Chamber Length?

[Rooster931]

I started a new thread after WV Sendero peaked my interest. I could have slid this into his thread but I did not want to JUMP it. I have a factory barreled/chambered Sendero SFII in 7mm Remington Mag. The gun shoots great and have found several "very good" reloads for this rifle. I have noticed however that after a range session of 15 -20 rounds (over several hours) I get a somewhat sticky bolt. Also the brass is heavily carboned on the neck.
I ran with WV Sendero's question and ordered a chamber length gauge from Sinclair and found that my rifles chamber case OAL is 2.560. Suspecting that a carbon ring could be to blame for the sticky bolt.

Now for the question? has anyone else measured their Chamber Length for a 7mm Mag. Seems very strange that most factory ammo IME is near 2.500 or 2.490 (case length) which is published trim to length. 2.560 seems pretty long.

 

[WeiserBucks]

Heavy soot on the neck, shoulder or both are usually an indication of a very low pressure load that isn't allowing the brass to seal the chamber upon firing.

 

[std7mag]

How do you mean, "chamber length"?
Bolt face to end of neck?
Or bolt face to where the lands start?

 

[FEENIX]

How do you mean, "chamber length"?
Bolt face to end of neck?
Or bolt face to where the lands start?

I know what you mean; sometimes, it is now as clear, but here's Sinclair's video on their chamber length gauge.

 

[Ol' Red]

Interesting. Now there is something else that I feel compelled to buy.

 

[FEENIX]

Interesting. Now there is something else that I feel compelled to buy.

I purchased one in .30 cal to try a few years ago that I stopped using. "I" prefer referencing off the lands, and I have a tracking log to monitor it.

If you have not seen it, here's a free (almost) technique instead of a modified case.



You can fast-forward it to the ~6 min mark if you do not want to see his intro/baseline comparison.

 

[Ol' Red]

I was thinking I could use this gauge to tell me if I am trimming cases too much. I dislike trimming cases. When loading I use the lands for bullet seating depth.

 

[Capt RB]

How to Make a Chamber Cast Using Cerrosafe - Gunsmithing Journal

Cerrosafe is the easiest product to use when making a chamber cast. Simply wipe the bore, plug the barrel, and pour it into the chamber.

kurtthegunsmith.com

This will tell you what you want to know and it's reusable

 

[kfreeze]

I was thinking I could use this gauge to tell me if I am trimming cases too much. I dislike trimming cases. When loading I use the lands for bullet seating depth.

That is exactly what those are made for. Keep your brass .010" shorter than that measurement for a hunting rifle at min.

 

[orange1948]

I know what you mean; sometimes, it is now as clear, but here's Sinclair's video on their chamber length gauge.

This is what I use. It's simple and works!
Duane

 

[BrentM]

I started a new thread after WV Sendero peaked my interest. I could have slid this into his thread but I did not want to JUMP it. I have a factory barreled/chambered Sendero SFII in 7mm Remington Mag. The gun shoots great and have found several "very good" reloads for this rifle. I have noticed however that after a range session of 15 -20 rounds (over several hours) I get a somewhat sticky bolt. Also the brass is heavily carboned on the neck.
I ran with WV Sendero's question and ordered a chamber length gauge from Sinclair and found that my rifles chamber case OAL is 2.560. Suspecting that a carbon ring could be to blame for the sticky bolt.

Now for the question? has anyone else measured their Chamber Length for a 7mm Mag. Seems very strange that most factory ammo IME is near 2.500 or 2.490 (case length) which is published trim to length. 2.560 seems pretty long.

I see chamber length vs case trim length to be on 2 different planets. I have sinclair gauges and as a general rule you skip case trim length on most anything. Clearly that is not a good practice but I'm just illustrating a point.

 

[KsKevin]

I have those Sinclair chamber length gauges for all my calibers. They are inexpensive and I use it with ever new barrel / chambering once to log each particular rifles chamber length and set my brass trim length based on this. I've not done it (because I have a bore scope) but I would think you could use it to help detect a carbon ring as well (chamber length measurement would start to show decreases in length).

 

[FEENIX]

I see chamber length vs case trim length to be on 2 different planets. I have sinclair gauges and as a general rule you skip case trim length on most anything. Clearly that is not a good practice but I'm just illustrating a point.

This!

 

[Ol' Red]

So am I wrong in thinking that this gauge for chamber length would help me determine how far to trim cases to avoid a carbon ring?