6.5 creedmoor seating advice for tight chamber

[Break Bad]

Screwed a new 24" Kreiger barrel in 6.5 creedmoor on my AW last week. Go-Gauge loaded, but was tight. Then I shot some factory 140's and some factory duplicates loaded by a buddy. Everything shot great, 6-7 inch group at 835 yards.

Heading to a match soon, don't have time to work up my own load so I was going to keep the same specs. However, to be thorough I got out my hornady oal gauge and measured my chamber at 2.64 coal (measure 3 times with 3 different bullets). Factory ammo is 2.8. So I've probably been jamming my rounds in the lands about .15, and I do recall a couple rounds that were difficult to chamber. I can't measure to the ogive yet, the 26 comparator is on order.

I already have my DOPE figured out for the most part...but I am inclined to seat back to 2.64 or less for safety and chambering issues. If I do, I 'may' have some time this weekend to confirm DOPE, before loading a couple hundred rounds.

Advice?

 

[MDM]

Re: 6.5 creedmoor seating advice for tight chamber

That is a severely short throat. Like way shoter than it should be. If you are jamming .15 the bullet has to be mashing back into the case. My chamber measures about 2.84. If your measurements are right, your throat needs lengthened 2 tenths of an inch.

 

[Rob01]

Re: 6.5 creedmoor seating advice for tight chamber

What MDM said. Whoever chambered that barrel needs to lengthen the throat if you are into the lands at 2.64".

 

[Break Bad]

Re: 6.5 creedmoor seating advice for tight chamber

Thanks for the replies.

Just so I know, why do I have to get the throat lengthened and not just seat the bullet back .17 so its a .01 jump? Are we talking standards/safety here (maintaining the benefit of shooting factory ammo)? Or is it that and I'm running out of case capacity? Jamming the bullet back that far cause loss in precision?

Thanks again.

 

[MDM]

Re: 6.5 creedmoor seating advice for tight chamber

All the above. The chamber is not even to SAAMI spec I would guess. I really don't understand how you are able to close the bolt on a 140 factory round.

 

[Break Bad]

Re: 6.5 creedmoor seating advice for tight chamber

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MDM</div><div class="ubbcode-body">All the above. The chamber is not even to SAAMI spec I would guess. I really don't understand how you are able to close the bolt on a 140 factory round.</div></div>

I'll triple check the measurement tonight

 

[treymchattie]

Re: 6.5 creedmoor seating advice for tight chamber

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BreakBad</div><div class="ubbcode-body">Thanks for the replies.

Just so I know, why do I have to get the throat lengthened and not just seat the bullet back .17 so its a .01 jump? Are we talking standards/safety here (maintaining the benefit of shooting factory ammo)? Or is it that and I'm running out of case capacity? Jamming the bullet back that far cause loss in precision?

Thanks again. </div></div>
i wouldnt thing seating a little deeper would be an issue, except for the fact that it is a 6.5cm, i crunch powder with 140's seated pretty long

 

[Break Bad]

Re: 6.5 creedmoor seating advice for tight chamber

Verified, cleaned chamber, then seated an empty case, starting at 2.8, got to about 2.65 when the resistence fell off. Here's a pic of it at 2.65 with 139scen

 

[Sportin Wood]

Re: 6.5 creedmoor seating advice for tight chamber

Damn.... The factory 140's jump somewhere around .040-.050 I believe in my 6.5CM. I run 142gr Matric way out there. Who did your chambering?

 

[broke_again]

Re: 6.5 creedmoor seating advice for tight chamber

You are potentially creating excessive pressure and an unsafe condition. I would not jam my bullet farther into the case compressing the powder. Make your gunsmith recut the chamber.

 

[majohnson2]

Re: 6.5 creedmoor seating advice for tight chamber

Why do you want to work around the problem? Reloading is all about balancing the pressure and performance to achieve a goal. Maybe its a sub 1" moa at 1000 yards, or a hunting load that drops that big buck dead in his track, at a range that makes all your buddies envious.

None of the reloading info I have read over all the years mention anything about covering up poor machining. I would think you paid to have the chamber cut for the 6.5CM round. There aren't many off the rack setups in the Creedmoor size, its not like a 308 or 223.

Stop regroup, have the error corrected before you have a problem. I've been waiting now for 2 and half months on my 6.5CM but I know for certain Mark will have made it as perfect as is possible. You should not be wondering if or how tight its going to be to close the bolt. Plus now your going to end up damaging the bolt and or the receiver by forcing it closed. Standards are set for a reason.

 

[Break Bad]

Re: 6.5 creedmoor seating advice for tight chamber

There is not much compression at 2.65 oal with 42.5 of h4350. Test fire showed no signs of pressure. The load actually shoots well. While verifying dope out to 950 I got a 3-4 inch pair at 700 and a couple 5-6 inch pairings at 900, light condition.

Chronograph results were great, showing an ES of 24 (2814,2790), however, I did loose about 40fps from 2850 to 2810, probably due to the bullet no longer being jammed.

Regardless, barrel is getting sent back.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: majohnson</div><div class="ubbcode-body">Why do you want to work around the problem?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BreakBad</div><div class="ubbcode-body">
Heading to a match soon.... </div></div> </div></div>

Agree with everything you said. Reloading is not meant to be a tool to work around errs in gun smithing, however, it can.