7.62x51 NATO bullet pull spen

[TheFalconeer]

Lads & Gents,

À friend of mine asked me what is the specifications for the minimum force of bullet pull for the NATO spec 7.62x51.

I know that I have the spec book somewhere but I can't find it now... Does anyone have the value on hand?

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[Humpy70]

I am in Myrtle Beach on vacation and don't have the specs with me but IIRC correctly the MINIMUM bullet pull on the M118 LR ammo is 10 lbs. As I remember there is no max pull. You can find ammo that has upwards of 300 lbs bullet pull so that is one reason why the SD on MATCH ammo is so high. The inside of the case mouth is coated with a lacquer that hardens with age as this is part of the waterproofing for ball and match ammo made to gov't specs.

Several things account for this, when match ammo is loaded it is checked for bullet pull and then sent to deep storage where it may sit around for years before it is shot.

Such is very evident if you get into downloaded match ammo as you will find quickly some will just come out easily and some you may have to grip several times to get it to release.

The military teams would take their match ammo and "bump" it by running it into a seat die, setting the bullet back .005 - .010 to "break the seal" and you can hear it when it loosens up.

Ball ammo can be a real bear to pull as it is not only lacquered, it is crimped into a cannelure. MATCH ammo does not have a cannelure as such is detrimental to accuracy.

If you pull the bullets with a collet puller you will note the black lacquer stays on the bullet mostly. When I pull down match ammo I dump the bullets in a cleaner I get at Home Depot and I fill a jar with bullets then pour in the solvent and let them sit over night and next morning they look brand spanking new.

Having a uniform bullet pull is the key to long range accuracy as the small the SD the less vertical dispersion you are going to see starting about 600 yards if you have a very good rifle. 1000 yard targets have a 20" 10 ring. 50 fps of dispersion vertical will give you a 20" group so what you need to strive for is ammo with a SD of like 10 or less.

[TheFalconeer]

Thank you for your feedback.

I looked in the MOPI and it state that a minimum of 256 Newton should be necessary for bullet extraction.

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[Humpy70]

It depends on what your game plan is. If you want feed reliability from a magazine you need to hold the bullet tighter. If you want absolute best long range performance you want the bullet seated so light that you have to ease it into the chamber and gently close the bolt to get the more uniform release from round to round.

[Bimmer]

I looked in the MOPI and it state that a minimum of 256 Newton should be necessary for bullet extraction.

Wow, that's ≈189ft-lbs!

[markm]

I didn't know that M118 LR had neck sealant. I assumed it didn't because we used pulled bullets that had no lacquer on them. Maybe they chemically removed it. ??

[Humpy70]

https://i.imgur.com/b9Qr6QKh.jpg
173 gr. Match bullets as pulled showing mouth lacquer residue

https://i.imgur.com/fvC5KbFh.jpg
173 gr Match bullets cleaned

I get the degreaser at Home Depot in the chemical department. ZEP 505 and sells for 8.96 per gallon. Comes in gallon cans and you can reuse it several times.

https://i.imgur.com/ablWzgNh.jpg

Bullets soaking in ZEP 505. Note the lacquer falls off bullets intact and does not dissolve that much.

There were some lots run without sealant as the Army Marksmanship Unit requested they be run. The Match ammo with the 175 grain Sierra MKs did not have it.

When I pull bullets from new match I clean them up and reload them and when the case is fired it burns off what did not come out on the bullets.

[Steve Shannon]

Wow, that's ≈189ft-lbs!

I’m sorry to correct you, but that’s 57.5 lbs.

A Newton is a unit of force, specifically the force required to accelerate one kilogram at a rate of one meter per second per second.
Ft-lbs. is a measurement of energy.


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[Humpy70]

I had a contact at Olin who told me he had seen ammo that took 300 lbs of pull to move bullet.

[Bimmer]

I’m sorry to correct you, but that’s 57.5 lbs.

A Newton is a unit of force, specifically the force required to accelerate one kilogram at a rate of one meter per second per second.
Ft-lbs. is a measurement of energy.


OK, I'll bite...

If its 57.5lbs moved a meter (3.28 feet), then isn't that 57.5lbs x 3.28 ≈ 189 foot-pounds?

[Steve Shannon]

OK, I'll bite...

If its 57.5lbs moved a meter (3.28 feet), then isn't that 57.5lbs x 3.28 ≈ 189 foot-pounds?

What you’re referring to is work, rather than force.
If you had to apply 57.5 lbs the entire time to move the bullet one meter, then yes, you would have done 189 ft-lbs of work.
But all the previous statement mentioned was the force required to pull the bullet. And to convert from Newtons to pounds of force doesn’t consider the distance. Simply divide Newtons by 4.45 to get pounds.
You could certainly calculate the work to pull a bullet. If the force is constant the entire distance then it would be the force x the distance.


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[TheFalconeer]

Gentlemen,

Thank you for your feedback and input.

I will look at building an inexpensive and easy device to measure (roughly) the extraction forces required for a couple of 308Win to get a roughly estimated value of different ammunitions.

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[Humpy70]

I had a contact at Olin factory and he told me a bullet pull of 300 lbs could be experienced.

[anachronism]

The black colored bullet sealants are usually a black ashpaltic sealer. Don't ask me why I know that, I just do, for some reason. A quick internet search turned up this: http://www.hernon-ammosealing.com/

[Humpy70]

To my knowledge the mouth lacquer is only used on military ammo. Most commercial ammo does not have waterproofed primer sealer either.

[jsbhike]

The black colored bullet sealants are usually a black ashpaltic sealer. Don't ask me why I know that, I just do, for some reason. A quick internet search turned up this: http://www.hernon-ammosealing.com/

I have had pulls with the asphalt sealant once. Seems like tracers that mostly ended up missing the igniter.

[Ned Christiansen]

I pull bullets from Swiss 7.5X55 GP11 ammo to make Mexican Match (drop in a Match King). The black sealant for those comes off nicely in low-odor mineral spirits (or, I'm sure, any petro-based liquid). Never tried to gage the pull but it's pretty consistent.

My best info on pull specs is from a gov't producer of 5.56 so FWIW and as best I remember it's min. 45 pounds and tested by pushing it in, not pulling it. Much easier to test and one would think it would be the same either way.

[jsbhike]

I pull bullets from Swiss 7.5X55 GP11 ammo to make Mexican Match (drop in a Match King).

How much improvement do you get with the Match King? Just about every review of K31's I can recall mentioned it was difficult to just short of impossible to beat GP11 ammo with hand loads by any significant level.

[Ned Christiansen]

I've had a lot of good groups with GP11, under an inch sometimes. This is in a Remington long action with an econo-tune by Short Action Customs (highly recommended for your bolt-gun needs). I've run it with a 20", 1/10 barrel and a 26" 1/12 barrel, both factory .308 take offs, but fresh, and reamed to 7.5X55.

But..... flyers persisted. Like, 4 into 7/8" and then one out there 2" from the others. I tried several thing. I made a tool for removing the crimp on loaded rounds. I bumped bullets back to break the seal. I checked for runout. I made small lots, each lot having one mod, and a lot having all three. None of it seemed to tame the flyers... frustrating! I considered that it could be my technique but it was no different really than anything else I do and it seems to work for other rifles. Still I tried different rests and techiques, I even wrapped a front rest in Teflon tape to get a very free slide. No real dif..... flyers persisted.

My best and definitely improved results were with Mexican match using SMK's and 178 AMaxes, simply dropped in. Have experimented with seating depth and being a long action I have a ton of room for loading long although the chamber is the limit. After a round or two of testing I must have seen something shiny and have not been back on it for a while.

But still, even with stock GP11, it's decently accurate enough to learn the art of the wind call and such.