reloading with different bullet lengths

eajonesyk2 · February 6, 2011, 05:25 PM

I just finished loading up about 250 .40 cal rounds. I am concerned about the effect of bullet length on the pressures that will build up in the case. The bullets are Rainier 165 gr plated hollow points. I picked out 20 bullets and measured lengths from .574 to .585 and everywhere in between. I attempted to load the rounds with a OAL of 1.125 but had some come out short and some long (not because of the bullet length).

My main question is even if I got all the rounds to come out with a OAL of 1.125 wouldn't the rounds with a longer bullet build up more pressure in the case because the longer bullet would be reducing the case volume? It seems to me that loading a longer bullet at the same OAL as a shorter bullet would mean that the longer bullet is occupying additional case volume. If this is so, would the pressure build up be the same as loading a bullet with a shorter OAL? For example would a .585 long bullet loaded in the case at a 1.125 OAL have comparable pressure as a .574 bullet loaded in the case at 1.114 OAL?

Also, is this normal for bullets to have this much variance in lengths (.574 to .585)?

I have not seen bullet lengths referenced in the load data recipes that I have looked at so far.

huntinaz · February 6, 2011, 06:13 PM

Quote:

My main question is even if I got all the rounds to come out with a OAL of 1.125 wouldn't the rounds with a longer bullet build up more pressure in the case because the longer bullet would be reducing the case volume?

In theory yeah, this should happen.

Quote:

It seems to me that loading a longer bullet at the same OAL as a shorter bullet would mean that the longer bullet is occupying additional case volume.

You are correct, this must be so.

Quote:

If this is so, would the pressure build up be the same as loading a bullet with a shorter OAL? For example would a .585 long bullet loaded in the case at a 1.125 OAL have comparable pressure as a .574 bullet loaded in the case at 1.114 OAL?

Yes, that should produce a bullet seated to the same place in the same case.

Quote:

Also, is this normal for bullets to have this much variance in lengths (.574 to .585)?

Probably it is with pistol bullets. I have never checked but wouldn't be surprised.

Although pressures may be a little different, you probably won't notice a difference. It's not like the pressure spike is going to be incredibly large with the longer bullets. 1 hundredth of an inch isn't likely to make much difference. If it did, you would get a whole lot of kabooms. Assuming you are within the correct powder range and close to the recommended OAL, you will be fine.

SL1 · February 6, 2011, 09:27 PM

Basically, your understanding of the effect of seating depth on peak pressure is correct.

However:

The length of your hollow point plated bullets may or may not be causing the bullets to have different seating depths in your cases. If the difference in bullet length is due to variation in the nose shape around the nose cavity opening, it MIGHT not affect the seating depth, because the seating die plug probably is pushing the bullet at a different place on the bullets nose, not on the cavity opening. So, a variation in the cavity mouth shape can give a different bullet length and a different COL while the seating depths are the same. Conversely, if the ogive of the bullet's nose is not uniform from bullet to bullet where the plug contacts it, then even bullets exactly the same length can be seated to different depths and give different COLs. With plated bullets either or both situations might be occuring.

You can check by measuring individual bullet lenghts, then seating the bullets and measuring corresponding COLs, then calculate individual seating depths.

IF your seating depths are varying by something like 0.01", it may or may not cause a pressure difference that is significant. It depends on your powder and charge weight, which you did not provide. Since Ranier doesn't provide load data, you are PROBABLY using data for a different bullet anyway, and probably not going to the max value for jacketed bullets of the same weight. So, you PROBABLY aren't using loads that are near the SAAMI peak pressure limit, and the 0.01" COL variation isn't likely to cause you any problems.

HOWEVER, that is not a generalization that you can apply to jacketed bullet loads at max charge weights, ESPECIALLY with fast powders under heavy bullets in short, high-pressure pistol cases.

SL1

eajonesyk2 · February 10, 2011, 01:17 PM

Hello,

I just wanted to provide an update for anybody who cares about the performance of the Rainer 165 HPs that varied greatly in length. I also received and loaded some of Berry's 180 gr FPs which performed much better than the Rainier bullets (or i got a bad batch of Rainiers).

Summary of loads. All loads were shot on rest at 15 yards out of M&P 40 full size:

Rainer 165gr HPs measured 20 bullets and length ranged from .574 to .585.

Loaded a total of 30 Rainiers OAL between 1.123 and 1.130, all Rainiers loaded with Universal powder (I will try Bullseye in the HPs next time).

10 at 4.8gr Uni (best group of three, grouping still sucked)

10 at 5.0gr Uni (grouping getting worse)

10 at 5.2gr Uni (worst grouping, really ugly).

No signs of excessive pressure in any of the cases.

All cases ejected close by and behind me.

I am an inexperienced shooter so I didn't expect great groups but these HPs were all over the place. None of these loads grouped well but the 4.8gr load was the best of the three.

Berry's 180gr Flat Points, measured 20 bullets and length ranged from .595 to .598. Most of the twenty were .596 to .597, only three were outside that range (two at .598 and one at .595). This leads me to believe Berry's has a much better process than Rainier.

Loaded a total of 60 Berrys 180s. 30 with Universal and 30 with Bullseye powder. OAL between 1.125 and 1.127.

10 at 4.2gr Bullseye (pretty good grouping about 6 inches one flier, that's good grouping for me)

10 at 4.4gr BE (another ok grouping, one flier)

10 at 4.6gr BE (group opened up quite a bit plus 3 fliers)

10 at 4.7gr Universal (pretty good grouping about 8 inches no fliers)

10 at 4.9gr Uni (ok about the same 8 inches no fliers)

10 at 5.1gr Uni (another aprox. 8 inch grouping no fliers)

No signs of excessive pressure in any of the cases.

All cases ejected close by and behind me.

So the Universal 180 loads held pretty much the same group size. I didn't feel like any of the loads were over the top power wise. I shot a few Federal 155 HST's for comparison and they produced a lot more recoil and they throw the brass much farther away (three times the distance for sure).

I also shot a bunch more of the Rainier HPs standing from 7 yards to 30 yards. From 7 yards I could hit the center target pretty well from 30 yards forget it. These were almost all 5.0gr loads. I did load and shoot a few HPs with 5.4gr and 5.5gr of Uni. None of these loads showed any signs of excessive pressure.

If anybody has had a more positive experience with the Rainier 165 HPs and Universal powder let me know what the load data was. I still have half the box left to experiment with.

Cheers

February 6, 2011, 05:25 PM	#1
eajonesyk2 Junior Member Join Date: February 25, 2008 Posts: 7	reloading with different bullet lengths I just finished loading up about 250 .40 cal rounds. I am concerned about the effect of bullet length on the pressures that will build up in the case. The bullets are Rainier 165 gr plated hollow points. I picked out 20 bullets and measured lengths from .574 to .585 and everywhere in between. I attempted to load the rounds with a OAL of 1.125 but had some come out short and some long (not because of the bullet length). My main question is even if I got all the rounds to come out with a OAL of 1.125 wouldn't the rounds with a longer bullet build up more pressure in the case because the longer bullet would be reducing the case volume? It seems to me that loading a longer bullet at the same OAL as a shorter bullet would mean that the longer bullet is occupying additional case volume. If this is so, would the pressure build up be the same as loading a bullet with a shorter OAL? For example would a .585 long bullet loaded in the case at a 1.125 OAL have comparable pressure as a .574 bullet loaded in the case at 1.114 OAL? Also, is this normal for bullets to have this much variance in lengths (.574 to .585)? I have not seen bullet lengths referenced in the load data recipes that I have looked at so far.

February 6, 2011, 09:27 PM	#3
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	A few more thoughts Basically, your understanding of the effect of seating depth on peak pressure is correct. However: The length of your hollow point plated bullets may or may not be causing the bullets to have different seating depths in your cases. If the difference in bullet length is due to variation in the nose shape around the nose cavity opening, it MIGHT not affect the seating depth, because the seating die plug probably is pushing the bullet at a different place on the bullets nose, not on the cavity opening. So, a variation in the cavity mouth shape can give a different bullet length and a different COL while the seating depths are the same. Conversely, if the ogive of the bullet's nose is not uniform from bullet to bullet where the plug contacts it, then even bullets exactly the same length can be seated to different depths and give different COLs. With plated bullets either or both situations might be occuring. You can check by measuring individual bullet lenghts, then seating the bullets and measuring corresponding COLs, then calculate individual seating depths. IF your seating depths are varying by something like 0.01", it may or may not cause a pressure difference that is significant. It depends on your powder and charge weight, which you did not provide. Since Ranier doesn't provide load data, you are PROBABLY using data for a different bullet anyway, and probably not going to the max value for jacketed bullets of the same weight. So, you PROBABLY aren't using loads that are near the SAAMI peak pressure limit, and the 0.01" COL variation isn't likely to cause you any problems. HOWEVER, that is not a generalization that you can apply to jacketed bullet loads at max charge weights, ESPECIALLY with fast powders under heavy bullets in short, high-pressure pistol cases. SL1

February 10, 2011, 01:17 PM	#4
eajonesyk2 Junior Member Join Date: February 25, 2008 Posts: 7	Update from shooting Rainer HP's and Berry's FP Hello, I just wanted to provide an update for anybody who cares about the performance of the Rainer 165 HPs that varied greatly in length. I also received and loaded some of Berry's 180 gr FPs which performed much better than the Rainier bullets (or i got a bad batch of Rainiers). Summary of loads. All loads were shot on rest at 15 yards out of M&P 40 full size: Rainer 165gr HPs measured 20 bullets and length ranged from .574 to .585. Loaded a total of 30 Rainiers OAL between 1.123 and 1.130, all Rainiers loaded with Universal powder (I will try Bullseye in the HPs next time). 10 at 4.8gr Uni (best group of three, grouping still sucked) 10 at 5.0gr Uni (grouping getting worse) 10 at 5.2gr Uni (worst grouping, really ugly). No signs of excessive pressure in any of the cases. All cases ejected close by and behind me. I am an inexperienced shooter so I didn't expect great groups but these HPs were all over the place. None of these loads grouped well but the 4.8gr load was the best of the three. Berry's 180gr Flat Points, measured 20 bullets and length ranged from .595 to .598. Most of the twenty were .596 to .597, only three were outside that range (two at .598 and one at .595). This leads me to believe Berry's has a much better process than Rainier. Loaded a total of 60 Berrys 180s. 30 with Universal and 30 with Bullseye powder. OAL between 1.125 and 1.127. 10 at 4.2gr Bullseye (pretty good grouping about 6 inches one flier, that's good grouping for me) 10 at 4.4gr BE (another ok grouping, one flier) 10 at 4.6gr BE (group opened up quite a bit plus 3 fliers) 10 at 4.7gr Universal (pretty good grouping about 8 inches no fliers) 10 at 4.9gr Uni (ok about the same 8 inches no fliers) 10 at 5.1gr Uni (another aprox. 8 inch grouping no fliers) No signs of excessive pressure in any of the cases. All cases ejected close by and behind me. So the Universal 180 loads held pretty much the same group size. I didn't feel like any of the loads were over the top power wise. I shot a few Federal 155 HST's for comparison and they produced a lot more recoil and they throw the brass much farther away (three times the distance for sure). I also shot a bunch more of the Rainier HPs standing from 7 yards to 30 yards. From 7 yards I could hit the center target pretty well from 30 yards forget it. These were almost all 5.0gr loads. I did load and shoot a few HPs with 5.4gr and 5.5gr of Uni. None of these loads showed any signs of excessive pressure. If anybody has had a more positive experience with the Rainier 165 HPs and Universal powder let me know what the load data was. I still have half the box left to experiment with. Cheers