Originally Posted By ABOne3:
I think I’ll go with an inexpensive bcg and I’ll order the JP hp bolt. Thank you for all the input!

Originally Posted By FALARAK:
6.5 CM is high pressure.

My rifle was initially built with a DPMS LR308 BCG.  I was getting a LOT of primer flow into the firing pin channel.  You don't necessarily need a high pressure bolt, but you should get one that has a reduced firing pin channel diameter, and pin diameter.  There are several brands to choose from and some people have posted this in the past.... and it is always changing.

I installed the JP high pressure bolt and firing pin kit, into my bone stock DPMS LR308 carrier, and zero issues.

On my bolt gun in 6.5CM, I was using a custom rifle built from a Remington 700 in .308 originally.  I was also seeing primer flow into the channel, however it was totally functional and I was able to run my loads up pretty hot and no primer piercings.  However, when I switched to Lapua SR primer brass, I worked up a new load and could barely even reach a "warm" load before I started piercing primers.  I found out this was a very typical experience and I needed to get my bolt sent out to have it bushed and smaller pin installed.

Originally Posted By drfroglegs:
Has anyone had issues with pierced primers with ammo that has small rifle primers?

A lot of the draw for small rifle brass was that the primers are harder and that there is less stretching of the primer pocket (longer brass life).

Seems like a lot of the issues are from standard off the shelf ammo, which a majority of use large rifle primers.

I got the aero nickel boron (which for some stupid reason is more money but not HP rated), but I'll be reloading exclusively small primer brass.

Wondering if I should sell the bolt and just get the phosphate version. Hell, I've never even shot it... Still working on piecing together my build.

Originally Posted By drfroglegs:
Has anyone had issues with pierced primers with ammo that has small rifle primers?

Originally Posted By ian187:

6.5 Creedmoor has the same 62K SAAMI maximum pressure as 308 Winchester. The JP bolt simply has a smaller diameter firing pin. I get cratering and primer flow with 308 Win using regular AR10/AR308 bolts too. "High Pressure" is a misnomer.

The JP bolt and LM carrier are worth the money.

Originally Posted By Vespid_Wasp:
Krieger barrels has a statement on their website about the consistent quality and uniformity of JP bolts.  Their pre-headspaced barrels are setup to use JP bolts, and there is a comment about lack of uniformity among other unnamed brands.

That says a lot to me.

Originally Posted By ian187:

6.5 Creedmoor has the same 62K SAAMI maximum pressure as 308 Winchester. The JP bolt simply has a smaller diameter firing pin. I get cratering and primer flow with 308 Win using regular AR10/AR308 bolts too. "High Pressure" is a misnomer.

The JP bolt and LM carrier are worth the money.

High Pressure Ammo: Problems and Solutions
By John Paul
Ammo compatibility in large-frame gas guns has always been a problem. In 2007, we introduced our LRP-07 and found that even some factory .308 exhibited signs of high pressure. Turns out the other .308/7.62 gas-operated AR-10 platforms on the market don't fare much better.

Running .308 through a rifle like the LRP was still doable if you chose your ammo carefully. Start running a non-standard caliber gas gun, and the problem is amplified. This is the case with any of the 6mm or 6.5mm cartridges:

.243 Winchester
6mm Creedmoor
6.5mm Creedmoor
.260 Remington
Any of several other less common .308 parent cartridges
These calibers do something similar to what the 6.5 Grendel or .204 Ruger do with .223. Each is designed to achieve higher velocity than the .308 while still using its approximate case dimensions. This means more powder and higher pressure.

So, why is this a problem in larger calibers but not in small-frame ones like the 6.5 Grendel?

Aside from the fact that the AR-10 never went through the rigors of military testing like the original Stoner design, it's really a matter of scale. A large-frame AR is still using the same materials as the AR-15, just scaled up.

A .223 case capacity is too small to exhibit major pressure problems. You can't fit enough powder in the case to reach that point.

Not so with a .308. Scaling up the case actually reduces structural integrity. Then, you add more powder for a bigger explosion, and you're pushing what the materials can handle.

Symptoms of High Pressure
There are several signs that your ammunition pressures are too high. Most of these are thanks to the considerable force of ignition distorting the case and primer adversely. Here are the most common issues:

Primer Cratering — The point of impact of the firing pin shows a raised lip indicating where the primer started to extrude around the pin into the firing pin hole. In extreme cases, this leads to…

Pierced Primers — The primer deforms so severely around the pin that the surface ruptures. In addition to possibly ejecting loose material, this causes the gasses in the cartridge to escape to the rear.

Case Head Flow — The brass of the case itself deforms under the ignition pressure, extruding into open cavities around the ejector pin area. This will cause small flecks of brass to shear off the case.

Brass Smear — Brass from the case deforms into any small negative space in the bolt face and deposits there. Some degree of this is natural, but high pressure loads will exacerbate the issue.

The results on these phenomena are reduced service life and reliability.

Pierced primers will erode the bolt face prematurely. Deformation of primers and case heads will lead to loose material in the receiver cavity. These metal shavings will eventually foul the ejector and can even impact function of the trigger group.

Shavings that fall into the magazine can also cause problems. Even a small piece of brass adhering to the exterior of a case can cause a failure to go into battery. One might also wedge the case into the chamber making it difficult to unload an unfired round.

The Prevalence of High Pressure Ammo
If high-pressure ammo is so problematic, why is it so common? The short answer is that these problems are particular to gas guns. Yet, load development for these cartridges is almost exclusively done with manual rifles.

Ammunition manufacturers are not concerned or often even aware of the pressure issues that show up in semi-auto platforms. Amazing as it is, a particular round might function problem-free in a bolt gun yet be completely incompatible in a semi-auto.

Most ammunition manufacturers are concerned only with meeting SAAMI spec. in their load test fixtures. The compatibility of their ammo with gas-operated, semi-auto rifles was not even considered in many cases.

The major difference here is one of the bolt design. The standard .308 bolt uses a firing pin that is inherently too large and an ejector design that exacerbates the problems mentioned above. As avid competitive shooters, we at JP wanted a workable solution.

The only solution is a new bolt design, or should that be was…

Troubleshooting
This might come off sounding like a sales pitch, but if you've read this far, the subject must matter to you. If so, it's worth your while to know that we've solved this problem and to see how we did it.

The pressure issues with large-frame rifles like the LRP-07 have been well-known for years. The solution was obvious once I thought about it. It just never seemed the highest priority, so the concept for our high pressure bolt collected mental dust.

Still, there was one customer that called every few months for a couple years just to find out where the project stood. I regretted having to tell him repeatedly that it was still on the back burner. That was my real motivation.

Finally, I pushed it to the top of the list. We put a lot of thought and effort into the high-pressure bolt, both in concept and in development. I was glad to see this show through in the final product.

Our EnhancedBolt™ line has been a great success for us, but I won't go into every little improvement we've made. When it comes to high pressure ammo, there were two major changes to the design of the .308 bolt that have all but licked the problem:

Reduced Diameter Firing Pin — Taking the cue from bolt gun design, we reduced the firing pin diameter along with the corresponding hole size in the bolt face. The smaller hole reduces the possibility of the primer deforming into it.

As a side benefit, this reduces the mass of the firing pin significantly, cutting down lock time and further enhancing the potential accuracy of the platform.

Redesigned Ejector/Pin Hole — Altering the extractor design has eliminated the features most prone to case head flow. This means less distortion into the extractor cavity and elimination of brass shavings even when some extrusion occurs.

While these are hardly the only advancements of the HP bolt design, they are the most important. Changing these two features virtually eliminates the negative symptoms of high-pressure ammo in gas guns. Considering that treating the "disease" means just switching ammo, we'll take this happily.

At this point, I would not run a large-frame gas gun without this new bolt design.

Originally Posted By ian187:
I will also stand by the assertion that "high pressure" is a misnomer in that Creedmoor is loaded to the same pressure as 308 Winchester and both exhibit pressure signs with legacy firing pins and bolts.

Originally Posted By ian187:

That's odd, I don't think bolt actions have gas ports and they suffer from the same problem. Primer flow and pierced primers occur on bolt guns too and are the reason several well know builders use smaller diameter pins. That is also why GreTan turns firing pins and bushes bolt faces. There is nothing higher pressure about Credmore than 243win, 260 Remington, or 308win, which also have this problem. No, I adequately described what is taking place and port pressure has nothing to do with it. As JP specifically states, their "high pressure" bolts are not to be used with ammunition loaded higher than SAAMI pressure. The only difference between a JP "high pressure" bolt and a JP legacy bolt is the firing pin diameter and the firing pin aperture in the bolt face. The fact of the matter is the AR10's firing pin is too large even for 308 and should have been redesigned a long time ago. If you're building a new AR308, regardless of 308 or 6.5C, start with a small diameter firing pin bolt.

Originally Posted By fsjdw2:
I wasn't aware that 6.5 CM was a high pressure round(abnormally vs normal rifles at about 60k ), early rounds had a mis stated high pressure that might have caused some issues, but dunno.

Originally Posted By brasidas:
Isn't the problem with creedmoor that it has greater bolt thrust?

Same pressure with a smaller bore pruduces greater bolt thrust.  With more rearward rearward force exerted by the propellant gases on the bolt, you get these primer problems.

RCA quality complete Titanium AR-10 DPMS style BCG with proprietary aerospace grade, patented ARMORTI surface treatment.
Carrier has FORWARD ASSIST  and Includes RCA’s billet gas key
Bolt face is specifically machined to handle high pressure rounds. The firing pin is custom matched to this firing pin hole.
Caliber Compatible With:
260 Rem
6.5 Creedmoor
22-250
6mm Bench Rest
And many others designed to use a .470 +/- bolt face diameter
Fully Titanium carrier
This fills the space of an AR-10 DPMS-style carrier while reducing weight substantially. at 10.3 ounces
Aerospace surface treatment provides ultimate durability and wear resistance.
Bolt material 9310
RCA billet gas key torqued and staked.
Tool steel extractor
*We highly recommend the use of an adjustable gas block to reduce over-gassing issues when using this carrier in a standard AR-10.*
*LIFETIME WARRANTY*