Signs of high pressure test?

[Disciple]

Received confirmation from technical support. It's going back.

Found out that these have not been high pressure tested, that copy was put in and it should not have been. They actually have a way now of high pressure testing that does not require actual firing a round, Geissele utilizes this method on their bolts they say are high pressure tested.

But that bolt is not high pressure tested and that is being removed from the specs.

[mexica]

Is the pressure test a hard requirement, because from what I've been reading, it may just weaken the bolt. Buy from a reputable company and you should be good.

Sent from my Pixel 7 Pro using Tapatalk

[Disciple]

Is the pressure test a hard requirement, because from what I've been reading, it may just weaken the bolt. Buy from a reputable company and you should be good.

Sent from my Pixel 7 Pro using Tapatalk

Welcome to the forum, master lurker!

[lysander]

That makes sense. Would a hydraulic test jig be faster than using a proof cartridge jig? I am guessing the answer is yes.

It probably wouldn't be faster, but it would certainly be cheaper to operate, you can reuse the hydraulic oil.

[lysander]

Is the pressure test a hard requirement, because from what I've been reading, it may just weaken the bolt. Buy from a reputable company and you should be good.

Sent from my Pixel 7 Pro using Tapatalk

The requirement for high pressure testing, either with M197 or SAAMI commercial equivalent is still on the Army's bolt drawing.

[mexica]

Understood, but as constructor has said, metallurgy is much better now than in the 50s and 60s. Since many companies aren't doing it anymore, i wonder if it's necessary, especially if it shortens the life of the bolt.

Sent from my Pixel 7 Pro using Tapatalk

[lysander]

Understood, but as constructor has said, metallurgy is much better now than in the 50s and 60s. Since many companies aren't doing it anymore, i wonder if it's necessary, especially if it shortens the life of the bolt.

Sent from my Pixel 7 Pro using Tapatalk

It shouldn't reduce the life of the bolt, if the bolt is up to snuff . . .

It's one event out of 10,000 plus or minus 2 or 3 thousand.

[constructor]

The requirement for high pressure testing, either with M197 or SAAMI commercial equivalent is still on the Army's bolt drawing.

It says "high pressure test cartridge" , proof loads are higher pressure than M193 usually 25% higher than SAAMI max, that means apx 78000psi for the 5.56.
The big question is still can any company prove they high pressure test bolts other than Colt and FN. Now that SIG has a major contract they should have the same federal inspection requirements.

[prepare]

I retired in 2017. Blackstone Arms is taking over my business including my Microbest account. After he gets the 5.56 products going he will sell Microbest bolts.

In all fairness I think the guy was saying 3% of some bolts that are high pressure tested will fail the MPI, not "will fail and break in the rifle". We don't know what type/brand of bolts he was referring to. Microbest will not make Grendel bolts and SOLGW sells Grendel bolts so...who makes them and do they also use the same brand 5.56 bolts?
I've never used SOLGW and they have a VERY limited description of their bolts. https://sonsoflibertygw.com/shop/solgwbolt556158c/

Here's the description of the SOLGW BCG with all the details;
https://sonsoflibertygw.com/product-...arrier-groups/

[lysander]

It says "high pressure test cartridge" (1) , proof loads are higher pressure than M193 usually 25% higher than SAAMI max (2), that means apx 78000psi for the 5.56.

(1) No.

The drawing 8448510, (19204), Bolt, Revision AD, dated 2011-04-21, says:

"8. EACH BOLT MUST WITHSTAND FIRING OF A HIGH PRESSURE TEST CARTRIDGE M197, OR SAAMI COMMERCIAL EQUIVALENT, WITHOUT EVIDENCE OF FAILURE. MAGNETIC PARTICLE INSPECT IN ACCORDANCE WITH ASTM E1444 USING A STANDARD 5 TURN MAGNETIZING COIL WITH A CURRENT OF 200 TO 300 AMPERES. CIRCULAR AND LONGITUDINAL CONTINUOUS MAGNETIZATION AND A WET FLUORESCENT SOLUTION SHALL BE USED."

(My emphasis.)

(2) SAAMI proof guidelines are higher than military.[/I][/U] According to SAAMI Z299.4 - Voluntary Industry Performance Standards for Pressure and Velocity of Centerfire Rifle Ammunition (available for free on SAAMI's website) give the proof range for .223 Remington as:

MINIMUM AVERAGE DEFINITIVE PROOF PRESSURE - 73,500 psi
MAXIMUM AVERAGE DEFINITIVE PROOF PRESSURE - 78,500 psi


M197 is not 78,000 psi, it's requirements are still the same 70,000 psi +/- 3,000 psi (average) they have been since at least 15 October 1964 (look it up, you should be able to find MIL-C-46936B on line). But, M97 is not what is used these days.

The current HPT cartridge for 5.56mm weapons is M197A1, covered under MIL-DTL-32530. The requirements for M197A1 are also below 78,000 psi; the average chamber pressure at 70 degrees F shall be 73,000 psi +/- 2,000 psi.