Lapua Center-x Vs Eley Tenex visual compare

[GuideDog]

Most likely this has been done before. I wondered how Center-X vs Tenex would look pressed into the same guns bore, extracted without firing to view the lead impression from rifling lands. I attached a photo.
I noticed the Center-X took quite a bit more force to seat the rim to the chamber edge. Perhaps double. I didn't have a calibrated gauge to measure force. CZ 457 MTR was used.

Tenex is on the bottom. What interesting is Center-X has the rifle land mark deep into the sealing groove area while Tenex the striations are still very visible.
Brass looks very different too.

I also took bore scope shots but couldn't see the contact area of course.

Different lead and coatings but what else? Anyone else try this?

 

[epags]

Think you need the same photos before you insert them and then after. Since I don;t know what they looked like before, I have no basis on the difference.

 

[smelv]

G'day GuideDog,the base to ogive measurement (where the curve on the lead starts ) is longer on the centrex compared to the tenex. I batch all my ammo and tenex is .754 in long whereas the centrex is .768 in so they are going further into the lands and grooves of the barrel .Pic of eley match (same as tenex ). Scott in AU.

 

[obx22]

Interesting experiment.
Try removing the lubricants on a couple of slugs with some form of solvent, then repeat your test. Easy enough to make a guage with a compression spring and long bolt. Use a sharpie to mark the spring compression on the bolt at the moment the cartridge is fully seated (aiming such a loaded chamber at a safe direction of course). Comparing the two compression rates will give you a measurement.
It could be the lead, the lube, a combination of the two.

 

[grauhanen]

More visuals are shown below. These have been posted elsewhere in the past. Eley is either on left or top.

 

[GuideDog]

Interesting experiment.
Try removing the lubricants on a couple of slugs with some form of solvent, then repeat your test. Easy enough to make a guage with a compression spring and long bolt. Use a sharpie to mark the spring compression on the bolt at the moment the cartridge is fully seated (aiming such a loaded chamber at a safe direction of course). Comparing the two compression rates will give you a measurement.
It could be the lead, the lube, a combination of the two.

I pushed the rounds in with a wood dowel for safety and did not use the bolt. My test was to see if the contribution to what ammo shoots best can be due to rifle land contact. After research that's just a small factor. The lubricants are a factor, and yes the lead hardness too. It's a complex group of differences that even if we understand there's still too much variation in barrels to determine what ammo is best other than shoot it.

This started since I noticed closing the bolt took a bit more force with ammo brands, and it was not a headspace issue.

 

[obx22]

I pushed the rounds in with a wood dowel for safety and did not use the bolt. My test was to see if the contribution to what ammo shoots best can be due to rifle land contact. After research that's just a small factor. The lubricants are a factor, and yes the lead hardness too. It's a complex group of differences that even if we understand there's still too much variation in barrels to determine what ammo is best other than shoot it.

This started since I noticed closing the bolt took a bit more force with ammo brands, and it was not a headspace issue.

I’ve noticed the hard closing on tightly chambered single shots (match rifles) that gradually increased through a match (carbon ring?)
As for chambering/engraving differences I’d imagine if the rim thickness match your chamber’s headspace, you would have things almost perfect.
Then it’s time to test the powder column

 

[Fasteddie01]

I have a VMTR with about 2500 rounds fired. I recently 'tested' the engraving for another thread concerning SK ammo and got pics. I just used SK Magazine, which is purportedly the 'same cartridge' as SK Standard and SK-RM - Just different Lot speeds. I also had some Norma Sub-sonic on hand and ran one of them too. The bullets I chambered using the bolt, 'carefully', and BOTH were hard to close fully. From my reading this is mostly due to the diff between SK/LAPUA and ELEY 'rim thickness'. Thus, the engraving might be a bit less with SK since the rim would 'hold the bullet a bit further away' than the Eley. I didn't think to run some Eley thru also. The 'Engravure' looks about the same length IMO.

SK MAGAZINE

NORMA SUB-SONIC

 

[Fasteddie01]

As a further 'issue' I just now found this link to a discussion about 'engraving' (tho from 2011, it may still be relevant) and though I'd post it for 'food for thought'. I haven't read all 5 pages of it so I have no further comment . . . yet.
http s://www.rimfireaccuracy.com/Forum/index.php?threads/testing-chambers-for-lapua-use.23372/