If it is on loading then were the rounds fired in the same rifle? after that are your dies set correctly or are you effectively slightly squashing the cases which can cause them to be tight.

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It shouldn't be when unloading a fired round as the case should swell to fit the chamber and it can't swell any more then as it cools rapidly you get a slight contraction. If it is on loading then were the rounds fired in the same rifle? after that are your dies set correctly or are you effectively slightly squashing the cases which can cause them to be tight.

 

In my experience, a sticky or abnormal bolt lift is a sure sign of over pressure.

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Hi jamie, looks like you have found a winning combination with the 32grn blitzking and IMR 8208 XBR powder at around the 28grn charge mark.

Shoot several more groups at this charge weight to make sure that is the best overall combination and not just the best on the day.

Once this is extablished, fine tune by playing around with seating depth. when you have found the optimum seating depth. you could if you wanted play around with neck tension but this would the merit need for interchangable bushing dies.

IMO this will not show many accuracy benefits in a factory chamber/barrel, however all these little tweeks ensure maximum ammunition consistancy, which in turn gives you ultimate confidence in your ammo which will be a psychological boost to your shooting.

 

Ian.

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In my experience, a sticky or abnormal bolt lift is a sure sign of over pressure.

Thanks for the reply 1066,

I've had a close look at my used cases, especially the hottest loads of both my IMR and BL©2 .

Both lots of primers in the hottest loads show slight signs of flattened primers, when compared with the lowest loads in each category.

I'll going to start at one grain lower than max and work up slowly checking for over pressure, and see where we go....

I'm also going to have another read of my Lee book regarding over pressure......

Thanks to all the members who have given me advice and not just criticism... :good:

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If they are tight going in then its sizing, I get this when my previously neck sized ammo starts to tell me its time for the full resizing die to come out, then I full size the whole batch. If the bolt is stiff to lift after firing, as said in previous posts it will be over pressure. Flattened primers are not always an indication of over pressure as some are softer than others. There is a picture in your lee manual somewhere of the differance in case base change with pressure.

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Just a quick update folks.

It does seem to be excessive pressure.

I've cycled the brass from the lowest, and mid-range charges for each powder and they cycle ok.

Yet when i cycled the highest charges the bolt was stiff when closing.

I intend to full length size all of them and check the higher charge primers with the lowest charge primers and see if there's much of a difference.

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If they are tight going in then its sizing, I get this when my previously neck sized ammo starts to tell me its time for the full resizing die to come out, then I full size the whole batch. If the bolt is stiff to lift after firing, as said in previous posts it will be over pressure. Flattened primers are not always an indication of over pressure as some are softer than others. There is a picture in your lee manual somewhere of the differance in case base change with pressure.

 

Redgum,

I've searched on the web and web pictures for signs to look out for with over pressure. But it would be good if a "reloader" as per yourself could also give me some more things to look for?

From what pictures on the web i've seen there doesn't appear to be and head seperation starting.

Cheers

Jamie

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I've full length sizedthe 50 odd cases and de-primed them.

I looked at my used primers and compared them with new primers under a magnifing glass and there was no flattening. Apart from the obvious firing pin dent they looked identical. So to be honest i'm at a loss as to why the used cycle rounds were hard to cycle?

And as i've said in my previous post there doesn't appear to be any signs of head seperation either. ???

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Bit confussed on what you actually mean there Jam1e, if the bolt is stiff to lift after the rnd has been fired then it is over pressure, you shouldnt need to worry about head seperation, this is really from alot of resizing.

I'm probably getting my wires crossed. When i was initially having problems removing a spent round from the chamber with a relatively hot load, i was concerned about over-pressure. I cycle the used low powder charge brass cases when i got home and the bolt closed and opened smoothly.

Yet when i tried to do the same with the high powder loads, in both BLC 2 and IMR 8208 they were "sticky" and a little stiff to cycle.

Reading my lee manual and researching on the web. It stated it may be due to over pressure and between them stated to look for flat primes or the beginnings of head seperation. It did however, also mention what you stated. In that the primer may just be made of soft metal and would make the primer look flattened, giving false readings of over pressure. I initially thought my primers looked flat. But since looking at them under a magnifying glass they aren't flattened and look the same shape as the same brand of un-used primers i have left. So, although the used brass which contained a "hot load" is stiff to cycle the primers show no signs of over pressure. So, would i be right in thinking the stiff brass just needed a full length size, (which i've just done) to put them bad into shape after being used between 3-5 times?

Hope that makes sense!??

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Are you saying Jamie, that a round has chambered normally, without undue bolt tension/stiffness, then fired and when extracting the round the bolt is stiff to operate? or are you saying that when you have rechambered a fired case the bolt is stiff to operate?

 

If the round chambered normally and fired then the bolt was stiff to operate when trying to exctract, then that most probably indicates to me that high pressure is involved.

 

If the fired case doesn't chamber easily then that will be sorted when you resize - full length resizing will get you back to factory spec. Again a photo of the cartridge head before decapping may tell us more. any sign of ejector marks showing on the head?

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Are you saying Jamie, that a round has chambered normally, without undue bolt tension/stiffness, then fired and when extracting the round the bolt is stiff to operate? or are you saying that when you have rechambered a fired case the bolt is stiff to operate?

 

If the round chambered normally and fired then the bolt was stiff to operate when trying to exctract, then that most probably indicates to me that high pressure is involved.

 

If the fired case doesn't chamber easily then that will be sorted when you resize - full length resizing will get you back to factory spec. Again a photo of the cartridge head before decapping may tell us more. any sign of ejector marks showing on the head?

 

Yes, as per your above now in blue. When i extracted a few "fired" high powder charged cases the bolt was stiff.

I think i'm confusing it as i also had a few unfired rounds that were a little stiff to cycle into the chamber to fire, hence them needing to be full length sized.

I can't show you any pics as they've been deprimed... Any other way to tell?

In fairness the best groups were a full grain lower anyhow, so i'll lower the powder charge anyhow....

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