Fireforming help needed

[lancetkenyon]

You are so right so many people never tear their bolt apart and clean it.MAY JUST BE THE PROBLEM. Old oil, bolt grease even powder blow back. Best of luck.

Ask my cousin how that works.
Right before a late season elk hunt, I told him to clean out his bolt. He didn't. His 7RM on the last evening with a bull in sight went "clunk". I grabbed my rifle, and he dumped the bull with it.

Got home, and he cleaned the bolt body insdoe with degreaser. It was black running out.

 

[Coyote Shadow Tracker]

^^^^^^^^^
Try cleaning your bolt. It is pretty easy. If you do not know how to dissemble your bolt there are many U-Tubes to help you out.
Over many years I have had hunters tell me that they have misfires. Sometimes when it is very cold out. Their bolt fires when at the range. then when hunting in the cold temps they had misfires. They would test by placing their bolt in the freezer over night and then putting in the rifle and had misfires. I would always tell them that their bolt was either dirty and or had bad oil in the bolt. Never use Rem OIL. It turns to sludge after years and in the cold.
Had a really good friend that lived several hundred miles away. He had a beautiful Sako in .243. Was having misfires. I told hin to clean the bolt. Well he didn't want to take it apart by himself. I used to do all the work on his firearms. He took it to a local GS Shop to have it cleaned. It shot well at the range. He went out and the temp was down around ZERO. He had a beautiful 8 Point White tail walk into his shooting lane. He squeezed his trigger and "Click" and no fire. He racked another cartridge in and the ejected cartridge hit his climber and made a loud "DINK". The Buck took off. He was very unhappy! He was going to take the Sako to the Gun Show and just get rid of it.

I happened to visit him and I took the bolt apart. It had gunk in it. The previous GS never took apart to clean. Just cleaned the outside.
I cleaned the bolt and it never misfired again-even after putting in the freezer for two days.

I periodically take every bolt apart and clean. I then use G-96 to coat and Lub the bolt. I spray the bolt parts, let them sit, for a while, then wipe down and assemble. We use G-96 on everything. It coats and doesn't leave residue to collect impurities.

 

[Phil Rizzo]

You will need some resistance when closing the bolt to confirm the
false shoulder is pushing back hard enough on the case head/bolt face.
Dont gall the lugs though!

 

[MagnumManiac]

The primers were all seated to the same depth. So that doesn't explain why 50% ftf

Well it does actually, because as the primer cup is driven down, the amount of spring will change and so will the force on the priming pellet.

Cheers.

 

[MagnumManiac]

After reading some of your answers, I believe your headspace is wrong, too long, and suggest you stop shooting it with BULLETS and use a COW load and then measure everything again.
Anytime a chamber is cut that requires fireforming, it should have .005" NEGATIVE HEADSPACE…your does not sound like it has.
Even a very small false shoulder should allow for 0 headspace and ample impact on a primer. Something in your system is way off. Who chambered the barrel, what headspace gauge did they use?

Cheers.

 

[Mike Matteson]

Following

 

[300 Driver]

So I tried 17.5gr Greendot and COW with a false shoulder. No issues other than it likely needs a stiffer charge. Shoulder was slightly rounded. I measured the COW, one fired Hornady, and 3 fired Peterson cases. The fired cases did not originally have a false shoulder. Just a .010 jam according to my notes.

COW:
Base to shoulder: 2.152
Neck dia: .372
Shoulder dia: .520
Base dia: .532

Fired(3 different cases):
Base to shoulder: 2.157 to 2.164
Neck dia: .370 to .371
Shoulder dia: .520 to .521
Base dia: .535 - .536

Unfired Peterson 300PRC with .356 false shoulder:
Base to shoulder: 2.120
Neck dia: .367
Shoulder dia: .516
Base dia: .530

Nothing seems incredibly off base with these measurements. I think the false shoulder may be a better choice for me since the jam was not giving me the proper bolt/case head interface.

Hornady COW, Hornady 70gr 780, Peterson 70gr 780, Peterson loaded with false shoulder and .020 jam.

 

[MallardAddict]

I've typically always fireformed with the false shoulder and cheapest bullet I could find and whatever appropriate left over powders I had. I've never jammed my bullets but using the false shoulder until the bolt closes with just a tad of resistance has always done me well.

 

[Mike Matteson]

I would 2nd on bullets when possible and powder you don't like.

 

[Jim’s Hunt]

Most people are over thinking this. It is the case shoulder not seating in chamber right aka headspace. You need to make a false shoulder on case. I prefer a false shoulder and the COW method it is easier on the case. I'm forming a 308 family cases to .264 with an Ackley shoulder

 

[Mike Matteson]

Some reason I felt I had posted on this blog. It didn't show up. So the other thing I do it I do a reduced powder load and set the bullet into the lands. That way it's places pressure against the case which puts the case base against the bolt faces. Forcing the shoulder to expand instead of the base. I place the bullet into the lands by about .005" to besure I get the base against the bolt faces.

 

[Willys]

Some reason I felt I had posted on this blog. It didn't show up. So the other thing I do it I do a reduced powder load and set the bullet into the lands. That way it's places pressure against the case which puts the case base against the bolt faces. Forcing the shoulder to expand instead of the base. I place the bullet into the lands by about .005" to besure I get the base against the bolt faces.

I agree that may work if bullet, throat, neck tension all work together to create sufficient resistance to firing pin strike to prevent brass movement.

 

[victor3ranger]

It sounds like you should take a look at your primer seating like M.M. said, or the case has too much play in the chamber and you either need to set up a sub shoulder or jamb a bullet as Dmagna suggested. The only time I've had issue with ftf's on any sort of fireforming, it was large headspace on my 7stw using Bertram 7stw brass, which is a bit small for my chamber (that batch has a bit of a shallow belt too). A simple sub shoulder cured the issue.

Explain what a sub shoulder is please.
I will be fire forming for my new 7STW soon

My plan is to do the COW method

 

[waspocrew]

It's probably the same as a "false" shoulder. When I form 6.5 Sherman from 280 Rem brass, I neck the brass down through a bushing die. I start long and check the brass in my chamber. Basically, keep adjusting the die down to the point where you can chamber it with a decent amount of resistance. This "false" shoulder ensures correct headspace.

In the case of the 7 STW, you could run your brass through an expander to .308, then neck back down to .284 in increments like I mentioned above until you have that resistance on chambering.