HELP Required: Excessive O.A.L.

Blobby159

Well-Known Member
On the two last occasions I joined in on a long distance Club Shoot at Bisley Ranges my rifle - a Tikka t3 in 6.5 heavy barrel 'Sporter' Swede - was giving me mediocre and unpredictable 'accuracy' which was far and away off what I have been used to from it once a month over the last couple of years. I thought it might have been due to some kind of 'brain fart' whilst I had been reloading my regular range ammunition for it. So I broke down almost 200 fastidiously built rounds made from quality products, and loaded them again following resizing the case necks.


Back at the range on my last visit prior to "Lockdown" and @ 600 yards my bullets were falling anywhere from V-Bulls on out to 3s, where on a good day a few months earleir in the year I had shot a session of 1 x Bull and 9 x V-Bulls with the same rifle/ammunition mix!?? I was crest fallen and dumbfounded both!.....

Then I watched something on YouTube about the effects on the throat of one's rifle barrel caused by successive firings, particularly when using 'hot' rounds... So I wondered if THIS might be part of my problem, and set about re-measuring the absolute length of a cartridge made up from the same components (case and projectile) as my regular range load.. .... ....

DID I GET A NASTY SURPRISE !!!!! I now think I know why my rounds are wandering all over even a relatively close 600 yard target.. The C.O.A.L. (Cartridge Over All Length) of my usual, best range load has grown by, as near as damn it, 100 thousandths (1/10th) of an inch (about 95 thou' to be more exact)!!! .... So the throat of my rifle has LOST this amount of rifling length down the bore and out, with the erosion caused by the hot gasses and burning kernels... DAMN!!...

I have just set about reloading some rounds, again with the same best components (Lapua cases and 139gr Lapua Scenar bullets over a stout measure of IMR7828 SSC reloading propellant) and find that, if I set the bullets up so that they are the regular 15->20 thou' off the jammed into the lands length, the projectiles have hardly ANY shank now down into the case neck, holding the projectile both in the case and in a concentric arrangement with the rifle bore... like just 50 thou' or so, not much more than that!!.... Not suitable for rangework or any other form of shooting really...

So, now down to my URGENT and important (to me) question wherein I seek the assistance of other, knowledgable S.C. Members:-...
Given that I am now technically unable to build rounds of sufficient OAL to suit the loooong free-bore now apparent in my heavy barrelled Tikka t3 rifle, how best to recoup the situation please friends?? I am thinking I could :-
1). get the rifle rebarreled - which is an expensive option in the order of £600 plus, depending on the barrel I choose and whom I ask to do the work? The problem is solved but I will be binning a possibly still perfectly useable barrel in the process...??
2). ask an experienced, skilled Rifle Smith to take the current barrel off and set it back say half and inch or so - taking length from the effected chamber end of the barrel - rechambering and then setting the altered barrel back into the receiver. With this option I am all at sea as to whom I could ask (and trust?) to do this, and if I do find someone whom is appropriately skilled, the cost to me and the impact it MIGHT have on my rifle's accuracy?

Any other ideas please peoples?.. And any suggestions as to whom I Might ask to do the work in my option 2). above if feasable, and costs too please??

So There it is... Your considered assistance would truly be and fully Appreciated...

Kind Regards,
Blobby159
 

Home Loader

Well-Known Member
Just looking outside the box. Over the lockdown period have you changed stature, is you strength/fitness at a different level? Could it be you are just out of practice? While it's not un heard of for a rifle to just drop off its generally a gradual process.
Can I also suggest someone else shoots your rifle and you shoot a different one it may give you the answers.
 

Uncle Norm

Well-Known Member
I had similar problems when I was trying to develop a load when I bought my Finnlight .243. Muir convinced me that the alleged benefits of 'land chasing' were a myth.
I started loading to SAAMI spec and used a Lee Factory Crimp Die. Muir was right and problem solved. Minimal cost option, so worth a try in your circumstances.
 

bryn

Well-Known Member
Your rifle, which normally shoots accurately has suddenly started to be in accurate. I would check the basics first, mod, mounts and scope. I had a midrange scope recently which suddenly couldn’t hold zero and had to go back.
Find someone with a bore scope and have a look down the barrel etc, it could be too much copper deposited which, your normal cleaning routine has allowed to build up.
I coming round to Muir’s way of thinking on bullet seating.
Good luck,
bryn
 

DCG

Well-Known Member
Check all of the above, also action bolts etc. As has been said above mechanical problems with the barrel usually show up gradually.
Other questions to ask, are you using a new batch of powder or primers or bullets.
It’s a well known phenomenon that different batches of the same powder can vary by as much as 10%. if you’ve used a chronograph in the past check the velocity of the new batch of loadings your currently using.
I noticed a similar problem a little while ago with a rifle I had, tried all of the obvious and those above, eventually I had some cases I had been using annealed and the accuracy was greatly improved as was the feel in consistency when seating the bullets.

I’m sure what I’m about to say will raise some comments, but here goes, I‘ll stick my head above the parapet.

If a barrels shot out, then its shot out, the bullet wobbling down the first couple of inches of barrel isn’t going to do anything for it’s accuracy potential. However, I’ve never been able to understand why people chase the lands unless their chosen round is a recipe which works on the bullet being “jammed“ into the lands. But even then, every time you move the bullet forward in the case, you're increasing the volume of the case and potentially changing, therefore, the pressure on ignition therein.
If adjusting the seating depth, is a function of adjusting barrel timing to get the bullet to leave the muzzle at a certain point in the barrels harmonic cycle, to find the “Accuracy Node” “Sweet Spot” or whatever you want to call it. Then the main measurement we’re interested in surely, is the distance of the bullet to the muzzle, not to the lands.

There I’ve said it, Ill go get my tin hat out of the cupboard.

DCG
 

Stalker1962

Well-Known Member
.., eventually I had some cases I had been using annealed and the accuracy was greatly improved as was the feel in consistency when seating the bullets.
As a man who has recently wasted a fortune invested in an AMP MkII (thanks dodgyknees!) you have no idea how happy you have made an old man when reading that.
 

Andy RV

Well-Known Member
Is your stock tight? Check the recoil lug for wear, Tikka used to use an aluminium lug which would wear allowing movement of the action within the stock.

How many rounds has the barrel had through it?
 

Blobby159

Well-Known Member
OK, thanks fellas. A few ideas to follow up on here, especially the 'Muir(ism)'. I had last night been considering JUST what you suggest here Muir and have measured the COL and OTBL of a singular pack of PPU rounds I bought when this loss of accuracy first raised its ugly little head. Didn't use them then, as a comparatoron target, but will be now - as well as trying out loads to THEIR measurements. Coincidentally they too are topped off with 139gr projectiles, though whether or not they are made in LAPUA presses is yet to be discovered...
I will also take the barrelled action out of the stock and check the recoil block. I have a brand new synthetic Tikka t3 'Varmint' stock in my cupboard and think it has a STEEL recoil block in it. If I can I will swap the over and test.
That way I will also be checking/retightening the stock screws.
Whilst I am at it I will re-check the scope mounts for security, though that is the very first place I went when my rounds stateed to go off course.
B.t.w. this problem was not quite as 'SUDDEN' as my original request for help would suggest, though it did occur through maybe three visits without any additional rounds released between each.

Again my thanks.
I shall be back....
Blobbs....
 

Muir

Well-Known Member
Hope it works out for you. I never seat to the lands unless it's with lead cast bullets at high velocities. Jacketed bullets are seated to specified data OAL. Never fails me.
And my apologies. THIS was where the original posting was. Sorry. I thought it was under Reloading and didn't look elsewhere. Not enough coffee, too many hours at work. ~Muir
 

Blobby159

Well-Known Member
Hope it works out for you. I never seat to the lands unless it's with lead cast bullets at high velocities. Jacketed bullets are seated to specified data OAL. Never fails me.
And my apologies. THIS was where the original posting was. Sorry. I thought it was under Reloading and didn't look elsewhere. Not enough coffee, too many hours at work. ~Muir
Hahahahahahaaaaa!!.. Hiya Muir... I know what you mean 'bout the lack of those first few coffees my friend!!... Being a fairly typical Brit in these circumstances I am the same, but my requirement is for multiple, hot sweet mugs of that stuff which caused a lotta problems in a famous American harbour a coupla hundred years back... Ha!!

I have just spent a good(?) while digging out that box of PPU 139gr 'Target' ammo (damn but I had really hidden it for some reason??) and measuring the Bullet Engaging width to Base with a newly bought set of Hornady Equipment that screws latches onto the jaws of one's calipers. (BTW Muir, what the devil is that length measure called please? If ANYONE is to know I am certain YOU are the man that does! .... <<BULLET Datum line to Cartridge Base??>>. Then I have set the SAME measure to a number of newly made up homeloads comprising 139gr Scenars in TWICE fired and minorly body died then necksized Lapua 6.5 Swede cases over 48.5gr IMR7828 SSC propellant - I seem to recall this was a fave load of yours too, or am I confusing you with another friendly, helpful Swede reloader??

So I am now off out to a convenient field where I have permission to shoot and that has sufficient background room for my potential(??) "misses" to try then out versus my regular C.O.A.L loads and a selection of bullet depths from out to the lands (-30 thou) right back to less than that set as above (a commercial bullet seating depth) in 50 thou steps. Gotta say I WON'T likely be using that lands -30 thou setting or anything much near this as the depth of bullet in the neck of the case is pretty minimal and I doubt it will help much with consistent ignition. Another Potential problem I do NOT wish to bring into the mix here!!!!!..... (( Perhaps I could EVEN start to employ your much vaunted neck crimping suggestions as per when we have conversed at some length over our joint love of that beautiful wee .22 Hornet cartridge?? )). B.T.W. I have a selection of .22 Hornet loads that I have crimped light/medium & heavy, with differing powder/projectile homeloads that I will ALSO be testing should the sun still be lighting my progress later today, or maybe later this coming week if the weather holds. [[As you may have heard other of your Countrymen complaining about when they visit the good ole 'Mother Country', our weather here tends to be just a tad unpredictable with the rain & wind.. Hahahhahaaa!!]]

You are starting to get under my skin my friend.... 😋 😋 😋.

I shall be back!

All the Very Best,
Blobbs.....
 

stubear

Well-Known Member
Agree with Muir 100% - just seat to SAAMI spec max OAL and be done with it, then tailor the powder weight for maximum accuracy. Or if you have a mega accurate factory load you want to duplicate then measure the cartridge and seat to that.

Thats works a treat on every rifle I've worked up a load for (not many but its had a 100% success rate so I am assuming its working ok for me!), and the only one I havent done this for is my .25-06 where I got hold of the same bullets as the factory ammo the rifle likes (which is sub MOA) and I just duplicated that.
 

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