Trimming fire formed brass

[HarryPottar]

HI,

I'm starting my journey into my 308 precision hand loading, I have 3 sizing dies, full length for when I have range brass or for when my cases have expanded they start to have difficulty in chambering. Shoulder bump die that size just the shoulder and neck. Then have a bushing neck die for just sizing the neck.

I now have a bunch of once fired brass, fire formed to my rifle, so I plan just to neck size.

I'm having trouble with the concept of precision trimming 308 fire formed brass, with my 223 I always full length size and trim back to SAAMI specs.

If this brass is fire formed how do I know how much to trim back to?

I have a head space gauge, do I take this once fired brass, measure and use as my "yard stick" so the next firings I check and if needed trim back to this.

If I trim back to SAAMI specs "2.015" then does that not defeat the purpose of the fire formed term.

I have a Hornady Overall Length Gauge so I can measure my overall length for my rifle. Is there any thing that measure the head space for your rifle?

Thanks in advance

harry

 

[josh2600]

I would trim to spec, the fire forming part is really in the neck and shoulder dimensions, not so much neck length. I would be interested to hear what a benchrest guy would say though.

 

[edhead35]

Trimming is overall length and is separate from what we refer to as fire formed which is shoulder headspace. Some even trim to saami spec minimum which is below the trim to length in the books so they never have to trim again.

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[mac1911]

You could take a chamber casting.
I'm no expert but the time it would take for your brass to stretch to the point where your neck is,beyond the space provided in the chamber you may just end up with some case separation issues.
I'm not saying I shoot with high precision but I either trim to minimum spec and set my dies up for a specific rifle. Then I trim when I fined a case that's pushing max specs.
Now for my 1903a4 clone I use a neck sizing die after fire forming. I chose to trim at max. I have not seen any case neck stretch yet after 5 loads.
Although the neck metal is getting "harder" as the more I load a piece of brass it starts to to "sing" on the trimmer and begins to "feel" different on the press.

So for precision your going to have to pic a spec and go with it. Will you be turning your necks for uniform thickness?

 

[HarryPottar]

I picked up a bunch of measuring tools, probably more than I need. I did pick up a Hornady Ammunition Concentricity Tool and the neck wall thickness adapter for the same. I haven't picked up the neck turning tool and will see if I need it.

I did pick up the Hornady cam lock trimmer, but now debating if I should swap out the for the Redding Case Trimmer as that as a micrometer for precision length setting , Also debating if the Hornady case prep center is a good tool, so many mixed reviews, I want consistency in my trimming. Be cheaper if I got into crack as a hobby instead.

I'm investing for the long haul so I want to buy the right tool for the right job. I read the Giraud Tri Way Trimmer does not work on fire formed brass and that you can not just neck size when using it.

BTW, I shop a round, Natchez whom normally have some of the best deals around have a 10% site wide sale that ends tonight (Friday June 23 2017) at midnight, code PO170622. Although keep an eye of their shipping costs.

harry

 

[Stape]

I'm curious, what rifle are you dialing in a load for?

 

[HarryPottar]

Starting out with a Ruger Precision Rifle, just starting out, but want to make sure I go in the right direction for reloading. Who knows what it will lead to

 

[edhead35]

I use the trim it 2, with the tri way cutter. Nice cheaper alternative to the giraud. I used a coupling to hook it up to a bench Grinder.

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[Stape]

Theres lots of great advice so far, let me see if I can change that lol. IME, even with dedicated bench guns, some of the tried and true methods for wringing the most accuracy out of a given load/rifle set up were not fruitful. Please let me explain. I started off with a trued and blueprinted rem 700 action, Hart barrel and custom stock, niceBR glass, and I went to town with my reloads. I sorted brass by headstamp and weight, sorted bullets, you name it, powder tricklers to exact weight, run-out guages, competition seating dies, and so on.

I tried neck sizing but surprisingly this did not give me my best results, nor did the most expensive premium bullets. In the end, winchester brass, IMR 4198, CCI BR4's and get this, a Sierra #1310 (an economical dog-town varmint bullet) gave me my best results (.37). And that's probably the best I could do with my skill. This was a .223, of course not a long range performer but the principles remain the same.

I guess what I'm saying is start with one thing, say a load duplicating factory loads, and change one thing at a time until you get to a point of diminishing returns, then go back to what worked best. Then move onto the next variable. I've found seating depth to have the greatest inpact on a load. Keep your variables down to one at a time or you'll be chasing your tail with this powder or that powder, this bullet with that primer with this brass ect.....

The accuracy game can ruin you! I've got great rifles that are super accurate that I'm hesitant to throw an optic on because then I'll get neck deep obsessed with working up a load for it and then take all the fun out of casual range days.

Best of luck.

 

[cockpitbob]

I've always worried about things like concentricity, flash hole uniformity and neck wall thickness more than case length. I just make sure they are all the same length. I never gave much though to if the length should be 0.010" longer or shorter.

 

[akma]

I started a similar quest over a year ago. The Hornady tools are essential IMHO to get some base data to work around. The chamber tool lets you set your shoulder length and the bullet depth tool lets you get accurate bullet depth within a certain brand of bullet or if you are switching between various manufacturers using one seating die. I keep master dummy brass and dummy loaded shells to reset my seating die for a certain bullet. Also I write on these cases the dimensions with a sharpie for quick reference. Also writing these notes on a piece of paper and leaving it in the die case is helpful too. As Stape said full length sizing has worked best for me too. No more neck sizing. I started with a rifle that could barely make 1 MOA on a good day now it's down to .625. Haven't been able to do any load development in a while. I'm using new LC brass weighed to one grain and do the flash hole, Fed 210 LG rifle primers and Varget.

 

[highscore]

If your empty fire formed brass chambers with a slight drag on bolt that wasn't there on an empty chamber, your shoulder is pretty close to being where it should be. I wouldn't bump the shoulder back until the drag on the bolt becomes excessive. If the bolt doesn't have escessive drag, the case probably isn't too long. SAMMI specs make sure that at the max length, the case won't bottom out. Unless your barrel has a custom cut chamber, a case could probably be longer than the max length and still not be too long for your barrel. Color you longest case with a magic marker on the top of the neck and chamber it, if it doesn't take the color off and roll the sharp edge it's not jamming itself in and isn't too long.

How long to trim them??? Trim the whole lot to the same length, either the max SAMMI length or whatever you need down to the min SAMMI length to get them all the same. I prefer the longest SAMMI length (or even longer if they fit but that's just the way I am) although I can't say that one will be more accurate than the other. I never even trimmed my .223 gas gun length to the min and just kept a good eye on it, although I had a case that was .010 over max and it chambered fine. Of course maxing everything out in a gas gun can cause catastropic results, the rules are not the same.

I'd be willing to wager than you don't have one case that it too long for your chamber, let me know if you find one.

 

[mac1911]

Starting out with a Ruger Precision Rifle, just starting out, but want to make sure I go in the right direction for reloading. Who knows what it will lead to

Careful it may lead to load development syndrome.
The signs of this dreadful sickness is more time spent loading and testing than shooting and fundamental skill improvement.
Have you tested the rifle out with any factory match ammo. Do you have regular access to longer range shooting?
I'm pretty much stuck @ 200 yards so 90% of my loads are geared towards that.
Only rifle I shoot beyond 200 is my AR and my skills keep me from being a "precision" shooter. No load will help. As right now one of the better shooters I know can shoot either one of my ARs to MOA or better with my "match" reloads.
On a good day prone supported I can get down into MOA land.

 

[HarryPottar]

Yes, although only out 100 yards, my local range only goes to 200 yards but I need to qualify. I'm going to join another range as well they go out 1025 but it will be a while before I get out that far. They're about hour & half each way so probably only go every other weekend.

The reloading is for later on when I'm more accurate, although, I'm buying Fredral 308 168gr Match king at $1 a shot. I caculated, buying 8lbs of powder (Varget) and 168gr Match King heads 1800 at a time, I can load for around 44-45 cents a shot not including brass.

harry

 

[mac1911]

Yes, although only out 100 yards, my local range only goes to 200 yards but I need to qualify. I'm going to join another range as well they go out 1025 but it will be a while before I get out that far. They're about hour & half each way so probably only go every other weekend.

The reloading is for later on when I'm more accurate, although, I'm buying Fredral 308 168gr Match king at $1 a shot. I caculated, buying 8lbs of powder (Varget) and 168gr Match King heads 1800 at a time, I can load for around 44-45 cents a shot not including brass.

harry

Reloading is fun and you can get the total cost per round down by purchasing in bulk. Don't deserve discount other bullets. I shoot 110-130 varmint bullets in,my 30-06 and they are great for 200 yards. Which is another great benefit of reloading you can tailor loads to your needs.
I shoot a lot of reduced loads with H4895 out to 200 yards to conserve powder.