Help with sizing

[viva la figa]

So I bought some once fired Norma brass for my 300 wm from a member here on the hide. I have full length sized it and it does not chamber (it chambers but barely and only after some force is applied to the bolt handle...certainly not ideal). I got out my calipers and checked it for SAAMI spec and the brass is either smaller or spot on size. I compared each of the measurements I got for the FL sized Norma brass to a piece of once fired (in my rifle) Federal brass that easily chambers. The two are identical in every measurement except for the brass just above the case belt. The FL sized Norma brass was .001" bigger than the fire formed (in my custom rifle) Federal brass.

I cant imagine that .001" or even .002" for that matter would affect the bolt close that much.

Why is the FL (using an RCBS FL 300wm die) not bumping everything back to just under SAAMI spec?

Do I have to go and buy one of those million dollar belted magnum collets that resize the brass above the belt?

HEEEEEEEEEELLLLLPPPPPP!!!!

 

[Supersubes]

If you plan to use that brass, yes. Have you tried to mark up a case with sharpie to confirm thats where the interference is happening?

I wouldnt take someone elses once fired even if it was free. There are a few reasons for that, and what your experiencing now is one of them.

 

[Strykervet]

You said you used calipers but not a gauge... A gauge like a Wilson or Dillon cannot be beat and it'll measure OAL and indicate how much to trim or not. It measures from the neck down so you just drop it in. If the shoulder has been pushed back enough, it'll chamber. Paid for itself the first time I used it as far as I'm concerned. I own them for every round I load now --they should really be a required item IMO.

I ran into this exact thing with .50BMG brass. All MG fired brass in bulk from the army, 10,000 pieces. So I had to make it work. Turns out all I needed to do to FL size it was overcam my press a bit more, use plenty of lube and bump it twice and bingo. Loads like it's supposed to now and brass is in spec., and no, .001 generally doesn't make that much of a difference at the base when all else is in spec. but YMMV. Magnum brass can be a pain to work, even with the four stage Dillon press .50 BMG is still a monster to work with, and proper lubing is a must (it needs a lot so you gotta let 'em dry or you'll get hydraulic dents like a motherfucker).

Without those gauges, it's hard to know what your dies are doing or if they are pushing the shoulder back.

Once you get 'em FL sized and fire form them to your rifle, I'd look into getting a shoulder die and using that from then on.

 

[JoeBUtah]

I don't load for belted cartridges, but I just googled "300 win mag won't chamber' a couple of responses suggest bumping the shoulder back which I don't quite understand since it headspaces off the belt. One post suggested "Try backing the RCBS die out an additional 1/4 to 3/8 turn. It could be contacting the brass causing it to swell in the shoulder area." and it solved the problem... http://www.longrangehunting.com/thre...300-wm.127419/

You mention it's a custom rifle and I wounder if this is a situation where your chamber is tight and you need to turn the necks a bit. As Supersubes suggests, you need to determine where the interference is, and as Strykervet suggests, with out some sort of definitive gauge reading you're guessing at best. Good luck.

 

[supercorndogs]

I use once fired brass, but would not buy once fired brass if it was belted. You need to size the brass just above the belt. The Larry Willis Collet dies are the cheapest way I know of to achieve this.

 

[Supersubes]

I don't load for belted cartridges, but I just googled "300 win mag won't chamber' a couple of responses suggest bumping the shoulder back which I don't quite understand since it headspaces off the belt. One post suggested "Try backing the RCBS die out an additional 1/4 to 3/8 turn. It could be contacting the brass causing it to swell in the shoulder area." and it solved the problem... http://www.longrangehunting.com/thre...300-wm.127419/

You mention it's a custom rifle and I wounder if this is a situation where your chamber is tight and you need to turn the necks a bit. As Supersubes suggests, you need to determine where the interference is, and as Strykervet suggests, with out some sort of definitive gauge reading you're guessing at best. Good luck.

On the first firing, the belt is controlling headspace. On subsequent loadings, it's treated like any other cartridge. The swelling above the belt is a common issue because most sizing dies dont do much sizing in that area.

 

[domdoc]

Yes, you need the Larry Willis Innovative Technologies collet die. It is about $100, and you'll be glad you got it. It works on all the standard belted magnums with a maximum case diameter ahead of the belt of 0.510". The collet die has a built-in gauge.

 

[FLIGHT762]

O/P, are you using a gauge to measure your shoulder bump? What is the shoulder bump measurement off of the shoulder datum line with your brass fired from your rifle? What is the measurement off of the shoulder datum line on the once fired brass you bought? Your F/L die might not be bumping the shoulders the brass you bought back enough due to them possibly being harder brass with less spring back than your brass fired in your rifle and where your F/L die is currently set..

If you're not using a shoulder datum gauge, you don't know where you're at. You can turn your die in another 1/8th turn and resize a piece of the purchased brass and try chambering it to see if that is it.

I have a Larry Willis collet die for loading 300 Win Mag. I've had it for a few years and haven't really needed it. Most of my chambering problems have been due to shoulder bump not being pushed back far enough due to brass hardness with less spring back.

You can also anneal one of the purchased fired cases, F/L resize it and try chambering it. I know after annealing, brass shoulders get pushed farther back.

It is possible you have an issue above the belt, but I would try what I suggested before buying a Willis collet die.

 

[viva la figa]

O/P, are you using a gauge to measure your shoulder bump? What is the shoulder bump measurement off of the shoulder datum line with your brass fired from your rifle? What is the measurement off of the shoulder datum line on the once fired brass you bought? Your F/L die might not be bumping the shoulders the brass you bought back enough due to them possibly being harder brass with less spring back than your brass fired in your rifle and where your F/L die is currently set..

If you're not using a shoulder datum gauge, you don't know where you're at. You can turn your die in another 1/8th turn and resize a piece of the purchased brass and try chambering it to see if that is it.

I have a Larry Willis collet die for loading 300 Win Mag. I've had it for a few years and haven't really needed it. Most of my chambering problems have been due to shoulder bump not being pushed back far enough due to brass hardness with less spring back.

You can also anneal one of the purchased fired cases, F/L resize it and try chambering it. I know after annealing, brass shoulders get pushed farther back.

It is possible you have an issue above the belt, but I would try what I suggested before buying a Willis collet die.

Yes I am using a gauge to measure the shoulder bump. I have screwed the FL die in so that I get solid pressure and a stiff cam over, I would risk breaking something if I went for more pressure by turning it another 1/8 of a turn. So I am pretty sure that is not the problem.

Using the shoulder gauge, the case (FC brass) fired from my rifle measures 2.295 and the brass (Norma) that I FL sized measures exactly the same at 2.295.

The only place there is a "significant" difference is in the total length of the brass...SAAMI spec is 2.620" and my FC once fired brass in my rife is 2.619" where as the trimmed and FL sized Norma brass is 2.605". Again the brass that is smaller/shorter is the one that is sticking.

Hence my confusion.

I have hesitated to buy one of the Larry WIllis Collet dies because I dont think you would need them all that often....its an expensive bit of kit to have collecting dust at the back of your bench.

So if the head space is the same, and the neck is trimmed shorter than the case that fits fine....what is left to cause the case to stick?

 

[FLIGHT762]

So the shoulder bump checks out. It could be the case web above the belt is swelled from firing in the other rifle. Your rifle may have a tight chamber. I had a SSG 69 that wouldn't chamber fired cases from other rifles, turned out to be the case web. The SSG was really tight in the web area. A RCBS small base die didn't size cases down enough. The cure turned out to be a Redding small base body die. Worked like a champ for that extra .001" at the web.

If you were near me, I'd let you try my Wllis die.

 

[viva la figa]

So the shoulder bump checks out. It could be the case web above the belt is swelled from firing in the other rifle. Your rifle may have a tight chamber. I had a SSG 69 that wouldn't chamber fired cases from other rifles, turned out to be the case web. The SSG was really tight in the web area. A RCBS small base die didn't size cases down enough. The cure turned out to be a Redding small base body die. Worked like a champ for that extra .001" at the web.

If you were near me, I'd let you try my Wllis die.

Thanks thats good intel. I would not have thoucht that .001" above the belt (web???) would make such a huge difference in ability to chamber. I have some unfired brand new norma brass in the garage somewhere. Ill dig that out and see how it chambers.

 

[viva la figa]

If you were near me, I'd let you try my Wllis die.

Where do you live?

 

[pell1203]

Where do you live?

Per his profile info, California/SFO

 

[viva la figa]

was just there last week......I am in LA

 

[FLIGHT762]

Yep, near SFO Airport San Mateo County.

 

[EXTREMEPREJUDICE]

Have you tried to mark up a case with sharpie to confirm thats where the interference is happening?

Based on your description of the problem use SS suggestion.......................might save you some time, money. Just run a line from the neck all the way to the case head.

 

[Strykervet]

Well, if it's still a problem I'd recommend trying a comparator. I doubt you have one, but you have access to one or know someone that does. You can compare the ideal to the "bad" case and see shadow profiles magnified on a grid side by side. You may be able to get a die company to do that for you, many of them will offer varying degrees of help with overcoming problems. Tell them you need a solution but don't know what, they'll request the brass, look it over and get back to you with both the problem and a solution.

Short of that, the only way I know to do it is to measure the geometry of the case using gauges and tools.

Those Wilson case gauges are a must have IMO/E (though I got by for years before ended up needing one, then couldn't live without 'em). They don't measure everything but there are a multitude of gauges and such that do, you just have to know which one(s) to get.

I'm guessing the dies are clean and you are using appropriate lube. When I have problems, I always lube up the brass with Imperial Sizing Wax, nothing works better (though I spray with Dillon lube unless I run into a problem). For .50BMG at least, an improperly lubed case may go into the die but it won't size properly. Also assuming the shellholder is in spec. --I was talking to a die maker a while back and he's been in it for a while and he schooled the shit out of me. Anyway, shellholders can vary from mfg. to mfg. and can affect how the sizing die works too.

Good luck! I'm sure you'll get it figured sooner or later, let's hope for sooner! And sending it to a die maker is a sure-fire way to solve this.