RCBS Rock Chucker Priming Arm Issue?

bchandler44

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Hey guys - I am just getting into reloading and fired off my first batch of rounds this weekend. Overall everything was good, however, I had 4 out of my 20 270 loads that did not fire so I am investigating. Hoping someone with more experience could give me some input.

I'm using my RCBS press w/ the priming arm that it came with to prime. I noticed that it's putting circle indents on the primers after seating - and I feel like i've had to put a ton of force on it to get the primers seated deep enough...it seems excessive but if I don't they end up protruding out. I already took apart the arm and cleaned it, but I can see a small circle barely sticking out on the plug. Anyone know if this is normal with RCBS or is my plug messed up? I'm going to shop for a hand priming tool today...it sounds like that is the way to go anyways.

Any other suggestions to troubleshoot a misfire? I did have one factory Winchester round out of 20 fail to fire as well. Since my 270 is fairly new, I tore the bolt apart and cleaned/lubbed the firing pin assembly. I lubbed it good when I first got the rifle, but I did not take apart the bolt, so I wouldn't be surprised if the firing pin was slightly goobered up with whatever they put on it in the factory..

Thanks for any input,

Pics attached are the rounds that didn't fire (one on the right I tried to fire multiple times thus the bigger crater), a newly primed round with the primer circle i'm seeing and a pic of my primer plug

20200929_080756.jpg 20200928_193648.jpg 20200929_080552.jpg
 

RVTECH

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The little circle on the plug is a protrusion left over from manufacturing and is no big deal but you could 'stone' it out of the plug and make it flatter for better contact with the primer.

The two rounds in the middle of your hand do not seem to have a deep enough primer strikes to reliably ignite them.

A 'ton of force' is not normal with the RCBS priming system. It does take firm pressure but it's typically very smooth and you can feel the primer 'bottom out' fairly easily.

I will admit however from using one for many years they need to be tight and adjusted properly for proper operation. It seems I once experienced something similar to what you described and after inspection, resetting it and making sure it was tight it worked much better however I eventually went to a hand priming system and wish I had much sooner!
 
OP
bchandler44

bchandler44

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I think part of the 'excessive force' is also my bench, my press is attached to 1/2" plywood that flexes a bit when I am priming. If I can't find a hand primer today i'll try to reinforce it a bit more.

Really appreciate the info, thanks!
 

WillametteWill

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Did you confirm the primers were seated deep enough? You are using the same setup that I've used since 1983. Some cases / primers (especially if the primer pocket is dirty) don't like to seat deep enough so energy is used when the firing pin presses the primer the rest of the way in, sometimes resulting in a misfire. This can result in the light looking strikes you have on the left three (and they now are likely seated ok). Since it happened with a factory round you could likely be on to something with the gun. Personally I'm not going to claim that my primer seating is as consistent as a factory round; might just need to take advantage of this nice sunny weather to go out an shoot some more and see!
 

awshoot

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To my eye, the one on the right (multiple strikes) looks like a pretty normal strike and the ones on the left look a little light. And maybe it is my imagination, but the one second from the left looks like the top of the primer has bent downward in sort of a shallow bowl shape -- as if it was set high and the firing pin dished the top down while the sides stayed in their position. Could just be an illusion too though.

I think the first thing I'd try is beefing up the press attachment even if you get the hand primer. It is much easier to feel what is happening with the round you are working on if the press isn't wobbling around. A stable press also lets you feel other things beside primer seating, such as how the bullet is seating but wobble will interfere with that information. If the press is rock solid, you can also do things very gently if desired because you don't have to overcome the wobble -- just the resistance on the part you're working on.

I have all my presses bolted through 3" of wood -- if you can get some 2x6 or 2x8 and attach that to the bottom of your bench or table (or the top) it should help stabilize things. If possible, I'd run the reinforcing wood the length of the table because the more you can spread the force, the more stable things will be. This is a case where more is better (wider, longer).
 
OP
bchandler44

bchandler44

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Did you confirm the primers were seated deep enough? You are using the same setup that I've used since 1983. Some cases / primers (especially if the primer pocket is dirty) don't like to seat deep enough so energy is used when the firing pin presses the primer the rest of the way in, sometimes resulting in a misfire. This can result in the light looking strikes you have on the left three (and they now are likely seated ok). Since it happened with a factory round you could likely be on to something with the gun. Personally I'm not going to claim that my primer seating is as consistent as a factory round; might just need to take advantage of this nice sunny weather to go out an shoot some more and see!
Is there a good way to verify a 'good' primer seating depth? I tried to seat them to the point the primer was slightly recessed in the case.

To my eye, the one on the right (multiple strikes) looks like a pretty normal strike and the ones on the left look a little light. And maybe it is my imagination, but the one second from the left looks like the top of the primer has bent downward in sort of a shallow bowl shape -- as if it was set high and the firing pin dished the top down while the sides stayed in their position. Could just be an illusion too though.

I think the first thing I'd try is beefing up the press attachment even if you get the hand primer. It is much easier to feel what is happening with the round you are working on if the press isn't wobbling around. A stable press also lets you feel other things beside primer seating, such as how the bullet is seating but wobble will interfere with that information. If the press is rock solid, you can also do things very gently if desired because you don't have to overcome the wobble -- just the resistance on the part you're working on.

I have all my presses bolted through 3" of wood -- if you can get some 2x6 or 2x8 and attach that to the bottom of your bench or table (or the top) it should help stabilize things. If possible, I'd run the reinforcing wood the length of the table because the more you can spread the force, the more stable things will be. This is a case where more is better (wider, longer).

Primers were Rem 9 1/2. I'll definitely work on my bench - I was thinking of doing exactly what you suggested, but had a 2x4 support in the way of where I could mount a flat board under the plywood. After I get back from my deer season I'll probably cut it out and redo things to get it nice and sturdy. Thanks for the advice
 

RVTECH

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I think the first thing I'd try is beefing up the press attachment
Ditto this!

Having the press with minimal to no movement is really important.

I still have my Rockchucker and it is mounted off to my left at a angle on a piece of 3/4 " aluminum plate. Even then it still has slight movement but it is more less a 'solid' movement as opposed to flex. I don't use it much as my Co Ax handles most of my reloading but I do use it for bullet pulling, rifle brass resizing etc.
 

MechaNik

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Like awshoot said, those look like Winchester primers. I have a few Magnum rifle that had a failure rate of about 5% if memory serves. Even restruck a few times with no joy, fired on a different rifle with no joy. Left a bad taste in my mouth for gold primers
 

awshoot

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Like awshoot said, those look like Winchester primers. I have a few Magnum rifle that had a failure rate of about 5% if memory serves. Even restruck a few times with no joy, fired on a different rifle with no joy. Left a bad taste in my mouth for gold primers
He mentioned they were Rem 9.5s -- I've never used any Remington primers personally but that's only because of inertia really (and I've not often seen them in stores) -- I started using CCI decades ago and just kept on using them except for one specific load I worked up for a hunting rifle that uses Winchester primers. I have a few hundred of the Win primers but when I run out, I'm going to redo that load because they're hard to work with in my opinion (but to be fair, I've never had one dud). More recently I've grown pretty fond of the Federal Match primers but that's probably just me falling for the marketing. ;-)
 

DizzyJ

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As mentioned, the light strikes may be because the primer wasn't fully seated. The firing pin hits the primer and it moves deeper in the pocket, in the process giving a light strike.

Stiffen up the press mount area. You should be able to easily "feel" when the primer bottoms out.
 
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OP
bchandler44

bchandler44

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I think you guys nailed it..

I was able to pick up a Lee hand primer and brought it home. I pulled the bullets and dumped the powder on the loads that failed, and used the hand primer on them to see if there was any movement. Sure enough, it felt like they moved a pretty noticeable distance.

So, i'm sure it was probably a rookie mistake, at least I have something to contribute to the handloading mistakes thread now :rolleyes:

Appreciate all the info from everyone, and I'll definitely be reengineering my bench!
 

ma96782

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It's simple to check......if it's your reloads or if it's a firearm issue. Try some factory loads vs your reloads. So, if you decided that it's your reloads.....

Well.....
Its hard to describe it over the internet but I'll add my $0.02.

1) Deprime.....cleaning the primer pocket helps to get uniformity. But me, I don't always do it. But, with my Match Rifle ammo....I do.
2) If the brass has a primer crimp......remove it. Ream or swage. Your .270 brass should have no crimp.
3) Select the "correct primer". Brands vary and after more experience, you'll probably end up liking one brand over another. IF a particular brand doesn't seem to be working out for you, try switching brands.
4) Seating methods vary. Although a primer method is usually found on your press......well, I like using a hand priming tool. It shouldn't take a great amount of force to get a primer seated correctly. Rrrrright......some people do it with a hand tool (in my case with thumb pressure and my hand tool). Hummmm..... And, remember what I said about primers brands. Yup.....you can feel the difference while seating different brands.
5) Primer seating depth is important. Google search says: Maximum primer depth is -0.006″ and minimum is -0.002″. But, I've never bothered to measure. LOL.....just run the pad of your finger over the seated primer. You'll feel it if it's high and likewise if it's low. Flush (or just slightly below) is GTG.

If you're leaning towards a firearm issue....don't rule out.....
Checking the firing pin protrusion on your firearm. And, clean out the firing pin channel. If your firearm has a firing pin spring.....check that too. And also the pin's overall length.

IMHO.....
It wouldn't hurt (or cost very much) to file that seater plug "flat". Change out the Remington primers for another brand. And run your finger pad over the primers.

Aloha, Mark

PS....OK I see that I'm late by 4 mins. LOL.
 
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I've had good luck with the primer arm on my Rockchucker - it definitely involves some feel to make sure all is seated well.
If I'm doing a few cases I'll use the priming arm for simplicity... if I know I'll be doing 50 or more I'll install the RCBS Priming Ram.
You can set it up pretty quick for ideal depth when the arm on the press cams-over. Perfect primer seating each time with no guess work.
LINK
 
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Went from a Lee to a RCBS hand loader for decades and recently got the RCBS Universal hand primer with good results. Doesn't need proprietary shell holders, just grips any caliber shell and gives you the same options of priming large or small primers. Decently priced at $60 and I’m not having to tear it all apart to take out a stuck case as often.
 
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