New BRA, fireforming question

[Gilbert Garza]

Just chambered up my new barrel in BRA. Got a few questions on fireforming. I ran some loads to check the chamber for any burrs or nicks. Fireforming load was 29.5g Varget with a 105 Hybrid jammed .010” in lands with 450 primer. As I expected closing the bolt was firm, not hard, but had slight pressure. But opening the bolt was “stiff” as well. Harder to open the it was to close.

Was my fireforming load to stiff?

Just to add, I used a BR-.004” gauge as a go gauge as that’s what the reamer print asked for.

Thanks for any help in advance

 

[newbieshooter]

Was my fireforming load to stiff?

I see posted FF ranges from 29.5gr-30.0gr Varget using a variety of 103-108 bullets. YMMV: http://forum.accurateshooter.com/threads/one-more-bra-fireforming-thread.3952140/

 

[Nature Boy]

I used 30.0g of varget for FF with no issues

 

[BRGUY]

What is your free bore length? If your barrel is short throated, that could explain the bolt being stiff when opened.

Back off the load 2.0 grains with no other changes, and see how that effects bolt opening.

 

[R.Morehouse]

29.5 RL-15 100FB fed primer.....Every one is a thing of beauty. No need to load into the lands ( but i still do).

 

[JMayo]

Make sure you're cleaning all the cleaner out of the bore, maybe.
Get good measurements, write them down. Bump those shoulders back.oo5+.
Anything less than 29.0 varget didn't expand my cases good.

 

[Gilbert Garza]

What is your free bore length? If your barrel is short throated, that could explain the bolt being stiff when opened.

Back off the load 2.0 grains with no other changes, and see how that effects bolt opening.

Freebore is .110”

 

[Gilbert Garza]

Make sure you're cleaning all the cleaner out of the bore, maybe.

This was it, since I had just took it out the lathe and put it in the rifle I had only cleaned the bore, but the chamber had a tad to much oil. After the i posted here I went back to measure everything and put a blue shop towel in it was greasy. So I had to much oil in chamber allowing to much case slippage creating heavy bolt lift.

Works great now

 

[BRGUY]

Good for you. Glad you got it figured out.

 

[JMayo]

Cool. I use too use bortec. I didn't clean chamber once After cleaning barrel and bolt lift was hammer hard.... Sticky stuff

 

[Gilbert Garza]

What is your free bore length? If your barrel is short throated, that could explain the bolt being stiff when opened.

I gotta ask, my freebore is .110” and I’m sure these first loads are jammed in the lands fairly healthy, would that increase pressure also ?

I have a clean chamber, running that same brass from yesterday to get “full blown measurements” and some have a very firm bolt lift.

I have not fully full length sized my brass cause I haven’t cut my Wilson Dasher die yet. So I’m reusing partial neck sized and minimal body sized brass. Since my die is about .080” to long.

 

[walker2713]

For FF'ing 6BRX brass I've always used a softer primer cup....Rem 6 1/2 because I had a lot of them.

 

[Gilbert Garza]

I didn’t have an issue with 450’s going off and ya I have a few thousand...maybe 6k

 

[walker2713]

I didn’t have an issue with 450’s going off and ya I have a few thousand...maybe 6k

I use the 450’s for formed brass...,

 

[BRGUY]

From Gilbert Garza:

I gotta ask, my freebore is .110” and I’m sure these first loads are jammed in the lands fairly healthy, would that increase pressure also ?

Yes, being jammed into the lands WILL increase chamber pressure! Being jammed into the lands can be a good thing.... at times.... but starting loads should be reduced a couple of grains before continuing on.

There are always a lot of variables when reloading for any cartridge. If you plan on seating bullets to jam against the lands, do it at the start of your loads, and not later as an afterthought. This will keep you from having pressure spikes and a potential "problem".

I have seen cartridges develope over an 8,000 psi pressure difference from seating bullets .020 off the lands, and then with no other changes to the load, seat the bullet to jam into the rifling.

No, this pressure spike does not always happen, but I have seen it enough to always pay close attention in this area of reloading.

 

[Gilbert Garza]

Another question
If let’s my brass is not fully grown in the fireforming process and I hard jam these bullets on the 2nd firing, would that give little room for the brass to grow and only stretch “longer” in the chamber since seated firmly against bolt face, hence causing heavy bolt lift.

To add, my brass has yet to be full length sized cause waiting for my die or still contemplating cutting my Wilson Dasher die.

 

[BRGUY]

Whoever cuts your chambers should ALWAYS use your new brass for the headspace gauge. This eliminates excessive case stretching, and if it is a tight chamber, it will eliminate the need for fire-forming.

If your brass has been full length resized, then headspace can be set for .000, .001, .002 or .003 headspace and minimize working of the brass.

 

[Gilbert Garza]

Sorry if that read wrong, this was new brass fired in this chamber. I had just previously shot it in this barrel yesterday and again today (2nd firing). I fire it a few times before bumping the shoulders to get full blown brass measurements to prevent over working the brass from premature bumping on a false shoulder. Had several friends have this problem with dasher. Would bump back shoulders on 1st firing, BTS was 1.2555 and would bump back to 1.2535 but actual BTS was 1.2610 so they were working the brass to much.

When we chambered this barrel yesterday, headspace was set at near .001” on the go gauge as recommended by JGS. They said to use a BR-.004 as a go gauge.

 

[BRGUY]

Ok, gotcha!

My apologies, I must have misunderstood.