Distance from lands 270 WSM

[Meglaman]

Hello all.
I have am finally just getting into reloading, the first Calabar I am working on is my 270 WSM, Tikka T3 as I have loads of brass. It has probably shot between 600 to 800 rounds through it. I had the rifling checked out as I was concerned with the drop in accuracy with factory loads and the report back was that it still ok. However, due to my lack of knowledge, I did not ask about throat erosion.

By creating the standard resized cartridge with a cut slit in the neck and placing a bullet in it I gently closed the bolt so that the lands would push the bullet in to measure the distance.

Following results using a bullet comparator: Imperial measurements.
Factory Winchester ammo: 2.1330"
Bullet depthMax size for the Tikka magazine: 2.2455"
Too Lands: 2.4550" (Normally the
Difference: 0.2095"
Is the difference 0.2095" still too deep and do I need to look at a new barrel?

Reg,

[in2anity]

aha the old "magazine length limiting factor" conundrum... Just to be clear, you're imagining a short-throat chamber as a fix to your woes? Could you cut down the barrel at the receiver end, then ream a new short throat chamber? no need for a whole new barrel...you also kill two birds with the one stone, cleaning up an eroded throat at the same time - you'll just lose a couple inches of barrel is all. Hopefully it's a 24"

The big question is, have you verified (via single loading) that the longer OAL solves your accuracy problems? That test needs to be carried out before doing anything...

[Oldbloke]

Hello all.
I have am finally just getting into reloading, the first Calabar I am working on is my 270 WSM, Tikka T3 as I have loads of brass. It has probably shot between 600 to 800 rounds through it. I had the rifling checked out as I was concerned with the drop in accuracy with factory loads and the report back was that it still ok. However, due to my lack of knowledge, I did not ask about throat erosion.

By creating the standard resized cartridge with a cut slit in the neck and placing a bullet in it I gently closed the bolt so that the lands would push the bullet in to measure the distance.

Following results using a bullet comparator: Imperial measurements.
Factory Winchester ammo: 2.1330"
Bullet depthMax size for the Tikka magazine: 2.2455"
Too Lands: 2.4550" (Normally the
Difference: 0.2095"
Is the difference 0.2095" still too deep and do I need to look at a new barrel?

Reg,

I think your asking,
Is the difference between factory ammo and your OAL measurement to the lands something to worry about?

May not be. Factory ammo is often made to give a big jump to the lands. (So they fit all chambers and mags) So proves zilch.

I would just load up some rounds about 2.235 (So they fit in the mag) and try them.

[Meglaman]

aha the old "magazine length limiting factor" conundrum... Just to be clear, you're imagining a short-throat chamber as a fix to your woes? Could you cut down the barrel at the receiver end, then ream a new short throat chamber? no need for a whole new barrel...you also kill two birds with the one stone, cleaning up an eroded throat at the same time - you'll just lose a couple of inches of barrel is all. Hopefully it's a 24"

The big question is, have you verified (via single loading) that the longer OAL solves your accuracy problems? That test needs to be carried out before doing anything...

Cool, Advise!
It is a 24" barrel and I was thinking of doing the two bullet seating depth loads: One to fit the mag and the other .002 back from what I think the lands are. With you suggesting it I will definitely do it. It is my deer rifle so if I can still get a good group at 200 yards then I will be happy. Shortening the barrel is something I have not thought of, that would be my next option instead of buying a new barrel.

Thank you

[Meglaman]

Hello all.
I have am finally just getting into reloading, the first Calabar I am working on is my 270 WSM, Tikka T3 as I have loads of brass. It has probably shot between 600 to 800 rounds through it. I had the rifling checked out as I was concerned with the drop in accuracy with factory loads and the report back was that it still ok. However, due to my lack of knowledge, I did not ask about throat erosion.

By creating the standard resized cartridge with a cut slit in the neck and placing a bullet in it I gently closed the bolt so that the lands would push the bullet in to measure the distance.

Following results using a bullet comparator: Imperial measurements.
Factory Winchester ammo: 2.1330"
Bullet depthMax size for the Tikka magazine: 2.2455"
Too Lands: 2.4550" (Normally the
Difference: 0.2095"
Is the difference 0.2095" still too deep and do I need to look at a new barrel?

Reg,

I think your asking,
Is the difference between factory ammo and your OAL measurement to the lands something to worry about?

May not be. Factory ammo is often made to give a big jump to the lands. (So they fit all chambers and mags) So proves zilch.

I would just load up some rounds about 2.235 (So they fit in the mag) and try them.

Thank you I will do that first when I do my test loads.

[marksman]

the 270wsm is one of my favourites

with your round count your throat will have moved, no doubt, causing a different pressure so you get a different load result than what you started with
so to get it back to where it was may be as easy as adding more powder to get back to the velocity sweet spot and keeping all else the same

a re-chamber is possible and not a bad idea really, that is a proven way of getting your presision back for about half the original round count

saving up for a new tube now would be a good idea IMHO

[Meglaman]

the 270wsm is one of my favourites

with your round count your throat will have moved, no doubt, causing a different pressure so you get a different load result than what you started with
so to get it back to where it was may be as easy as adding more powder to get back to the velocity sweet spot and keeping all else the same

a re-chamber is possible and not a bad idea really, that is a proven way of getting your presision back for about half the original round count

saving up for a new tube now would be a good idea IMHO

Could you recommend a barrel I could research just in case?

[bladeracer]

Before trying to create obstacles I would do some load development first and see if you even need to load to the lands. Lots of modern bullet designs don't care about bullet jump. Try to stay with tangent and hybrid bullets, secant ogives are the ones that tend to be jump fussy.

[Meglaman]

Before trying to create obstacles I would do some load development first and see if you even need to load to the lands. Lots of modern bullet designs don't care about bullet jump. Try to stay with tangent and hybrid bullets, secant ogives are the ones that tend to be jump fussy.

Thanks, I have Nosler 140gr AccuBond, Federal LRM Primers, ADI Powder AR2213SC, with once fried brass, will start charging my test loads this weekend.

[bladeracer]

The accubond bullet is a tangent design so it shouldn't be too fussy.

[Blr243]

This trying to fit long bullets into the mag thing is so annoying when we are trying to minimise our jumps .. bought my first comparator today , bought some new lead, cases are in the mail ...and then it all starts

[SCJ429]

Tikka barrels are screwed into the action really tightly, you often have to cut a groove into the Knox form to relieve the pressure and unscrew it. The barrels are also very hard, I broke a reamer trying to rechamber one. Never again.

If you cannot chase the lands because you are limited by the magazine then you can do some load testing at your preferred COAL and as Blade said use a ogive design that isn't fussy. I would try a Sierra or Berger.

My go to barrel maker is Maddco but I have have good experiences with Hardy, Benchmark and Shillen.

[marksman]

Before trying to create obstacles I would do some load development first and see if you even need to load to the lands. Lots of modern bullet designs don't care about bullet jump. Try to stay with tangent and hybrid bullets, secant ogives are the ones that tend to be jump fussy.

Thanks, I have Nosler 140gr AccuBond, Federal LRM Primers, ADI Powder AR2213SC, with once fried brass, will start charging my test loads this weekend.

this is IMHO a very good recipe
l like ADI ar2213sc for that weight bullet and heavier bullets, the accubonds are a good choice

RE22 is another good powder for that bullet weight if you can find it
if l were you l would be loading for concentricity at mag OAL and find the sweet spot

l have had good luck with shilen barrels myself but there are plenty of others worth while and maybe even better
l would advise to buy a stainless match grade barrel that has been hand lapped and a match grade reamer with tight tolerances

here is a photo of what my rounds looks like loaded with the 150gr SST bullets and group at 100 and 250, traveling at 3220fps
my barrel has a 400 round count and the throat has moved 1mm

[SCJ429]

I know that Marksman has had some good results with the secant ogive Hornady SST but I have struggled to get decent groups using them. The fussy seating depth and all over the place ogive length has made them a chore for me. I am a fan of the WSM case design and have seen some outstanding results when it is used in competition.

https://bergerbullets.com/faq-items/wha ... rid-ogive/

[bladeracer]

This trying to fit long bullets into the mag thing is so annoying when we are trying to minimise our jumps .. bought my first comparator today , bought some new lead, cases are in the mail ...and then it all starts

I don't worry about precise bullet jump, but being able to load long bullets well over spec gives you maximum boiler room for combustion, having to seat an 80gn bullet to 2.260" in a .223 really impinges on case volume. My Ruger let's me load to 2.460" and still feed through the AICS mag.

[Meglaman]

Thank all for the advice, I greatly appreciate it.

[in2anity]

I'm not a machinist, but I think some machinists can cut the throats seperately, i.e they start with a short throated reamer, then finish with a throat reamer to the customer's spec. I think you need to find a machinist with one of those short throat reamers (or order one yourself) - that way you could just stick it in, moving the chamber forward slightly (thus shortening the existing throat at the same time). After that, it's just a matter of shortening the barrel from the receiver end to headspace. I imagine you'd only lose a fraction of barrel that way, and it could be a fairly straight forward job. Like I said though, I'm no machinist, so correct me if I'm wrong oh mighty peoples!

[marksman]

I'm not a machinist, but I think some machinists can cut the throats seperately, i.e they start with a short throated reamer, then finish with a throat reamer to the customer's spec. I think you need to find a machinist with one of those short throat reamers (or order one yourself) - that way you could just stick it in, moving the chamber forward slightly (thus shortening the existing throat at the same time). After that, it's just a matter of shortening the barrel from the receiver end to headspace. I imagine you'd only lose a fraction of barrel that way, and it could be a fairly straight forward job. Like I said though, I'm no machinist, so correct me if I'm wrong oh mighty peoples!

they definitely can cut the throats separately, even by hand with a "T" handle

IMHO if you are going to re-chamber for best results it should be done before the barrel is to far gone and an inch of chamber should at least be taken off to get at some fresh metal, my 270wsm barrel is 28" long and l will be getting it re-chambered when the time comes probably around the 800 rounds
being a magnum they are hard on the barrel but that is what they are, l have slowed my velocity down to 3220 fps at the lower node after seeing the fine fire cracking at the throat, it is a great round IMO, very flat shooting

[Larry]

This info about cutting an inch of the chamber end of a barrel is only applicable in a very small number of barrels. it depends on the profile of the barrel. Most factory barrels simple taper off to quickly to allow an inch to be taken off. If it were there would not be enough steel around the chamber to take the pressure.
It can only really be done in custom heavy barrels like a heavy varmint that has a full straight barrel for 5 inches before starting to taper. Even the barrels that have a 3 inch straight profile before tapering cut an inch of and the explosive part of the cartridge no longer has a lot of steel left around it. Factory barrels dont even have the same diameter to start with making the process even less viable.

[marksman]

"This info about cutting an inch of the chamber end of a barrel is only applicable in a very small number of barrels. it depends on the profile of the barrel. Most factory barrels simple taper off to quickly to allow an inch to be taken off. If it were there would not be enough steel around the chamber to take the pressure."

good point,
funnily l was having a chat with my smith today about rechambering my 270wsm when the time comes and asked about a factory tikka, his reply was that normally he would set the barrel shoulder back one thread (1/16th) and recut the chamber, it cleans everything up and saves as much barrel as possible, it also cleans up the lead angle and the throat, the barrel tenon will have to be shortened by the same amount, this would be ok as long as the throat was not to bad and was done early enough

"It can only really be done in custom heavy barrels like a heavy varmint that has a full straight barrel for 5 inches before starting to taper. Even the barrels that have a 3 inch straight profile before tapering cut an inch of and the explosive part of the cartridge no longer has a lot of steel left around it. Factory barrels dont even have the same diameter to start with making the process even less viable"

this is not quite right, my dasher barrel was a second hand 22Br light palma barrel that had the threads knocked off, set back and rechambered to 22 dasher, the barrel tenon started at 2.5" and my 270wsm has a #6 lightweight target barrel with a 3" tenon that will have no problems having an inch taken off then set back and rechambered, if you can cut an inch off it is the best way to do it

[SCJ429]

I have set a couple of barrels back after 1200 rounds, after that you may not get a good result depending on what sort of accuracy you are chasing. I normally get the threads cut off and then thread and rechamber but this is with match barrels which have very little taper.

Did your smith say he was happy to rechamber a factory Tikka barrel Marksman? If you do I would let him use his reamer just in case.

[TassieTiger]

Omg - reading all of the above just proves how damn much I still have to learn...I feel I should be wearing that tshirt “I’m with stupid” but with arrow pointing inwards...

Not to derail obviously - wife bought this home recently.

[marksman]

I have set a couple of barrels back after 1200 rounds, after that you may not get a good result depending on what sort of accuracy you are chasing. I normally get the threads cut off and then thread and rechamber but this is with match barrels which have very little taper.

Did your smith say he was happy to rechamber a factory Tikka barrel Marksman? If you do I would let him use his reamer just in case.

he did talk about the work hardening inside the chamber that needed to be tested before putting the reamer in,
but he was really talking about factory barrels in general not only a tikka, he said he would normally try and talk the owner into a new tube

l have heard that the cold hammer forging makes the tikka barrels barrels very hard and l would be thinking twice about running my reaming in

[duncan61]

It is good you have taken the actual measurement of the chamber.Consider this.For hunting standard factory specs are fine so you can reload PSP or ballistic tip rounds and go shoot whatever you wish/need to.If you are going to the range load target bullets so they are seated .8-1 mm of the lands and load them one at a time when doing your detail.A lot of the full bore guys can not load their rounds in a SMLE magazine and do just that.Happy hunting.by the way all my .222 and .243 loads are the same but for my 7mm Rem Mag I have 100 gn Sierra game kings on 2208 for when I feel nasty and go head shooting roos and for target I use 168 Match kings on 2213sc I also have a few boxes of corelokt and winchester failsafe that the rifle came with for big game.

[in2anity]

If you are going to the range load target bullets so they are seated .8-1 mm of the lands and load them one at a time when doing your detail.A lot of the full bore guys can not load their rounds in a SMLE magazine and do just that.

Not too many fullbore shooters using the old LEs these days, especially not SMLEs, if that bygone era is what you’re talking about... But if you are referring to service, I suppose that’s possible for the application or deliberate stages perhaps - but for the commonly shot snaps, especially doubles and triples, I have never seen any LE-user choosing to single load. That 10 shot mag is what makes the LE so damned popular (vs say a 5-shot Mauser). Your are right about the mag length in the LE being the limiting factor though - and groups do come in when you seat them out there as long as is possible (vs the inherently shorter factory stuff). I seat the SMK as far out as the SMLE magazine will handle, with adequate results, better than I can shoot across irons anyway.

[duncan61]

I am just going by what I saw shooters doing.They all had service rifles with a sling and prone and open sights.There was only 3 of us optical shooters so we just go in the same 10 shot details as everyone else.I believe its called field rifle now instead of optical.I am going Saturday will post some pictures soon

[Meglaman]

Hello all

Thank you for all your advice. It looks like I still have life in my barrel, the following is my first batch of reloads results.
Date shoot 19/07/2020
Federal Brass once fired, full resize, Nosler 140gr Accubond, ADI: AR2213SC
Load#
1/ 59.5g - 1.388"
2/ 60.0g - 0.633"
3/ 60.5g - 0.907"
4/ 61.0g - 0.863"
5/ 61.5g - 0.794"
6/ 62.0g - 1.178"
7/ 62.5g - 1.774"
8/ 63.0g - 2.163"
9 / 63.3g - 1.341"

Bullet depth is to mag size, which from the test round I made to measure the lands is still 5 mm away.

I will now play around in the 60-grain range and because there are no pressure signs at 63.3 I might try 64 and 64.5.

[SCJ429]

A plus two inch group at 100m, that ain't good. Let's hope you have more luck with a bit more speed.

[TassieTiger]

Couldn’t you hand load some longer rounds and individually load - to check the difference?
I have seen some ppl slot a metal replacement magazine to gain a mm or two believing it made all the difference...

[bladeracer]

Hello all

Thank you for all your advice. It looks like I still have life in my barrel, the following is my first batch of reloads results.
Date shoot 19/07/2020
Federal Brass once fired, full resize, Nosler 140gr Accubond, ADI: AR2213SC
Load#
1/ 59.5g - 1.388"
2/ 60.0g - 0.633"
3/ 60.5g - 0.907"
4/ 61.0g - 0.863"
5/ 61.5g - 0.794"
6/ 62.0g - 1.178"
7/ 62.5g - 1.774"
8/ 63.0g - 2.163"
9 / 63.3g - 1.341"

Bullet depth is to mag size, which from the test round I made to measure the lands is still 5 mm away.

I will now play around in the 60-grain range and because there are no pressure signs at 63.3 I might try 64 and 64.5.

5rd groups I hope?
I wouldn't be taking load development direction from anything less than 5rd groups, preferably more than one of each as well.