6.5cm shoulder bump

[Singleshot]

Hey fellas need help.

Just started reloading 6.5. Using Hornady competition FL & seating die set. This is shooting out of a Bergara HMR.

Got a batch of once fired Hornady brass from a buddy. Didn’t check shoulder when I first got it because I didn’t have the gauge yet. I set up my FL die, screwed it down until it just about touched the shell holder and then started FL size + fully prepped them for loading.

Loaded up a batch and went to work. Loaded 140 eldm .20 off land, using H4350 from 41-43.7. No pressure signs and Some decent results.

Now, as I am getting ready to load the second batch to go back for some more testing, this time I checked the shoulder and planned on bumping them back .002. Here’s what had me worried. The shoulder on these 2x fired are measuring 1.506. A friend is telling me it should’ve been in the 1.515 to 1.535 range. He believe I may have over-bumper the shoulder. I don’t have anymore brass to compare it to. And not sure how I could’ve over-bumped it by that much.

Does those #s sound right? Thoughts? Chuck them or shoot them?

 

[Timo Turl]

I’d shoot them. You’ve probably over-worked them and reduced brass life a little but if you aren’t getting pressure signs or any signs of case head separation then the shoulder should move forward after the next firing, assuming they chamber ok now.

 

[Singleshot]

Ya chambers smooth without any issues. No lines / signs of bad brass.

 

[XLR308]

Unless it was a typo the 1.515 - 1.535" range your bud suggested is a hell of a span.
With brass fired from another rifle you can first size a minimal amount and see if it will chamber and then a little at a time until it chambers easily with no resistence if you don't have a gauge to measure off of the shoulder.
A piece of pistol brass works pretty good also, haven't tried it with 65 Creedmoor but a 9mm casing was what I used on 68spc brass before I bought the comparitor set.

 

[Singleshot]

He was saying he had bumped all the way down to 1.515 and with factory or in some of his rifles he has left it as high as 1.535 ?‍.

What he was suggesting was he never seen or ever had to bump it that far down, and wasn’t sure if that’s considered excessive.

I had a gauge coming, just didn’t wait for it before I prepped and loaded up a batch. But, I have one now, that’s how I know it’s 1.506 =).

 

[spife7980]

I would say: don’t worry about what your buddy thinks it should be. If he can only give you a range of .020 then he would be better off not giving you anything.especially if he didn’t clarify it it was the .375 c or .4 d insert, that could be the only difference.

If your fired brass at 1.506 chambers then I wouldn’t bump the shoulder at all. Just size the neck a tad without coming down low enough to tough the shoulders and see if it chambers in your rifle. If it doesn’t fire it again and see how much/if it grows. If not then you know how big your chamber is and you can size accordingly.

 

[Supersubes]

If you’re able, remove the striker assembly out of the bolt, chamber one of your rounds, and thrust the bolt forward. That’s your headspace. You’ll have to learn the feel yourself, but .001 is very easy to feel. This works best on actions with plunger ejectors, and will not work on bolts with floating heads.

 

[Rmitch223]

That sounds pretty short. I just had a barrel chambered with a SAMMI min reamer and my headspace on fired brass is 1.560"
New Peterson unfired brass is 1.555".

 

[NukeMMC]

SAAMI headspace spec for chamber is 1.541 - 1.551. Cartrige headspace is 1.5368 - 1.5438.

 

[spife7980]

SAAMI headspace spec for chamber is 1.541 - 1.551. Cartrige headspace is 1.5368 - 1.5438.

That is correct, for the .400 datum. Using a smaller datum will be an even smaller diameter so it will be even further out towards the neck, AKA an even longer measurement.

OP, what gauge did you get that you used for your measurements?

 

[TheOfficeT-Rex]

OP, what gauge did you get that you used for your measurements?

I'd also doubt that any there is perfect precision in a $6 comparitor insert, so i wouldn't compare it to SAAMI either, necessarily. I only consider my measurements as being valid against my measurements on the same equipment.

If it chambers, it will fire form and blow forward, and then you can go on from there. I wouldn't get too wrapped around the axle - you can do fine adjustments next loading.

 

[Singleshot]

Thanks all. I’ll proceed and exercise extra caution looking for signs of case failure.

Case gauge I’m using is the brownells/Sinclair gauge

 

[Nitrosteel]

I bump back .004 from fired (from my rifle) brass. Custom rifle maker suggested this after I was having some chambering issues bumping back .002. No issues since. Get your dies set with a gauge (borrow one if you can) and you won’t have to worry about it anymore.

 

[JOE62]

They are called comparators for a reason. Unless you are using the same caliper and bushings (and I mean his) comparing measurements is useless. Take a piece of brass fired in your rifle and measure it. Write that number down. Now back the sizing die out a round or two and resize the piece you measured. No change, turn die down a quarter turn and measure again. When you are getting close your measurements will actually get longer first because you will be pushing the shoulder forward. When you get this, start turning the die in very small increments. When you get .002 less than the measurement you wrote down, try it in your rifle. If it chambers easy you’re good. If not try .003. ALWAYS using the same measuring tools you used to start with. These are YOUR measurements. If you measured them correctly, then regardless of what they are, they are your rifles numbers. My measurements with my tools are completely irrelevant to yours.

 

[FLIGHT762]

Just going to reinforce what ^^^^^JOE62^^^^^ was pointing out.

I use both Hornady and Sinclair bump gauge insert comparators. When they were checked to calibrate them to a 308 Win. SAAMI 1.630" minimum headspace gauge, the numbers were way off from one another even though they were measuring the same H/S gauge. Both numbers are correct indicating the 1.630" measurement. And both can be used with great accuracy for showing shoulder bump.

Even comparing one .400 Hornady insert to another Hornady .400 insert can be off quite a bit. I have two Hornady .400 inserts. One insert measures off of the 1.630" headspace gauge @ 1.611". The other insert measures the same 1.630" gauge @ 1.619". This is because each insert had a bit of a different chamfer from the machining.

I used the same digital calipers for all of the measurements.

 

[JOE62]

Correct. They are for comparing the measurement you have to the measurement you want. I machined my own comparator bushings out of steel so they won’t get worn as easy and to keep a defined edge. I checked my headspace go gauge so I would know what area of measurement to expect. My numbers don’t coincide with any SAAMI drawings or diagrams but technically correct. Like I said: check your own fire formed brass with your own tools and don’t pay any attention to what you may read or hear as to what the measurement should be.