How much insurance for power factor?

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barnacle

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How much do you pad out your loads to ensure your reloads to ensure you make Production's minimum power factor?

I've used a chrony to check my loads so far and have around 800 fps and 140 power factor. While I think that will make the grade for matches, how much would this change from the comfortable day (18 Celsius) I clocked them to a hot prairie afternoon (possibly 30 Celsius)?

I don't have a ballistics calculator and haven't used one before. If you don't have technical evidence, I'll take personal experiences and testimonials.

Thanks fellas.
 
when i do my BB courses i tell my students to carry 10 points over. so for 125 i tell them to load 135 at home.

A perfect example is the new "official" IPSC Alberta chrono. my Pact at home gives me a 170 powerfactor for my 38 supers. however on the "official" one i get only 166.
 
What matches are you shooting? IDPA only has two power factors, 125 and 165, so I'm thinking your either way over or way under.

I load to 129/130
 
10 points cushion no matter what Division.
Temperature and humidity can affect some powders adversely. Others, not at all. It's something you just have to account for.
 
for those shooting IDPA , here is a little tidbit not all might realize. note highlighted line.

Chronograph three (3) rounds at a distance of ten (10) feet using a
gun of MAXIMUM barrel length for the DIVISION of the same
gun type. If two (2) of the three (3) rounds exceed the power floor,
the competitor is in compliance. Prior to each shot, the muzzle of
the gun should be elevated to move the powder charge to the rear
of the case, thus giving the competitor every chance to achieve
maximum velocity.
Should the competitor’s ammunition fail to meet the power floor,
the competitor will have the option to chronograph three (3)
additional rounds through his gun.
If there is any question as to the bullet weight, a bullet should be
pulled and weighed using a powder scale. Any competitor whose
ammunition fails to meet the minimum power floor will be
disqualified from the entire match and receive a DNF score.
Click to expand...

what that means for IDPA shooters for example is that the 4.2" glock 17's ammo must make minor when shot out of the G34's 5.02" barrel since it is the longest barreled glock allowed in that class.... in this case SSP.

so there is a fudge factor built in..... the same would also apply in CDP when used with commander length or shorter and full size 1911's.... etc.
 
Wes, the Glocks polygonal barrel will increase velocity of rounds through it compared to barrels with cut rifling - that has been my experience anyhow.

(Last years IPSC Alberta provincials I used a Sig 226 with ammo I loaded and chono'd with my G17 - and just made PF by the skin of my teeth. Later testing showed 100fps average difference between the two guns, and their barrels are virtually identical in length.)

With regard to testing - it's my belief that if you are chono'ing guys at your matches, it should be done with their ammo and their pistols - as per IPSC.
 
beltfed said:
Wes, the Glocks polygonal barrel will increase velocity of rounds through it compared to barrels with cut rifling - that has been my experience anyhow.

(Last years IPSC Alberta provincials I used a Sig 226 with ammo I loaded and chono'd with my G17 - and just made PF by the skin of my teeth. Later testing showed 100fps average difference between the two guns, and their barrels are virtually identical in length.)

With regard to testing - it's my belief that if you are chono'ing guys at your matches, it should be done with their ammo and their pistols - as per IPSC.
Click to expand...

I agree with you, I am just making note that different sports have different chrono procedures, in IDPA we give the shooter as much benefit of the doubt as we can and we hopefully encourage a spirit in the sport that makes the competititor want to exceed the power factor and not try to game it, IDPA is meant to be shot with full strength duty ammo, which for 9mm is around 132-135'ish.... unless you go for some of the +P+ stuff.

I personally shoot 147gr Lawman as I believe the recoil is a little less whippy and it is far nicer to shoot then the 115gr stuff... 147gr x 985fps = 144 PF considered to the lawman 115gr loading 115gr x 1200fps = 138PF from listed product velocities.

so I am shooting a bigger PF but for me I find the recoil is a lot less.
 
Westicle said:
most factory 9mm is around 132-135 power factor..... so as long as its close to that why worry.
Click to expand...

which factory ammo is that:confused:,..just curious as I have not found anything under 138pf,....with most of the 147gr winchester 9mm at about 143-146pf.

the PF for the ammo I currently use (Combat Masters) is about 135pf out of my stock2.

If you load too light,....I think you could run into problems. Your guns recoil spring may be too strong and your gun may not function great.
 
Barnacle: Making power factor is highly overrated. Don't worry about it.:p

Seriously though I was padding my PF by 7 when I was shooting my .40 in standard. I never failed to make PF at a match. At 22C and 63% humidity I averaged 177 PF using 4.6 grains of Titegroup.

I'm making 136 PF with my 9mm reloads at 18C and 64% humidity with 3.9 grains of Titegroup. I haven't used them in a match because they won't feed 100% reliably in the Shadow. I should have some more data in a couple of weeks - hopefully it's warmer than 18C!

If memory serves you're shooting Titegroup. Here's some data from my .40 XD that will be only slightly relevant since we shoot different guns. Might make an interesting comparison though.

(180 grain cast lead bullets)
3.7 grains Titegroup = 149 PF
4.1 grains Titegroup = 166 PF
4.3 grains Titegroup = 170 PF
4.6 grains Titegroup = 177 PF
 
Simple..

Weigh 20 bullets, measure the variation.
Weigh 20 power dispenses, measure the variation.

that should give you a good indication on the variation on the two most common components..

take the lowest powder, lowest weight, and aim for about 10% higher..
 
I load for a pf of 135. At out provincials last week my pulled bullet weighed 175 instead of the 180 I declared (grabbed my practice ammo box instead of my match ammo speer bullets) and still had a pf of 127.7

10 over should work.
 
toxic said:
Barnacle: Making power factor is highly overrated. Don't worry about it.:p
Click to expand...
I sometimes feel the same way about using my sights.


toxic said:
If memory serves you're shooting Titegroup. Here's some data from my .40 XD that will be only slightly relevant since we shoot different guns. Might make an interesting comparison though.

(180 grain cast lead bullets)
3.7 grains Titegroup = 149 PF
4.1 grains Titegroup = 166 PF
4.3 grains Titegroup = 170 PF
4.6 grains Titegroup = 177 PF
Click to expand...
I've got 4.0grains of Titegroup currently for about 140. I'll have to check my numbers and do the math more carefully to determine how much better a Sig is than Springfield:wave:.
But wait, all hail the black Shadow.
 
Filthy1 said:
But going SUB-Minor at the Nationals is soooo much fun!
Click to expand...

but you looked so much more at ease that year dude!

I just chronoed the stuff I'm sending off to Halifax, 135-137 PF. that's 3.7grs Tightgroup under a 147 Gold Dot JHP. nice and easy recoiling.
 
barnacle said:
I I'll have to check my numbers and do the math more carefully to determine how much better a Sig is than Springfield:wave:.
Click to expand...

Damn Sigs...lol

I think the barrel on the XD is longer that the P226 so it should get a little more velocity. I use cast bullets too so they probably slide out the barrel easier than jacketed. Don't remember if you're using jacketed...
 
toxic said:
Barnacle: Making power factor is highly overrated. Don't worry about it.:p

Seriously though I was padding my PF by 7 when I was shooting my .40 in standard. I never failed to make PF at a match. At 22C and 63% humidity I averaged 177 PF using 4.6 grains of Titegroup.

I'm making 136 PF with my 9mm reloads at 18C and 64% humidity with 3.9 grains of Titegroup. I haven't used them in a match because they won't feed 100% reliably in the Shadow. I should have some more data in a couple of weeks - hopefully it's warmer than 18C!

If memory serves you're shooting Titegroup. Here's some data from my .40 XD that will be only slightly relevant since we shoot different guns. Might make an interesting comparison though.

(180 grain cast lead bullets)
3.7 grains Titegroup = 149 PF
4.1 grains Titegroup = 166 PF
4.3 grains Titegroup = 170 PF
4.6 grains Titegroup = 177 PF
Click to expand...



I'm curious about your overall length of your .40 rounds. I need about 4.8 grains of Titegroup to make 176 power factor with cast bullets, and about 5.1 grains to make the same power factor with plated or jacketed bullets. I shoot a CZ Tactical Sport in Standard, do you think that would make the difference in the powder requirements?
 
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