RARR FTF 2023

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Augenblick
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RARR FTF 2023

Post by Augenblick »

I've had my 300 AAC RARR for a couple of months now and I've experienced my first three FTFs (as in primer struck but no bang.) Two with hornady 90 gr xtp .309 bullets xtreme brass (yeah I know but I have a lot of it from cheap freedom munitions ammo) and wsr #41 primers. Case length was in spec but I did not measure head space specifically, but it did pass sheriden gauge. The other load that was FTF was a hornady 110 gr vmax. Same brass, primer and case gauge set and the other two FTFs except the case length was just short of spec 1.340" but again did pass headspace on sheridan gauge.

Most of the reading I did on the RARR FTF issues came down to three things 1) bolt extractor, 2) ammunition head space and 3) primer type and seating depth.

I would think that in the eight years since the extractor issues were being reported that Ruger has fixed that issue so I'm not looking too hard at that.

I haven't had any issues with factory ammunition as many reported in the 2015 dated thread. In all cases I set the FTFs aside and then sent them at the end of the day in my psa ar and the all went bang. Unfortunately since I fired it from a different chamber and it got mixed in with that chambers brass I can't measure the headspace on that case.

Several mentioned that using #41 primers might be too hard for the softer firing pin in a bolt action rifle. I did come across mention of primer seating depth as well. I do notice a slight difference in primer seating depth when done by hand. I can get more consistent seating depth when I prime with the hornady lnl ap but the primer tube is a PITA relative to a hand primer. Please feel free to add any input on primer seating and its effects on performance. All primers were of the same lot number.

So is anyone still having issues with RARR FTTs? If so any new conclusions?

Unfortunately my failure rate is on the order of 1% so now that I am more aware and educated about this. It is hard to track down with it happening so infrequently. While I know that there was a definite issue with certain factory ammo at one time what makes the most sense to me right now and seems the most actionable is to use a softer primer given the lighter firing pin of the bolt action.

The other problem besides the low occurrence rate is the large number of variables. I appreciate the tremendous experience in this forum. I hate to see the activity so low on posting even though I know people read here often.

The reason I was loading slightly short brass was to see if I could stretch them out a bit firing as supers and get back into spec length after resizing. For those of you without experience with the xtreme brass it is a thicker walled case, weighs about 15 gr heavier than my LC brass and has reduced case volume so it is a factor in charge weights as well.
Augenblick
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Re: RARR FTF 2023

Post by Augenblick »

Ask and ye shall receive. 3 FTFs in 30 rounds so clearly light primer strikes

Image

I pulled these three and they measured 1.047" to 1.057"for head space so way short. Most of the other thirty were short as well in the 1.069" range. I'll have to look into this more. I used a new Hornady die set for resizing and maybe I should have checked more. My wife mixed all my brass together so that didn't help.

On another note I had some 110gr vmax with no other obvious pressure signs but this happened.

Image

I'll have to measure that one as well and check the primer pocket to sort out.
Roadrunner1969
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Re: RARR FTF 2023

Post by Roadrunner1969 »

I've got several hundred rounds through mine, both factory and reloads, with no issues, except for some feeding problems with the Pmag that came with it. A Lancer mag solved that.
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dellet
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Re: RARR FTF 2023

Post by dellet »

A couple of thoughts.

Primers that are not fully seated, often will not go off. The reason is that the firing pin strike will move the primer forward, instead of crushing it. Sometimes a second or third hit will ignite it, once fully seated.

With a base to shoulder datum that short, you’re going to have problems. If that was new brass, it’s not uncommon. Just poor quality control. If it was resized, it was poorly done.

Measure the new or resized brass and compare to a case fires as a super, subs won’t have enough pressure to expand a case to full chamber length. Most super loads won’t either. I would measure the one that popped the primer. It is probably full length.

If using a case fired as a super, back your die out a full turn from where it is now, size and measure the base to shoulder point. It will probably actually be longer. Squeezing the sides in, makes the shoulder move forward. Turn the die 1/4 turn and check again. When you start to get a shorter measurement than you started with, stop when it is .002” shorter than fired length.

What you are likely to find is that after firing the second time, it will be longer the .002” you shortened it before. Backnthe die out and repeat the process.

When sizing for a bolt action, I check to see it the fired brass will chamber without sizing. If it does, I back the die out and only size the case far enough to reduce the neck diameter to hold a bullet and fire again. This will insure the case is expanded to full chamber length. Then set the die to move the shoulder back .002”
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Augenblick
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Re: RARR FTF 2023

Post by Augenblick »

The primers were well seated. Repeated attempts to fire the FTFs did not ignite the rounds.

Image

As you can see the cases themselves are too short in the Sheridan gauge. However when they were loaded with the stubby xtp 90 gr bullets they were in the go zone. To test for bad primers after decapping them I smashed them with a hammer and they went bang. I can always insert primers into the short cases and see if I get light strikes again.

As to the short sized cases that is on me. A combination of a new die, consolidation of all my brass from my three guns and running them all through after only checking the first few for .002" setback. The supersonic fired brass did indeed measure to close to minimum spec 1.071" and they did drop right in to the chamber. I did insert a dowel from the muzzle to poke them out with only minimal force.

Your description of resizing for the bolt action was really clear and I'll put that into action.

On the other issue of the blown primer here it is post firing in the Sheridan gauge.

Image

The were 110 gr VMAXs with 19.4 gr of H110 individually weighed. I didn't want to go any higher because of the reduced case volume with the x-treme brass and loaded to COAL 2.05" per Hornady manual. MV was 2337 fps. Liberty Anthem S suppressor. No pressure signs on any of the other 19 rounds. Each charge was verified on a second scale before loading.
In processing my brass I uniform the pocket and check with primer no go gauge and they all passed. So when I checked the blown primer pocket post firing it was no go, out of spec, but depth was still good.

So could it be anything other than out of spec headspace of the case? I think that would explain both failures.
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dellet
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Re: RARR FTF 2023

Post by dellet »

Plain and simple, you have a headspace problem.
Complicated by thick brass, or a seating problem with the bullets.

The empty case fails the gauge, that will not change when you seat the bullet. The bullet is causing the false reading.

There are a couple of reasons this might be happening. Bullet diameter to large, brass thickness in the neck, causing loaded neck diameter to be larger than .334”. Easily enough checked. With a .309” bullet and a .334” max diameter leaves .025” for brass or .0125” neck thickness.

A bullet seated crooked will do the same thing.

Last and most likely is the bullet seared too long. The .308” portion of the bullet contacting the lands. If you look at SAAMI specs for the cartridge the distance from base of the cartridge to .308” diameter of the chamber is roughly 1.740”.

This is when you need to invest in a comparator if you don’t already have one.

You can cheat it with the gauge and your barrel. Take a loaded, inert round and push it into the chamber with your finger, it should drop out freely, it it sticks, it’s hanging up on the bullet. Same can be done with the gauge. My guess is that if you seat the bullet .010” deeper, it will fail the gauge.

Over all length does not matter if the headspace is off, the cartridge will seat on the bullet. You could push the shoulder back an inch, and it would still pass the gauge, because it’s making contact on the bullet instead of the shoulder.

The light primer strikes are because it’s easier to force the bullet into then lands than crush the primer and ignite.

The blown primer is likely due to excessive headspace and exceeding low capacity case due to short base to shoulder datum length with added pressure from the bullet being jammed into the lands.

Basically some rookie mistakes, that can be deadly.
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Augenblick
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Re: RARR FTF 2023

Post by Augenblick »

I think that is exactly the case with the .309 xtps. Its the reason why the cartridge passed the gauge but the case didn"'t. I loaded the 90 grain xtps to 1.649" IIRC but the neck diameter was right at 0.334". So it was hitting the gauge either at the bullet or the neck.

So is all the brass under 1.0707" base to shoulder datum trash? Or can the 1.069" ones be resized or fireformed safely? The ones that were 1.047" - 1.057" are now in the trash.
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dellet
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Re: RARR FTF 2023

Post by dellet »

If the loaded rounds measure .334”, they should not be tight in the chamber. The chamber should actually be .335” That’s why checking the round in the chamber is a good idea. You never know. Compare maximum cartridge with minimum chamber specs.

Image

The brass is actually salvageable, using the same technique that got you in trouble. Just use a light charge. It’s done all the time, fire forming. The reason you don’t want to use a full power load is that it can over stretch the brass down at the case head and cause a separation. Just back off a couple grains.

Again the popped primer case is a good example for what your chamber actually measures.

The other option is to expand the neck with a larger diameter sizing ball or mandrel and then size it in a blackout die.

Main thing is to know for sure where the round is touching.

Is that a slotted gauge or full round?
This is why the slotted was developed, so you can see where it touches.
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Augenblick
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Re: RARR FTF 2023

Post by Augenblick »

It is the slotted gauge. It really is helpful when used correctly.

I just got some x-treme 125 gr FMJ SP bullets on sale so I'll use those to fireform the brass. Good place to use up my remaining cfeblk and maybe some A1680.

I feel like I'm putting on a clinic of what not to do but I am learning. I'm still in my first year of reloading. Thanks as always for your thoughtful responses.

I would normally be asleep right now but Air Force Special Operations Command (AFSOC) decided that 11pm is a great time to fire 3000 rounds of 30mm auto cannon in the gulf right outside my house. I'm used to the Ospreys flying up the sound or the AC 130 auto cannons and 105mm howitzer on the range to the north but there was a full blown 10 minute firefight that just woke everyone up. I'm all for the sound of freedom but that was crazy.

Also cancer sucks.
popper
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Re: RARR FTF 2023

Post by popper »

That Vmax load is pretty hot. And HS is too great - primer pops out. May need to lightly jam the lands to get primer to fire when fire forming to push out the shoulder.
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