Falure to fire saga

[milkman]

I hope this will help someone else who is having failure-to-fire problems.
I decided that I REALLY NEEDED a rifle in 7 T/CU. I don't believe there are any factory bolt rifles in that caliber so.....
I bought a Savage Axis rifle for a donor action. I got a Shilen 24” 1:12 twist barrel pre-chambered in 7mmT/CU and had a smith mount everything in a Boyd's walnut stock. I did not have, and could not find any go, no-go gauges so I took some 223 brass, which is the parent cartridge, ran a 35 cal expander into it, which left a straight wall, straightish wall, case. Then ran it into a 7 t/cu full length die seated against the shell holder and backed off slightly and the gunsmith used these cases to head space the barrel.

While waiting on the smith to finish the rifle I prepared more cases by running 223 cases into the 7 t/cu die to expand the neck and use the existing shoulder till it was fire formed to the chamber then cast up some Lee 130g soup can boolits that have shot well for me in other rifles. When the rifle was delivered I loaded some cases and seated the cast bullets long so they would be forced into the rifling to hold the case in place while fire forming. Everything looked good but I had a FTF in about 1 in 10 rounds. The primer was dimpled and on some of the removed primers the anvil had backed out of the cup.
I checked the primers and they were standing proud of the case. I was using a primer arm that was new and it just wasn't seating the primers fully. Problem solved!! NOT
FTF's about I in 8...I changed primer brands and had a couple of decades worth of manufacture dates in different brands. No help.
I disassembled the bolt and checked, cleaned, lubed everything. No help. I took the bolt from another Axis, swapped the bolt heads and tried again. No help. After a couple months of hair pulling and teeth grinding my son loaned me his fancy-schmancy case length gauge which measures to a shoulder datum. The 223 cases which I had only expanded the neck on were about .030” shorter than my chamber as measured on the longest cases. Even after fire forming with a cast bullet some were still .020” short. They had enough extra room in the chamber to invite friends for a sleepover.
I went through all 100+ cases that I had formed, pulled all that were over .005 shorter than the longest cases. On those I expanded the necks to 35 cal and then back through the full length sizing die set to about .002 below fired length. No more FTF's

Milkman

[Gtek]

“Its the not the Destination, It's the journey.” Sorry, I know, really didn't make me feel better when it was said to me either. Anyway congratulations on your victory, enjoy!

[Walks]

Boy Howdy !!!
That was a whole lot of head scratching and gnashing of teeth.
I bought a Contender bbl and a set of RCBS dies about 30 some years ago. The dies set had a tapered expander in it. Used R-P once-fired cases, lubed inside & out. Seated some Hornady 139gr Spirepoints quarter-turn by quarter-turn until the action would just close. Fireformed 200 cases that way. Adjusted the FL sizer to partial-size and never looked back. Cases have rarely had to be trimmed, they seem to grow to 1.750 and stop. Although I have annealed them a few times.
Sorry, but I think it was your initial case forming technique.

[Oldfeller]

When cranking up my 350 Legend "experiments" the great variations in case length from the factory brass plagued everybody. People were studying brass primer strikes and getting concerned over deep and light primer strikes as meaning low pressure and high pressure rounds. Failure to strike hard enough to light the rounds was also present and was quite aggravating.

The variations of the factory case lengths had made a complete joke out of the standard amount of firing pin protrusion.


Numbers more like .060" protruding from the AR bolt face were needed to get stable reliable ignition with the then prevalent Winchester factory trimmed brass variations.

Firing pins as driven by the stock hammer mass did not ever pierce the primer as was 100% predicted by the nay sayers.

A new method to quickly and correctly trim brass was needed to correct the overlength brass found in once fired factory brass.

AND YES, you are treading turf that has been well walked on before.

Did you Know that your break action rifle actually headspaces off the case extractor groove mating to the spring driven extractor a set up which is engaged as you push the brass into the chamber?



Go here and read the whole thing for more such gems from other people's experiments. It is even color coded to clue you not to go down disproven pathways ......

https://castboolits.gunloads.com/sho...d-Cast-Boolits

[jimb16]

I have to agree with Walks. Your forming technique was at fault. I've been forming brass for both pistol and carbine for years and never had any problems. I start by annealing the cases then expand with the tapered plug. After expanding, I anneal again to remove the strain from the expanded necks. Fire forming goes smoothly from there. I rarely loose any cases and never have any problems with ftf.

[405grain]

milkman; the cases that did fire in your rifle may have stretched because of the excessive headspace. Check them for incipient case head separation. Look to see if there's a bright ring in the brass about 3/8" above the case head. Also take a paper clip and unbend it into a long wire to feel around inside the case. If you feel or see a groove inside the case walls ahead of the case head discard these cases. 223 brass is cheap and plentiful, and having the case head blow off and wreck your gun if you reload brass like that just isn't worth it.

Long ago I used to have a contender in 7mm TCU to knock over metal chickens, pigs, turkeys, and once and a while a ram or two. It's a fine cartridge, but the contender never fit my hand right so it went down the road. I've always wanted a rifle in that caliber, but would prefer a falling block single shot instead of a bolt action. I've got the barrel blank and the reamer + gauges, so it's on my "to do" list. If you haven't already done so, I recommend that you go online and purchase a copy of either the Complete Reloading Manual for the Thompson/Center Contender (volume 1), or the RCBS cast bullet handbook. Both have lots of cast bullet loads for the 7mm TCU.

[MT Gianni]

A stevens 200 or a savage axis sold last year on GB. It was a rebarrel and rechamber. Nice idea.

[milkman]

Sorry it took so long to get back. Things have been crazy here.

No doubt that I caused of the problem. There is only .012" difference in the shoulder length of the 2 cartridges so I took a shortcut and only expanded the necks. However my barrel is head spaced about .020" longer than spec because I did not have access to a set of gauges so I tottered off down the path of confusion for awhile. The more I live the longer I learn. As a bonus it is really close to MOA with a case full of R15 and it now goes boom every time I jerk the trigger.

[Three44s]

Sorry it took so long to get back. Things have been crazy here.

No doubt that I caused of the problem. There is only .012" difference in the shoulder length of the 2 cartridges so I took a shortcut and only expanded the necks. However my barrel is head spaced about .020" longer than spec because I did not have access to a set of gauges so I tottered off down the path of confusion for awhile. The more I live the longer I learn. As a bonus it is really close to MOA with a case full of R15 and it now goes boom every time I jerk the trigger.

I do a lot of Savage bolt gun builds and in your original post you stated that you set your new barrel down to your sized brass, then backed it off a little. That last part made me cringe.

It’s very hard to “back off a little” and know just what that amount is.

What I do is either set right at my full length case sized brass head space if I do not have the gauges or at the most I use one layer of cellophane tape over the case head to add just a scosh of room.

After more builds I have just went cold turkey and skipped adding any head space.

You may not have the tools but in my case I own my own action and barrel nut wrenches so if I end up too tight I can remedy it on my own. Have not had to though yet.

Glad you got your Savage/7mm TCU going. Enjoy!

Three44s

[milkman]

three44s -I set my full length die to the shellholder and then backed the die off a little. this was my first attempt at a build without the correct gauges. My thinking was to allow a little space so I could either make the brass shorter or longer as needed. Bad decision. I probably should have just used a 223 case to headspace on and all would have been a lot easier. I suspect the smith did the same thing with the barrel, backed it off a little, so I ended up quite a bit longer than I desired.