Fireforming PMC 308

[DougGuy]

Getting some PMC .308 brass that I assume is sized, it's cleaned and polished, what would be a good way to fireform it to my M77 .308?

I looked and found one question on forming 308 brass and it wasn't really responded to very well so, asking here. I would prefer to do this with CoW if it will work good enough. Not like forming a new case from 308, I just want to blow this out to fit my chamber.

Do we have a sticky for fireforming somewhere that I might have missed?

[reed1911]

Generally speaking The best way will be to FL size and shoot with normal loads, or better yet a load ladder where a given load is stepped up in small amounts to see what shoots best. This allows both jobs to be done at once. If a given load is not accurate with FL sized brass, having it formed to the chamber will not make it much if any better. Once FF to your chamber they can be set aside until you find a promising load, then begin neck sizing only and start working on the OAL and tension to fine tune it.

If you are totally focused on FF with COW, I'd opt for the 10% method. Take one of the fired brass, fill to the top with Bullseye or Red-Dot (or your choice of fast pistol powder), dump the powder into your scale pan and take down the weight. From that weight determine 10% and that will be your charge for fire forming the brass. Pack the remaining volume with COW. Some use wax, or clay, or tissue to hold it all in place, use what you have on hand. Ensure that you are shooting at or into something you don't mind damaging, you would be very surprised how much sheet tin tissue will punch through.

That is the nuts and bolts of FF'ing

[EDG]

Just shoot the full power loads you plan to use. Otherwise you are wasting time, components and energy.
If you want to be sure load 20 and shoot them for accuracy using some of those cheap 147 gn FMJs.

[ShooterAZ]

Full length size and use full power loads to start, then neck size or X-Die size after that.

[DougGuy]

Generally speaking The best way will be to FL size and shoot with normal loads, or better yet a load ladder where a given load is stepped up in small amounts to see what shoots best. This allows both jobs to be done at once. If a given load is not accurate with FL sized brass, having it formed to the chamber will not make it much if any better. Once FF to your chamber they can be set aside until you find a promising load, then begin neck sizing only and start working on the OAL and tension to fine tune it.

If you are totally focused on FF with COW, I'd opt for the 10% method. Take one of the fired brass, fill to the top with Bullseye or Red-Dot (or your choice of fast pistol powder), dump the powder into your scale pan and take down the weight. From that weight determine 10% and that will be your charge for fire forming the brass. Pack the remaining volume with COW. Some use wax, or clay, or tissue to hold it all in place, use what you have on hand. Ensure that you are shooting at or into something you don't mind damaging, you would be very surprised how much sheet tin tissue will punch through.

That is the nuts and bolts of FF'ing

Actually, I have gone through this process years ago. This from another thread:



I have a Ruger M77 made in the 1970s that has been worked over fairly well, lapped lugs, steel bedded all the way out with upwards pressure on forend, pillar bedded screws, I haven't loaded ammo for this old girl since the 1990s and would like to get it back on it's game again.

When I last shot it, it would routinely put 3 into a guitar pick @200yds. I used fireformed brass neck sized only, I used 180gr plain base pointed soft point Barnes Burners, seated out about .025" shy of engaging the rifling, held in place with a collet crimp on top of 41.5gr H4895. This was the cold barrel, first shot, hit a golfball with it every time load. I was VERY happy with this load and this rifle.

I'm just wanting to ff the new brass before I begin loading being that I already have a more than stellar load for it.

I don't see the advantage of loading full power loads to arrive at a point I have previously been with this rifle. Will the 10% + CoW method yield basically the same brass as full power loads?

Edit: When I previously loaded for this rifle, I took 100 ff cases, weighed every charge, I set aside any that looked really full or the powder was further down in the case, I seated boolits and set aside the ones that seated lightly, and also the ones that seated hard. I crimped and set aside ones that had the crimp band right on the mouth of the case, set aside the ones that had the crimp further down, came away with about 30 rounds which were pretty much the mean average of the string. Out of those I set aside any that chambered too easily, set aside the ones that the bolt was harder to close on.

I think I wound up with 15 - 18 rounds that I could count on cold barrel first shot to hit dead in the middle of a 2" square at 200 yards. This rifle put 3 of those into a group I covered with a guitar pick. I have 3 of those rounds left. The other 12 put deer in the freezer in the 2 or 3 seasons they lasted, and one hit a turkey at 340 yards, struck within 1/2" of point of aim.

Out of 100 PMC cases, I will be tickled if I get 20 rounds that are from the mean average of a load string of 100 cases.

Am I on the right track here?

[HangFireW8]

Do we have a sticky for fireforming somewhere that I might have missed?

We have a whole sub-forum for case forming. While it is oriented towards reforming, you can try the stickies there.

[DougGuy]

We have a whole sub-forum for case forming. While it is oriented towards reforming, you can try the stickies there.

Isn't this the case forming sub forum?


Forum (http://castboolits.gunloads.com/forum.php)
Bullet Casting and Reloading (http://castboolits.gunloads.com/forumdisplay.php?2-Bullet-Casting-and-Reloading)
Case Forming / Re-forming (http://castboolits.gunloads.com/forumdisplay.php?218-Case-Forming-Re-forming)
Fireforming PMC 308

[EDG]

>>>I don't see the advantage of loading full power loads to arrive at a point I have previously been with this rifle. Will the 10% + CoW method yield basically the same brass as full power loads?<<<
There may be zero advantage with messing with COW too. Many times the shoulder will not fill out on the first shot.

The advantage if loading full power loads is shooting without obsessing over a lot of details.


Am I on the right track here? NO

>>>Out of 100 PMC cases, I will be tickled if I get 20 rounds that are from the mean average of a load string of 100 cases.<<<

Your processes are not good if you cannot get 100 identical rounds out of 100 sets of components. Try loading 100 and segregate them and shoot groups with each lot and compare the results. Then figure out how to make them all the same so you are not segregating and culling "bad" rounds.

If your mind is made up just do it your way. There is no real reason to post here if you argue with the advice you receive.

[DougGuy]

If your mind is made up just do it your way. There is no real reason to post here if you argue with the advice you receive.

This is very true. Not trying to argue, all advice is well taken. On the other hand if you are telling me that any attempt at discussion will be deemed an argument and therefore I am not welcome to post here I will kindly ignore that comment.


Your processes are not good if you cannot get 100 identical rounds out of 100 sets of components. Try loading 100 and segregate them and shoot groups with each lot and compare the results. Then figure out how to make them all the same so you are not segregating and culling "bad" rounds.

I am sure the ones that all seated the boolit lightly and got culled will shoot to their own point of impact and may even group fairly well. I don't have a 200yd range close by so it will be a major endeavor to go sight in one load, then shoot only that load, sight in for the next group, shoot only those until they run out, etc. I rarely shoot this rifle. I hunt with it only when I can't get in the woods where it is so thick you can't get a shot with a rifle. I mostly hunt from a treestand with a revolver.

I know from experience if I take the rounds that are the mean average of the group that I can count on them to be accurate at 200yds without question and 20 of those will last me a good number of years hunting. I can spare myself the obsessing to diagnose why the culls are culls and whatever hoops I gotta go through to make them work. It's easier this way. I guess I am doing it wrong I just know it works.

[HangFireW8]

Isn't this the case forming sub forum?





So it is. LOL

[reed1911]

The 10% method will result in cases formed to your chamber in general terms. It will not provide the same results as a full pressure load as you are not shooting a full pressure load, however, in terms that would relate to the case's position in the chamber, yes it will do that. This is one of the drawbacks of using the COW method for forming brass.

As to the difference in powder height in the case, there are a lot of things that will effect this, if you use a longer drop tube or tap the case several times on your bench one the powder has been introduced into the case it will help settle the powder and allow for a more effective determination.

As to the neck tension, I would anneal all the necks first and then size and load and keep track of the loads and anneal them all together when it comes time to do so again. While some brass is uniform, not all brass is even from the same lot. And the percentage of drift in any given lot ranges from manufacturer to manufacturer as well as lot to lot. If you are going to spend the time to uniform the brass, failing to anneal will be a constraint just as failing to trim them all the same length will cause variance. But at least annealing will give you a more uniform neck tension.

[gunwonk]

and 20 of those will last me a good number of years hunting.

Most of my rifle shooting is in local matches of one kind or another, but I have hung out with hunters a little. Their processes can be quite different, and I think quite reasonable, based on what needs to get done.

My wife's father was a deer hunter, and that's all he ever did with his rifle. Here's how I used to invite him to try shooting a match, for fun:

"Just bring your rifle, ear protection, and about 30 years worth of ammo ..."


LOL :)

[toallmy]

DougGuy you can weigh and separate your brass , then pick the 20 close to the same weight , full length resize , full house load those 20 fire them to test your load ,then trim to length , neck size and probably be good for 5-10 more seasons . But all brass is different and every lot of powder and primers do different things , especially ones fired in different chambers . You should work up your load again just to be safe and shore of it .

[DougGuy]

Thanks for all the advice. There are a couple who see the logic in how I select hunting loads out of a batch of ammo. It is a bit different. I can see grouping them in lots because they will be similar and should predictably exhibit consistencies because of case length, neck tension, case weight, etc.

The hunter, only cares about groups and hitting dead on his aim point with the loads he will take to the field. The ones that didn't pass muster at the loading bench can get bullets/boolits pulled and loaded into the brass that did make it to the field and was fired. It's much like a sniper preparing for that one shot that counts. I could care less what becomes of the 70 or 80 rounds that didn't make that "one shot one kill" batch. They can get pulled and the powder dumped back in the can.

My rifle is bedded completely from the end of the tang to the end of the stock with steel bed. It is an epoxy full of stainless steel powder. If you heat epoxy, it softens and there goes your bedding AND your zero. This is the main reason I don't shoot this all day at the range. it is perfect when cold. It hits dead zero to the crosshairs @200 yards when cold. Why mess with it just to use up ammo that didn't make the "one shot one kill" batch?

[DougGuy]

You should work up your load again just to be safe and shore of it .

Here is data from Hodgdon for H4895:

http://i1202.photobucket.com/albums/bb374/DougGuy/QuickLoad/308WinH4895_zpsuga5lmgr.jpg (http://s1202.photobucket.com/user/DougGuy/media/QuickLoad/308WinH4895_zpsuga5lmgr.jpg.html)

Here is what QL shows for the same load, I seat out .025" from the lands (.060" longer COA than the Hodgdon data) and I am not so sure of how accurate the QuickLoad pressure BUT I also just ran this through the program using it's default values without actually having the case measurements here in front of me OR the amount of water to overflow, which I will do once I get brass ready to start loading.

http://i1202.photobucket.com/albums/bb374/DougGuy/QuickLoad/308Win180grQL_zpsyaj6rdha.jpg (http://s1202.photobucket.com/user/DougGuy/media/QuickLoad/308Win180grQL_zpsyaj6rdha.jpg.html)

I used 41.5gr H4895 with 150gr and 165gr loads but I was getting a LOT of torn up deer meat so I put a 180gr plain base on that same charge and it has worked out really well, best shooting load this rifle has ever fired, no pressure signs at all, good clean kills that flung one little button buck cartwheeling backwards the length of a Ford F-150!

[ShooterAZ]

I see your logic in case sorting & prep, having shot some bench rest. Truthfully though, for hunting, the deer will never know the difference!

[kycrawler]

Wow you are really over thinking this one

[DougGuy]

Wow you are really over thinking this one

I suppose you think it's a piece of CAKE to stroll into wallyworld and buy a box of .308 ammo that will shoot into a 5/8" group at 200yds. Ya right. Let me know how that works out for you. If it was that easy, the Girl Scouts would be shooting BR.

[slughammer]

I would FL size with my dies, trim to length then weight sort the brass. Pick the 30-40 in the middle of the weight curve and work with those.
I don't have much experience with COW and I'm not sure you'll get the pressure to FULLY form the brass to your chamber in one try. I've got random stuff in my stuff and would load and fire form with some of that. For example a fire forming load might be 110gr 30 carbine bullets, Alcan primers from 1973 and some of that 2oz of Herco lingering on the shelf. I'd stand on my hind two and shoot them at 50 or 100 yards to get a little trigger time and avoid the trip to the 200 yard range. With any luck I would form my brass without spending $.63 per shot, I would empty the 30 carb bullet box and I could sprinkle the dregs of Herco on the lawn.
I like your idea of sorting based on tension and would proceed from there.

[CHeatermk3]

When you get your cases, weigh them and sort into +or - 1 grain lots; .5 grain if good enough. Pick a lot and use your ball mike: I look for + or - half a thou variance for match but turn if over 2 thou variance.

This will narrow down the number of cases that you'll fireform. And yes, full-power loads do the best job of fireforming.
IMHO.