6mm Creedmoor (Possible) Troat Erosion or Freebore Issue

[riverrat13]

I recently picked a 6mm Creedmoor on a trade, and measured the COAL OGIVE today. I am using 105 Berger Hybrids, and if I seat to the lands then my COAL measures 2.900. I would of expected that number to be closer to 2.800.

I was told the rifle was only fired 350 rounds, and I believe the guy I traded with. That is way to much throat erosion for 350 rounds right?

Am I safe to load the that hybrids long? If the throat erodes much more then I will be maxing out my magazine length.

I’m considering getting it set back and rechambered (26” barrel now), or just rebarreling it.

Thoughts or guidance??

 

[steve123]

Well the good news is, hybrids are not depth sensitive at all in comparison to some other bullets. I had a huge jump going on with the 105 hybrids in my 6x47L because the reamer was cut for 115's out of the neck shoulder junction. That barrel and bullet combo shot fantastic!

A similar story for my 30-375R. Throated for 240 SMK but changed to 230 hybrid later on, very accurate with either bullet.

 

[riverrat13]

Well the good news is, hybrids are not depth sensitive at all in comparison to some other bullets. I had a huge jump going on with the 105 hybrids in my 6x47L because the reamer was cut for 115's out of the neck shoulder junction. That barrel and bullet combo shot fantastic!

A similar story for my 30-375R. Throated for 240 SMK but changed to 230 hybrid later on, very accurate with either bullet.

So you would just load them long, say a .04-.05 jump at a COAL of 2.85-2.86? See how they shoot and go from there.

 

[spife7980]

So you would just load them long, say a .04-.05 jump at a COAL of 2.85-2.86? See how they shoot and go from there.

I would start at your max mag length and run an ocw. Then do a depth test getting deeper after that.

You can’t guess at erosion numbers just by that measurement. Could have just been cut long to start with. Get a bore scope to check its condition.

 

[Blowby]

I saw .033” erosion at about 800 rounds using H4350 and DTAC 115’s if that helps.

 

[CJS-6.5]

What rifle? Barrel? Reamer? What did you use to check clto?

 

[riverrat13]

PVA Rock Hill Barrel on a Curtis Curtis Custom Action. I don't know the reamer, but I was told it was chambered for SMK 110. I used a Hornady OAL Gauge with Modified Case and Berger 105 Hydrids.

I just seated some at 2.88 OAL and I could pull the bullet loose with my hand. Peterson Brass that is unfired, but I ran it through a Redding Full Length Bushing Die with .270 bushing sizing for .002 - .003 shoulder bump.

 

[riverrat13]

SAMMI spec 6 Creed chambers have a. 183" freebore which is ridiculous. I have seen the same issue you are describing in other 6C rifles with a SAMMI freebore. I'm sure they do this so you can stuff just about anything in the rifle without jamming and having high pressure.

For a predictable erosion figure, plan on about .005" per hundred rounds. I've measured the erosion on six barrels. 6.5x47L, 6Dasher, 6SLR, etc. They have all run 4 to 6 thou per hundred. Understanding this is helpful to planning a reamer spec while working in the confines of a mag. My 6SLR has a .075" FB and allows for .100" of erosion before I run out of mag length. The neck is .025" longer than a 6Creed so the numbers aren't a direct comparison. I ran out of case neck with 130 Hybrids in a 6.5x47L with a FB set up for 140s. Hybrids have shorter bearing surfaces and long noses so they are more problematic in these situations. A 108 ELDM would be more forgiving. Something I've done in my Dashers is use 105's for the first 1000rds and then when I start to run out of neck, switch to 115 DTACs. You have that option or just find a longer jump that the bullet likes; in the neighborhood of 130 thou for instance.

Here is a 105 Hybrid seated to the lands in a chamber stub chambered with a .120" 6 Creed reamer. (Imagine it seated .063" farther out...)

Here is a list of measurements I took using that .120" chamber stub to seat bullets to the lands.

Maybe that is why I can pull the bullet out of the case when seated at 2.880.

 

[CJS-6.5]

Yep. That is ridiculous. My 6mm Creed at mag length is jammed. This is why the Creedmoor was developed...so this wouldn't happen...

 

[KZP]

Maybe that is why I can pull the bullet out of the case when seated at 2.880.

You need some TRT, Tactical Reloading Tape.

 

[steve123]

So you would just load them long, say a .04-.05 jump at a COAL of 2.85-2.86? See how they shoot and go from there.

Just take Spifes advise and keep going back into the case till you find a depth the barrel likes. If you have a bushing die I'd advise going down in diameter a thou or two.

Or get 115 DTACS or 110 SMK.

 

[riverrat13]

Talked to PVA today, and they were extremely helpful.

Apparently the rifle was chambered for Factory Hornady ELD ammo. The 108 grain hornady bullets nose is much shorter and it has larger bearing surface than the 105 Berger Hybrids. That is the reason I am having to seat the Bergers so long. Another interesting note, the difference between the two bullets is so large that if I had the rifle chambered for the Bergers, I wouldn't be able to shoot the factory ammo as it would be shoved into my lands.

Just wanted to post that in case someone else encounters a similar issue.

 

[B4Maz]

Great Article here at PRB

TL;DR .065-.085" of jump is ideal for 105 Hybrids

 

[Cascade Hemi]

I had something similar happen. The smith chambered my barrel so short that the 105 Hybrid I supplied him with would seat below the case mouth when .020" off the lands. Factory ammo would obviously not fit either. Sent it back and he hogged it out to a SAAMI chamber. The solution, unfortunately, is 108 ELDM or 115 DTAC.

 

[B4Maz]

I had something similar happen. The smith chambered my barrel so short that the 105 Hybrid I supplied him with would seat below the case mouth when .020" off the lands. Factory ammo would obviously not fit either. Sent it back and he hogged it out to a SAAMI chamber. The solution, unfortunately, is 108 ELDM or 115 DTAC.

What is the jump with a 105 hybrid with a .183" freebore?

 

[Nimothy]

I had this same issue on my wife’s 6cm. If the reamer is sammi, the freebore is probably to big for 105h without a big ol jump, the 108eld is a better match. Good news is, they typically shoot very well. And are usually cheaper. I wanted it to shoot 105h so I could just share Bullets between my bra and her 6cm. No such luck.

 

[B4Maz]

I had this same issue on my wife’s 6cm. If the reamer is sammi, the freebore is probably to big for 105h without a big ol jump, the 108eld is a better match. Good news is, they typically shoot very well. And are usually cheaper. I wanted it to shoot 105h so I could just share Bullets between my bra and her 6cm. No such luck.

Read this article, the large jump might not be a bad thing.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

 

[Cascade Hemi]

What is the jump with a 105 hybrid with a .183" freebore?

The jump is whatever your barrel likes best. I switched to 115 DTAC rather than dealing with SAAMI chamber and 105 Hybrid combo. CBTO for 105 Hybrid was 2.245" to touch the lands.

 

[B4Maz]

The jump is whatever your barrel likes best. I switched to 115 DTAC rather than dealing with SAAMI chamber and 105 Hybrid combo. CBTO for 105 Hybrid was 2.245" to touch the lands.

Did you measure your jump?

Check out the article. if you have a large jump, it might not be bad.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

 

[Nimothy]

Read this article, the large jump might not be a bad thing.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

That’s very interesting, I’ll read it in full when I have a bit more time but at a glance maybe i should have stuck with the 105h. The charts were very interesting.

 

[Carlos Danger]

Read this article, the large jump might not be a bad thing.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

Thanks for posting this. I was just discussing jump with a good friend (gunsmith) and his experience mirrored the concept of greater jumps as described in the article. I'll be testing this theory in the next couple days.

 

[B4Maz]

Thanks for posting this. I was just discussing jump with a good friend (gunsmith) and his experience mirrored the concept of greater jumps as described in the article. I'll be testing this theory in the next couple days.

Yes, its very interesting. I think this is a good data set to use considering there are so many rifles and chambers involved. But this is exactly something I have been looking for. I didn't always want to chase the lands. I wanted a chamber cut that was very forgiving over the life of the barrel.

 

[Cascade Hemi]

Did you measure your jump?

Check out the article. if you have a large jump, it might not be bad.

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

View attachment 7285937

Did you read my post?

 

[B4Maz]

Did you read my post?

You didn't say what your jump was

 

[Cascade Hemi]

You didn't say what your jump was

I didn't shoot the 105 Hybrids, I went to 115 DTAC. It is in my post.

 

[B4Maz]

I didn't shoot the 105 Hybrids, I went to 115 DTAC. It is in my post.

You need to read this article. Its says that a longer than usual jump between .065-.085" is ideal for 105 Hybrids. Measure the jump in your SAAMI cut chamber with 105 hybrids. It should work with a large jump.

 

[Cascade Hemi]

I read the article. Today isn't the first day I started reloading nor did I just learn about seating tests. Congratulations on your enlightenment though.

 

[B4Maz]

I read the article. Today isn't the first day I started reloading nor did I just learn about seating tests. Congratulations on your enlightenment though.

Yes but did you comprehend what was in the article? It doesn't sound like you understand. And you still didn't understand my question. With your "expertise" you should have measured your jump with 105s and .183 freebore. But it doesn't sound like you know how to do that.

 

[Cascade Hemi]

Yes but did you comprehend what was in the article? It doesn't sound like you understand. And you still didn't understand my question. With your "expertise" you should have measured your jump with 105s and .183 freebore. But it doesn't sound like you know how to do that.

This seems hard for you despite attempting to do some kind of victory lap. I didn't load the 105 Hybrid with that chamber, there is no jump to measure. I am using a 115 DTAC and jumping them .035". I ran the seating test out to .100" and didn't find the accuracy the article would justify. I have shot plenty of the 105 RDF Prime Scott Satterlee fauns over and I do not get the same results he has posted about on social media. Frankly, RDF bullets are a bust which is sort of disappointing considering I can walk in the front door at Nosler and b

On another 6CM barrel I have with a shorter throat I am jumping 105 Hybrid .045". I shoot with a few different F Open shooters and none of them jump anywhere close to that article. Anecdotally, most are .035" to .055". Matter of fact, that article isn't claiming the best accuracy from long jumps anyway, only that longer distances to the lands are more forgiving as the throat erodes. You posted the article multiple times in the same thread and don't seem to really understand that not everyone is competing in PRS and that throat erosion isn't all that scary. However, if one is more concerned with accuracy than loading 1500 rounds all to the same length then not being able to load the bullet to whatever the barrel likes best without the bullet falling out of the front of the case is kind of important.

 

[B4Maz]

This seems hard for you despite attempting to do some kind of victory lap. I didn't load the 105 Hybrid with that chamber, there is no jump to measure. I am using a 115 DTAC and jumping them .035". I ran the seating test out to .100" and didn't find the accuracy the article would justify. I have shot plenty of the 105 RDF Prime Scott Satterlee fauns over and I do not get the same results he has posted about on social media. Frankly, RDF bullets are a bust which is sort of disappointing considering I can walk in the front door at Nosler and b

On another 6CM barrel I have with a shorter throat I am jumping 105 Hybrid .045". I shoot with a few different F Open shooters and none of them jump anywhere close to that article. Anecdotally, most are .035" to .055". Matter of fact, that article isn't claiming the best accuracy from long jumps anyway, only that longer distances to the lands are more forgiving as the throat erodes. You posted the article multiple times in the same thread and don't seem to really understand that not everyone is competing in PRS and that throat erosion isn't all that scary. However, if one is more concerned with accuracy than loading 1500 rounds all to the same length then not being able to load the bullet to whatever the barrel likes best without the bullet falling out of the front of the case is kind of important.

If you look at the graph, it even shows less vertical spread for the 105s with a jump of .065-.085 than with 0.000-0.020. If you like to waste your time chasing lands, be my guest. It sounds like you are new to rifle shooting and have trouble understanding some fundamentals.

 

[spife7980]

If you look at the graph, it even shows less vertical spread for the 105s with a jump of .065-.085 than with 0.000-0.020. If you like to waste your time chasing lands, be my guest. It sounds like you are new to rifle shooting and have trouble understanding some fundamentals.

No more so than yourself apparently.

 

[Cascade Hemi]

It's going to be entertaining to read all of the threads resulting from that article. First the Zoomers will spam every conceivable thread proclaiming we've been missing the boat and there's a new NEW way. Then there will be a flurry of people doing there own tests and posting the results. Finally, everyone will go back to whatever they were doing before claiming it either worked or it was bullshit. Kinda like the "Satterlee Method".

 

[47guy]

WTF? is this guy for real? read one fuckin article and its gospel?

and this thread was started in 2018.