Creeping up on a hot load of SR4756 and 155 JHP [Archive] - Glock Talk

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jeffreybehr
07-31-2010, 11:20
Here's another of those high-powder-charge loads from the apparently-old Hornady data published in One Book / One Caliber--11.4g. for 1400FPS from a 5" barrel. Just to reinforce my opinion that there's no such thing as one maximum load for one particular combination, Hodgdon lists only 8.5g. maximum for 1310FPS, and Sierra lists 9.9g. for only 1250FPS with their 150g. JHP bullet.

Have crept up to 10.7g. for mid-1300s velocity*, still with rounded primers and tight pockets; will shoot more today. A lighter load displayed very low muzzleflash, and 10-odd grains is lightly compressed for stable position in the case, so this one's encouraging.


* sample was small and not statistically reliable

_The_Shadow
07-31-2010, 13:51
I have often wanted to try the IMR4756 but never purchased any yet! It does seem to be a good performer in many calibers.

jeffreybehr
07-31-2010, 16:27
Things are indeed looking up. The 10.7g. load produced just under 1350FPS (5.15" barrel, chrono screens centered at 10') while 10.9g. produced just over 1350FPS, both with low standard deviation. While primers are still radiused and pockets are still tight, 1350FPS is plenty 'nuff for me, so here's where I quit. (Well maybe I'll try a whole-number 11 grains. :embarassed: )

Will try to fotograf muzzleflash soon and add to my collection at http://jeffreybehr.zenfolio.com/p548446203/h13f95b3e#h13f95b3e .

SimonovsDog
07-31-2010, 19:24
I tried 10.5gr of IMR 4756 with 155gr XTPs. There were no signs of adverse pressure, but accuracy was terrible. I have since stopped using this powder. I am using a Std Length Bar-Sto barrel in my M20.

alpha6164
08-02-2010, 09:45
Jeffrey,

Which 155gr JHP are you using for this load? Also have you noticed what Simon says as far as accuracy problems?

jeffreybehr
08-02-2010, 11:18
Jeffrey,

Which 155gr JHP are you using for this load? Also have you noticed what Simon says as far as accuracy problems?

For all my muzzleflash loads and also 'creeping up' loads with 4756, I used Montana Gold JHPs.

I'm now testing accuracy of an 11-grain load of 4756 v. my PD load of A9. Preliminary results yesterday showed the accuracy of the 4756 load to be close enough to that of the A9 load. Will be shooting more this afternoon.

jeffreybehr
08-02-2010, 23:14
Final results for my PD load--while the loads using Accurate9 were slightly more accurate, the loads using 11g. of SR4756 and XTP 155s were plenty accurate enough, so I'm now carrying the 4756 loads.

11g. will produce c. 1360FPS at 10' from my 5.15" barrel and with VERY little muzzleflash, so I'm happy.

BTW I received the 500 cases from starline, so I've now bought 1750 new cases!* Maybe I'll never reload a 10mm case again!


* It's no wonder my wife calls me Mr. Excess. :upeyes:

alpha6164
08-03-2010, 08:21
11g. will produce c. 1160FPS at 10' from my 5.15" barrel and with VERY little muzzleflash, so I'm happy.


.


Is that velocity a typo? You mentioned in the thread before that 10.9g gave you 1350ft/sec.

jeffreybehr
08-03-2010, 10:51
Is that velocity a typo? You mentioned in the thread before that 10.9g gave you 1350ft/sec.

Yes it was; TY.

jeffreybehr
08-05-2010, 10:58
I finally got north to chrono that 11-grain load.

CED M2 chrono, screens centered 10' from gun, elevation c. 3000', temp about 100dF, velocity 1385FPS average from a 13-shot sample, SD 14.

SimonovsDog
08-05-2010, 18:23
Jeff, what is the COAL for your SR4756 loads. I loaded mine to 1.255+/- .001. I don't know why my groups are opened up so much. I know it's not the barrel. I have other loads that are real stackers!

jeffreybehr
08-05-2010, 23:48
Jeff, what is the COAL for your SR4756 loads. I loaded mine to 1.255+/- .001. I don't know why my groups are opened up so much. I know it's not the barrel. I have other loads that are real stackers!

About the same as yours...1.2555 - 1.259".

What's a 'stacker'?

chippy
08-06-2010, 09:53
About the same as yours...1.2555 - 1.259".

What's a 'stacker'?


One hole on top of another !
A very good thing....:cool:

JayAlonG2910mm
08-06-2010, 09:59
Very interesting!


What are the recoil characteristics like at 10.5g to 11g?

jeffreybehr
08-06-2010, 11:36
What are the recoil characteristics like at 10.5g to 11g?

I find as I shoot more that I'm becoming less sensitive to recoil. When I shoot my 3 Glocks in one session, I can definitely feel the lower recoild of the GAP, but there's little difference between the 357SIG and the 10. I find the recoil to be substantial but highly manageable. I expect more-experienced and -skillful shooters would be able characterize its recoil much better than I.

JayAlonG2910mm
08-07-2010, 10:56
How do you think SR4756 would work with a 180g-200g bullet?

I am thinking about SR4756, Clays Universal, or AA #9 with a 180-200XTP with low flash and around 1100fps from my G-29.

SimonovsDog
08-07-2010, 19:51
One hole on top of another !
A very good thing....:cool:

Yes, What Chippy said!:cool:

SimonovsDog
08-09-2010, 15:11
It seems I was wrong about SR4756 and accuracy. I went shooting this weekend and brought along my remaining loads of 155gr XTP on top of 10.5gr of IMR SR4756. The first time I tried this load, it was all over the target at 15yrds. This weekend was a different story. The only change I made was using a 22lb Wolff recoil spring instead of the standard 17lb spring. Accuracy this time was superb! I didn't stack any shots, but most rounds were touching. Maybe the first time I ran this load I was tired, or maybe the spring had something to do with it.

jeffreybehr
08-09-2010, 18:41
How do you think SR4756 would work with a 180g-200g bullet?

I am thinking about SR4756, Clays Universal, or AA #9 with a 180-200XTP with low flash and around 1100fps from my G-29.



Hodgdon lists a SR4756 load with the 180 Sierra, 7.6g. for 1155FPS @ 34,400PSI, the same pressure as their 155g. load of 8.5g. for 1310FPS, so I assume the two are equally conservative.

I'd choose 4756 and A9 over Universal, which IMO is rather fast-burning for 180g. bullets. And now that I reread that you're loading for a short barrel, I'd start with 4756.