Testing the 30XCB

[Bjornb]

[Bjornb]

Going out to longer ranges is the next move I will be making. I'm making plans with a buddy to travel up to the next county later this month, to a 200 and 300 yard range.
I feel that both the rifle and the cartridge have proven themselves on the 100 yard line.

[geargnasher]

I removed everything here,,,
Gear the message got through.
hopefully all parties involved with this thread and the other one got the message.

I have no idea how much data was lost in the time-out process but I bet it was enough that more than a few members feel slighted
R5R.

[No_1]

This is a good thread. Y'all need to work together without conflict. Any violation of the forum rules will be addressed.

[btroj]

Bjorn, have you ever checked fired cases, sized cases, or loaded rounds for runout?

I have not been doing so but will begin this week. I wonder if the reformed cases are going to have more runout that the factory 7x57 cases. That alone could explain some of the differences you are seeing.

Runout on the bullet is a bit tougher as my indicator picks up even the smallest imperfections like the part line on the bullet.

[Bjornb]

No, I don't have a runout gauge. Not really a big deal to get one. It's a standard step in bench rest and other competitive case and bullet prep, so knowing runout values can only help.

[cbrick]

No, I don't have a runout gauge. Not really a big deal to get one. It's a standard step in bench rest and other competitive case and bullet prep, so knowing runout values can only help.

Highly recommended. Spinning your loaded rounds under the dial indicator can be a real eye opener. If the bullet is canted in the case neck you can't really expect it to straighten itself out and enter the rifling straight. How it's launched is how it enters the bore, how it enters the bore has much to do with how it exits the muzzle.

Rick

EDIT to add: Previous posts on the Fed #210 I agree with, Powder Valley lists 210's in stock if you wish to try them.

[geargnasher]

No, I don't have a runout gauge. Not really a big deal to get one. It's a standard step in bench rest and other competitive case and bullet prep, so knowing runout values can only help.

Here's a 45 2.1 trick: Put a piece of glass on your bench, kneel down so you can look across it edgewise, and roll your loaded rounds across it. You'll see the bullet and the case rim going up-down-up-down if they aren't concentric with the case body. Learn to look closely and you can see very miniscule runout.

Do you want all of us to post shooting results here, or just share info focusing on your particular effort? We do have the other thread for general contributions/ramblings to the project.

Gear

[Bjornb]

Here's a 45 2.1 trick: Put a piece of glass on your bench, kneel down so you can look across it edgewise, and roll your loaded rounds across it. You'll see the bullet and the case rim going up-down-up-down if they aren't concentric with the case body. Learn to look closely and you can see very miniscule runout.

Do you want all of us to post shooting results here, or just share info focusing on your particular effort? We do have the other thread for general contributions/ramblings to the project.

Gear

Gear,
I'll be very happy to see yours and others' shooting results in this thread. That's why I started it.
And for everybody's edification, I wasn't around my computer when things evidently deteriorated, and I had no hand in shutting the tread down. That being said, I'm glad Run and others stepped in and got us back on track. I have tried to stay focused here, and I read and listen to each and every one of you and appreciate your input.

Good point on the "poor man's runout gauge".

Got a new batch of bullets cast up Saturday, and after a little aging they'll be ready to go. More to come.

[geargnasher]

Sounds good. In response to Larry's last post above, I'll keep it strictly about the XCB here and not muddy things with results from other rifles. We already have a thread going on my AM 31-190X design for the XCB but if anything important crops up relating to that bullet during my shooting exercises I'll share that here, too. So far I haven't had much luck with the matched throat taper such as this one and the NOE bullet at anything past "normal" velocities (really, about 1800 fps regardless of twist), but I still feel there's something to be learned from continuing to try. You're doing better with the NOE than I have with the 190X.

Larry, would you mind sharing the pressure estimates generated from QL? I haven't taken a minute to dig up my chronograph numbers and load data, but if memory serves I was shooting either 44.5 or 45 grains of H-414 under the 182-ish .30 Sil, which you have and I believe you already have measured approximate bearing length. My rifle has six traditional grooves, is .300x.3075" bore/groove, 23.5" barrel length, and I was sizing .3103". The average velocity of the load right before the groups went from 5/8" to bumping over an inch was dancing all around 2400 fps. I didn't calculate SD.

Gear

[Bjornb]

I also have QL. If nobody else has stepped forward by the time I get off work tonight (should be around 11 pm eastern, weather permitting) I'll pick up the laptop from my shop and try running some numbers. I've been using the 30-40 Krag as a comparison to the XCB in QL, it's been pretty close in velocities. Since I don't have any way to measure pressure you'll have to do your own interpretation of the pressure numbers.

[Bullshop Junior]

What is a runoff gauge if I may ask?

[Bjornb]

What is a runoff gauge if I may ask?

http://www.sinclairintl.com/reloadin...prod37479.aspx

It's runout gauge

[dragon813gt]

What is a runoff gauge if I may ask?

Search for "bullet comparator". There are a bunch of different tools on the market for measuring runout.

[runfiverun]

Larry indicated to me that H-414 wasn't reaching peak pressure until the boolit was down the barrel.
about 9" airc.
this is a case where the run and bump might be helpful to keep things centered.

[Bjornb]

Not sure if I follow you there R5R.

[runfiverun]

I don't remember where I posted about manipulating the powder burn slightly by using the boolits engraving pressure to bump the time curve a little higher sooner, [but until after the boolit had entered the barrel] by backing off the oal some.
this is a good one to use to help get the powder burning more efficiently sooner giving it time to drop off muzzle pressure some.

[detox]

Runout of .002 or less is very difficult to achieve with cast bullets (much easier with Jacketed bullets). I use my NECO gauge to measure runout of my cast loads and runout can vary from .001 to .015. My only solution to get all cases under .002 was to bend the case neck. Soft Remington brass works best or annealing your harder cases makes straitening easier. I know lots of prople are against bending the neck, but it is the only way I have learned to get consistant runout of less than .002.

[geargnasher]

Larry indicated to me that H-414 wasn't reaching peak pressure until the boolit was down the barrel.
about 9" airc.
this is a case where the run and bump might be helpful to keep things centered.

That's where buffer can help in certain situations (not this one with a 17-1/2 degree shoulder) by giving the powder something to work against (controlled restriction) inside the case. By the time the buffer extrudes through the neck it has pushed the bullet fully into the throat and pressure is higher at that point than it otherwise would be, in effect moving the pressure curve's peak toward the ignition side of the graph. Buffer obviously also increases effective load density in any case shape and raises initial pressure that way, too. Double advantage is keeping the fire off of the bullet during engraving and putting a little "Charmin" behind it and making a cleaner, higher-pressure initial burn.

9" to peak burn with H414 sounds very good to me. Low initial pressure works very well with the "run and bump" rather than "jam and smack". It's neat to work a load out with just targets/chronograph and then run numbers to see how things are doing inside the gun when groups are small, or, really any time. Last time I was out shooting the XCB with company using the H414/.30 Sil load the comment "DANG that thing is LOUD" was made several times, this from a guy shooting full-house loads with 168 SMKs in a 22", ported .308. It kicks, too. I'm sure the muzzle pressure is very high. I'm not using buffer,,,,yet.

Gear

[geargnasher]

Runout of .002 or less is very difficult to achieve with cast bullets (much easier with Jacketed bullets). I use my NECO gauge to measure runout of my cast loads and runout can vary from .001 to .015. My only solution to get all cases under .002 was to bend the case neck. Soft Remington brass works best or annealing your harder cases makes straitening easier. I know lots of prople are against bending the neck, but it is the only way I have learned to get consistant runout of less than .002.

With a straight chamber, modified FL sizer die (not bushing) with expander ball removed, RCBS cast bullet expander, and Forster seating die, I rarely get runout over .003". Rarely under .002", either.

How do you straighten your necks? I assume you sharpie a reference mark on the case, but what are you using to pull on the neck?

Gear