Strange problem with Winchester .270 Win ammo.

BC604

BC604

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Hi,

I got myself a Marlin XT in .270 Win.

To try it out, I got two boxes of Winchester ammo,
one is the Powermax 150gr,
the other is the SuperX 150gr.

The Powermax Chambered and fired flawlessly.

Ten I wanted to try the Super X.
As I was cambering the first round, It was very hard to close the bolt.
I ejected it (without firing it) and tried another one, this time
it was even worse, I could not close the bolt at all.
I tried a few more rounds and most of them would not chamber.

That was enough for me to put the box aside and try to figure out what is wrong.
Unfortunately I have no idea what could cause this to happen.

Both boxes are factory new.

Des anyone encountered something similar to this?
Any advice what could cause this?
Do I have to get the rifle checked by a gunsmith?
 
1: Anything in the chamber?
2: Measure with calipers the once fired against the won't chamber. A piece of scotch tape on the base is the difference between a go and a no-go gauge.
 
BC604 said:
1; The chamber is clean.
2; Which part should I be measuring?

Thank you.
Click to expand...

Measure the length of the brass and diameters of the neck, shoulder, and body. The once fired brass is exactly the same size as your chamber except for length. You can also look up the SAAMI specs for the cartridge and compare to those as well as they are the international standard by which caliber dimensions are set.

:cheers:
 
Freyr_255 said:
Measure the length of the brass and diameters of the neck, shoulder, and body. The once fired brass is exactly the same size as your chamber except for length. You can also look up the SAAMI specs for the cartridge and compare to those as well as they are the international standard by which caliber dimensions are set.

:cheers:
Click to expand...

I measured the fired brass and these are the measurements (red):



Is there anything unusual?
 
It was a frequent thing with some Tikka .270 W from the 90's with Winchester Fail Safe ammo. My guess is the neck. Measure the neck of a fired case vs the one of those not chambering.
 
Your case neck 7.9mm, my once fired case 7.76, factory new Fed 7.75, factory new win 7.72
your case shoulder 11.26, my once fired case 11.16, factory new Fed 11.03, factory new win 11.07
The cases you are having issues with are nickle plated correct?
So from here you get the material to cast a chamber mold and then measure it to compare.

Just reread your post didn't catch that that was the fired brass measurement. Measure the won't chamber stuff.
 
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Seems a fairly common problem with Winchester ammo these days. I've experienced in three different rifles in three different chambering in past couple months.
 
BC604 said:
In blue are the measurements of the unfired brass, bolt wont close:





What did you do when you encountered this problem?
Click to expand...

Can you check the length of the brass from base to shoulder of both fired and won't chamber? The rest look like they should fit but it's possible the chamber is a bit short or alternatively you could have a short throat to your gun causing the bullet itself to rest directly on the lands(rifling). So check the bullet of a cartridge that was really hard chambering for any markings on the bullet itself and also pay attention to scratch marks on the case as well as this will tell you(hopefully) where its making contact with your chamber. Look before and after you chamber a round and look extremely carefully. Sometimes it's just the barest of a scuff that will give it away.

Another thought is to check and make sure both fired and unfired brass are perfectly round. Close the caliper on it and turn the piece to see how concentric the case is as something could be out of round as well. This is kind of a long shot but one more thing to look at as winchester brass sucks nowadays...at least if their loaded ammo is as bad as their bags of brass.
 
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