Projectiles jamming in freebore before the lands??

[mkm]

Hey Guy's,
When seating the 250g and 300g Lapua Scenars in my .338 I find they have a tight fit in the freebore before they hit the rifling.

Using an OAL guage and a modified case it is very noticable there is a tight fit before the ojive hits the lands and the projectile will have a noticable mark on it from where it is fitting into the freebore area of the throat.

I have some 200g accubonds, due to the shape, they do not have this issue.

The rifle is a Savage 110 BA .338 LM.
Has anyone else found this with their 110 BA's?

The neck in it seems to be pretty tight, a fired case has a pretty close fit around a fresh projectile, but I am specifically wondering if someone can give me any feedback or experiences on this tight freebore area and how it may affect things.

Concerningly, if I use a whiteboard marker and mark the projectile before I place it in the OAL guage and take the measurement, I find the marks left by the freebore area of the chamber are not even and consistent.

There is an area, in one particular segment, on the contact point that marks the projectile more than the rest of the contact area. My worry is that it is skewing, or applying uneven pressure to, the projectile when chambering. But then again, considering the whole freebore area does make contact, would the projectile be held straight enough anyway?

Is this something to be worried about?
If so, any solutions?
Do I get a rechamber done, or is there another way?

If any of you guy's have any thoughts, I'd really love to hear 'em.

FYI: I'm gonna post this over on another forum and will update this if I get any relevant info.

mkm

 

[9H_Cracka]

Re: Projectiles jamming in freebore before the lands??

I know of a gunsmith that had several "high end" Savages in his hands where the freebore had rifling on one side due to Salvage cutting the chambers off center. When talking tenths of thousandths over bullet diameter, it does not take much of an eff-up or worn reamer to have the problems you are seeing.

Concentricity of the loaded round can also cause scuffing on one side of the projectile from a relatively tight freebore; I get a little bit of it in my 308s, but the freebore is .3083", and it causes me no problems.

A look at the chamber with a borescope as well as a chamber cast are what are needed to further diagnose your issue and potential problem.

 

[mkm]

Re: Projectiles jamming in freebore before the lands??

Hi _9H
Thx for the reply, makes perfect sense.

How do I take a cast of the chamber?

Reckon it's a warranty job, remember I'm in Australia though

?

mkm

 

[Gruff]

Re: Projectiles jamming in freebore before the lands??

Depending on how many rounds have been fired through it, could be a carbon build-up in the throat/freebore?

 

[9H_Cracka]

Re: Projectiles jamming in freebore before the lands??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mkm</div><div class="ubbcode-body">
How do I take a cast of the chamber?

mkm </div></div>

http://www.surplusrifle.com/shooting2005/chambercast/index.asp

 

[mkm]

Re: Projectiles jamming in freebore before the lands??

Thx Gruff,
But she's had 205 rounds through her and is clean as a whistle

_9H,
Damn, more work.

Thx heaps but, never know, I may even do it, or I may just buy a reamer, get the local smith to re chamber it and make me some f/l dies while he's at it!

Or I could send it back if I can't get her shootin in the next hundres or so rounds. This is downtime I really don't, I bought it to be able to shoot it, not send it away for months for what I (maybe) should have got the first time.

I've tried RL22, RL25, ADI 2225 and ADI 2217. The only one that has given me the velocities I want, without the pressure, is the ADI 2217(ADI 2217 is the H1000 equiv, ADI 2225 is Retumbo & RL25 equiv)

Don't get me wrong, it shoots well down around the 2500 mark for the 300g and 2650 for the 250g but surely it can be made to work around the 2750+ for the 300g and the 2900+ mark for the 250g?

mkm

 

[9H_Cracka]

Re: Projectiles jamming in freebore before the lands??

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mkm</div><div class="ubbcode-body">
Thx heaps but, never know, I may even do it, or I may just buy a reamer, get the local smith to re chamber it and make me some f/l dies while he's at it!

</div></div>

Unless you cut the camber area completely off, assuming the issue is a chamber cut off axis to the bore, running a reamer in the existing chamber is likely not to fix the problem to your satisfaction, unless the straight section of the new reamer is oversized.

Face it - you are dealing with a mass produced item. Get a smith that knows what he is doing make the chamber cast and take/record the dimensions as well as whether or not the straight section is smooth or is rifled on one side.

Assuming either or both problems exist with the barrel, you now have them documented and can work with Savage on a fix. I'd be lobbying for them to send you a replacement barrel as well as cover your costs for dealing with the gunsmith to diagnose the problem and spin on/headspace the replacement barrel.

EDIT TO ADD: your smith/machinist may also be able to run a small Tee gauge in to the chamber and check the freebore diameter this way as well.

 

[mkm]

Re: Projectiles jamming in freebore before the lands??

Hey guy's,
I have spoken with Savage, the AU Importer and a local gunsmith.

Savage say they will replace it, as sending out barrels and parts is not their usual practice, if there is a fault found regarding the chambering etc.

The Australia distributer say they can get their gunsmith to check it, advise Savage of the outcome and replace if they get the go ahead.

My local gunsmith reckons it may just be a lip left where the reamer cut the first edge of the freebore.
He said he'd see if he could see anything with a scope then maybe get some fine emry cloth around a dowell and give it a light rub just on the edge, then he could take a cast.
He is weary about taking a cast if there is a rough edge as he may not be able to get the cast out.

What do you guy's think?

AM I better off just sending it back and taking my chances on another stock std factory, or getting my gunsmith to try this providing it is only a rough edge/lip that can be rubbed out?


mkm