Ease of bolt lift after firing

[gunsandgunsmithing]

Mike I agree all those things are contributing factors BUT this is a Borden action (BRMXD) and without a round in chamber I can dry fire and still have heavy bolt life, like Alex said there is a lot in technique I still can't get it to do anywhere close to what I see others do. My BAT M is the best I have as far as opening and closing.

I think Alex hit on just about everything in his last post. You can check pin fall and spring pressure and yes, make sure the cocking piece or cross pin in there isn't rubbing the inside of the bolt shroud. All that can be toyed with a bit but everything's a compromise...for feel. Unless there is a physical issue or you find excessive fall or spring pressure, you start giving something up, somewhere..for feel. Let me or Brud or someone just take a quick look and see. It might be obvious in hand or it may just be you like a BAT roller cocking piece enough that you won't be happy with anything else. Personally, I love my Bordens, nuff said about that. I still think it's technique more than anything but without seeing it, can't say for sure. Unless something is wrong, you start trading important stuff away to make a tiny difference in..wait for it...feel. Can't go wrong if you pick up the phone and call Jim either.

I might have mentioned this to you before but have you filmed yourself shooting? It might help both of us in your quest here.

 

[Alex Wheeler]

@Alex Wheeler
when you cut the cocking helix deeper are you facing off the firing pin boss at the same time?
If you have 053ish of pin protrusion does cutting the helix deeper do any good?
In other words, at some point the pin is stopped by the primer
or am i way off

No Im not. Protrusion does not need to be altered so long as its in spec. .040 is really enough but .050 gives a little more room for error.

 

[Rocketvapor]

"when you cut the cocking helix deeper are you facing off the firing pin boss at the same time?"

On these actions, does (should) the cocking piece hit bottom on the helix?
Doesn't sound right.
I know on a Savage the pin should bottom on the back of the bolt head NOT the Helix (dry fire), with protrusion adjustable, and be stopped by the primer when fired. The adjustment is limited to 1/4 turn on a 28TPI thread (about 0.009"). Fine adjustment of protrusion can be done with the pin taken apart and the locking nut filed.
Some say 0.025" dent, plus any to cover case head gap to bolt head, plus a small margin is enough.
I think 0.038-0.040" is enough. Except for "SHORT" new brass.

 

[Alex Wheeler]

In actual use the firing pin is stopped by the primer. The actions we use are mostly based off the Remington design which stops the firing pin on the collar when dry firing. You could stop it with the cocking ramp like Tikka does but the Rem was not designed for it and the cocking piece will eventually break. How its stopped during dry fire is irrelevant so long as protrusion is correct.

 

[JMayo]

I kinda paid attention sat at the match. All ran really smoother if i kept the bolt greased better.....

Until the heat got up mid day, then i was over pressure and the cases got big... Darn near had to stand up to get it opened !
I'm backing off my load for sure.

 

[gunsandgunsmithing]

In actual use the firing pin is stopped by the primer. The actions we use are mostly based off the Remington design which stops the firing pin on the collar when dry firing. You could stop it with the cocking ramp like Tikka does but the Rem was not designed for it and the cocking piece will eventually break. How its stopped during dry fire is irrelevant so long as protrusion is correct.

I'm with ya and agree but have a question, sorta related. Primer indentation is nominally, lets just say .020. Protrusion is typically around .050, but I agree, .040 should be plenty. Here's the but and my question...I've seen several times while firing new brass that might be lets say .010 shorter than the chamber but @.050, we have, you'd think, ample reach to hit the primer with full force and full indentation depth. But, I see misfires with some regularity, especially with harder primers while firing the virgin brass. So what is cushioning the blow or whatever is going on that causes that. It can be frustrating. No fire forming here, in the typical sense. IOW, not wildcatting per se. This just makes me scratch my head at times is all. TIA

 

[Rocketvapor]

What if?
The cocking pin, like on a Savage is tilted a little because of spring pressure.
If it hits the bottom of the Helix, or some other place it shouldn't then the last bit of travel could be cushioned by the cross pin.
Misfires would be the extreme, but SD/ES with pin protrusion and impact energy (spring force and pinfall) would be a fine tune indicator of ignition.

Maybe I should put together a New Brass fire forming bolt, and a Match bolt for Flo's bolt gun

 

[Alex Wheeler]

I'm with ya and agree but have a question, sorta related. Primer indentation is nominally, lets just say .020. Protrusion is typically around .050, but I agree, .040 should be plenty. Here's the but and my question...I've seen several times while firing new brass that might be lets say .010 shorter than the chamber but @.050, we have, you'd think, ample reach to hit the primer with full force and full indentation depth. But, I see misfires with some regularity, especially with harder primers while firing the virgin brass. So what is cushioning the blow or whatever is going on that causes that. It can be frustrating. No fire forming here, in the typical sense. IOW, not wildcatting per se. This just makes me scratch my head at times is all. TIA

Two things are happening. The first is that clearance. Your wasting some energy pushing the case forward. The second is you dont have a real shoulder. Even if your not doing a wild cat the shoulder is not really formed fully and that soft shoulder acts like a cushion. Again absorbing energy. You see it all the time with guys that do Ackleys without a crush. Just a few thou is enough to waste enough energy to have some misfires. The deepest indention I have measured is .026. And that was testing some pretty extreme ignition. Not something we normally run. Add a few foe head space and a few more for primer depth and .040 should work so long as we dont do anything weird.

 

[gunsandgunsmithing]

Two things are happening. The first is that clearance. Your wasting some energy pushing the case forward. The second is you dont have a real shoulder. Even if your not doing a wild cat the shoulder is not really formed fully and that soft shoulder acts like a cushion. Again absorbing energy. You see it all the time with guys that do Ackleys without a crush. Just a few thou is enough to waste enough energy to have some misfires. The deepest indention I have measured is .026. And that was testing some pretty extreme ignition. Not something we normally run. Add a few foe head space and a few more for primer depth and .040 should work so long as we dont do anything weird.

I've come to the same conclusions fwiw. Thanks Alex. Amazing how little it takes to kill fp momentum enough to stop even ignition and we're not even talking accuracy here. Ignition is huge. Ironically, indentation may even still be sufficient but still no bang. I've looked at priming compound almost like glass. You can break it or you can shatter it. Shattering gives good ignition and just breaking it is not enough. Just my two cents.

 

[LeoHuhta]

Just a couple of things to consider
Keep the mating surface to the bolt lugs nice and clean.
Use the Sinclair bolt lug cleaning tool.
I then use a good grease on my bolt lugs.
A synthetic/ Graphite type is the best in my .02.

Then on the cocking ramp.
Cleanup all the mating pieces and mark up the ramp and cocking piece with a magic marker and see how much lack of uniform contact there is when you put everything back together and dry fire and cock the bolt a few times.
Then hone down the high spots until you get good uniform cocking surfaces.
I then use some lapping compound to polish these two surfaces to each other.
When all of that is done and everything cleaned up I use that same grease on the ramp as well.

Again just my .02

 

[Bill Norris]

Just a couple of things to consider
Keep the mating surface to the bolt lugs nice and clean.
Use the Sinclair bolt lug cleaning tool.
I then use a good grease on my bolt lugs.
A synthetic/ Graphite type is the best in my .02.

Then on the cocking ramp.
Cleanup all the mating pieces and mark up the ramp and cocking piece with a magic marker and see how much lack of uniform contact there is when you put everything back together and dry fire and cock the bolt a few times.
Then hone down the high spots until you get good uniform cocking surfaces.
I then use some lapping compound to polish these two surfaces to each other.
When all of that is done and everything cleaned up I use that same grease on the ramp as well.

Again just my .02

This procedure on rough ramps normally makes my Rem 700s cock easier.

 

[Shooter13]

I think Alex hit on just about everything in his last post. You can check pin fall and spring pressure and yes, make sure the cocking piece or cross pin in there isn't rubbing the inside of the bolt shroud. All that can be toyed with a bit but everything's a compromise...for feel. Unless there is a physical issue or you find excessive fall or spring pressure, you start giving something up, somewhere..for feel. Let me or Brud or someone just take a quick look and see. It might be obvious in hand or it may just be you like a BAT roller cocking piece enough that you won't be happy with anything else. Personally, I love my Bordens, nuff said about that. I still think it's technique more than anything but without seeing it, can't say for sure. Unless something is wrong, you start trading important stuff away to make a tiny difference in..wait for it...feel. Can't go wrong if you pick up the phone and call Jim either.

I might have mentioned this to you before but have you filmed yourself shooting? It might help both of us in your quest here.

I have filmed but been a while, will do it again at the next range session. Thanks Mike

 

[Eric Leonard]

Frankie, my BRM drop port was put together by @Alex Wheeler and timed to the Bix trigger and I can flip the bolt open with my trigger finger and it doesn’t move the rifle. It’s really smooth closing and opening ,

 

[Shooter13]

I wish the video would upload but I can't make it small enough to fit here.

 

[marazzi59]

Can any post before and after pics of recut cocking cams???

 

[marazzi59]

Or dimensions for a savage to recut or check the existing cams?

 

[21PHX]

You may be looking in the wrong area. You said this happens after firing so the problem may be in the lower area in the cartridge case. You may need to size the bottom of the case in addition to using an FL die. You may need a smaller based die.

I know some guy up around the “thumb” once made some ring dies to help with this problem. He used to float around the benchrest circuit and stir up trouble. Would you happen to know anyone like that? LOL..!! Hi, FB. Jim Bailey

 

[Shooter13]

Sent the bolt to Jim Borden to look at, pretty sure if anybody can fix it he can

 

[Eric Leonard]

Sent the bolt to Jim Borden to look at, pretty sure if anybody can fix it he can

Good idea.

 

[Shooter13]

Good idea.

I just hope the problem is not in the action because it is a glue and screw.