Using Longshot With 180XTP's?

[K10]

In my Kimber STII if I go above 8.4 grains the groups start opening up. I would like to load a little higher for deer hunting. Any suggestions? Would magnum primer help? Also, using AA#9, if I go above 13.9 the groups open up.

[sqlbullet]

How much do groups open up.  The vitals target on a deer is pretty big, so you may have to live with some trade off.  If the groups are opening from 2" to 3", no worries.

[Turo]

My Hodgdon manual says that 8.5gr is the starting charge for Longshot and 180gr jacketed hollow points. Any reason you're loading under the starting charge? My usual carry load is 9.8gr (over book max by .3gr) with the 180gr XTPs.

[The_Shadow]

If he is looking for better accuracy, he may want to try Blue Dot, 10.6gr or 10.8gr might provide him with great accuracy and performance with the 180XTP's seated to 1.255". 

[10mm-Admirer]

I've shot 9.2gr of Longshot with 180gr Hornady XTPs, Nosler JHPs and Hornady FMJs in my Kimber STII and Glock 20's with KKM barrels with great results.  Accuracy has been excellent.  I seated them to 1.255" also.

[K10]

 The groups went from about 1 1/2" to three when I upped the powder charged. They were seated 1.260. I will accurate load any day over a high velocity load. You have to hit what you are shooting at.

[The_Shadow]

K10, what comes to my mind is that the higher impulse ammo is causing your action to unlock early thus the groups are getting spread out.  Have you tried other recoil spring weights, Flat Bottom Firing pin Stop or heavier main spring to help your use of the heavier ammo impulse?

A friend of mine has the Kimber Stainless Custom Target II with a 22# recoil spring.  Not sure if he had other changes, but he was shooting some heavier loadings with his.

[K10]

I put a Sprinco recoil unit in it. I did not change the factory recoil spring. Someone said they come with a 20LB, and I thought that would be enough with the sprinco unit. I put a Harrison design flat bottom firing pin stop in it. Should I order a new 20lb spring for it?

[sqlbullet]

I would up the mainspring to 25 lbs before I upped the recoil spring.

[10mm-Admirer]

I shot some Longshot loads through my stock Kimber STII last night.  Recoil was sharp, fast and high impulse but accuracy was great.  I load to 1.250". Love this pistol.

[Pinsnscrews]

I was advised, not sure how true or not, that Longshot will not be available until March or April, which is when Hodgdon does that powder run. Fortunately, I was able to pick up a pound of 800x. (Helps to have Bruno's local ;-) )

[K10]

If I up the weight of the main spring, will it make the trigger pull heavier? It has a 2 1/2" lb pull which is real good.

[sqlbullet]

It will have an impact on the trigger pull.  If the sear, disconnecter and hammer bow surfaces have been properly prepped, the impact will be negligible.  If there are any imperfections in those surfaces it could introduce some gritty creep or change the pull weight noticeably.

Easy to change back if you don't like it.  Be sure to measure with a trigger pull gauge, average of 10 pulls before the change, then again after.  Otherwise you may get bitten by confirmation bias.  By seeing that the pull weight did not change in a measurable fashion it will help your mind not manufacture the expected higher pull feeling.

[The_Shadow]

I am not that familiar with the 1911 type guns, but changing the mainspring will not add to the dwell time to maintain lock up longer.  Correct me if I'm wrong on this modification.  However it may add to slow the slide's velocity during rearward travel.

The reason I suggest the stronger recoil spring is the added tension (at slide lock is still small and may only increase 1 pound say between a 20lb an 22lb) to hold the breech closed (added dwell time) just slightly longer would allow the bullet further travel and pressures to drop before the slide moves rearward and the breech unlocks and the barrel to drop down for ejection.

[sqlbullet]

Nope, mainspring change won't affect unlock time in a 1911.  Neither will changing the recoil spring.

As long as the bullet is in the barrel, the slide and barrel will remain locked together.

http://forum.m1911.org/archive/index.php/t-16298.html

I see two likely possibilities:

Higher impulse loads are causing more flinch.  I know they do with me and I have been shooting handguns for many years.  44 Mag gets me every time.  First shot, right down the pickle barrel.  Nothing I do gets the second shot on paper.  My autonomous nervous system is too full of NOPE.  Third-Sixth shots I usually get it back together.

Or

You are walking your load out of a harmonic sweet spot in your particular barrel.  Keep going up and you might see the groups tighten back up.