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6.5 CM can’t get any velocity, opinions please

ta6ppc

I Have a Remington (blue printed) with a custom barrel 8 twist stainless.. anyways it won’t chamber some factory rounds, they are too long. I have to run a oal of like 2.780 or maybe slightly longer if it’s a super pointy bullet like a vld. The most I can get from it is 2650 running 40.2 grains of H4350 and I get an ejection swipe around that, and that’s using Peterson srp brass

I have some really accurate loads running 42.5 of 4831 but it only goes 2550. I was happy until I recently got a lab radar and started seeing what my speeds are.

I got this rifle from someone second hand, however I know the gunsmith and have had rifles built by them before, what would you do?
I’m at a loss..
 
I don't know what i would do other than a chamber cast as a first step. I do recall hearing talk of some early reamers, I don't know who made them, that had a throat insufficient in length for some of the longer projectiles like the 140's. I don't even know if the rumors of short-throated reamers are true but again, personally me I'd do a chamber cast to get some idea of what dimensions I am working with.

As you know the Creedmoor is not really a 3,000 fps cartridge, not with 140's anyway. With RL16 and a 142 grain bullet I get around 2740 and with IMR4451 I get about 2550 for an accurate load.

ps; I'll PM a link to some discussion on throat length that may have some useful info.
 
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I'll tweak what I said in my post previously. I may have somewhat misstated..."early" reamers, disregard that. It seems some reamers are spec.'ed with custom throats significantly shorter than SAAMI for specific purposes and bullets and these my not chamber some factory rounds. You might have one of those chambers.
 
My barrel is 24” and has a brake so 26” overall..
If I load a round to spec, and paint the bullet with a sharpie I get a very large amount of engraving around the bearing surface of about .090” long

I totally get the creedmoor should be a 2700 fps load, and I am getting pressure before I can even get to 2700

hornady eldx factory loads had ejector swipe and was hard to chamber, I had to palm it in almost to get the bolt to close.
 
I’m gonna try and get a chamber cast done at minimum, it shoots 4831 with just about any bullet really well it’s just slow at 2550, maybe 2580 depending on bullet. (All I shoot are the 140 class)
 
ta6ppc said:
If I load a round to spec, and paint the bullet with a sharpie I get a very large amount of engraving around the bearing surface of about .090” long
Click to expand...

Just so I understand, the .090” is from the end of the neck to the point that the rifling engraves the bullet? To me that seems really short. I will add though I am certainly no expert on the 6.5 CM. Later today I'll load a dummy cartridge to jam in my SAAMI factory chamber and report back with that dimension.
 
ta6ppc said:
I got this rifle from someone second hand, however I know the gunsmith and have had rifles built by them before, what would you do?
I’m at a loss..
Click to expand...

While you might be at a loss, help is right around the corner.

You know the gunsmith and have a relationship with him/them, so give them a call and make an appointment to see them in person so they can help you determine what you need to have done in order to get the rifle working for you. Do not just drop in, call first for an appointment. This gives them some time to think through the problem and be prepared to help. They may still have the reamer used to cut that chamber, it's a good reference. They may want dummy cartridges to use to check the chamber so ask about that. Also take any examples of what is occurring with the dummy rounds you've already tried. They may request additional dummy rounds as well.
 
AccelR8 said:
Just so I understand, the .090” is from the end of the neck to the point that the rifling engraves the bullet? To me that seems really short. I will add though I am certainly no expert on the 6.5 CM. Later today I'll load a dummy cartridge to jam in my SAAMI factory chamber and report back with that dimension.
Click to expand...
If I load a dummy round to spec length of 2.80”
I have nearly .090” engraved around the bullet from the edge of the case mouth, almost as if there was no throat or lead at all.
I will stick a bullet much longer than 2.790 and would literally have to hammer the bolt open.

empty case after sized will cycle perfect so it’s not under/ oversized case sizing..
 
You have a short freebore chamber. Super short if you have to run 2.780. With a SAAMI length .199 freebore the 140 ELD-M will be touching about 2.870". You might be slow and getting low pressure from the barrel or possibly having the bullet jammed so deep into the case. I can load to 43grns with the 140s and no pressure.
 
Try a lighter shorter bullet like a scenar 123 or sierra 130 tmk .010 to .020 off the lands. Would be interested to know if speed increases. I now shoot the 130s with great accuracy after spending way to long with the heavies.
 
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Rob01 said:
You have a short freebore chamber. Super short if you have to run 2.780. With a SAAMI length .199 freebore the 140 ELD-M will be touching about 2.870". You might be slow and getting low pressure from the barrel or possibly having the bullet jammed so deep into the case. I can load to 43grns with the 140s and no pressure.
Click to expand...

My thoughts as well, I'd certainly do what Kurz said and take it to the smith to see if he can straighten it out. There's no way I'd just live with a rifle that's jamming bullets with factory ammo and showing pressure signs with sub-standard loads when I could probably just get it fixed without too much trouble.
 
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